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EPRI - SMARTech - Georgia Institute of Technology

1. Data name Press Help Enter Next Field Escl Leave Fore 1 the user has entered the name of the raw input data file the DYNAMP program be automatically executed After execution the newly created output file be stored with the same name as the raw input data file However the two s will continue to exist separately After the file is stored the output be printed to the screen for review by the user To return to the Module the user should press the Esc key Ev DYNAM REPORTS DYNAMP reports enables the user to print a formatted input file or output file These files may be written to a printer or to the computer screen In addition DYNAMP reports will allow the user to incorporate several different files into one large file This fiie called a print file can then be written to the screen or printer After selecting DYNAWP Reports from Module Menu the user is prompted for the irive letter and data file name as shown in the screen image below DYNAMP reports Press Fil Help Enter Next Field Escl Leave Fore his file name will include the formatted input file as well as the output file fter the user has entered the file name the following menu will appear on the creen DYNAMP DYNAMP reports Data name VITO Report Selector Analysis Output Print File Select New Data LEAVE Press F1 Help Space Bar Next
2. oOo Statistical Analysis of DYNAMP s Predicted Temperatures for a Total of 24 700 Data Points 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 e e 00 98 5 97 8 97 2 95 9 94 9 94 7 91 7 89 9 86 4 86 1 84 5 86 8 80 9 79 8 81 5 78 0 80 5 72 4 77 3 80 9 89 8 89 1 96 4 91 3 88 9 80 0 75 0 60 0 87 5 85 7 100 0 90 0 66 7 91 7 71 4 100 0 50 0 100 0 100 0 83 3 100 0 100 0 100 0 100 0 75 0 DYNAMP PREDICTS EXACTLY AS MEASURED FOR 11 4 7 DYNAMP PREDICTS HIGHER THAN MEASURED FOR 61 5 4 DYNAMP PREDICTS LOWER THAN MEASURED FOR 27 1 7 MEAN TEMPERATURE ERROR IN DEGREES C DYNAMP gt MEASURED 4 5 4 5 MEAN TEMPERATURE ERROR IN DEGREES C DYNAMP MEASURED 3 6 3 7 NUMBER OF DATA POINTS DYNAMP MEASURED 15191 NUMBER OF DATA POINTS DYNAMP MEASURED 6692 NUMBER OF DATA POINTS DYNAMP MEASURED 2817 TOTAL DATA POINTS ANALYZED 24700 Table 4 Continued E T BASE STATION TEMPERATURE RANK PERCENTAGES DYNAMP PREDICTS HIGHER THAN MEASURED ERROR NO PERCENT PERCENT AV ANGLE ANGLE AV SPEED SPEED CONV REGIME C PTS lt DEG ST DV FT S ST DV FREE INTP FORCED 1 3314 13 4 34 0 55 7 20 7 6 1 2 8 1 7 0 00 98 3 2 2856 11 6 49 9 54 6 20 9 6 8 3 2
3. e 28 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR pg WIND DIRECTION WIND SPEED wy DEG 24 00 x 2 Y Oo 25 LI z ed Oo zo z lt 98 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR z Figure 8 Measured and Predicted Conductor Temperatures and Weather Conditions at Remote Site Number 2 for June 30 1986 200 00 175 00 150 00 100 00 125 00 10 CURRENT AMPS 75 00 AD 250 00 12 00 8 00 IND SPEED MPH 4 00 00 W 2600 TEMP DEG C 50 00 75 00 100 00 125 00 150 00 25 00 00 8 00 10 56 00 12 00 WIND ANGLE WITH COND 299 3 gj MEASURED 10 00 10 00 COMPARISON OF DYNAMP AND EXP TEMPS REMOTE SITE 3 EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 30 1986 DYNAMP A AMB TEMP CURRENT 200 00 175 00 100 00 125 00 150 00 10 CURRENT AMPS 9 00 250 00 12 00 14 00 0 20 00 22 00 24 00 16 00 18 0 TIME HOUR pj WIND DIRECTION WIND SPEED 12 00 8 00 4 00 IND SPEED MPH TI i u ali ti M IM TNT 12 00 14 00 16 00 18 00 20 00 22 00 24 00 2600 TIME HOUR 00 W Figure 9 Measured and Predicted Conductor Temperatures and Weather Conditions at Remote Site Number 3 for June 30 1986 15 MEASURED 80
4. Uu Ee E EE ee An Equal Education and Employment Opportunity Institution A Unit of the University System of Georgia analysis shows the obvious result that DYNAMP s accuracy falls off dramatically as the weather station moves further from the test span Errors in the DYNAMP temperature ranged up to 65 C from the farthest weather station Several problems have surfaced with the remote station weather data For two of the weather stations the data are recorded on strip charts and the data must be taken from the chart by hand before they can be placed on diskette This process is time consuming and very subject to error Small errors in recording either the wind velocity and to a lesser degree the wind direction are known to produce large errors in the predicted temperature Furthermore one of the weather stations contained data collected on 15 minute intervals These data are far enough apart that they are practically the same as the thermal time constant of the line Therefore DYNAMP sees nearly steady state data when it processes weather data on such a long time interval clearer picture of how these factors affect the program accuracy will appear after all of the data are analyzed with the statistical package The Forest Park test span has been partially dismantled and it is no longer operational KEURP Project The data collection phase of the KEURP project has now been completed but the data has not yet been se
5. 5 Ke 56 Qc c za 2 8 y 710 00 12 00 14 00 16 00 18 0 0 00 22 00 24 00 26 00 28 00 TIME HOUR WIND DIRECTION WIND SPEED o S un 2 Co e ib m 1 oS Sint ES Ea Im 5 Y 4 M ThE N ox i Sm i cS gt J en t D Q 25 9 0 gt 5 lt 28 S 210 00 12 00 14 00 16 00 18 00 20 00 24 00 26 00 280 TIME HOUR Figure 25 Comparison of DYNAMP and Line Monitor for KG amp E Rail Conductor on September 23 1986 50 COMPARISON OF DYNAMP AND EXP TEMPS WEAVER EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO RAIL CONDUCTOR ACSR 45 7 954 KCMIL SEP 24 1986 MEASURED DYNAMP TEMP CURRENT 5 KR 8 8 NT a 2 5 gt 5 ay 2 19 2 i m 82 i or Ac gt D 3 0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 18 00 TIME HOUR g pj WIND DIRECTION WIND Pffi i e 25 Ge ox o 2 T O o gis ge s 2 9 2 9 0 00 2 00 4 00 5 00 10 00 12 00 14 00 16 00 18 0 8 00 TIME HOUR Figure 26 Comparison of DYNAMP and Line Monitor for KG amp E Rail Conductor on September 24 1986 zB ou COMPARISON OF DYNAMP AND EXP TEMPS WEAVER EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO RAIL CONDUCTOR ACSR 45 7 954 KCMIL SEP 25 1986 g 8 MEASU
6. For EPRI Use Only CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER Wm Z Black School of Mechanical Engineering Georgia Institute of Technology Show EPRI portion of the contract only Do not Include contractor cost sharing Jan Feb Mar May Jun Aug Oct Nov Dec Year Current Year Actual Current x Future orecast to Year s complete the 19 8L Years s Forecast future year s Remarks Comments on significant tenis PREPARED BY Wm Z Black Print name EPRI CONTRACTOR COST PERFORMANCE REPORT EPAI 177 1849 COHTHACT NUMDER DIVISION HUMDQDER For EPRI Use Only COHTRACTORn NAME ADDRESS AND TELEPHONE NUMBER np 2 5 16 01 i Wm Z Black eT DE School of Mechanical Engineering EPRI PROJECT MANAGER PERIOD OF Georgia Institute of Technology Nama Vito Longo From 7 1 84 6 30 87 Atlanta GA 30332 Prior Year s Actual Note Instructions for completing this form are on the reverse side All figures are to be shown U S dollars whole thousands only Show EPRI portion of the contract only Do not Include contractor cost sharing Current Actuat booked Year cost In the Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Actual current year NN 30 NE Current Forecast to Year complete the Jan Fe
7. coupe bm cep weg NEN UND UEM Qd odi Sed nam UHR Que cuum end dins dius ee ei curn diam Overhead Line Research Center um ee ee ne GRUND ee ee d ee Owner Georgia Power Co Location Address 62 Lake Mirror Rd Forest Park Ga Latitude 33 37 25 N Longitude 84 23 10 W Equipment Manufacturer Weathertronics Wind Speed Sensor Model Number 2032 Threshold 0 5 mph Accuracy 30 15 mph or 1 ry n dil GNU RUN ccu ee dices a Wind Direction Sensor Model Number 2020 Threshold 0 5 mph Accuracy 1 Temperature Sensor Model Number 4480 Accuracy 0 17 Output Data Medium HP Format Tape Time Interval 5 minutes s TM uem adu RN Qus Amis NEM Quei dud This station Coes not read temperature Remote Site 1 High Voltage Lab Georgia Power Co 5351 Kennedy Rd Forest Park Ga 33 36 29 N 84 23 19 WeatberMeasure W203 HF 3SS 0 9 mph 0 15 mph or 1 W104 0 75 mph 1 8 or 0 5 Type T Thermoccuple 1 5 Apple Format Disk 5 minutes Remote Site 2 South Dekalb State of Georgia 3251 Panthersville Rd Decatur Ga 33 41 26 N 84 16 28 W Climatronics 0 75 mph 0 025 mph 0 75 mph 1 5 EWS 1 F Strip Chart Continuous Remote Site 3 Conyers State of Georgia
8. M ee DEVELOPMENT OF TETT Introduction E TE Mathematical Basis of Program VIAE P XQ n Conductor Properties osa er ee Convection Vea RAN S e Properties of TERR Radiation nnQ Numerical Methods d Ped REN Tnm adve Capabilities of DYNAMP Tm ESOS ESAE TEMPERATURE GRADIENTS WITHIN OVERHEAD CONDUCTORS T PROGRAM US Georgia Power Test Span Pau bed QE Ced ves Kansas Gas and Electric Field Site vadat s s Pacific Gas and Electric Wind Tunnel AEE COMPARISON OF PROGRAM RESULTS WITH MEASURED CONDUCTOR TEMPERATURES T Georgia Power Test Kansas Gas and Electric Field 51 Pacific Gas and Electric Wind 1 STATISTICAL ANALYSIS OF PROGRAM 5 CRITICAL SPAN ANALYSIS 225 v ES 60999999 e Introduction EE EE SE EE EE nn sensitivity Parameters ooi EV ERE 5 ENS Remote Weather Station 514 5 10 11 12 EVALUATION OF LINE MONITORS 69er o ora 5 0 5 REFERENCES RENATA EPA US APPENDICES 4 5 4 5 35 55 RETE Wa Sad List of Papers Pr
9. Waco s Block Diagram of Data Acquisition System at Field Sites L EE SE SE EE EE EE EE I EE Measured and Predicted Conductor Temperatures for October 15 1086 PER Measured and Predicted Conductor Temperatures for Measured and Predicted Conductor Temperatures for October 21 1986 i RUE RS Measured Predicted Conductor Temperatures for October 22 1986 Measured and Predicted Conductor Temperatures Showing Excellent Accuracy for Conductor Temperatures in Excess of 1300 odi eene 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Measured and Predicted Conductor Temperatures Showing Errors which Result from Rainfall between 2 and 5 EE MEER EE REEF C PK ON OR Comparison of DYNAMP and Line Monitor for KG amp E Drake Conductor on July 31 1086 Comparison of DYNAMP and Line Monitor for KG amp E Rail Conductor on September 24 1986 Comparison of DYNAMP and PG amp E Wind Tunnel Data for Marigold Conductor After a Step Change from 300 101200 5 A WILEREEQAVENAECERESESEFEC FEE Comparison of DYNAMP and PG amp E Wind Tunnel Data for Marigold Conductor after a Series of Seven Current Step CHANGES
10. From data name To data name Press Fil Help Enter Next Field Esc Leave Form user should enter the drive letter in response to the first prompt The From Data Name asks for the present name of the data set The prompt Data Name asks for the new name of the data set After the prompts are wered the Module Menu will return Y A DATA SET se user wishes to CODy a data set from one file to another Copy a Data Set ild be selected from the Module Menu The following prompts will appear 2395 DYNAMP Copy a data set From t Dats name TRANSI Press Fi Help Enter Next Field Esc Leave Form ne first prompt asks the user to enter the name of the data set that is to be pied The user then enters the name of a second file to which the contents of ne first data set is to be copied DATA SET the user wishes to erase a complete data set De ete a Data Set is selected the Module Menu The following prompts will appear DYNANP Delete a data set 4 8 Data name Press F1 Help Enter Next Field Esc Leave Form user should respond by entering the drive letter and tne name of the data set t is to be deleted 2302 QIRECTORY LISTING Directory listing ailows the user to review the names of all raw input data files aocumented input data files and output data files After selecting Directory i sting from the Modu
11. 0 48 0 28 CROSS FLOW WIND SUMMER SUN LOAD AIR TEMP 25 C 0 5 1 0 1 5 2 0 2 5 3 0 39 WIND VELOCITY mph CURRENT NECESSARY TO PRODUCE A CONDUCTOR TEMPERATURE OF 120 C Several proposed design changes have been considered to minimize lightning susceptability at the Forest Park Facility During the last week of Qctober John Czuba of Power Technologies Inc visited the Atlanta site for the purpose of making recommendations to minimize lightning susceptability of the existing test facility To date a written report has not been submitted but discussions after the site inspection indicate several areas in which improvements can be made These areas are 1 make the thermocouple shielding continuous from the point of measurement to the data acquisition system 2 install all instrumentation in steel conduit 3 run all instrumentation conductors in close proximity to the test conductor and 4 use fiber optic data transmission where possible Suggestions 1 3 and 4 will be implemented cost and difficulty of implementing suggestion 2 are currently felt to be prohibitive relative to the anticipated gain in system reliability Specific tasks to be accomplished include 1 replacing the existing thermocouple extension wire from the test points to the junction box at the end of the test span 2 suspending the thermocouple wire from either the test conductor or a span guy in close proximity to the test conductor 3 changing t
12. po 4 7 where the lay factor values from Ref 30 have been used to correct the length of strands for a unit length of conductors The program uses the following values of density 2703 kg m3 for 5005 H19 1350 H19 and 6201 T81 aluminum p 8890 kg m for copper p 7780 kg m3 for steel p 6590 kg m3 for alumoweld The specific heat at constant pressure for each type of conductor material is assumed to be a linear function of conductor temperature The program uses the following expressions for cp 0 32236 T 929 4 for 5005 H19 1350 H19 and 6201 T81 aluminum Cp 0 02512 422 0 for copper Cp 0 47517 441 2 for steel 0 4061 T 621 0 for alumoweld Cp where T 15 in 0 and is in J kg 0C When a conductor consists of one type of material for the supporting strands and second type of material for the conducting strands the expression for the mass specific heat product of the composite conductor is mcp m Cp c m 8 The electric resistance per unit length of conductor is calculated by using the input values of conductor type and the AC resistance at 20 C The program calculates the D C resistance at 20 C from the conductor cross section and the electric resistivity for each conductor type The calculated D C resistance and input value for A C resistance are used to calculate a skin effect and this value is assumed to be a constant at all temperatures The D C resi
13. The diameter of individual core strands This value is ignored for conductors with no core strands that is conductors for which the core strands and conductor strands are made of identical materials as for example AAC AAAC and all copper conductors This value must be greater than zero but less than 0 5 inches The number of strands of conductor material not including the core strands This integer value must not exceed 300 and must be greater than 0 The number of strands of core material This integer value must not exceed 300 s10 A C Resistance The a c resistance of the composite Ohms mi 25 CJ conductor in ohms per mile at 25 degrees Celsius This value must be greater than 0 3 Date and Time ine four date and time variables are used in a subprogram that calculates the incident solar energy on the conductor Each of these four quantities are integer values Month Month of the year Day The day of the month Tine Twenty four hour clock time as hours minutes midnight 00 00 noon 12 00 3 pm 15 00 etc Use standard time only not daylight savings time Time Zone One of the four time zones in the continental U S Eastern Central Mountain or Pacific If you wish to calculate temperatures for a conductor that is not located in any of these time zones i e Hawaii Alaska then choose one of the four time zones in the continental U S and calculate the twenty four hour clock time at the conduct
14. eee 2 ea me m ee M ee 3 0 MINUTES MINUTES Variables CURRENT 750 iMITINO TEMPERATURE 100 0 DEG L Figure 4 5 ccumenfed Input File for Predictive Example 5b re p Mec ent ang Noc i i cit 4 Hf S ae a i 4 gt Figure 4 5 Weather Voriablrnms As LIN OND ME APS DEG mE sut usd E 2m O DEP aad eos 0 oU Ti 750 s CI 250 zs 7595 41 cgo Lg 4210 xe 0 25 0 410 25 0 4 0 2 410 25 0 A41 44 5 0 1110 29 U 410 410 Eie 410 25 0 410 15 0 410 153 0 410 15 WIND 0 go 90 Gi 01 oO gu S ga GO 930 90 90 Ju Q Q WIND SPEED Fir 1 0 Te Y 3 0 10 0 10 0 10 9 10 0 10 0 19 0 10 0 10 0 19 0 10 0 10 0 10 0 10 0 19 0 10 0 10 0 10 40 10 0 10 0 10 0 10 0 10 0 190 0 Lj 4 Documented Input File for Predictive Example Continued U Y Ho M I D rMamiz acitv FRUGRAM version 1 240 Pe b anal institute of Technoloav and gia Fower Compaiv Under EFI NKF2540 1 PREDICTIVE CALCULATIONS for LINNE F Conductor ON Gn dactor tir zcerties pa no LL ne e
15. ohms 1000ft cm 0 kg m 0 cm 0 cm C g m s km hr ohms m 10 Does your steady ampacity model consider incident solar energy on the conductor If yes what is the value for solar energy Does it change with season or with geographical location Do you consider the direction of the conductor when considering the influence of sun on the conductor temperature What values of infrared emissivity and solar absorptivity do you use in your ampacity model Do you consider only a single wind velocity in your steady ampacity model If yes what is the value V If no what is the minimum and maximum value for wind velocity and what dictates the selection is between the two values V min Do you assume the wind is always oriented perpendicularly to the conductor If no what is the angle of wind relative to the axis of the conductor Do you calculate conductor ratings for Normal Conditions Emergency Operation Fault Conditions Emergency If yes for emergency operation and fault time conditions give estimates for time that Fault you would expect ampacity values to be valid time Yes No Yes No pa Yes No ft sec ft sec ft sec Yes NO degrees Yes NO 2 2 L1 2 L1 min min 11 12 13 14 Does your steady ampacity model consider the following factors Magnetic heating Temperature gradient in the conductor
16. After entering the name of the input file the Module Menu will return to the SC reer Editing Conductor Properties Editing conductor properties can be accomplished by specifying the code name of the conductor such as DRAKE or VIOLET cr by manually entering the desired conductor diameter number of conductor strands etc As an example suppose it is desired to change the conductor properties in the input file TRANS to those for a CURLEW conductor After selecting d t Create input Data from the Module Menu the user will receive the following prompt DYNAMP Edit Create input data Edit or Create E C DRIVE E i Data name ee eT LI INALALA Press 1 Help UEnter Next Field Esc Leave Form ince it is desired to edit the file TRANS the user should respond to the prompts 5 follows DYNAMP Edit Create input data Edit or Create E gt 3 8 Press F1 Help Enter Next Field Esc Leave Form 35 After entering the name of the input data file the user will receive the Input Cata Selector Menu DYNAMP Edit Create input data Edit or Create E CI E Input data selector Run Type Date amp Time Line Location Radiation Properties Transient Variables Current amp Weather LEAVE Edit ade a a eras Press F1 Help Space Bar Next Choice
17. If a real time rating program were available state the type of computing equipment your company L mainframe would use to implement the program personal computer both neither Give important factors that should be used in providing information from a real time ampacity model Yes No Simplicity Ability to handle all types of conductors and all possible weather conditions Completeness of information Others specify r1 q How should information from a real time ampacity program be conveyed to the user Yes No A conductor time constant g A time required to reach a predetermined limiting temperature A set of curves that predict temperature vs time behavior of the conductor g Other specify n SECTION IV Ampacity Instrumentation and Critical Span Analysis 1 Does your company at the present time measure the conductor Yes No temperature on any of its energized lines o If yes how many instruments are installed If yes what type of instrumentation do you use made in house or manufactured by others Briefly describe these devices 2 Does your company have any future plans to install Yes No temperature measuring devices on energized lines 3 Does your company utilize the concept of a critical Yes No span in determining the real time rating of its network If yes how does your company define critical span If yes do you consider a critical span to vary from o
18. PER CM DEG kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk COMMON BSTO RMST RMCOND ICOND ISTEEL PARAMETER CONST1 0 32236 CONST2 0 02512 CONST3 0 47517 PARAMETER CONST4 929 4 CONST5 422 0 CONST6 441 0 IF ICOND EQ 1 THEN CPCOND CONST1 TEMP CONST4 ELSE IF ICOND EQ 2 THEN CPCOND CONST2 TEMP 5 END IF CPST CONST3 TEMP CONST6 IF ISTEEL EQ 2 THEN CPST 0 0 END IF COMPUTE RMCP AND RETURN ITS VALUE TO MAIN e e e e e e de ee e e e e e ede e e ee e ee e ee e e e e eee e e e e e fee ee ee eee eee ec ee dece ee eee RMCP RMST CPST RMCOND CPCOND END OO Purpose Input Output Common Blocks FUNCTION YINT This subprogram provides interpolated values within an ordered array of tabulated data X an array of N data values Y an array of N data values N an integer value equal to the number of ordered X and Y values M order of interpolation i e M 2 for linear interpolation 3 for parabolic interpolation etc P value for X at which interpolated Y is desired YINT the interpolated value for Y at the X value equal to P Computer Symbols and Description of Variables symbol I J L MO 1 X XP XQ XX Y YY Description Units Variables used as counters Variables used as counters or Half the order of interpolation The order of interpolation
19. The concept of critical span is important one for a utility that has decided to monitor or calculate the real time temperatures of their overhead transmission network Theoretically a critical span 1 that span or spans that operates at the highest temperature in a transmission system and thereby limits the amount of power that can be delivered by the circuit Regardless of whether a utility has decided to measure conductor temperatures with line monitors or predict them with a computer model based on measured weather conditions the concept of a critical span will help reduce the capital investment necessary to institute a thermal line monitoring scheme This paper identifies those factors that influence the location and number of critical spans Quantities called sensitivity parameters are introduced and used to show how the critical span is influenced weather conditions conductor properties and conductor current The weather conditions along the route of the line are shown to be the dominant factors which affect the conductor temperature and ultimately the number and location of critical spans The conclusions provided by the sensitivity parameters are verified by an experimental phase of the work This effort consisted of a fully instrumented test span and five weather stations located at various distances from the test span The weather data was used in a computer program that has the capability of predicting the rea
20. ZI gt 5 g 0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 1850 TIME HOUR g m WIND DIRECTION WIND eo 22 OF in d gt I i hm e Ve 59 eu lt 0 O a 2 2 g7 59000 2 00 4 00 6 00 12 00 14 00 16 00 18 00 8 00 10 00 TIME HOUR Figure 19 Comparison of DYNAMP and Line Monitor for KG amp E Rail Conductor on September 24 1986 PACIFIC GAS AND ELECTRIC WIND TUNNEL Additional verification of the DYNAMP program was performed by the PG amp E Department of Engineering Research in San Ramon California in a specially designed wind tunnel By accurately varying the weather parameters a check of the DYNAMP program could be obtained under very controlled test conditions Tests were obtained on both all aluminum and ACSR conductors and both the core and surface temperatures of the test conductor were measured The DYNAMP predicted conductor temperatures consistently fell between the measured core and surface temperatures This trend is expected because the DYNAMP program assumes that no radial temperature gradient exists in the conductor and it therefore predicts an average conductor temperature The transient response of DYNAMP was evaluated by subjecting a 1113 kcmil AAC Marigold conductor to a step current change from 300 to 1200 amperes The conductor response and DYNAMP predictions are shown in Figure 20 for a perpendicular wind at 4 4 mph and an ambie
21. t OMEaciteo PROGRAM wx version 1 a institute of and Geor Under EFRI 7248 1 STEADY STATE CALL lt 0 gia Fower Company RATIONS fur LINNET Conductor Q 5171 LBS FT 0 1455 LEG FT 0 2640 SQ IN 9 0420 30 IN Is CUNA CUNE TE ME DEG C 100 Output File for Steady State Example 49 AMPS FOR DEG C 5396 Continued TPANSIENT OPTION example to illustrate the use of the program for transient or real time temperature calculations is identical to the one in the previous section except that the calculations are made for varying currents and weather conditions Using the same conditions as stated in the previous example for steady state calculations calculate the temperature of a Linnet conductor for currents ranging cetween 350 and 410 amps for air temperatures between 15 25 C for wind directions between 0 and 90 to the conductor axis and for wind speeds between 1 anc 10 it sec All current and weather data are separated by 5 minute intervals and the conductor temperatures are to be calculated on 5 minute intervals The documented input file for this example is shown in Figure 4 3 The input values for all data with the exception of the Transient Variables and the Current and weather data are identical to the values used in the previous example The Transient Variables are new for this example and they are 5 minutes for both the current and weather time
22. Case Type Conductor Core 1 ACSR 1350 H19 Aluminum Steel 2 AAC 1350 H19 Aluminum 1350 H19 Aluminum 3 AAAC 6201 T81 Aluminum 6201 T8 Aluminum 4 ACAR 1350 H19 Aluminum 6201 T8 Aluminum 5 All Copper Hard Drawn Copper Hard Drawn Copper 6 Al umoweld 1350 H19 Aluminum Alumoweld 2 Forest Park Test Span Facility Progress has been made in several areas relating to the Forest Park Test Facility New thermocouples have been installed on the steel core and outer strands of the Linnet conductor and a new fiber optic link has been attached to the load cell The Ontario Hydro sag Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 e a er ee AT Fanal Edk cason aA f cployment Opporte tutior A Unit of the Uravers i stem cf Georgia device has been pretested in the laboratory and the existing sag device installed on the conductor has been calibrated new guying design that will assure minimum pole deflection is now complete Also new spacers that will be used to adapt the Linfo monitor to the larger conductor have been ordered 3 Data Collection Project A new program has been written so that data collected at the Forest Park Facility can be recorded on a floppy disc The format of the data is such that the information can be interfaced directly with the IBM version of DYNAMP
23. DYNAMP DYNAMP reports Data name VITO Report Selector Documentation of Input Analysis Output Select New Data Action Selector be tak o3 Print the Print File Purge the Print File n ae Press F1 Help Space Bar Next Choice UEnter Select Choice This menu wil allow the user to perform three tasks First the user may review znae print file on the screen by selecting Review the Print File Second the iser may send the print file to the printer by selecting Print the Print File Pird the user can select Purge the Print File to completely erase the Print ile f Select New Data is selected from the Report Selector then the user will be ompted for the name of another data set at any t me the user wishes to leave a menu to return to a previous menu then eave should be selected from the last menu appearing on the screen FACILITY in this facility 1 selected a condensed users guide will be printed to the een Most general questions may be answered through this facility DYNAMP n the user completes calculations with DYNAMP and wishes to return control to TLworkstation Master Menu the Leave DYNAMP command should be selected from Mcdule Menu Section 4 EXAMPLE PROBLEMS This section illustrates the use of DYNAMP with three typical examples a steady state a transient and a predi
24. Evaporative cooling How is your ampacity information made available to your operating personnel those who run the system on a daily basis CRT display Tables Standards Manual Other specify What are the maximum conductor temperatures your company considers for the following conditions Normal Emergency Fault If you have different ratings for different conductors give ratings and basis for different ratings Are the limitations for the maximum operating temperature dictated by Clearance Loss of strength Creep Degradation of terminations splices Economic Other specify Yes OOOO lt D 00900 lt D 1010000 OOO 0000 5 001000 CIS SECTION III Real Time Ampacity Calculations Does your company at the present time have the ability to Yes No predict the real time rating of your overhead system CJ If no would you consider implementing a real time rating Yes No program if it were available Where do you feel the greatest application a real time Planning rating system would have within your company Operations Design If real time conductor temperature program were available how accurate would it have to predict the conductor temperature before you would 1 C 596 109 20 C consider using it What is the priority of a real time ampacity program High within your transmission and distribution division Moderate Low
25. L PERIOD OF PERFORMANCE CONTRACTOR COST PERFORMANCE REPORT EPRI 177 534 CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER William Z Black School of Mechanical Engineering Georgia Institute of Technology For EPRI Use Only Vito Longo 7 1 84 6 20 87 Atlanta Georgia 30332 Name eee rom o RET MEE eee x Prior Note Instructions for completing this form are the reverse side Year s All figures are to be shown in U S dollars whole thousands only Actual Show portion of the contract only Do not Include contractor cost sharing 1 Current ctual booke Year current year Uu fe fe te fs Petals Current Forecast to Year current year va T tT ssl Jo 7 Future Unbooked Forecast to 87 Remaining Year s liability complete the 19 Years s Forecast Please list doilar ture year 57 57 amount descrip 4 tion of cost and month year in which costs are expected to be booked Remarks Comments on signilicant items Grand total of Iines 1 2 3 4 498 Bills that have accured from Georgia Power Subcontract but have not been paid by Georgia Tech through September 1986 total 39 736 PREPARED Print nar Tite 1 EPRI CONTRACTOR COST PERFORMANCE REPORT EPRI 177 CONTRACT NUMBER DIVISION NUMBER For EPRI Use Only CONTRACTOR NAME ADD
26. R3 are assumed constant for small temperature changes frequently can differ by several ft sec along the conductor span changes in conductor temperature are often in excess of 10 C simply as a result of uneven wind distribution along the route of the conductor The sensitivity parameters which appear in Table 9 are obviously functions of numerous factors and it is difficult to graph or display the trends in the sensitivity parameters without establishing a set of fixed parameters A standard reference set of parameters was therefore selected to simplify the results and these values are given in Table 10 Also the correlation for the convective heat transfer coefficient with respect to wind direction and velocity was adopted from Reference 27 Table 10 Input Variable Reference Set absorptivity 0 5 emissivity 0 5 ambient temperature 25 C sun radiation 1000 W m2 wind direction wind velocity conductor types 90 normal flow 2 ft sec 0 61 m s Curlew 54 7 1033 kcmil Linnet 26 7 336 kcmil 958 amps PM 492 amps Linnet current 75 C ampacity The graph of the wind velocity sensitivity parameter Figure 22 illustrates that the conductor temperature is far more sensitive to changes in wind velocity when wind conditions are nearly calm At high wind velocities a change in velocity has only a minor effect on the conductor temperature Under normal conditions it
27. Two thirds of the companies accounted for solar heating of the conductor while the remainder ignored the influence of the sun when determining the temperature of the conductor With the exception of one company the emissivity and absorptivity of the conductor regardless of whether the conductor 15 aluminum or copper is assumed to be 0 5 None of the companies considered the effect of age on the radiative properties of the conductor All companies calculated a normal ampacity rating while only seventy five percent calculated an emergency ampacity rating Normal ampacity values corresponded to a wide range of conductor temperatures the most common value being 75 C The maximum temperature used for a normal rating was 120 C while some companies provided for different ratings depending upon the construction of the conductor Of those companies that consider emergency ratings the most commonly mentioned limiting time for an emergency rating was two hours Other values for a limiting time during which an emergency overload would be tolerated ranged between 30 minutes and 4 hours and one company permitted emergency conditions to exist for up to 500 hours per year The temperatures that were acceptable during the emergency current overload ranged between 80 C and 140 C with the most commonly mentioned figure being 93 C Some companies have established different acceptable values for emergency ampacity calculations depending upon different types of cond
28. b023 dye imr variables gt SGEN L ATURE 15 LOU DEG t WIND WIND DIR SPEED i DEG C DEG FT S Sow i G Figure 4 1 Documented Input File for Steady State Example 47 i Y N A Hr AMPacitv FROGRAM x gt Version 1 20 Ue P loced Georgia Institute of Technology and Georgia Fower Company Under F254 1 LRU LATA STEADY CALCULATIONS for LINNET Conecuctor i n ductcor Froperties 15 ACSR ALUM 1330 COND STEEL CORE OUTSIDE DIAMETER 0 7700 INCHES CONDUCTOR STRAND DIAMETER 0 11237 INCHES LORE STRAND DIAMETER 0 0884 INCHES NI MHZR OF CONDUCTOR STRANDS 26 OF CORE STRANDS 7 4 RESISTANCE 25 DEG Q 2750 HMS MILE Location Variables DATE AND TIME ERN 9 04 EASTERN TTUDE 14 20 DEG T DE 84 1 DEG CONDUCTOR INCLINATION O O CONDUC TOR AZIMUTH 0 0 DEG oe ABOVE SEA LEVEL 1000 Ft Frooerti es SULAR ABSCR 71 1 0 50 Q 50 Figure 4 2 Output File for Steady State Example 48 Y ed J T td CU STA Figure 4 2 s J iN CE MT LUIS ML E aes MASI MASS CHNISICTOR AREA BITEDUT tate Calculations AIR WIND WIND SS COND GUT ED AMPS DEC 7 FT S s pi yat 6 PET HM F1 if
29. 100 00 75 00 250 00 8 00 12 00 4 00 WIND SPEED 90 Ge UD CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 17 1986 m MEASURED DYNAMP A MONITOR 150 00 125 00 d 96850 TEMP 25 00 0 00 0 00 0 00 1 50 3 00 9 00 10 50 12 00 13 50 6 00 7 50 TIME HOUR Figure 38 Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 17 1986 150 00 125 00 DEG C 75 00 100 00 TEMP 50 00 25 00 0 00 15 00 DEG 00 30 00 60 00 0 00 WIND ANGLE WITH COND COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 23 1986 9 MEASURED DYNAMP A AMB TEMP 4 CURRENT 8 dicic AH HHHH reete ee 5 am S ult 9 feof fh X dg lt m y lt wee gz Sir tc 5 8 8 16 00 17 00 18 00 19 0 20 00 21 00 22 00 23 00 2400 TIME HOUR m WIND DIRECTION WIND SPEED g 1 cm eon 4 41 e oo 3 2 yee DA 16 00 17 00 18 00 20 00 21 00 22 00 25 00 2 TIME HOUR Figure 39 DYNAMP Predictions for Curlew Conductor on October 23 1986 CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 23 1986 5 MEASURED DYNAMP a MONITOR 956 0 50 00 25 00 15 00 16 00 17 00 18 00 19 0 00 21 00 22 00 23 00 24 00 TIME
30. 1986 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 9 OCT 22 19B6 m MEASURED DYNAMP a AMB CURRENT a 2 AA Y 20 e G a v 4 7 58 55 go A bp ar 9 ET aig bd m hi X zx PS 85 Q n 5 g 8 6 8 9 20 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 18 00 TIME HOUR WIND DIRECTION WIND SPEED S 4 B 9 tee Ld 08 dr ee n gt I T z3 0 2 2 295 8 00 10 00 16 00 18 00 TIME HOUR n Pr for October 22 1986 The data Fig 15 for October 22 1986 show more sustained errors as a result of much longer periods when the weather station was indicating no wind was present at the conductor location The weather station reported practically no wind from midnight until slightly after 6 00 am Program errors during that same period averaged about 20 C Figure 16 shows the expected predicted temperatures within 10 C of the measured temperature even when the conductor temperature exceeded 130 C for a brief period of time During the sixteen hour period that data was collected for Fig 16 the wind direction was highly variable and unpredictable but the wind direction did not fall along the conductor axis and the velocity did not drop below two mph As
31. AIEE Trans Vol 82 pp 767 75 Oct 1963 D O Koval and Roy Billington Determination of Transmission Line Ampacities by Probability and Numerical Methods IEEE Trans PAS Vol 89 No 7 pp 1485 92 Sept Oct 1970 Glenn A Davidson Thomas E Donoho Pierre R H Landrieu Robert T McElhaney and John H Saeger Short Time Thermal Ratings for Bare Overhead Conductors IEEE Trans PAS Vol 88 No 3 pp 194 99 March 1969 T Morgan Rating of Bare Overhead Conductors for Intermittent and Cyclic Currents Proc IEE Vol 116 No 8 pp 1361 75 Aug 1969 15 16 17 18 19 20 21 22 23 24 25 26 27 V T Morgan Rating of Conductors for Short Duration Currents Proc IEE Vol 118 No 3 4 pp 555 69 Mar Apr 1971 Murray W Davis A New Thermal Rating Approach The Real Time Thermal Rating System for Strategic Overhead Conductor Transmission Lines IEEE Trans PAS Part I Vol 96 No 3 pp 803 09 May June 1977 Part II Vol 96 No 3 pp 810 25 May June 1977 Part III Vol 97 No 2 pp 444 55 Mar April 1978 Part IV IEEE Paper F 79 710 15 Part V IEEE Paper F79 711 3 V T Morgan Unsteady State Current Rating of Bare Overhead Conductors Inst of Engrs Elec Engr Trans Vol 16 Vol 3 pp 114 19 1980 Stephen D Foss Sheng H Lin and Roosevelt A Fernandes Dynamic Thermal Line Ratings Part I Dynamic Ampacity Rating Algor
32. Also the program that is used to poll the weather station and average the data for wind direction and Speed has now been completed Several other sites for collection of weather data in the Atlanta area have been investigated The sites will be narrowed to one or two within the next month Sincerelv Ville Le DIAGUAK N Professor WZB maw 4S V GEORGIA TECH 1885 1985 DESIGNING TOMORROW TODAY September 12 1985 5 Vito J Longo Project Manager AX Electrical Systems Division EPRI 3412 Hillview Avenue Palo Alto CA 94303 Dear Vito Here s a brief report of our progress since our Atlanta meeting on July 30th 1 Development of DYNAMP Version 1 1 of DYNAMP is nearing completion and it will be offered within the next few weeks to those who have version 1 0 The new version of DYNAMP contains several improved features not available in the original version Three errors were corrected in the WIRE DAT file and one error has been corrected in the file called WIRED Also the program has been modified and expanded to accommodate an additional conductor type Furthermore DYNAMP has been modified so that it can calculate ampacity values for an unlimited number of ambient conditions rather than data arrays that are limited to less than 200 values 2 Program Verification DYNAMP has been used to analyze approximately one week of ampacity values for the Curlew conductor The program accuracy is similar to that expe
33. Conductor current amps Air temperature Wind direction 80 from north 98 from east Wind speed feet second i Press Help Enter Next Field Esc Leave Fora 231 The user is now given the opportunity to modify any of the displayed data Suppose for example it is desired to change the current from 403 amps to 509 amps The user also wishes to change the wind speed from 6 5 feet second to 8 0 feet second The user simply enters the correct values for those two fields The a r temperature and wind direction fields will remain unchanged if the Enter key is pressed without making changes to those fields After the new value for wind speed has been entered the following form is displayed DYNAHP oo Current amp Weather Reading 8 14 of 25 Me ei a am sedat a Time 18 88 Conductor amps Air temperature C Wind direction ie Gis RENAE eae 8 from north 98 from east Wind speed feet second Choose One Previous Edit Jump Insert Select Delete Leave The menu on the bottom of the screen gives the user eight options 15 Delete is selected to delete the set of data displayed on the screen 2 Previous 15 selected to edit the current and weather data set that is on th
34. HOUR Figure 40 Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 23 1986 Aler CONCLUSIONS A real time ampacity program called DYNAMP has been developed to predict the transient temperatures of overhead conductors The menu driven program is simple to operate and it predicts real time conductor temperatures that have been verified in two separate outdoor test programs and a series of indoor wind tunnel tests When the program results are compared with temperatures measured with thermocouples attached to the test line the program ylelds conservative results that are within 8 C over 90 percent of the time program requires input weather conditions of air temperature wind speed and wind direction all of which can be accurately measured with an inexpensive weather station located near the line Therefore the real time program can accurately predict conductor temperatures using only an inexpensive device to provide weather conditions for input information The program does not require that any device be mounted directly on the conductor The results of the program have shown that there are significant periods of time that the conductor temperature is lower than calculated by steady state thermal models However it has also shown that there are brief periods when the conservative steady state model will under predict the conductor temperature because wind speeds can fall below the values assume
35. Y A QE go am i m dry C Cera py seer ops opr x sed Lo MEE l oar a E 417 E e gt 15 4 aa 0 2 182211 L a AD 2 0 1 1 4 42 1 CR ue PIRE n 5 3 C 4 NT Y Figure 4 3 Documented Input File for Transient Example Continued rt Toba X Ver amp SIOH Le 2G aGftbitons o and Georgia Power Company COLULL DT TC Conductor ET eek bue ost INU HES CV ln INCHES PU REED 5 jt es O TTUO OMS MILE VINO IMP EARUC ERN i er wo rT ry m RE i41 rU e4 OPEN THE iv XE t7 3 0 Ha 2 C4 50 4 eA TES 4 4 File for Transient Example fn S nd te 4 4 p gt Figure 4 4 o t if et 1 a it hu aem it oad a 4 ts 5014 3 tu pe XOT i Jo 70 e gd CNN AE en PES 5 0 i i bw pmo 42 iQ M cu ge 12 0 gi uw e 100 253 1142042 a ne CU 1 ERE 90 30 60 ides du 2 oue bj 1 C C xe 0 102 0 E lt 10 0 Q 19 0 irc 10 0 0 10 0 L3 Q 10 0 lu Pto 10 0 IR t 1 0 C Io 0 4 gt bud TO lees eo Cher 1
36. and the elapsed time required for the conductor to increase from its present value to the value given by the emergency limiting temperature If the elapsed time is on the order of a few seconds or minutes the user will know that the line is near its thermal lim t and its temperature will quickly reach the limiting value in a very short period of ime If the elapsed time is on the order of an hour the line is very lightly icaded and it has a great deal of excess thermal capacity as reflected by its high iue of emergency time program calculates an elapsed time up to two hours the value exceeds 120 minutes the calculations are terminated and a value of 29 minutes is printed in the last column In this event the conductor emperature calculated at the end of the two hour period is printed in the revious column output shown in Figure 4 6 gives a brief view of typical predictive results Linnet conductor The first two lines of output show the large effect that nd velocity can have on the temperature and elapsed time to reach a temperature 109 C When the wind velocity is 1 ft sec and the conductor current changes om 350 to 750 amps the conductor temperature changes from 65 1 C to 100 C in minutes When the wind velocity increases to 5 ft sec and the conductor riences the same change in current the conductor temperature changes from 1 to 100 C an elapsed time of 8 7 minutes The remaining lines of output a Sh
37. defined above In the transient mode tne program automatically calculates the conductor temperature for the first set of weather and current conditions at the time corresponding to the date and time given in the Date and Time input group program then increments time by a value equal to Time Intervai and uses the second set of weather and current data The program continues to increment the time by a value equal to Time Interval and it calculates the temperature for each set of weather and current data as long as data is available The program terminates when no further data is found Tne user can prin conductor temperatures on a time interval equal to Printing Interval By selecting a print interval less than the time interval for the eather and current data the user can print temperatures that are closely spaced i time On the other hand if output temperatures are needed at widely spaced ime intervals the user can select a larger value for the Printing Interval ESCRIPTION OF INPUT VARIABLES PREDICTIVE CALCULATIONS he predictive program option permits the user to predict the temperature of the nductor when it is subjected to a step change in current the user must specify value of overload current and the program returns the time required for the nductor to reach an emergency limiting temperature which is also specified by e user in the Run Type data qroup e scheme used by DYNAMP for calculating an emergency tim
38. dollars whole thousands only Actual e Show EPRI portion of the contract only Do not Include contractor cost sharing 22 5 Current Aclual booked Year costin the Apr Jun Jul Aug Dec Current year j 4 P i 19 86 30 Current Forecast to Year complete the Apr Jun Jul Aug Dec Forecast current year 19 86 21 2 0 18 18 17 17 201 Future Unbooked Forecast to Remaining Year s liability complete the s 19 Years s Forecast Please list dollar 30 amount descrip Lion ol cost and month year in which costs are Grand total of 1 2 3 4 486 expected to be booked Hemarks Comments on simeilicant items PREPARED BY Print Wm Z Black EPRI CONTRACTOR COST PERFORMANCE REPORT 177 S b1R CONTRACTOR ADORESS AND TELEPHONE NUMBER EPIRI DIVISION HUMDER PERIOD OF PERFOIMANCE 7 1 84 6 30 87 CONTRACT NUMBER np 2454 j 6 1 0111 PROJECT MANAG TAGER Vito Longo Name A s m For EPRI Use Only School of Mechanical Engineerins Georgia Institute of Technology Atlanta Georsia 39332 From Prior Year s Actual Note Instruction
39. gt H 0 n gt LIN hd C L L 2 H lt Y A lt LEGEND E SURFACE TEMP Last Calibration Avg Error 3 6 C Avg Surface Temp 90 6 C Avg Monitor Temp 94 2 C Avg Ambient Temp 14 4 C 222 MONITOR 9 y MLM 2 N ie 15139 S338930 dN31 24 272 271 269 268 270 272 274 270 274 267 DEGREES WIND DIRECTION Errors in Line Monitor Temperature when Wind is from the West Figure 15 II THEORETICAL PHASE A Additional Developments with DYNAMP Version 1 2 The computer program has remained practically unchanged since the last meeting in Boise Idaho been uncovered and the only major changes to the code have been to improve program efficiency or decrease run time 1 2 are listed below d The expression for the free convection Nusselt number calculated in the subroutine HTC Heat Transfer Coefficient was modified to account for the angle that the conductor makes relative to the horizon The previous expression assumed that the conductor was horizontal when calculating the free convection Nusselt number The new expression decreases the Nusselt number as the conductor 15 inclined to the horizon The result of this change will be to increase the conductor temperature at low wind velocities when the conductor is not horizontal The expression that calculates the angle
40. project were used to evaluate the accuracy of the line monitor and to compare the temperatures measured with the monitor to those values predicted by DYNAMP Data was collected over a one month period for four different conductor sizes At each site the line monitor was installed on an energized line and a weather station was located in the immediate vicinity of the monitor Since the transmission lines were energized thermocouples could not used to provide a base line temperature against which the monitor or DYNAMP results could be compared Results obtained on the Drake conductor on July 31 1986 show some of the best temperature comparisons between the monitor and program Figure 18 In general the comparison was not as good as indicted in Figure 18 and the differences between predicted and measured temperatures were far greater than the data collected in Georgia Weather conditions were somewhat different than experienced in Georgia because the Kansas wind velocity in general was much higher and fairly sustained The data collected on September 24 1986 on the Rail conductor produced very poor correlations as shown in Figure 19 Differences between the monitor temperature and the DYNAMP predicted temperature exceeded 10 C for substantial periods of time Also between midnight and 4 am the monitor temperature was lower than the ambient temperature raising serious doubt about the accuracy of the monitor during this period Analysis of the
41. surface temperature of a Drake conductor for constant current and varying wind velocity The results show the sizeable effect that the wind velocity has on the temperature of the conductor The conductor temperature with no wind over the surface is approximately 759C and the average temperature drops to below 35 C when the wind velocity increases to only 5 mph 2 24 m s The difference between the surface and center temperatures of the conductor is nearly constant at slightly over 19 for all wind velocities T C T C 35 0 346 34 4 DRAKE CONDUCTOR I 630 Amps V 5 6 mph 90 Te 25 T center _ T surface 34 2 34 0 lO 20 30 40 o0 THERMAL CONDUCTIVIT Y OF CONDUCTING MATERIAL W m C Figure 5 Temperature as a Function of Effective Thermal Conductivity of the Outer Conducting Strands 65 0 45 0 35 0 Figure 6 DRAKE CONDUCTOR I 630 0 Amps T center T surf ace 5 0 10 0 15 0 20 0 25 0 300 AIR VELOCITY mph Temperature as a Function of Air Velocity for a Drake Conductor at Constant Current The results shown Fig 7 are similar to those in Fig 6 except that they are calculated for a varying current and a constant surface temperature of 72 40C Maintaining a constant surface temperature requires an increase in conductor current as the air velocity increases These results show that the difference in the center and surface t
42. the wind was very calm and the program predicted temperatures that were at times both high and low of the measured values As the wind velocity began to increase after 1 00 am the usual accuracy of the program returned and it remained excellent with the exception of one brief period at approximately noon At that time the wind was blowing down the axis of the conductor wind angle 0 and the program briefly predicted a temperature that was about 30 C higher than the measured temperature Once the wind changed direction and the wind angle increased the program accuracy returned The data in Figure 19 for October 22 1986 shows more sustained errors as a result of much longer periods when the weather station was indicating no wind was present at the conductor location The weather station reported practically no wind from midnight until slightly after 6 00 am Program errors during that same period averaged about 20 C COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 20 1986 5 mj MEASURED DYNAMP A AMB TEMP 4 CURRENT s 5 a a g OQ 4 o8 TY ey g E 8 5 52 c nN o 00 00 00 12 50 14 00 15 50 17 18 50 20 00 21 50 23 00 2430 TIME HOUR m WIND DIRECTION _ WIND SPEED e 9 T 7 N m p t T Lil la a yi as zd T Qe bac SQ TOR
43. 00 100 00 120 00 QEG c mart TEMP 40 00 20 00 o 9 00 00 10 00 10 36 00 COMPARISON OF DYNAMP AND EXP TEMPS REMOTE SITE 4 EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 30 1986 AMB TEMP DYNAMP CURRENT 200 00 100 00 12500 150 00 175 00 10 CURRENT 5 5 00 20 00 12 00 14 00 0 20 00 22 00 24 00 16 00 18 0 TIME HOUR pj WIND DIRECTION WIND SPEED 2 00 1 om One urs Tite oe Aet 7 0 Hostes e AN n 2 e Cs zs ds z e Be 8 lt 98 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 26 00 O TIME HOUR 2 z Figure 10 Measured and Predicted Conductor Temperatures and Weather Conditions at Remote Site Number 4 for June 30 1986 the test span maintained a good correlation but sites 2 3 and 4 show large errors Remote sites 2 and 3 show errors in prediction of 50 C when the wind speed as measured at these sites dropped to zero At low wind speeds the two state EPA sites sites 2 and 3 consistently showed poor correlations The data collected throughout the Idaho Power Project is being statistically analyzed to evaluate the applicability of this information to critical span analysis C Project The Kansas Electric Utility Research Program KEURP entered into a co funding agreement with EPRI on work relating to
44. 1986 when the experimental verification portion of the project was completed KANSAS GAS amp ELECTRIC FIELD SITE One of the goals of the research project was to verify the accuracy of DYNAMP using data collected at a field site Unfortunately no existing facility was found that could be economically converted for use as a second instrumented test span To remove the obstacle a commercially available on line monitor was purchased and used to provide line temperature data on a set of KG amp E existing operating lines Kansas Gas and Electric KG amp E under a co funding agreement with Kansas Electric Utilities Research Program KEURP and EPRI agreed to be the host utility for collection of line temperature data The alternate site study was a cooperative effort between KG amp E the Center for Energy Studies at Wichita State University WSU the Kansas Technical Institute KTI Georgia Power Company and the Georgia Institute of Technology WSU was the main contractor in charge of overall coordination of the project was subcontractor to WSU and they were responsible for the design construction and operation of the data recording system KG amp E provided facilities and engineering assistance Georgia Power provided additional equipment and assistance in experiment design of the test apparatus Four conductors were selected for instrumentation with both the on line monitor and with a weather station located at line height
45. 27 of the predicted temperatures were less than the measured value This behavior of over predicting the conductor temperature was intentional because the program was designed to be on the conservative side The data in Tables 5 and 6 contain the same data as shown in Table 4 except that Table 5 contains only those points for which DYNAMP over predicted the temperature and Table 6 shows only those cases where DYNAMP calculates a temperature lower than the measured value These values show that more accurate predictions occur at higher wind ee ERROR C d O O0 WYK ON Cn WD W C C9 CO C9 CO Ww CO CO amp WwW MB TEMPERATURE BASE STATION RANK NO PERCENT PERCENT AV ANGLE ANGLE PTS 2817 5423 4277 3123 2238 1628 1210 935 686 474 368 281 215 193 146 109 87 76 66 47 49 46 28 23 27 15 8 10 8 7 5 10 9 Ne 1 OON CO M Table 4 MN CO O QO O QO O O O O QO QO QO QO QO QO m mn rn t t ft WWE 00 UND KS lt or 11 4 33 4 50 7 63 3 72 4 79 0 83 9 87 7 90 4 92 4 93 8 95
46. 37 0 1226 0 858 Magnolia 954 0 37 0 1606 1 124 Carnation 1431 0 61 0 1532 1 379 Conductor and supporting strands 1350 H19 Aluminum The thermal model can be used to investigate the influence that the effective thermal conductivity has on the temperature distribution of a conductor In Fig 5 the outer surface and centerline temperatures of a Drake conductor are plotted fixed effective conductivity of the supporting strands a variable effective conductivity of the outer conducting strands The results show that the value for effective conductivity of the conducting strands has practically no influence on the surface temperature of the conductor Also significant changes in the effective conductivity of the conducting strands have only a minor influence on the centerline temperature and only as the effective conductivity of the strands drops below a value of about 10 W me C does the center temperature show any significant change These results imply that conductors with compact segmental strand resulting in reduced air gaps between strands should be an effective method of reducing temperature gradients within a conductor In order to more fully understand the impact of the weather conditions on the temperature distribution within an overhead conductor the program was used to calculate the conductor temperature when the weather conditions were varied A typical example of this process is shown in Fig 6 which plots the center and
47. 4 FEY month year in which costs are expected to be booked Currenl Remarks Comments cn tems PREPARED BY Prin name Title ______ EPRI EPAI CONTRACT rap 2154 4 6 EPAI PROJECT MANAGER Name Actual booked cost In the Currcnt year 19 Forecast to complete the current year 19 Unbooked liability Please list dollar amount descrip tton of cost and month year in which costs are expecled lo be booked CONTRACTOR COST PERFORMANCE REPORI EPA 177 S BaR CONTRACTOR NAME ADORESS ANO TELEPHONE NUMBER Wn Z Black 404 894 3257 School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 EPRI DIVISIDN NUMOER For EPRI Use Only PERIOO DF PERFORMANCE 741 84 6 30 87 Vito Long E Prior Year s Note Instructions for completing this form are on the reverse side Actual All figures are to be shown in U S dollars whole thousands only Show EPRI portion of the contract only Do not include contractor cost sharing Current Yoar May Jun Jul Actual Jan Current Year Jul Forecast Jan Feb Apr May Jun Year s Forecast to Forecast complete the future year s Remarks Comments on signilicant items PREPARED BY Print name EPHI EPRI CONTRACT NUMBER PROJECT MANAGER EPRI DIVISION NUMDER 2 5 1 15
48. 4 00 6 00 8 00 10 00 12 00 14 00 16 00 TIME HOUR WIND DIRECTION WIND SPEED OND DEG 60 00 30 00 WIND ANGLE WITH C c9 00 00 2 00 4 00 12 00 14 00 16 00 8 00 10 00 TIME HOUR 200 00 175 00 150 10 125 09 100 00 CURRENT AMPS 75 00 5 12 00 8 00 INO SPEED MPH 4 00 W 18 00 Figure 16 Measured and Predicted Conductor Temperatures Showing Excellent Accuracy for Conductor Temperatures in Excess of 1300C COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 8 JULY 1 1986 Sy MEASURED DYNAMP AMB TEMP 4 CURRENT 8 5 aei nita 2 gt fe FL D E ay m dE d a e m D 8 o 5 M P LB s 9 y P 4 o s NS bec ae 96 00 2 00 4 00 8 00 10 00 12 00 14 00 16 00 TIME HOUR 2 WIND DIRECTION WIND SPEED g C 1 Lui 25 5 a e uj 9 lt 0 00 2 00 4 00 6 00 12 00 14 00 16 00 8 00 10 00 TIME HOUR Figure 17 Measured and Predicted Conductor Temperatures Showing Errors which Result from Rainfall Between 2 and 5 pm 75 00 100 125 00 45 50 00 CURRENT AMPS 25 00 8 1800 4 00 8 00 12 00 IND SPEED MPH e Wag STATISTICAL ANALYSIS OF PROGRAM RESULTS During the two year period in which the te
49. 4 00 6 00 8 00 10 00 12 00 14 00 16 00 1800 TIME HOUR 2 gj WIND DIRECTION WIND SPEED 9 T gt e B 21 a 55 n ur d lg 29000 18 00 Figure 19 Measured and Predicted Cond for October 22 1986 uctor Temperatures 3 Since the test span at Forest Park has been partially dismantled no more experimental data can be collected and the program to check DYNAMP s accuracy has been completed 2 Interactive Version of DYNAMP A copy of Version 1 2 was forwarded to Power Computing Company in September 1986 PCC revised the program by inserting an Interactive User Facility IUF front end program The IUF version of DYNAMP has been check at both EPRI and Georgia Tech and several errors have been corrected Other suggestions have been made to improve program operation A preliminary version of the IUF program is now available and will be demonstrated at the end of the meeting B Statistical Analysis of DYNAMP s Predictions During the two year period in which the test span was operated the Curlew conductor was in place for about 15 months During that time over 26 400 data points of weather conditions current and conductor temperature were collected and recorded on diskette This number represents nearly 92 days of continual operation 11 of these data points have been analyzed with DYNAMP anda statistical analysis of the program accuracy has been performed The result of the statistical ana
50. 84 5 1 1 95 0 35 6 25 6 4 7 2 9 13 2 0 00 86 8 0 9 95 9 34 0 24 6 4 5 3 1 19 1 0 00 80 9 0 8 96 6 35 7 24 8 4 1 2 9 20 2 0 00 79 8 0 6 97 2 38 0 27 5 4 6 3 2 18 5 0 00 81 5 0 4 97 7 32 1 25 2 4 7 3 5 22 0 0 00 78 0 0 4 98 0 34 0 25 0 4 4 2 2 19 5 0 00 80 5 0 3 98 3 29 6 24 8 4 6 3 2 27 6 0 00 72 4 0 3 98 6 31 0 27 5 4 0 2 8 22 7 0 00 77 3 0 2 98 8 28 7 28 2 5 1 3 1 19 1 0 00 80 9 0 2 99 0 31 4 26 8 5 2 3 5 10 2 0 00 89 8 0 2 99 2 32 7 26 5 5 6 3 5 10 9 0 00 89 1 0 1 99 3 30 4 27 7 5 4 3 0 3 6 0 00 96 4 0 1 99 4 28 1 23 9 4 8 3 6 8 7 0 00 91 3 0 1 99 5 24 5 22 4 5 7 3 6 11 1 0 00 88 9 0 1 99 5 42 1 26 4 4 3 2 3 20 0 0 00 80 0 0 0 99 6 24 4 26 3 5 0 4 5 25 0 0 00 75 0 0 0 99 6 33 5 30 2 3 7 3 0 40 0 0 00 60 0 0 0 99 6 45 0 25 9 4 1 2 9 12 5 0 00 87 5 0 0 99 7 31 3 31 5 4 4 2 1 14 3 0 00 85 7 0 0 99 7 16 8 18 1 5 6 1 3 0 0 0 00 100 0 0 0 99 7 26 4 26 3 5 1 1 6 10 0 0 00 90 0 0 0 99 8 17 5 26 7 5 9 2 1 33 3 0 00 66 7 0 0 99 8 35 1 29 8 4 7 2 0 8 3 0 00 91 7 0 0 99 9 22 4 20 5 4 8 1 6 28 6 0 00 71 4 0 0 99 9 32 3 36 1 6 3 1 7 0 0 0 00 100 0 0 0 99 9 14 5 14 4 4 2 1 5 50 0 0 00 50 0 0 0 99 9 38 0 1 4 5 7 3 1 0 0 0 00 100 0 0 0 99 9 26 2 4 6 4 0 1 7 0 0 0 00 100 0 0 0 99 9 24 0 11 0 4 3 1 4 16 7 0 00 83 3 0 0 99 9 13 0 0 0 5 3 0 0 0 0 0 00 100 0 0 0 99 9 19 0 0 0 2 4 0 0 0 0 0 00 120 0 0 0 99 9 69 1 0 0 2 8 0 0 0 0 0 00 100 0 0 0 100 0 1 0 0 0 5 5 0 0 0 0 0 00 100 0 0 0 100 0 36 1 27 5 4 3 3 2 25 0 0 00 75 0 Statistical Analysis of D
51. 86 CURRENT 1200 1200 1400 1000 800 1100 1200 1400 1200 1000 800 1200 800 1000 1100 TABLE 1 DATA COLLECTION LOG _0 LINE 10 54 23 55 0 00 23 55 0 00 00 17 17 02 23 55 0 00 15 23 8 29 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 06 22 13 58 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 17 33 6 24 23 55 0 00 23 55 0 00 23 55 0 00 05 56 6 47 23 55 0 00 20 09 6 37 23 35 0 00 23 0 00 18 56 6 33 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 16 29 16 53 23 55 0 00 15 09 15 31 23 55 0 00 21 55 22 16 23 55 0 00 12 55 17 17 23 55 0 00 16 39 16 11 23 55 0 00 06 37 REMOTE 1 HV 8 30 23 55 0 00 09 20 12 05 23 55 0 00 15 25 11 35 23 55 0 00 23 55 0 00 23 55 0 00 08 55 9 05 23 55 0 00 23 55 0 00 23 55 0 00723 55 0 00 13 40 14 00 23 55 0 00 23 55 0 00 23 55 0 00 19 00 19 20 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 10 00 10 10 23 55 0 00 14 10 16 00 21 55 0 00 23 55 0 00 16 55 17 05 23 55 0 00 23 55 0 00 23 55 0 00 13 20 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 19 30 9 00 23 55 0 00 23 55 0 00 23 55 0 00 10 15 11 15 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 08 10 8 20 23 55 0 00 23 55 0 00 23 55 0 00 05 45 REMOTE 2 S DEKALB 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 2
52. BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 20 1986 m MEASURED DYNAMP a AMB TEMP CURRENT Ff d e P I Y v aC Pr Ph 4 20 00 21 50 25 00 17 18 50 WIND DIRECTION WIND SPEED 77700 1850 2000 2150 2500 TIME HOUR Figure 13 Measured and Predicted Conductor Temperatures for October 20 1986 1 150 00 20 eig 1 90 S 60 00 CURRENT AMP 50 00 3 2430 12 00 8 00 4 2430 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL g OCT 21 1986 MEASURED DYNAMP a AMB TEMP CURRENT 200 00 125 175 00 a 8 oo 82 do p Om e 52 Luv Cer gt 3 a 2 gc LU 12 9 eu 00 5 00 0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 1 abo TIME HOUR 8 m WIND DIRECTION WIND SPEED 9 oD C 55 Qe uc UJ og e 58 UA uji 10 12 hs 70 3 1 UTE gt hi 2 94 2 QS n Ju 1 5 0 00 2 00 4 00 10 00 12 00 14 00 16 00 1830 8 00 TIME HOUR Figure 14 Measured and Predicted Conductor Temperatures for October 21
53. Company Box 70 Boise ID 83707 208 383 2948 R L Trotter Illinois Power Company 500 South 27th Street Decatur IL 62525 217 424 6760 Eric Norberg Minnesota Power Co Duluth Minnesota 218 722 2641 ext 3612 EPRI Vito J Longo EPRI 3412 Hillview Ave P O Box 10412 Palo Alto CA 94303 415 855 2287 J F Hall Pacific Gas amp Electric Company 3400 Crow Canyon Road San Ramon 94853 415 820 2000 ext 291 Hosea Lee Pacific Gas amp Electric Company 77 Beale Street Room 1995 San Francisco 94106 415 972 6752 R E Carberry Northeast Utilities Box 270 Hartford CT 06101 203 666 6911 Lowell Fink Wisconsin Electric Power Co 23 West Michigan St Technical Services Bldg Station 2C Milwaukee Wisconsin 53201 414 277 2400 Richard W Quinzani Boston Edison Co P253 800 Boylston St Boston Mass 02199 617 424 3511 GEORGIA TECH William Z Rlack School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 404 894 3257 Georgia Power V 5 Harper Georgia Power Company 62 T Lake Mirror Road Forest Park GA 30050 T C Champion Georgia Power Company 62 T Lake Mirror Road Forest Park 30050 404 362 5367 R A Bush Georgia Power Company 62 T Lake Mirror Road Forest Park GA 30050 404 362 5369 Progress Report EPRI Project 2546 CONDUCTOR TEMPERATURE RESEARCH Georgia Intitute of Te
54. Enter Select Choice he user should respond to this menu by selecting Conductor Properties since it s desired to edit those properties fter making that selection the following form will appear DYNAMP Ee Conductor Properties onductor code ERR STANDARD 1 9 ACSR otal conductor outside diameter Cinches 8 7286 bameter of individual conductor strands Cinches 8 1137 lameter of individual core strands inches 8 0884 weber of conductor s rands enn nnn 26 weber of core E resistance at 25 C ohms mile Press Fi Help Enter Next Field Esc Leave Form 2962 This form gives the conductor properties for the present conductor in the input Cata file TRANS To change these properties to those for a CURLEW conductor the user enters CURLEW in the field following the prompt for the conductor code name After entecing CURLEW program automatically changes the properties to tnose tor a CURLEW conductor and the following screen image appears DYNAMP SG RI I I IO I oR Conductor Properties ee ETE Conductor code CURLEW Conductor ACSR Total conductor outside diameter inches 1 2458 Diameter of indiv
55. I 1 END IF MO I MI M0 M 1 IF MO LT 1 THEN MO 1 ELSE IF ME GT N THEN MO N M 41 END IF p03 1 1 L I 1 XP I 1 P XQ I X L 3 YY I Y L 5 2 DO 4 J M XX J 1 xP D YY J XP I 10 C XQ J xQ 1 10 4 CONTINUE po 5 1 M YY J XX J M I 33 5 CONTINUE YINT YY M END e CONDUCTOR TEMPERATURE C 186 233 204 1631 209 256 279 MAX TEMPS FOR ZERO WIND VELOCITY 8 WIND w mwee 4 9 lO VELOCITY r a I2 3 mph FIGURE FOREST PARK TEST SPAN CURLEW CONDUCTOR 54 7 1033 kcmil amp 7048 0 28 CROSS FLOW WIND SUMMER SUN LOAD AIR TEMP 25 C Id 15 le 17 18 I9 20 22 23 V FOREST PARK TEST SITE WORK Task 3 A decision has been reached to make both hardware and software modifications in the existing weather data acquisition system located at the Forest Park test facility Ihe weather station hardware will be modified to allow for polling of the weather station by the system control computer Currently the weather station sends data at one minute intervals The system control computer must continually monitor the data link to intercept the incoming data The proposed hardware modification will allow the control computer to request data from the weather station as needed thereby freeing t
56. In addition weather data has also been collected at four weather stations located between 1 mile and 25 miles from the test Span This phase of the experimental work is summarized in Section B Finally a separate phase of the experimental work funded by KEURP was carried out by Kansas Gas and Electric A line monitor initially used at the Forest Park test span was calibrated and sent to Kansas There it was installed at four different sites on four different conductor sites The results of this work is reported in Section C A Operation of the Forest Park Test Span Since the last report presented in late July at Idaho Power Company the Forest Park test span has been operated for nearly 50 days The times of operation are listed in Table 1 With the exception of a few minor outages the operation of the line and the data collection system has been routine At this time the test line has been partially disassembled and the collection of weather data and conductor temperatures at the test span is now complete DATE 6 16 86 6 17 86 6 18 86 5 19 86 6 20 86 6 21 86 6 22 86 6 23 86 5 24 86 6 25 86 6 26 86 5 27 86 5 28 86 6 29 86 6 30 86 7 01 86 7 02 86 7 03 86 7 04 86 7 05 86 7 06 86 7 07 86 7 08 86 7 09 86 7 10 86 7 11 86 7 12 86 1 13 86 7 14 86 7 15 86 7 15 86 7 17 86 7 18 86 7 19 86 7 20 86 7 21 86 7 22 86 7 23 86 7 24 86 7 25 86 7 28 86 7 29 86 7 30 86 7 31 86 8 01
57. KG amp E data is somewhat difficult since there is no measured conductor temperature against which to compare the monitor or DYNAMP results This difficulty emphasizes the need to perform comprehensive testing such as was performed at the Georgia Power Test Span and in the PG amp E wind tunnel Only by calibrating a line monitor under expected field conditions can one be assured that it is measuring the conductor temperature accurately COMPARISON OF DYNAMP AND EXP TEMPS GORDON EVANS EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO DRAKE CONDUCTOR ACSR 26 7 795 KCMIL JULY 31 1986 don MEASURED DYNAMP a AMB TEMP 4 CURRENT 2 B 9 2 gt 5 Bo e uus n bed gt x ES 82 0 c Q 2 ga 8 g O 3 09 15 00 17 00 19 00 21 3 00 25 00 27 00 29 00 310 TIME HOUR 8 m WIND DIRECTION WIND SPEED e Q bu 23 o 5 t I v e E Bu 2 a8 RE 2915 00 15 00 17 00 19 00 100 2300 25 00 7 00 310 TIME HOUR Figure 18 Comparison of DYNAMP and Line Monitor for KG amp E Drake Conductor on July 31 1986 COMPARISON OF DYNAMP AND EXP TEMPS WEAVER EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO RAIL CONDUCTOR ACSR 45 7 954 KCMIL SEP 24 1986 8 MEASURED DYNAMP A AMB TEMP CURRENT 8 n 8 So oT en WE aa rata 5n 9 gt E 52 ex 0
58. Power Company L INNET Conductor wo FT t he due 1 14 GSO TH 50 IN IL 002 COND TEME DEI 65 1 HO t 32 6 i c 43 59 0 409 4 40 7 40 9 40 9 40 9 44 2 2 4 amp Slab 65 4 64 65 2 55 1 60 0 20 1 257 1 26 92 Output File for Transient Example Continued PREETCTIVE OPTION eS firal of DYNAMP s capabilities consider a case of using the program t zredict the conductor temperature when it is subjected to a step change in Larront Suppose the Linnet conductor experiences a step change in current from tre values given in th previous example to a current of 750 amps Calculate the tine required for the conductor to reach an emergency limiting temperature of 105 C Atl other conditions given in the previous two examples remain unchanged documented input file for this example is shown in Figure 4 5 he Output for this example is shown in Figure 4 6 The only addition to the input file is the value for the Predictive Variable which consists of an overload current The last portion of the output file shows the weather conditions conductor current and real time temperature in a format similar to the two previcus examples However three additional columns of data have been added to the output calculations The last three columns list the overload current in amps the emergency limiting temperature in
59. SPEED B S F oD O LU O 8 Sc 25 Sz o 50 lt E g 291500 15 00 17 00 19 00 21 00 25 00 27 00 29 00 3190 23 00 TIME HOUR Figure 23 Comparison of DYNAMP and Line Monitor for KG amp E Drake Conductor on July 31 1986 The temperatures in Figure 24 show more typical results and the sizeable errors that frequently occurred in the Kansas data The difference between DYNAMP s predicted temperature and the line monitor s measured temperature exceeded 20 C on several occasions This particular line was rather lightly loaded with a nearly constant current of approximately 1200 amps For times between midnight and 6 00 am the conductor was only a few degrees C above ambient temperature and during that period the difference in monitor and program temperatures was very small About 7 00 am the monitor began to indicate a temperature below the air temperature while the program predicted a temperature increase resulting from changes 1n the wind direction and velocity The curves in Figure 25 show a reasonable trend in the two temperatures but the program is consistently 5 10 C higher than the monitor temperature Once again the monitor measured a temperature below the ambient temperature for a brief period near midnight The curves in Figure 26 are a continuation of those in Figure 25 The monitor continues to measure temperature lower than the surrounding air temperature for a period of over four hou
60. a brief report on our progress on Project 2546 since the Paris CIGRE meeting 1 Development of DYNAMP Version 1 2 of DYNAMP has been completed and the user s manual has been changed to reflect operation of the revised program Version 1 2 differs from 1 1 in the revisions that were outlined in the last quarterly report presented in Boise Idaho Two copies of Version 1 2 have been mailed in addition to the copy that I mailed to you in October They were sent to R A Fiqueroa of San Diego Gas and Electric and J J Hipius of Niagara Mohawk Power Corporation 2 Program Verification All line temperature data collected at the Forest Park test site has been analyzed with DYNAMP and the difference between the Measured temperatures and predicted values have been analyzed with our statistical package Errors continue to be less than 10 C for more than 92 of the data points and over 75 of the data is within 5 C of the temperatures predicted by DYNAMP Weather data at the four sites remote from the Georgia Power test span has been collected and put into DYNAMP These data were obtained over a common three week period at sites between two miles and 30 miles from Forest Park All of these data have been collected as part of the Idaho Power project and they have been run through DYNAMP but not yet analyzed statistically However preliminary Georgia Institute of Technology Atlanta Georgia 30332 0405 heo bobo vm e
61. and Axial Temperature Gradients in Bare Stranded Conductor IEEE Paper No 85 5M 402 3 presented at the 1985 Summer Meeting Vancouver B C Jeffrey W Jerrell Critical Span Analysis of Overhead Lines M S Thesis School of Mechanical Engineering Georgia Institute of Technology March 1987 A C Resistance of ACSR Magnetic and Temperature Effects Prepared by the Task Forces of the Working Group on Calculation of Bare Overhead Conductor Temperatures 84 SM 700 1 pp 1578 1584 June 1985 D m Tg APPENDICES The following papers were presented at the Real Time Ampacity Seminar held in Atlanta on May 20 21 1986 Table 12 Titles of Presentations at the Real Time Ampacity Seminars Seminar on the Effects of Elevated Temperature Operation on Overhead Conductors and Accessories May 20 1986 Alurninum Conductor Elevated Temperature Considerations W B Zollars Aluminum Conductor Products Company High Temperature Operation of ACSR Conductors J S Barrett Ontario Hydro The Effect of Temperature on the Loss of Tensile Strength of Overhead Conductors V T Morgan CSIRO Division of Applied Physics How Maximum Conductor Temperature Affects Line Costs D A Douglass Power Technologies Inc Thermal Ratings for Bare Overhead Conductors Pennsylvania New Jersey Maryland PJM Interconnection Guive Nabet Baltimore Gas amp Electric Company Current Cycling Connectors in Tension C B DeLuca P
62. c vea ORE Wind Velocity Sensitivity Wind Direction Sensitivity Current Sensitivity Emissivity Sensitivity Absorptivity Sensitivity Location of Test Span and Remote 514 5 Measured and Predicted Temperatures for Base Station Measured Temperature at the Base Station and Predicted Temperature at Remote Site 1 Errors in Predicted Conductor Temperature as a Function of Distance Between Span and Weather Errors in Predicted Conductor Temperature as Function of Wind Velocity for Five Weather Stations Errors in Predicted Conductor Temperature as a Function of Wind Direction for Five Weather Stall ONS da bs Initial Monitor Calibration Final Monitor Calibration DYNAMP Predictions for Curlew Conductor on October 16 M eer TT m 36 37 38 39 40 Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 16 1986 T DYNAMP Predictions for Curlew Conductor on October 17 1986 dis Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 17 1986 DYNAMP Predictions for Cu
63. cost and month year in which costs are Grand total of lines 1 2 3 4 486 expected to be booked Current Year Actual Current Year Forecast Future Year s Forecast Remarks Comments on significant Items CONTRACT NUMBER 2 15 1416 I LJ PROJECT MANAGER Name Actual booked cost in the a BD year Forecast to complete the current year 19 86 Unbooked liability Please list dollar amount descrp lion of cost and month year in which cosis are expecied to be booked ito Lon Note Instructions for completing this form are on the reverse slide Remarks Comments on siguificant lems Based on total authorized expenditures through Dec 31 1986 of 400 000 plus 41 000 proposed new funds for final quarter of 1986 Bills that have accured from Georgia Power sub contract but have not been paid by Georgia Tech through August 1986 total 33 118 eer 1 0 CONTRACTOR COST PERFORMANCE REPOHT 177 5 b3R CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER William Z Black School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 404 894 32 DIVISION HUMBER _ PERIOD OF PERFORMANCE From 7 1 84 For Use Only Prior Year s All figures to be shown In U S dollars w
64. de Je e Je de de e dee Je de de Je e de de de dee Je de de dee Je de de Je dede Je dee Je Je dede dede e Ra DENSTY PRESR R TEMP 273 15 END uu Purpose Input Output Common Blocks Computer Symbols and Symbol A AU A2 A3 1 82 83 DENS GBETA GM GR FUNCTION HTC This function subprogram calculates the free and forced convection heat transfer coefficient for the conductor in the surrounding air The forced convective heat transfer coefficient is primarily function of the air velocity The free convection heat transfer coefficient is primarily a function of the temperature of the conductor above the ambient air temperature TIME The local time which in turn can be used to calculate the values for the local weather conditions such as wind velocity and air temperature TEMP The conductor temperature in degrees C HTC convective heat transfer coefficient from the conductor to the surrounding air in W m Description of Variables Description Units Nusselt parameter for free convection Coefficients for free convection Coefficients for forced convection Density of air at average air temperature and logal elevation kg m g8 v for air 1 m Line axis orientation from south radial Grashof number of air Thermal conductivity of air W m 9C Logarithm to the base of 10 for the free convection Nusselt number Nusselt number Forced convection Nusselt number uncorrected for wi
65. desired selection the user should press the Enter If the user desires a better understanding of the items on the menu the i key should be pressed for help the example shown below the user is being asked to select between steady te transient or predictive run types Run Steady state Predictive F1 Help Space Bar Next Choice Enter Select Choice s18 The cursor is presently positioned over the transient selection If the user sresses the Enter key the program wil assume the user wishes to calculate conductor temperatures for transient operation Prompts her tne user is asked to answer a question prompt the program will provide a to the rignt of the question for the response Conductor code tne example above the user is prompted for the conductor code name eld which is shown as a highlighted block will appear on the computer screen 12 aid in the response to a prompt the following instructions are displayed at pottom of the screen Press Fi Help Enter Next Field Esc Leave Form f the user wants information on the input data field the F1 key should be elected To return to the previous menu or screen display the Esc key should selected To move to the next prompt next field the Enter key should be assed ta Files ere are three different
66. entering the desired conductor current amps and weather conditions The weather conditions include the ambient temperature eg C wind direction degrees and the wind speed feet second ter the current and weather data have been entered the user will have entered of the necessary information needed for this example which is a steady state out file However if it ts desired to further edit the contents of the file fore saving it the user will be given a chance to do so If no furtler editing desired the program will save the newly created file in this example the file ed 4EWDAT and return the user to the Module Menu ting Input Data Files General If the user has chosen to edit an existing data file the following i will appear after the data file name has been entered uns DY NAP 5 Edjt Create input data Edit or Create E Input data selector Conductor Properties Date amp Time Line Location Radiation Properties Transient Variables Current amp Weather LEAVE Edit ai Press F1 Help Space Bar Next Choice Enter Select Choice ris menu referred to as the nput Data Selector allows the user to select any ne of the data groups listed on the screen Each data group exists on a separate cf input and any one of the pages may he selected for editing the reen image shown above the highlighted block is positioned over th
67. file called wEWDAT DYNAMP Edit Create input data Edit or Create E C o c 4 Press F1 Help Enter Next Field Esc Leave Form After entering the name NEWDAT the following menu wil appear to prompt for the run type options DYNANP ee a 224 Transient Predictive Press F1 Help Enter Next Field Esc Leave Form If the user is not sure of the definitions of the selections the F1 key can be pressed for help Since it is desired to run the program for steady state conditions tre default selection Steady State is selected After pressing the Enter key the following display appears DY NAMP STEADY STATE sow wol o sron 4 w 9 9 V Maximum conductor temperature C 188 8 Choose Edit LEAVE If the user desires to edit the run type option again d t is selected If the user desires to move to the next data group then Next is selected If the user desires to leave the create file session without saving the new file LEAVE 15 selected and program control returns to the Module Menu lf Next is selected the following prompts for the Conductor Properties data set appear JY MAH Conductor Properties Conductor code mame STANDARD Conductor A ACSR Total coaductor outside diam
68. file within that sata set wi have the same name as the raw input data file Hence the data 526 wil have that name also ETTING STARTED fter selecting DYNAMP from the TLWorkstation Master Menu the following Module enu will appear on the screen The Module Menu is the base from which a DYNAMP ession wil be operated Dynamic fmpacitu for Overhead Transmission Lines NAMP Version 1 8 EPRI Project RP 2546 a t EC EE Via a C EP Gm f oe erat 0 d u 1 H n u ee ee a en Runtime Features Data Management amp Utilities Execute DYNAMF Rename a data set Review input data Edit Create input data Cupu a data set DYMAMIP reports Purge output data only Delete a data set Additronal Features DYMNAMP help facility LEAVE Press F1 Help Space Barl Next Choice Enter Select Choice From this menu the user selects one of several features 1 Data Management and Utilities ox Runtime Features 3 Additional Features Data Management and Utilities enables the user to perform tasks such as editing input files creating input files purging files and other data management tasks Runtime Features allow the user to execute the DYNAMP program and to obtain printed copies of output Note that before the user can execute the DYNAMP program an input data file must have already been created or one of the example input files must be used S
69. in Forest Park on three seperate occasions Results obtained during the first series of tests showed that the device on average was reading temperatures that were 10 low The monitor was sent to the manufacturer for recalibration and repair The jaws were adjusted so that the contact between the temperature sensor button and the conductor was improved The power supply was adjusted so that the threshold current was reduced from 500 amperes to 150 amperes Also the radio signal output from the device was reduced from 2 watts to 250 mw The monitor was then calibrated in a wind tunnel and returned The monitor was re installed on the test span for approximately one week A plot of randomly selected temperatures measured during these tests are shown in Figure 33 These data indicate that the monitor indicates a temperature that is usually within 5 d of the measured line temperature After the monitor was re calibrated by the manufacturer it was forwarded to KG amp E for use in field tests described in Section 5 After the KG amp E field tests were completed the monitor was returned to Georgia Power and reinstalled on the test span for a period of ten days The calibration was rechecked to verify that no significant drift of the output of the device occurred during the KG amp E test program Examination of the data shows that no significant drift occurred although individual temperature variations of 10 to 15 C were encountered Figure 34 Durin
70. is far more common for the wind velocity to show large variations when conditions are calm Therefore calm weather conditions promote large variations in the local conductor temperatures as a result of variations in wind velocity from point to point along the route of the transmission line As the wind velocity increases the conductor temperature becomes less sensitive to changes in wind velocity and the temperature becomes more uniform ft sec LINNET PERPENDICULAR CURLEW PERPENDICUL AR LINNET PARALLEL CURLEW PARALLEL oV 10 20 30 WIND VELOCITY ft sec Figure 22 Wind Velocity Sensitivity Parameter The graph of the wind direction sensitivity parameter shown Figure 23 confirms that the conductor temperature is more sensitive to changes in wind direction as the wind blows down the axis of the conductor This result implies that a wind oriented along the axis of the conductor will be accompanied by larger swings in the conductor temperature than when the wind blows across the conductor Therefore when the wind blows down the axis of the conductor the location of a critical span will have a tendency to move from one location to another while cross flow wind will promote a more stable location for the critical span 0 5 2 Q o A f V IO CURLEW DRAKE ROOK LINNET 1 5 O 30 60 90 WIND DIRECTION Degrees Figure 23 Wind Direction Sensitivity Parameter The
71. is selected If e user wishes to terminate the created file session LEAVE is selected fter selecting NEXT the form for Date and Time input data set will appear Dr NAHP Date amp Time Seca iR MEX Month January February March April May June 24 hr clock Time Zone gust Septesher October November December ress Help Space Bar Mext Choice Enter Select Choice This form allows the user to select the month from a menu Once the user fias sejected the month he is expected to enter the day and time based on a 24 hour clock To complete the Date and fime information a menu will appear requesting the user select one of the four time zones the continental United States The screen image requesting time zone information is shown in the figure below DYNAMP Date amp Time 24 hr clock Zone Time Zone Central Mountain Pacific Press Fi Help Space Bar Next Choice Enter Select Choice rer the Date and Time variables have been entered the user must respond to the shown below Choose One Previous Edit Select LEAVE order to go to the next data group to edit date and time variables or to minate the session er selecting to proceed to the next variable group the user will see following screen image which prompts for the Line Location data set up e DYNAM
72. number of line temperature monitors Locations known to have thermal problems in the past Locations on critical spans Spans that are experiencing exceptional load growth Other locations specify Does your utility utilize the concept of a critical span in determining the real time rating of its network If yes how does your company define a crit cal span clearance below NESC minimum above a given temperature Yes 30 Yes 0000 Yes 9 O No 16r 12 WPM LIOULUS No 6 Give important factors that should be used in providing information from a real time ampacity model Simplicity Ability to handle all types of conductors and all possible weather conditions Completeness of information Others specify should information from a real time ampacity program be conveyed to the user A conductor time constant A time required to reach a predetermined limiting temperature A set of curves that predict temperature VS time behavior of the conductor Other specify Which ampacity method do you feel would give you the greatest confidence in knowing the temperature of the conductors in your service area Computer model On line monitors Explain Yes 5 O 15 O 5 O Cn ro 4 OOO Os No 7 20 70 If multiple answers are checked indicate what factors dictate which limitation is considered in any application 1 Clearance limitat
73. obtained over the past year Differences between DYNAMP s predicted temperatures and the measured line ey ae COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 2 OCT 15 1986 0 MEASURED DYNAMP A AMB TEMP 4 CURRENT g 80 00 t 956 09 TEMP 20 00 40 00 0 00 8 00 10 00 12 00 14 00 TIME HOUR m WIND DIRECTION WIND SPEED OND DEG 60 00 0 00 30 00 WIND ANGLE WITH C c 0 00 8 00 10 00 12 00 14 00 TIME HOUR 16 00 16 00 Figure 16 Measured and Predicted Conductor Temperatures for October 15 1986 175 00 150 49 125 00 CURRENT AMPS 100 00 75 00 PH 4 IND SPEED M Pe temperatures average less than about 5 C over the 14 hours that data were collected The data for October 20th shown in Figure 17 was collected during a period of much higher current and during that period the conductor temperature exceeded 125 C Even at these high temperatures the trends predicted by DYNAMP remained excellent The data in Figures 18 and 19 give an indication of the relatively large errors that can result when the wind velocity decrease to zero and the wind direction is down the axis of the conductor Figure 18 for conditions on October 21 shows expected accuracy except for two brief periods Around midnight between 0 00 and 1 00 am
74. of Dekalb Junior College It was owned by the Department of Natural Resources of the State of Georgia The data were recorded continuously on a strip chart recorder and averaged in fifteen intervals because the chart scale made it too difficult to obtain five minute averages Personnel from the Research Center went to the office which stores these charts to visually average the data over 15 minute periods The fifteen minute averages were then entered into a portable IBM PC compatible computer which stored the data in the format of DYNAMP data files Remote site number three was located at the Trappist Monastery in Conyers Ga This facility belonging to the Department of Natural Resources of the State of Georgia was the only site where ambient temperature was not available Wind speed and wind direction were recorded continuously on a strip chart recorder The data was visually averaged over 5 minute periods then stored on disk in DYNAMP format Remote site number four was located at the Shenandoah Solar Center in Shenandoah Georgia This facility routinely monitors weather as part of ongoing research for Georgia Power and Department of Energy projects Weather data were sampled every twelve seconds and averaged for each minute The one minute averages were stored on tape by a DEC mini computer For this project the one minute averages were transferred to the Research Center using a modem The data were then averaged for each five minute peri
75. of a critical span will have a tendency to move from one location to another while cross flow wind will promote a more stable location for the critical span 00 0 30 Wind Direction deg 60 90 Figure 2 Wind Direction Sensitivity Parameter The current sensitivity parameter is plotted in Figure 3 These curves show how the current affects the temperature for a wide range of conductor sizes When a conductor at a given load has the current changed by a fixed amount the larger conductor will experience smaller change in temperature while the temperature of the smaller conductor will change a greater amount At higher currents the sensitivity to a change in current is greater for all conductor sizes Therefore a heavily loaded small conductor will experience large temperature changes for relatively small changes in current Large lightly loaded conductors are less sensitive to changes in current The implication of the sensitivity parameters shown in Figures 1 2 and 3 can be applied to the task of predicting the location of a critical span The desire to locate a critical span will coincide with conditions that lead to a maximum conductor temperature A system operator would have the 100 80 fs Remote Site 60 2 Remote Site 2 Remote Site 3 Remote Site 4 Base Station Percent of Data O 10 20 30 40 50 60 Differencein Measuredand Predicted Temperature C Errors in Predicted Conductor Temperature as a F
76. option is chosen Preiictive Variables Overload Current The program assumes chat there will be a step change Amps from the normal current to the overload current n the program is in the predictive mode the time required for the conductor to zh the iimiting temperature specified in the Run Type Variables is calculated the current increases in a step fashion to the overload current This ulated time internal is shown as At in Figure 2 2 5475 Section 3 DYNAMP OPERATION GENERAL OYNAMP FORTRAN program is part of the Ti Workstation Software Package user executes the interactive DYNAMP software system through a series of interactive menus and prompts which are displayed on the screen With this system the user can create and edit input data files rename data files execute the DYNAMP FORTRAN program and perform severa other tasks Menus The menus are designed so that each is responded to in a similar fashion When a ser is presented a menu the following instructions will be displayed at the wttom of the screen Pross 71 Help Space Bar Next Choice Enter Select Choice hese instructions can be used to select a choice from the menu For menus e method is the same Selections are made by positioning a highlighted cursor ver the desired selection The cursor is moved from one selection to the next by essing the space bar or by pressing the cursor keys t the rsor is positioned at the
77. spans showed that the number of critical spans increases as the wind velocity decreases as the wind blows down the axis of the conductor and as the conductor current increases Since all of these trends produce high conductor temperatures the greatest need to know the location of a critical span coincides with conditions which make it most difficult to predict the location of a critical span Therefore while the concept of critical span may be very appealing one to an operating or design engineer it is also an extremely difficult one to implement The experimental data collected in support of the critical span study has shown that weather stations installed to support the ampacity model or line monitors installed to measure the conductor temperature must be spaced on the order of one to two miles apart when the wind velocity is low For periods when the wind velocity is higher and more sustained reasonable accuracy can be achieved when weather stations or line monitors are much more widely spaced Good correlations were obtained from the program at higher wind speeds with weather stations located up to twenty five miles apart Each utility must take into account their own geographical location transmission routes and predominant weather patterns when siting locations for either weather stations or monitors UA T 5 10 11 12 13 14 SECTION 11 DRAE E George E Luke Current Carrying Capacity of Wires and Cab
78. station These data then could be used to show the temperature variations that a conductor would have at different locations as a result of different weather conditions Also these data could be used to show how the conductor temperature would vary from spot to spot at the same time and ultimately support the predictions provided by the sensitivity parameters Three of the four remote sites were chosen because the requ red weather data was alr ady available and recorded by existing equipment in five or fifteen minute time intervals Equipment to measure and record weather data at a fourth remote site was assembled and installed when no other existing location could be found which could provide weather data in less than hourly intervals Table 11 contains a brief summary of information for the four Remote Sites plus the Base Station Table 11 Weather Station Site Summary Distance From Test Span miles automated automated manual manual automated Remote site number one was located one mile 1 6 km south of the test span A pole was set at this site and the weather station sensors were installed on the top of the pole desktop microcomputer and data acquisition system were used to read the sensors once each minute These readings were averaged for five minute periods and stored on diskettes Remote sites number two and three are located 7 6 miles 12 2 km northwest and 18 3 miles 29 3 km east of the test span respectively
79. the 1sothermal ampacity model will not provide a conservative estimate of the conductor temperature It merely provides an average conductor temperature and strands near the center of the conductor will be hotter than it ROOK HAWK LINNET N DRAKE 115 lOS 95 j iii T C ko 2 0 Wmm C Ks 1 5 W m C a SURFACE SOTHERMAL MODEL 1000 1500 2000 I Amps Figure 2 Temperature as a Function of Current for Several ACSR Conductors predicts even though the temperature of the center strands will be underestimated by only a few degrees in worst of conditions For example the Isothermal Model curves in Fig 2 show that the 750C ampacity value for the given conditions and a Hawk conductor is 960 amps The Non Isothermal Model reveals that the Hawk conductor with this current will actually have a center temperature of approximately 78 7 C and a surface temperature of about 73 40C These figures tend to reinforce the conclusion that ampacity calculations based on an isothermal mode are sufficiently accurate for normal rating purposes Figure 3 provides an illustration of the radial temperature var ation in a typical ACSR conductor The curve shows that the Drake conductor at 1100 amps results in a maximum difference in conductor temperatures of about 40C Furthermore the temperature is practically isothermal in the steel core and the vast majority of the temperature drop occurs in the aluminum strand
80. the EPRI research project 2546 KEURP provided funding to evaluate dynamic line rating systems using data collected at field sites for four conductor sizes Both the weather data based DYNAMP program and the l ne monitor were evaluated The operation of DYNAMP for weather conditions that exist in Kansas will give an idea of the program accuracy for weather that differs significantly from that in Georgia Also the program carried out in Kansas will give added operating experience in use of line monitors The weather conditions and topography of each service area greatly affect the current carrying capacity of an overhead conductor The strong prevailing winds and flat terrain in Kansas contrasts drastically from the Georgia Piedmont which typically has light to moderate wind speeds and a hilly terrain The results obtained in Kansas coupled with the data generated in Georgia will hopefully show the applicability of 2 17 x dynamic line rating system for two greatly different geographical locations Between July 23 and October 7 1986 data was collected on four different conductor sizes at two different locations as shown in Table 35 Table 3 Kansas Field Sites Conductor Size Conductor Type Generating Plant 795 ACSR Drake Gordon Evans 666 ACSR Flamingo Gordon Evans 954 ACSR Rail Weaver 477 ACSR Hawk Weaver The initial work was performed on a 795 Drake conductor adjacent to the Gordon Evans Generating Plant Substation outside
81. the concept of critical span is quite simple unfortunately it 15 difficult to put into practice The temperature of an overhead conductor is a complex function of a wide variety of parameters including conductor size current electric resistance weather conditions line location and orientation localized sheltering of the conductor and radiative properties of the surface of the conductor Any computer mode or line monitoring equipment must successfully account for all of these factors if they are expected to accurately predict the conductor temperature In order to predict the location of the critical span one must know how sensitive the conductor temperature is to the numerous parameters which influence it This requirement leads to the definition and derivation of sensitivity parameters which are discussed in the next section These parameters wil help determine whether a critical span can located with any accuracy and repeatability SENSITIVITY PARAMETERS The transient or real time variation in the temperature of an overhead conductor can be determined by solving the following differential 12 ST Q 1n 4emzDT xDh DQ c un e o PATERE en el t g 0T 4 eoxDT gt xDh I OR 9 4eaxDT sDh 2 Ro Table 1 A _ x0 T T Kio a Rey 2a Replog oRep 1 194 sinu 0 194cos2us0 36851n2u R 8T 4ecwDT xh 10 T T cosu 0 3
82. the line A static wire was installed above the test span to further enhance the protection of instrumentation attached to the conductor All thermocouples and signal leads were provided with transient protection The output signal from the weather station was transmitted to the data acquisition system via a fiber optic link Despite these protective measures lightning damage still occurred occasionally to various parts of the measuring system The test system was originally built in 1981 and it was originally designed for a two year test program The test span was operated with a Linnet conductor from August 1982 to October 1985 In the fall of 1984 the EPRI Conductor Temperature Research Project was initiated and the existing facility was upgraded The lightning protection system was reviewed resulting in the following changes A fiber optic link was installed to the weather station and the thermocouple shielding was made continuous from the point of conductor attachment to the entry of the data acquisition system Additional ground rods were driven to provide a more substantial ground field Also software modifications were written to allow the polling of the weather station to collect data Additional software allowed transfer of data from the HP cassettes to floppy disks The Curlew conductor was installed on the span in November 1985 Additional guying was added to support the heavier conductor The Curlew conductor was used until October
83. the strands The implications of this assumption are discussed more thoroughly in Section 4 An energy balance on a unit length of conductor results in a governing equation which can be solved for the conductor temperature T as a function of time t the mass of the conductor m specific heat of the conductor and the various contributions to the heat input to the line The energy balance equation is z aa rti 7 1 This equation is identical to the steady state energy balance a conductor except that the term on the left side of the equation has been inserted to include energy stored in the conductor during periods of transient operation The symbols mcp in Eq 1 represent the average mass specific heat product of the composite conductor on a per unit length basis The symbol Qgen represents the rate of heat generation per unit length due to current in the line This term is a function of both time and conductor temperature became the current is a function of time and the conductor resistance is a function of temperature term Qsun is the rate of both direct and diffuse solar energy absorbed per unit length of conductor This term is a function of time due to the variation of solar energy incident on the conductor during the day term Qrad is the emitted radiation from a unit length of conductor This term 15 a function of the conductor and environment temperatures Finally t
84. their own steady state ampacity value various forms of the steady state ampacity values that are presently used by the various utilities are quite different Ampacity values are primarily in the form of tables and they appear to be fairly evenly split between the aluminum association tables manufacturer tables and tables that were developed with internally generated computer programs most frequently mentioned program was one based on the House and Tuttle method The conditions used in the ampacity tables are fairly consistent among those utilities that have steady state ampacity programs Two thirds of those who responded report that they calculate their ampacity values for a constant wind velocity of 2 ft sec remainder use velocity of 4 4 ft sec with the exception of one company which calculates ampacity based on a zero wind velocity Two thirds of the companies account for solar heating of the conductor while the remainder ignore the influence of the sun when determining the temperature of the conductor With the exception of one company the emissivity and absorptivity of the conductor regardless of whether the conductor is aluminum or copper is assumed to be 0 5 None of the companies consider the effect of age on the radiation properties of the conductor All companies calculate a normal ampacity rating while only seventy five percent calculate an emergency ampacity rating Normal ampacity values correspond to a
85. within twenty feet of the conductor The experiments were conducted at two sites the KG amp E Gordon Evans generating station and the KG amp E Weaver substation Gordon Evans is approximately six miles northwest of Wichita and the Weaver substation is located about eight miles east of Wichita The first series of tests were performed at the Gordon Evans site between July 21 and August 1 1986 The next series of tests were performed at the Weaver Substation between September 15 and September 25 1986 The conductors involved in the test program are described in Table 5 Table 5 Field Site Conductor Characteristics SUBSTATION CONDUCTOR STRANDING AREA DIAMETER VOLTAGE Gordon Evans Flamingo ACSR 24 7 666 kcmil 1 000 in 138 kV Gordon Evans Drake ACSR 26 7 795 kcmil 1 108 in 138 kV Weaver Hawk ACSR 26 7 477 1 0 858 69 kV Weaver Rail ACSR 45 7 954 xcmil 41551 138 The data recording equipment was designed constructed and operated A block diagram of the recording system is shown in Figure 11 The wind speed wind direction and air temperature sensors were mounted near the conductor on a wood pole which was installed by KG amp E line crews The wind speed sensor was a Cup anemometer manufactured by Maximum Inc which has a sine wave output with the output frequency proportional to wind speed The pulse accumulator counts the anemometer output and produces a pulse for each 1 60 mile of w
86. 0 5 21 20 363 361 358 357 358 359 359 361 360 360 WIND DIRECTION DEGREES Errors in Line Monitor Temperature when Wind is from the North Figure 12 Monitor Temp 88 5 C MONITOR SURFACE TEMP 2 Q J NE Average Surface Temp 92 1 C Average Ambient Temp 19 0 C Last Calibration Average Average Error 5 2 C Y y MQ 2 LOZ gt gt mE P 20 I E S lt _ pO E 2 X O lt T ay lt w fr G CONS O RO 22 c RQ MN 9 o o Oo 5015 139 5334930 31 292 Errors in Line Monitor Temperature when Wind is from the South Figure 13 SURFACE TEMP Avg Surface Temp 83 0 C Avg Monitor Temp 82 1 C Avg Ambient Temp 16 3 C Last Calibration Avg Error 1 9 C 7222 MONITOR LEGEND x O Y LJ OIA ES 74 SOL 0 lt lt Z Wea jd lt O P IA A dl YE tae 5115133 338939 9 31 92 89 T 94 89 95 88 92 95 87 88 a o o WIND DIRECTION DEGREES Errors in Line Monitor Temperature when Wind is from the East Figure 14 MONITOR E 2
87. 0 c e d gt 50 6 S 9 a Marigold Conductor 4 5 N 40 gt mp lt 30 90 Teo 304 C 30 15 30 45 60 7 90 105 120 TIME MINUTES Figure 21 Comparison of DYNAMP and PG amp E Wind Tunnel Data for Marigold Conductor after a Series of Seven Current Step Chanqes SECTION 8 0 A CRITICAL SPAN ANALYSIS INTRODUCTION bap The utility survey See Section 2 revealed the fact that many utilities subscribe to the concept of a critical span Most engineers define a critical span as one which operates at a temperature above the remaining spans in the transmission line and it therefore thermally limits the amount of power that can be delivered by the circuit Regardless of whether a utility has decided to measure conductor temperatures with line monitors or predict them with a computer model based on measured weather conditions the concept of a critical span will help reduce the capital investment necessary to institute a thermal line monitoring scheme Therefore the concept of a critical span is a desirable one because it tends to simplify the complicated problem of predicting the real time temperature of an entire transmission circuit The critical span therefore represents a thermal chokepoint which limits the amount of power that can be delivered by the circuit The concept of a critical span is a particularly attractive one to an operating engineer who has the responsibili
88. 0 95 9 96 6 97 2 97 7 98 0 98 3 98 6 98 8 99 0 99 2 99 3 99 4 99 5 99 5 99 6 99 6 99 6 99 7 99 7 99 7 99 8 99 8 99 9 99 9 99 9 99 9 99 9 99 9 99 9 99 9 99 9 100 0 100 0 53 7 54 5 53 1 52 1 50 7 48 8 45 9 44 7 40 1 37 9 35 3 35 6 34 0 35 7 38 0 32 1 34 0 29 6 31 0 28 7 31 4 32 7 30 4 28 1 24 5 42 1 24 4 33 5 45 0 31 3 16 8 26 4 17 5 35 1 22 4 32 3 14 5 38 0 26 2 24 0 13 0 19 0 69 1 1 0 36 1 DEG ST DV 21 3 21 2 21 4 22 6 22 9 23 3 23 8 24 7 25 3 24 2 24 6 25 6 24 6 24 8 27 5 25 2 25 0 24 27 28 26 26 27 23 22 26 26 30 25 31 18 26 26 29 20 36 14 4 0 LK We NOD CO FP NOD M Ob 0 0 0 27 35 Ch US CO BR CH UO o FT S C9 Un OO 4 SO I KALKI OWS O9 I Q OS P OS I US S S O00 ND P9 P MO AV SPEED SPEED ST DV NS O O O FP KH Ui Os OS UWI bo IN UW DO IS Ome SM IN S B D O QO t KF QC PN IN FD DW N WW CO UL C UO IO UO UO W DW DW DW CO CO UO W W W PERCENTAGES CONV REGIME FREE INTP FORCED LO Wo OO Un amp AAD C iO ON I CO CO eS I OO BD UA f dM 9
89. 0 14 00 16 00 8 00 10 0 TIME HOUR m WIND DIRECTION WIND SPEED DEG oo 60 00 30 00 WIND ANGLE WITH COND 0 00 12 00 14 00 16 00 00 2 00 4 00 6 00 8 00 10 00 TIME HOUR Figure 35 DYNAMP Predictions for Curlew Conductor on October 16 1986 180 00 120 150 00 407 90 60 00 0 CURRENT AMPS 30 00 18 50 12 00 B 00 WIND SPEED MPH 4 00 00 18 00 TEMP 40 00 CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 16 1986 5 pj MEASURED DYNAMP MONITOR 8 inp zi S 8 8 235 0 00 2 00 4 00 12 00 14 00 16 00 18 00 8 00 10 00 TIME HOUR Figure 36 Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 16 1986 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 17 1986 S m MEASURED AMB TEMP CURRENT EN o of g A p Me NC 8 a 0 00 1 50 3 00 6 00 7 50 9 00 10 50 12 00 TIME HOUR g m WIND DIRECTION WIND SPEED uJ a 5 584 4 E unt r 4 4 n uj D dim Oo Wi V 7 gt n OI LU lt j 1 Y n 1 0 00 1 50 3 00 9 00 10 50 12 00 6 00 7 50 TIME HOUR Figure 37 DYNAMP Predictions for Curlew Conductor on October 17 1986 200 00 150 175 00 40 125 00 CURRENT AMPS
90. 0 99 9 26 2 4 6 4 0 1 7 6 0 0 100 0 24 0 11 0 4 3 1 4 1 0 0 100 0 13 0 0 0 5 3 0 0 1 0 0 100 0 1 0 0 0 5 5 0 0 5 0 0 100 0 21 0 34 4 2 3 3 6 5 CONV REGIME 7 FREE INTP FORCED 98 3 98 1 97 6 96 8 96 9 96 1 94 9 92 7 94 5 91 4 94 3 89 6 88 2 91 7 87 4 93 8 82 3 85 2 83 3 88 6 88 1 95 8 91 3 88 5 75 0 83 3 60 0 87 5 85 7 100 0 90 0 66 7 88 9 71 4 100 0 50 0 100 0 100 0 83 3 100 0 100 0 40 0 L e o D e e ON S SON Us Gi CO WW IND mem e o oe Oc U O O O J O Ui J NO NONN Ov OO ON Ut C2 1 SO I IN USO dM N P C QN Table 7 Statistical Analysis of Data Points Where Predicted Temperature is Greater than Measured Values BASE STATION TEMPERATURE RANK PERCENTAGES DYNAMP PREDICTS LOWER THAN MEASURED ERROR NO PERCENT PERCENT AV ANGLE ANGLE AV SPEED SPEED CONV REGIME C PTS lt DEG ST DV FT S ST DV FREE INTP FORCED 1 2109 8 5 51 8 52 8 21 8 5 0 2 3 3 07 0 00 97 0 2 1421 5 8 66 7 50 0 22 1 4 4 2 2 4 8 0 00 95 2 3 918 3 7 76 4 47 0 23 7 3 9 2 1 8 0 0 00 92 0
91. 0 ft sec while the actual wind speed was not recorded but was somewhere between 0 and 0 5 ft sec The lack of accurate wind velocity data resulted in a predicted temperature that was higher than that measured During this same time period the monitor temperatures remained within a few degrees of the measured conductor temperatures as shown in Figure 40 The monitor and measured line temperatures were compared when the wind was oriented both parallel and perpendicular to the conductor and the results indicated that the monitor accuracy was affected by wind direction The monitor tends to read high when the wind is blowing from the west on the monitor installed on a North South line This trend occurs because the back of the monitor shields the conductor from the wind and a local hot spot in the conductor is produced Depending on the direction of the wind the monitor can act as a heat sink wind shield or combination of both resulting in measured conductor temperatures that can be either higher or lower than the true temperature COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 16 1986 MEASURED DYNAMP AMB TEMP CURRENT 120 00 o 2 m 4 ze F pt 80 00 RES C TEMP e 40 00 c gt E 2 FE 20 00 lt 0 00 00 2 00 4 00 0 12 0
92. 00 Select a value greater than 0 but less than 25 000 ft Input Value of has been set ace er M v9 a Mam a A Tm a mnm mee m e rr as m Solar Absorptivity Urreasistic Input Value for Solar 21 ty of Conductor unrealistic Input Infrared value for Emissivity Emissivity of Ccrductor Conductor Temperature Conductor is Above 400 C and is Temperature cut of Range stic fone value for the Month the Year unrealistic Input Day alue for the Day of the Month reaiistic Input Value Hour r the Hour of the realistic Input Value or the Minute cf AE Hour 61 Select a value between 0 and 1 0 Select a value between 0 and 1 0 The program is attempting to calculate a conductor temperature which exceeds 400 C Reduce the conductor current or increase the conductor Select an integer value between 1 and 12 Select an between 1 integer value and 31 Select an integer value between 0 and 23 Select an integer value between 0 and 59 e M Unrealistic Input Wind Velocity Select a positive value value of Conductor is less than 100 000 amps Current Unreaiistic Input Limiting Select a value between 20 value for the Emergency Temperature and 300
93. 1 6 48 6 0 00 51 4 15 22 0 1 99 1 38 3 27 9 2 0 1 6 59 1 0 00 40 9 16 22 0 1 99 3 34 0 26 2 1 6 1 6 59 1 0 00 40 9 17 14 0 1 99 5 34 3 19 9 1 2 1 4 71 4 0 00 28 6 18 12 0 0 99 6 37 9 29 9 1 3 1 3 58 3 0 00 41 7 19 5 0 0 99 7 31 7 30 9 2 6 1 6 40 0 0 00 60 0 20 5 0 0 99 7 45 5 18 0 2 5 1 1 0 0 0 00 100 0 21 4 0 0 99 8 47 0 14 3 2 6 0 7 0 0 0 00 100 0 22 4 0 0 99 8 44 1 17 8 3 0 0 4 0 0 0 00 100 0 24 1 0 0 99 8 37 0 0 0 1 8 0 0 0 0 0 00 100 0 25 3 0 0 99 9 62 7 11 0 4 0 4 0 0 0 0 00 100 0 26 2 0 0 99 9 10 1 2 8 8 1 9 8 50 0 0 00 50 0 33 3 0 0 99 9 78 3 11 2 2 5 0 5 0 0 0 00 100 0 42 1 0 0 99 9 19 0 0 0 2 3 0 0 0 0 0 00 100 0 43 1 0 0 99 9 69 1 0 0 2 8 0 0 0 0 0 00 100 0 50 7 0 0 100 0 46 8 16 7 5 7 2 2 0 0 0 00 100 0 Table 6 Statistical Analysis of DYNAMP s Predicted Temperatures for Data Points Where DYNAMP is Less Than the Measured Temperatures 38 BASE STATION TEMPERATURE RANK PERCENTAGES DYNAMP PREDICTS EXACTLY AS MEASURED ERROR NO PERCENT ANGLE ANGLE SPEED SPEED CONV REGIME 2 C PTS DEG ST DV FT S ST DV FREE INTP FORCED 0 2817 11 4 53 7 21 3 5 7 2 6 1 5 0 00 98 5 Table 6 Continued 39 velocities see column labeled AV SPEED and when the wind is more in cross flow than parallel flow see column labeled AV ANGLE C Analysis of Remote Weather Data The weather data collected at the test span and the four remote sites were used as input to DYNAMP and line temperatures were calculated for
94. 1 9 0 00 98 1 3 2205 8 9 62 2 54 1 21 8 6 9 3 4 2 4 0 00 97 6 4 1643 6 7 71 3 52 8 22 2 6 5 3 4 3 2 0 00 96 8 5 1216 4 9 78 0 50 9 22 7 6 1 3 3 3 1 0 00 96 9 6 913 3 7 83 1 47 9 23 4 5 8 3 2 3 9 0 00 96 1 7 700 2 8 87 0 46 8 24 8 5 5 3 1 5 1 0 00 94 9 8 523 2 1 89 9 41 8 24 9 5 3 3 2 7 3 0 00 92 7 9 345 1 4 91 8 40 7 23 7 5 0 2 8 5 5 0 00 94 5 10 268 1 1 93 3 37 5 25 0 5 3 3 2 8 6 0 00 91 4 11 212 0 9 94 5 36 7 26 0 5 4 2 9 5 7 0 00 94 3 12 163 0 7 95 4 34 5 23 9 5 2 3 1 10 4 0 00 89 6 13 144 0 6 96 2 35 4 24 0 4 9 2 9 11 8 0 00 88 2 14 109 0 4 96 8 36 3 26 8 5 5 3 1 8 3 0 00 91 7 15 87 0 4 97 3 30 5 24 4 5 4 3 5 12 6 0 00 87 4 16 65 0 3 97 6 34 0 24 8 5 3 3 1 6 2 0 00 93 8 17 62 0 3 98 0 28 5 25 8 5 3 3 0 17 7 0 00 82 3 18 54 0 2 98 3 29 4 27 0 4 6 2 7 14 8 0 00 85 2 19 42 0 2 98 5 28 3 28 2 5 4 3 1 16 7 0 00 83 3 20 44 0 2 98 7 29 8 27 3 5 5 3 5 11 4 0 00 88 6 21 42 0 2 99 0 31 3 27 1 5 9 3 6 11 9 0 00 88 1 22 24 0 1 99 1 28 2 28 6 5 8 3 1 4 2 0 00 95 8 23 23 0 1 99 2 28 1 23 9 4 8 3 6 8 7 0 00 91 3 24 26 0 1 99 4 24 0 22 7 5 9 3 6 11 5 0 00 88 5 25 12 0 0 99 5 37 0 26 9 4 3 1 9 25 0 0 00 75 0 26 6 0 0 99 5 29 2 29 3 3 9 2 0 16 7 0 00 83 3 27 10 0 0 99 5 33 5 30 2 3 7 3 0 40 0 0 00 60 0 28 8 0 0 99 6 45 0 25 9 4 1 2 9 12 5 0 00 87 5 29 7 0 0 99 6 31 3 31 5 4 4 2 1 14 3 0 00 85 7 30 5 0 0 99 7 16 8 18 1 5 6 1 3 0 0 0 00 100 0 31 10 0 0 99 7 26 4 26 3 5 1 1 6 10 0 0 00 90 0 32 9 0 0 99 8 17 5 26 7 5 9 2 1 33 3 0 00 66 7 33 9 0 0 99 8 20 7 15
95. 2 Future Unbooked Forecast to Remaining Year s liability complete the Years s Forecast Please list dollar future year s bon cost and month year in Ch Lie E Grand of lines 1 2 3 14 exnecied to be booked Remarks Comments on significant items Based on total authorized expenditures through Dec 31 1986 of 400 000 plus 41 000 proposed new funds for final quarter of 1986 Bills that have accured but have not been paid are as follows Georgia Power April 8181 May 7456 June 472 July 10 000 Aug 7000 Total 33 118 PREPARED BY W Z Black Print name Georgia Tech expenses for summer quarter 1986 p Total 26 000 Title rofessor J CONTRACTOR COST PERFOR R MANCE REPORT PRI 177 FERLCONTRACT EPRI DIVISION NUMDER For EPRI Use Only CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER 2 5 4 6 W Z Black 404 894 3257 EPRIPROJECT MANAGER School of Mechanical Engineering M ein buda cu 6 30 87 Georgia Institute of Technology Mane Vito Longo os hee cca Atlanta GA 30332 Prior Year s Actual Note Instructions for compleling this form are on the reverse side All figures are to be shown in U S dollars whole thousands only Show EPRI portion of the contract only Do not Include contractor cost sharlng Actual booked current year 19 11 Forecast to complete the Jan Feb Mor
96. 2370 Ga Hwy 212 Conyers Ga 33 35 8 N 84 4 O W Climet 0603 0 6 mph 19 0603 0 75 mh t3 Strip Chart Continuous Remote Site 4 Shenandoah Gcorgia Power Co 7 Solar Circle Shenandoah Ga 33 24 17 N 84 44 52 W Climatronics 5 10 0 5 mph 0 15 moh or 1 WD 10 0 25 mph 2 58 TN 10093 0 2 DEC Tape 1 minute Mini Warehouses n 20 20 20 10 10 10 6 Foot Fence Weather station 39 Feet High 700 ft Test Span Transformer Storage Racks Base Station L 1 Research Center Scale Test Span 1 inch 60 Feet Figure 1 ene View of Base Station at Forest Park Test pan COCOS eX UE OO 6 Foot Fence Parking Area 6 Foot fence 6 Foot Fence Gravel Weather Station Scale 1 inch 60 Feet Remote Site 1 High Voltage Lab Figure 2 Plan View of Remote Weather Station Number 1 Street e 46 Foot 1 22 Foot e X 30 Foot Svc Pole Weather Station Pole Instrumentation Trailer Scale Remote Site 2 1 inch 30 Feet South Dekalb College Figure 3 Plan View of Remote Weather Station Number 2 Road O Magnolias Scale 1 inch 30 Feet Hardwood Trees Parking Lot 22 High Weather Station umentation Trailer V 12 High O S Shrubs MS 10 1 os 0 0 9 000000000000607700 22 2522 5 Foot Shrub
97. 3 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 REMOTE 3 CONYERS 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 REMOTE 44 SHENANDOAR 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 23 55 0 00 22 50 B Weather Data Collection at Remotes Sites The utility industry has found little information available to guide the transmission engineer in positioning the data collection equipment necessary to implement a dynamic line rating system Each utility is faced with different length transmission lines unique weather conditions and varying terrain Idaho Power having a strong interest in EPRI project 2546 has contracted with Georgia Power Company through SEI to determine the effects of weather station site selection on line temperature predictions The existing transmission line test span used in the EPRI Project was operated for over two months while time line current conductor temp
98. 4 595 2 4 82 7 44 8 23 6 3 6 2 1 10 3 0 00 89 7 5 412 1 7 87 0 42 7 24 0 3 5 1 9 11 9 0 00 88 1 6 297 1 2 90 1 39 7 28 1 3 4 2 4 21 9 0 00 78 1 7 235 1 0 92 6 38 6 23 2 3 2 2 4 24 7 0 00 75 3 8 163 0 7 94 3 34 8 25 6 2 9 2 3 33 7 0 00 66 3 9 129 0 5 95 7 30 3 24 0 2 8 1 7 36 4 0 00 63 6 10 100 0 4 96 7 29 4 22 7 3 1 2 0 34 0 0 00 66 0 11 69 0 3 97 4 32 5 24 4 2 4 1 4 36 2 0 00 63 8 12 52 0 2 98 0 32 4 27 1 2 4 2 0 46 2 0 00 53 8 13 49 0 2 98 5 36 8 27 2 2 0 1 5 44 9 0 00 55 1 14 37 0 1 98 9 43 0 29 5 1 8 1 6 48 6 0 00 51 4 15 22 0 1 99 1 38 3 27 9 2 0 1 6 59 1 0 00 40 9 16 22 0 1 99 3 34 0 26 2 1 6 1 6 59 1 0 00 40 9 17 14 0 1 99 5 34 3 19 9 1 2 1 4 71 4 0 00 28 6 18 12 0 0 99 6 37 9 29 9 1 3 1 3 58 3 0 00 41 7 19 5 0 0 99 7 31 7 30 9 2 06 1 6 40 0 0 00 60 0 20 5 0 0 99 7 45 5 18 0 2 5 1 1 0 0 0 00 100 0 21 4 0 0 99 8 47 0 14 3 2 6 0 7 0 0 0 00 100 0 22 4 0 0 99 8 44 1 17 8 3 0 0 4 0 0 0 00 100 0 24 1 0 0 99 8 37 0 0 0 1 8 0 0 0 0 0 00 100 0 25 3 0 0 99 9 62 7 11 0 4 0 4 0 0 0 0 00 100 0 26 2 0 0 99 9 10 1 2 8 8 1 9 8 50 0 0 00 50 0 33 3 0 0 99 9 78 3 11 2 2 5 0 5 0 0 0 00 100 0 42 1 0 0 99 9 19 0 0 0 2 3 0 0 0 0 0 00 100 0 83 1 0 0 99 9 69 1 0 00 2 8 0 0 0 0 0 00 100 0 50 7 0 0 100 0 46 8 16 7 5 7 2 2 0 0 0 00 100 0 Table 8 Statistical Analysis of Data Points Where Predicted Temperatures are Less than Measured Values KANSAS GAS AND ELECTRIC FIELD SITE The weather data and the conductor currents collected as part of the KEURP
99. 5 1985 1 Utility Survey Two additional utility surveys were received during this month They are from Don Smith Transmission Planning Manager Georgia Power Company J Babbitt Supervisor of System Planning Gulf Power Company Responses for these two surveys are being incorporated into the master questionnaire 2 Development of DYNAMP The IBM PC version of DYNAMP has been completed and a preliminary floppy disk copy was forwarded to EPRI In addition a rough cut version of a users manual to accompany the program has been sent to EPRI Additional statements have been included in the program to warn the user to improper operation Modifications have been made to the program so that it is capable of predicting conductor temperatures for six different conductor types have been completed 3 Data Collection Project A computer program that modifies the Georgia Power test data and puts it into a form that can be directly interfaced with the IBM PC version of DYNAMP has been completed Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 ENI Foy gt pe 3 Gual EduGaniean and Emeleyement Opisortunity institusion A Unit of the University System of Georgia 4 Forest Park Test Span Facility The Ontario Hydro sag monitor has been installed and tested The output of the device has been interpreted and its accuracy has been evaluated This device will be returned to Ontario Hydro All
100. 70 76 Oct 1956 Frank Kreith and William Z Black Basic Heat Transfer Harper and Row Publishers Inc N Y 1980 28 29 30 31 32 33 34 35 36 37 38 Jan Kreider and Frank Kreith Solar Heating and Cooling rev 1st Ed McGraw Hill New York 1977 Glenn A Davidson Thomas E Donoho George Hakun III P W Hofmann T E Bethke Pierre R H Landrieu and Robert T McElhaney Thermal Ratings for Bare Overhead Conductors IEEE Trans PAS Vol 88 No 3 pp 200 05 March 1969 ASTM Standards Section 2 Nonferrous Metal Products Volume 02 03 Electric Conductors Philadelphia Pa 1986 J A Robinson and C T Crowe Engineering Fluid Mechanics 2nd Ed pp 39 40 Hougton Mifflin Co Boston 1980 M L James G M Smith and J C Wolford Applied Numerical Methods for Digital Computation 3rd Ed pp 94 96 and pp 447 459 Harper and Row NY 1985 i Computer Code Manual TLWorkstationl DYNAMP Version 1 2 EPRI Research Project 2546 Electric Systems Division June 1987 W Z Black S S Collins and J F Hall Theoretical Model for Temperature Gradients with Bare Overhead Conductors IEEE Paper No 86T amp D 501 1 to be published in Trans of IEEE S S Collins Analysis of the Radial Temperature Gradients in Uninsulated Electric Conductors M S Thesis School of Mechanical Engineering Georgia Institute of Technology August 1985 D A Douglass Radial
101. 88sin2u 0 736cos2u ECT _ AE _ 5 10 5 A ag a logRegta logRep o 0 070431 a 0 31526 a 0 035527 ORac k Rp R4 a R R 20 8820 9 R R2 a5 20 a R 20 pO are assumed constant for small temperature changes equation which is the result of an energy balance taken on a unit length of the conductor HT mc I 2 RactadQ sun 070 17 12 hxD T T 1 Equation 1 shows that the conductor temperature 1s a complex function of many factors Obviously not all of the parameters affect the conductor temperature equally Some have a major impact on the conductor temperature while others have practically no influence In order to quantify the effect of each of the variables on the conductor temperature quantities which are called sensitivity parameters have been derived by using the steady state form of Equation l Expressions for each of the sensitivity parameters result by taking derivatives of temperature with respect to each of the independent variables This process produces the seven sensitivity parameters listed Table 1 A detailed derivation of the sensitivity parameters is given in Reference 1 The sensitivity parameters are convenient quantities which show how each variable influences the conductor temperature Therefore they will help to determine the location of critical spans For example the sensitivity parameter for wind velo
102. 9 5 4 1 7 11 1 0 00 88 9 34 7 0 0 99 8 22 4 20 5 4 8 1 6 28 6 0 00 71 4 35 3 0 0 99 9 32 3 36 1 6 3 1 7 0 0 0 00 100 0 36 6 0 0 99 9 14 5 14 4 4 2 1 5 50 0 0 00 50 0 37 2 0 0 99 9 38 0 1 4 5 7 3 1 0 0 0 00 100 0 38 4 0 0 99 9 26 2 4 6 4 0 1 7 0 0 0 00 100 0 39 6 0 0 100 0 24 0 11 0 4 3 1 4 16 7 0 00 83 3 41 1 0 0 100 0 13 0 0 0 5 3 0 0 0 0 0 00 100 0 44 1 0 0 100 0 1 0 0 0 5 5 0 0 0 0 0 00 100 0 50 5 0 0 100 0 21 0 34 4 2 3 3 6 60 0 0 00 40 0 Table 5 Statistical Analysis of DYNAMP s Predicted Temperatures for Data Points where DYNAMP is Greater than Measured Temperatures BASE STATION TEMPERATURE RANK PERCENTAGES DYNAMP PREDICTS LOWER THAN MEASURED ERROR NO PERCENT PERCENT AV ANGLE ANGLE AV SPEED SPEED CONV REGIME Z C PTS lt or DEG ST DV FT S ST DV FREE INTP FORCED 1 2109 8 5 51 8 52 8 21 8 5 0 2 3 3 0 0 00 97 0 2 1421 5 8 66 7 50 0 22 1 4 4 2 2 4 8 0 00 95 2 3 918 3 7 76 4 47 0 23 7 3 9 2 1 8 0 0 00 92 0 4 595 2 4 82 7 44 8 23 6 3 6 2 1 10 3 0 00 89 7 5 412 1 7 87 0 42 7 24 0 3 5 1 9 11 9 0 00 88 1 6 297 1 2 90 1 39 7 24 1 3 4 2 4 21 9 0 00 78 1 7 235 1 0 92 6 38 6 23 2 3 2 2 4 24 7 0 00 75 3 8 163 0 7 94 3 34 8 25 6 2 9 2 3 33 7 0 00 66 3 9 129 0 5 95 7 30 3 24 0 2 8 1 7 36 4 0 00 63 6 10 100 0 4 96 7 29 4 22 7 3 1 2 0 34 0 0 00 66 0 11 69 0 3 97 4 32 5 24 4 2 4 1 4 36 2 0 00 63 8 12 52 0 2 98 0 32 4 27 1 2 4 2 0 46 2 0 00 53 8 13 49 0 2 98 5 36 8 27 2 2 0 1 5 44 9 0 00 55 1 14 37 0 1 98 9 43 0 29 5 1 8
103. AK KAYAK KIBE KENCH KAKI KAZQO REMEX 20I T81 Aluminum Core and Conductor RELEY IRU NTON DARIEN FLINT ELGIN BUTTE ALLIANCE AMHERST 64 GOLDENTUFT CANNAPEACH DAFFODIL TULIP PEONY LAUREL DAISY VALERIAN SNEEZEWORT OXLIP PHLOX REX RAGOUT REDE REDE ANAHEIM AZUSA AMES ROSE BELL SYRINGA COSMOS IRIS ANEMONE LILAC ARBUTUS ASTER POPPY PANSY REDIAN RADAR RAMIE RATCH ALTON AKRON ALAR 6201 181 Aluminum Core and 1350 H19 Aluminum Conductor 2550 d PALL 299 2 RAIL2 2355 3 RAIL3 31 RAILA 8 LES TRE RAILS BLUEBIRDJ DRAKE KIWI DRAKE2 1812 DRAKE3 KIWI DRAKE4 DRAKES HUKAR2 DRAKE6 HUKAR3 TERN LEWING TERNZ 2PWING2 TERN3 i2WING3 TERN t TERNZ BUNTINSI BUNTING2 BUNTINGS BLUEJAY BLUEJAY2 BLUEJAY3 CURLEWI CURLEW2 CURLEW3 CURLEWA ORTOLANI ORTOLAN2 ORTOLAN3 CARDINAL CARDINAL 2 CARDINAL3 GROSBEAKI GROSBEAK2 GROSBEAK3 GROSBEAK4 DOVE1 DOVE2 PELICAN PELICAN2 MERLIN MERLIN2 ACAR900 1 ACAR2000 1 ACAR1600 1 ACAR1000 1 ACAR1000 2 ACAR1200 1 ACAR1200 2 CONDUCTOR TEMPERATURE RESEARCH Research Project 2546 Ok Final Report June 1987 Prepared by Georgia Institute of Technology George W Woodruff School of Mechanical Engineering 275 North Avenue Atlanta Georgia 30332 Georgia Power Company Research Center 62 Lake Mirror Road Forest Park Georgia 30050 Principal Investigators W Z Black Georgia
104. Aw May Jun Jul Aug sep current year M 19 7 E Unbooked Forecast to 422 1 Current Year Actual Future Year s Forecasl Picase list dollar amount descrip ton of cost and month year in which eae are Grand total of lines 1 2 3 4 expected to be booked Remarks Comments on significant items Deliverable 45 PREPARED BY Print name Title EPRI EPRI CONTRACT NUMBER ae 2454 44 6 EPRI PROJECT MANAGER Vito Longo Name Actual booked cost in the current year 19 Forecast to complete the current year 19 ____ Unbooked liability Piease list dollar amount descrip of Cost and month year in which costs are expected to be booked iemarks Comments significant items CONTRACTOR COST PERFORMANCE REPORT 177 5 b4R EPRI DIVISION NUMBER _ PERIOD OF PERFORMANCE 7 1 84 CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER W Z Black 404 894 3257 School of Mechanical Engineering Georgia Institute of Technology Atlanta GA 30332 For EPRI Use Only 6 30 87 From to Prior Year s Actual Note Instructions for completing this form are on the reverse side All figures are to be shown U S dollars whole thousands only Show portion of the contract only Do not includ
105. C Limiting Temperatures The Conductcr Temperature Limiting Value of Wind Speed but less than 85 ft sec 58 Bua Urrealistic Input Wind Direction Select a value between Yalue for Mind Direction 0 and Modi nrealistic Input Air Temperature value 50 fcr the Ambient and 5096 jemp Unrealistic Input Current a positive value that QR Select value for the emergency limiting temperature that exceeds the present conductor temperature when in predictive mode Select a value which is greater than 1 0 is Already Atove the Temperature Emergency Overload Current Ratio Unrealisttc Input yalue of Multiplier for Overload Current Unrealistic Input Value for the Printing Printing Interval I X Mom Select a value that is between 1 and 60 minutes Time unrealistic Input Time Interval Select a value that is value for th Time peeves 1 and 60 minutes Interval MU 62 APPENDIX B LIST OF CONDUCTOR CODE NAMES A separate subprogram within DYNAMP contains conductor properties outer diameter natoer of strands diameter of strands and resistance and these properties be automatically entered into the input file by
106. Choice Enter Select Choice a i ihe Report Selector Menu allows the user to select either the documented input file corresponcing to the file name just entered or the output file analysis Output corresponaing to the file name just entered If the user wishes to have a documented input file and no documented input file exists then a documented input file will be created for the user In addition the user can select a print fi 2 or a new data set name Se ec New Data If either Documentation of Input or Analysis Output 15 selected the Device Selector Menu wil appear on the screen superimposed over the Report Selector Menu DYNAMP DYNAMP reports VITO Data name Report Selector Analysis Output Print File Select New Data Device Selector Output to the Printer Add to Print File LEAVE Help Space Bar Next Choice Enter Select Choice 115 menu allows the user to select the printing destination of the file either If it is desired to print the file to the If the file s to be routed to a Finally the file can also be ie Documented Input or Output file then Output to the Screen is selected inter the Output to the Printer 15 selected ded to the print file which can be sent to the printer at a later time Print Fite is selected from the Report Selector Menu the Action Selector will appear as shown below 44
107. D AD NNN Ie dea m O f OY G0 GC P CO NI Gi P0 C0 NI BASE STATION TEMPERATURE RANK PERCENTAG DYNAMP PREDICTS HIGHER THAN MEASURED NO PERCENT PERCENT AV ANGLE ANGLE AV SPEED SPEED PTS lt or DEG ST DV FT S ST DV 3314 13 4 34 0 55 7 20 7 6 1 2 8 2856 11 6 49 9 54 6 20 9 6 8 3 2 2205 8 9 62 2 54 1 21 8 6 9 3 4 1643 6 7 71 3 52 8 22 2 6 5 3 4 1216 4 9 78 0 50 9 22 7 6 1 3 3 913 3 7 83 1 47 9 23 4 5 8 3 2 700 2 8 87 0 46 8 24 8 5 5 3 1 523 2 1 89 9 41 8 24 9 5 3 3 2 345 1 4 91 8 40 7 23 7 5 0 2 8 268 1 1 93 3 37 5 25 0 5 3 3 2 212 0 9 94 5 36 7 26 0 5 4 2 9 163 0 7 95 4 34 5 23 9 5 2 3 1 144 0 6 96 2 35 4 24 0 4 9 2 9 109 0 4 96 8 36 3 26 8 5 5 3 1 87 0 4 97 3 30 5 24 4 5 4 3 5 65 0 3 97 6 34 0 24 8 5 3 3 1 62 0 3 98 0 28 5 25 8 5 3 3 0 54 0 2 98 3 29 4 27 0 4 6 2 7 42 0 2 98 5 28 3 28 2 5 4 3 1 44 0 2 98 7 29 8 27 3 5 5 3 5 42 0 2 99 0 31 3 27 1 5 9 3 6 24 0 1 99 1 28 2 28 6 5 8 3 1 23 0 1 99 2 28 1 23 9 4 8 3 6 26 0 1 99 4 24 0 22 7 5 9 3 6 12 0 0 99 5 37 0 26 9 4 3 1 9 6 0 0 99 5 29 2 29 3 73 9 2 0 10 0 0 99 5 33 5 30 2 3 7 3 0 8 0 0 99 6 45 0 25 9 4 1 2 9 7 0 0 99 6 31 3 31 5 4 4 2 1 5 0 0 99 7 16 8 18 1 5 6 1 3 10 0 0 99 7 26 4 26 3 5 1 1 6 9 0 0 99 8 17 5 26 7 5 9 2 1 9 0 0 99 8 20 7 15 9 5 4 1 7 7 0 0 99 8 22 4 20 5 4 8 1 6 3 0 0 99 9 32 3 36 1 6 3 1 7 6 0 0 99 9 14 5 14 4 4 2 1 5 2 0 0 99 9 38 0 1 4 5 7 3 1 4 0
108. E Homac Manufacturing Company Elevated Temperature Performance of Conductor Accessories W B Howitt Alcoa Conductor Accessories Inc Seminar on Real Time Ampacity Ratings of Overhead Conductors 21 1986 Dynamic Thermal Line Ratings Summary and Status of the State of the Art Technology Gregory J Ramon Tampa Electric Company Considerations in the Application of Advanced Conductor Rating Concepts Glenn A Davidson CH2M Hill The Real Time Heat Balance for Overhead Conductors V T Morgan CISRO Divislon of Applied Physics DYNAMP A Real Time Ampacity Program for Overhead Conductors W Z Black Georgia Institute of Technology and R A Bush Georgia Power Company Ampacity Field Studies On Line With Low Operating Temperature W A Chisholm Ontario Hydro Minnesota Power Conductor Monitoring Program Eric R Norberg and Andrew R Lucero Minnesota Power _ Transmission Line Dynamic Thermal Rating Studies James F Hall Pacific Gas and Electric Company The Table below lists conducted in 1985 those engineers who participated in the Utility Survey Table 13 Participants in Utility Survey Company Boston Edison Company R W Quinzani Baltimore Gas and Electric Company Guive Nabet City of Lakeland Electrical Utilities H Curran Duffey Florida Power amp Light Co 6 Raine Renowden Rhine Sooty Florida Power Corporation H E Brown Gainesville Regio
109. ECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL g JUNE 30 1986 s m MEASURED DYNAMP A AMB TEMP CURRENT 8 8 2 D Q 7 A DEG C 69 00 eet 5 Pg 2 amp 58 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR Q WIND DIRECTION WIND SPEED Gl Te Se bh 5 E NE o z 98 00 19 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR Figure 28 Measured and predicted Temperatures for Base Station 200 00 175 00 150 0 125 00 100 00 CURRENT AMPS 75 00 8 20 12 00 MPH 4 WIND SPEED 00 e c COMPARISON OF DYNAMP AND EXP TEMPS GPC SITE NO EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 2 JUNE 30 1986 MEASURED DYNAMP A AMB TEMP 4 CURRENT 8 8 2 4 8 MU o 08 D nm a Ps 9 8 58 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR g WIND DIRECTION WIND SPEED ao Y mir n g mic E Li s Ll of jh fi 2 MESES 1 Qs Bib 5 118 Ga UI j ji 1 d un gt ui lt 8 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 TIME HOUR Figure 29 Measured Temperature at the Base Station and Predicted Temperature at Remote Si
110. EMPERATURE IN DEG C kkxkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk COMMON BRES DAL DCU DST STRAL STRCU STRST SKIN C BSTO RMST RMCOND ICOND ISTEEL PARAMETER AAL 4 716E 12 BAL 1 1685E 08 CAL 2 62E 06 PARAMETER ACU 7 396E 13 BCU 7 049E 09 CCU 1 5793E 06 PARAMETER AST 4 0500E 11 BST 6 9068E 08 CST 1 8149E 05 PARAMETER PI 3 14156 INTOCM 2 54 TMAX 400 0 TMIN 50 0 kkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk CALCULATION OF THE AREAS OF EACH CONDUCTOR e eee ee dee eee eee eee 7 e dee ARAL PI STRAL DAL 2 0 INTOCM 2 ARCU PI STRCU DCU 2 0 INTOCM 2 ARST PI STRST DST 2 0 INTOCM 2 kkkkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk WARNING STATEMENTS FOR INVALID TEMPERATURE DATA TEMP GT TMAX OR TEMP TMIN THEN PRINT 44 TEMP IS OUT OF RANGE OF RESISTIVITY EQUATIONS PRINT 22 SINCE TEMPERATURE IS TEMP DEG C 22 FORMAT 1X A F5 1 A PRINT 44 HOWEVER CALCULATIONS WILL CONTINUE 44 FORMAT 2X A END IF RHOAL AAL TEMP 2 BAL TEMP CAL RHOCU ACU TEMP 2 BCU TEMP CCU RHOST AST TEMP 2 BST TEMP CST RESAL RHOAL ARAL RESCU RHOCU ARCU ye de ee de e dee se de de se e e de e de de de dee de dee e e de de e de de de se de e de dee de dede se Ye e dede de dece de s
111. GA 30332 For EPRI Use Only Vito Longo Name Prior Year s l Igures to be shown in U S dollars whole thousands only Actual Show EPRI portlon of the contract only Do not Include contractor cost sharing __ Current Actual booked Year current year CEU Forecast to complete the Jan Fcb May Jun Jul exi year 0 LI ef ele fel _ Unbooked Forecast to liability complete the Instructlons for compicting this form on the reverse slde Current Year Forecast Future Remaining Year s Years s Forecast Please list dollar future year s amouni descrip tion of cost and month year in which Grand toial of lines 1 2 3 4 487 expected to be bookcd Deliverable 39 Remarks Comments on significant items PREPARED na Titio vorne vus 177 5 84R EPRI CONTRACT NUMBER DIVISION NUMBER For CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER RP 2 Black 404 894 3257 School of 1 Engineering EPRI PROJECT MANAGER PERIOD OF PERFORMANCE Georgia Institute of Technology Atlanta Georgia 30332 Name yro Longo From _7 1 84 to 6 30 87 Prior Note Instructions for completing this form are on the reverse side E Year s Figures not In U S do
112. Georgia Power Test Span before and after use on the KG amp E system More detailed information on the calibration check of this device is presented in Section 9 The monitor clamps onto the conductor and a temperature sensor mounted in the jaws contacts the surface of the conductor Power to operate the monitor is drawn from the transmission line using a current transformer Therefore the line must be energized and the conductor current must be at least 150 amperes to have Sufficient power to record conductor temperature line outage was usually arranged when the monitor was installed However during one of the experiments it was not possible to obtain an outage and the monitor was installed on an energized 138 kV line using a hot stick which is supplied with the instrument The installation was completed without incident by a KG amp E crew A transmitter in the monitor sends a radio signal to a receiver which records a voltage proportional to the line temperature Some operating difficulties were encountered when the monitor was installed on the Hawk conductor at the Weaver substation Random readings or no readings were being received from the monitor requiring that the device be returned to the manufacturer The manufacturer was unable to uncover any problems with the device and when the monitor was re installed temperature readings were again obtained Signals from the various sensors were delivered to a custom built board which contained a
113. Hewlett Packard 9835 Desktop Computer used as a controller a scanner a digital voltmeter a printer plotter and custom built interface Figure 10 is a block diagram of the data acquisition and control structure edel d Thermocouples Voltmeter ine Currents Protective Relaying Control i 1 Relaying d i Li e so 1 Data Acquisition Custom Interface System Plotter Printer Auto Transformer Desktop Computer Figure 10 Block Diagram of Data Acquisition and Control System at Test Span The current loading of the line was controlled by the data acquisition system Sinusoidal ramp step and second order current curves could be impressed on the line The motor driven variac was adjusted continuously to maintain the desired load cycle Trip conditions such as a maximum line temperature or current could be set The data collected using the data acquisition system included line current line temperatures wind speed wind direction and ambient temperature The data was stored digitally on a cassette tape The tape data was subsequently transferred to floppy disk and the time weather data and line current were input to DYNAMP for comparison to the measured temperatures To minimize the effects of lightning and induced voltage the test span was grounded to the midpoint of the loading current transformers on one end of the line A number of 1 kV lightning arresters were tied to ground at the other end of
114. Institute of Technology R A Bush Georgia Power Company Prepared for Electric Power Research Institute 3412 Hillview Avenue Palo Alto California 94304 EPRI Project Manager V J Longo Electric Systems Division NOTICE This report was prepared by the organization s named below as an account of work sponsored by the Electric Power Research Institute Inc EPRI Neither EPRI members of EPRI the organization s named below nor any person acting on behalf of any of them a makes any warranty express or implied with respect to the use of any information apparatus method or process disclosed b assumes any liabilities with respect to the use of or for damages resulting from the use of any information apparatus method or process disclosed in this report Prepared by Georgia Institute of Technology Atlanta Georgia and Georgia Power Company Atlanta Georgia CONTENTS SECTION PAGE ABSTRACT 9 9 6 6 9 9 e 9 o 06 e 9 e 9 o e 8 ACKNOWLEDGEMENTS NOMENCLATURE 4 m LIST OF FIGURES LIST DF TABLES al ASSESSMENT OF STATE OF THE Seminars TOTO PUN En Utility Survey cesses
115. MPS DcG C DEG FT75 DEG AMFS DEG L MINS gt e 2 4 50 29 0 1 0 65 1 750 100 0 4 2 505 35 25 0 73 PUN zu 750 100 0 5 1 Fite 7S0 25 0 Go ast 56 750 100 0 6 5 izle 350 25 0 90 5 0 S0 i 750 100 0 Baz 24 50 25 0 10 0 42 6 50 100 0 15 8 9 39 3509 ut 90 10 0 58 8 750 97 9 120 0 wild 350 25 0 90 10 0 37 8 750 7 5 120 0 ZF 750 25 0 10 0 57 6 75 80 8 120 0 7 44 410 c9 GO 10 0 39 0 750 75 4 120 0 3 455 410 25 0 SO 10 0 40 4 750 73 7 120 0 7154 410 25 0 90 10 0 40 7 750 721222 120 0 2 5 410 253 0 90 10 0 40 9 750 73 7 120 0 rsd 410 25 0 30 10 0 40 Zu0 73 7 120 0 DH 410 25 0 90 16 0 40 750 yos 120 0 TER IE 410 ds C 10 0 44 6 50 76 5 120 0 Son by 410 cou K 10 0 gt 750 78 8 120 0 pete 4 410 25 0 10 0 28 5 750 a5 0 120 06 puse 412 25 0 10 0 41 4 750 92 9 120 0 O 4 410 yu 5 10 0 63 4 750 100 0 3 6 4 27 41 7 25 0 10 0 64 5 750 100 0 S l 22 44 41 aus Q 10 0 65 750 100 0 2 0 214 410 15 02 10 0 65 41 750 100 0 5 4 s 4 410 15 0 2 10 0 60 9 50 100 0 Se dade 410 159 0 10 0 58 1 750 100 0 be 3 1 04 410 159 0 10 6 57 1 750 100 0 6 6 410 15 9 OO 56 95 750 100 O 6 6 714 io 15 0 oO 10 0 J 2 780 100 0 4 Figure 4 6 Output File for Predictive Example Continued 359 APPENDIX A TROUBLESHOOTING JYNAME s execution is regulated by a series of error criteria that prevents
116. N 22 uper b M gt NS CN em i E x UE 4 Uy E MEE d SE 154 a _ sd 1 xag ee e Mid tt 1 e 7 x TN 1 M P 1 E 2 Re 2 22 s 1 pos bi t E Doy i TEE olor uhi 7 I t 1 2 ttt ag i 1 A 2 i 2 D 4 ee eS d 5 o a E Es gt t 37 H SEES P ut 1 nnmn aor A E 1 I gt d 2t f A 7 58 i n t vee 1 H i eoi en 1 gt gt m d ttt ua 1 4 UN T ERE Sq du t PO Ta me ues 4 x teal 5 ene Joc 1 Pun q met UNITED STATES b 13 Cre p Gees Pom fie its 120 N Longitude N Latitude Latitude and Longitude for Continental U S Figure 2 1 conductor lies 33 degrees above the horizon then the inclination angle is 33 degrees If the conductor is horizontal the inclination angle
117. NTERPOLATED VALUE FOR THE C NUSSELT NUMBER 18 IF NU2 GT NU AND RE EQ 100 0 THEN S NU2 NU 100 0 RE VAIR DIA DENS VISC NU S RE NU GO TO 90 ENDIF C IF NU2 GT NU THEN NU NU2 ENDIF C e He He He de He He Fe He He He He de He He He He He He He de He de Fe He A He HEH de He Fe Fe He de ye He Fe He He Fe He He e HEH Ye He Fee H He He He eH Fe eH CALCULATION OF THE HEAT TRANSFER COEFFICIENT Cc He ede se fe de se fe de de He e He He He He Fe se He e e He He e e e e He ve de He He He efe He Fe He de de He He de dee Hee H He Hee He He He He 90 HTC NU DIA C END 10 Purpose Input Qutput Common Blocks FUNCTION QROUT This function subprogram calculates the rate of radiant energy that it transferred from a unit length of conductor to the surroundings TIME Local time which in turn is used to calculate the local ambient air temperature TEMP The conductor temperature in QROUT Net radiant energy leaving a unit length of conductor in W m Computer Symbols and Description of Variables Symbol DIA EPSILN SIGMA TEMP TINF Description Units Qutside diameter of conductor Emissivity of conductor Stefan Boltzmann constant W m Conductor temperature Subroutine that calculates ambient air temp PC 20 FUNCTION QROUT Initialize SIGMA PI Compute QROUT RETURN FUNCTION QRO
118. P Line Location sam Latitude Degrees North Longitude Degrees East Conductor inclination angle degrees ANDER 8 8 Conductor axis azimuth degrees 8 8 Elevation above sea level feet 8 Press Help Enter Next Field Esc Leave Form The user should respond to these five prompts by entering the desired values for atitude Longitude Conductor inclination angle Conductor axis azimuth and Flevation above sea level If the user is unsure of the definitions of these variables the F1 key should be pressed After the desired values are entered tne user should respond to the menu Choose One Previous Select LEAVE y selecting NEXT next data set to be entered is Radiation Properties and the prompts shown will appear on the screen DYNAMP Radiation Properties 5 Solar Absorptivity 9 8 Conductor Emissivity Press Help Enter Next Field Esc Leave Form The next data set to appear will be the Current and Weather variables as illustrated in the screen image shown below DYNAMP Current amp Weather Reading 8 1 of 1 T ime Conductor current amps Air temperature 7 Wind direction UA 8 from north 98 fr east Wind speed feet second Press Help Enter Next Field Esc Leave Form sre the user must respond by
119. RED DYNAMP A AMB TEMP 4 CURRENT S 3 8 3 A m 68 RA d gt Pr 11 5 5 Pd a6 N gt p o 00 25 00 8 8 0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 18 00 TIME HOUR pj WIND DIRECTION WIND SPEED o 4 r DO 14 3 e T 3n s or mU 4 T hi jj gt oT Fae e o S S 90 00 2 00 4 00 6 00 12 00 14 00 16 00 18 00 WIND ANGLE WITH COND 8 00 10 00 TIME HOUR Figure 27 Comparison of DYNAMP and Line Monitor for KG amp E Rail Conductor on September 25 1986 52 35 C greater than those measured by the monitor The monitor measured conductor temperatures as much as 15 C below the surrounding air temperature and it indicated a temperature lower than the air for a period of 9 hours The program responded quickly to the step increase in conductor current from about 500 to 850 amps nearly a tripling in heat generated and a decrease in wind velocity which both occurred around 8 00 am The monitor responded much more slowly and it eventually measures temperatures close to that predicted by the program nearly 6 hours after the step change in current had occurred APPENDIX 54 CRITICAL SPAN ANALYSIS OF OVERHEAD CONDUCTORS Jeffrey W Jerrel W Z Black George W Woodruff School of Mechanical Engineering Georgia Institute of Technology ABSTRACT
120. RESS ANO TELEPHONE NUMBER 21514 6 L W Z Black 404 894 3257 School of Mechanical Engineering PROJECT MANAGER PER ne Oe 6 30 87 Georgia Institute of Technology Name 2 150 Longo rom 7 1484 6 30 Atlanta GA 30332 Note Instructions for completing this form are on the reverse side Year s All figures are to be shown U S dollars whole thousands only Actual Show EPRI portion of the contract only Do not include contractor cost sharing Current Year Actual Actual booked uem om re ow we om oe current year Su oe fos fos Current Year Forecast to complete the current year T Future Unbooked Forecast to Year s liabitity complete the Forecast Please list dollar future year s amount descrip tion ol cost and s month year in which costs are Grand total of lines 1 2 3 4 expecied to be booked 498 Deliverable 38 Remarks Comments on significant stems PREPAREO Print na EPRI CONTRACTOR COST PERFORMANCE REPORT 17 5 EPR COHTRACT NUMDER 2 5 4 6 PROJECT MANAGER EPRI DIVISION HUMDER PERIOD OF PERFORMANCE 7 1 84 6 30 87 eee to CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER W Z Black 404 894 3257 School of Mechanical Engineering Georgia Institute of Technology Atlanta
121. TELEPHONE NUMSER Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 404 894 3257 2 state Hol 4 EPRI PROJECT MANAGER PERIOD OF PERFORMANCE From 7 1 82 Name Vito Longo t 6 30 87 Prior Year s All figures are to be shown In U S dollars whole thousands only Actual Show portion of the contract only Do not Include contractor cost sharing m Actual booked pod current year Note Instructions for completing this form are on the reverse side 19 Forecast to currept year us 7 26 Unbooked Forecast to Please list dollar future year s NM amount descrip 4 tion of cost and month year In which costs are Grand total of lines 1 2 3 4 300 expected to be booked Current Year Forecas n 7 Future Remaining Year s Years s Forecast Remarks Comments on significant items PREPARED BY Print name M 7 Black EPRI CONTRACT NUMBER p 11 4 9 0 2 EPRI PROJECT MANAGER Name Actual booked cost in the current yoar 1985 __ Forecast to complete the current year 19 35 Unbooked liability Please list dollar amount descrip tion ol cost and month year in which costs are expect
122. The weather stations at both sites are owned by the Department of Natural Resources of the State of Georgia and used strip chart recorders to store data Data on these charts was averaged visually and typed into a portable microcomputer for storage on diskette The data from remote site three was averaged in five minute intervals The chart scale on remote site two made it necessary to average data in fifteen minute intervals The ambient temperature from the base weather station was used for remote site number three because it did not have a sensor to read ambient temperature The Shenandoah Solar Center 25 6 miles 40 1 km southwest of the test span served as remote site number four This facility gathers and records weather data continuously as part of various research projects Weather data was sampled every twelve seconds and stored as one minute averages For this investigation the one minute averages were transferred to a desktop computer using a modem The computer then averaged the data in five minute intervals and stored the results on diskette Recognizing the high probability of multiple critical spans it is natural to ask how closely spaced line monitors or weather stations must be order to accurately predict the conductor temperature for a line of reasonable length To answer this question weather data was collected at the test span and the four remote stations The weather data were then run through DYNAMP and the line temp
123. UT TIME TEMP THIS FUNCTION SUBPROGRAM CALCULATES THE RATE RADIANT HEAT TRANSFER FROM A UNIT LENGTH CONDUCTOR C TO THE SURROUNDING IN WATTS PER METER C Fe Fee e fede o He He de see e He deve de He He He de He de fede He He COMMON BROUT EPSILN C BDIA DIA Z C PARAMETER SIGMA 5 67E 08 PI 3 14159 C QROUT PI EPSILN SIGMA DIA TEMP 273 15 4 C TINF TIME 273 15 4 C END a o Purpose Input Qutput Common Blocks Symbol AAL ARAL ARCU ARST BAL BCU BST CAL CCU CST INTOCM MAXTEMP MINTEMP RCUND RESAL RESCU RESST RHOAL RHOCU RHOST FUNCTION RAC This function subprogram calculates the A C resistance for a unit length of conductor ACAR solid copper conductors and reinforced with a steel core TEMP the temperature of the conductor in RAC the AC resistance of a unit ohms cm Computer Symbols and Description of Variables Description Constants relating to the electrical resistivity of aluminum Copper and Steel as a function of temperature Cross sectional area of the aluminum conductor Cross sectional area of the copper conductor Cross sectional area of the steel conductor Constants relating to the electrical resistivity of aluminum copper and steel as a function of temperature Constants relating to the electrical resistivity of aluminum copper and steel as a function
124. W 2600 COMPARISON OF DYNAMP AND EXP TEMPS REMOTE SITE 1 EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 30 1986 e o 9 MEASURED DYNAMP A AMB TEMP CURRENT S S 3 Q rh Bo on e r TI T 5 Q y 9 S Bo deed T do p YE Wor raf pv TP UOI aw Qe leg fL 3 M e sii HHHH Hi 2 D Q 8 S 38 00 10 00 12 00 14 00 ME HOUR 20 00 22 00 24 00 26 00 5 pj WIND DIRECTION WIND SPEED 2 N Qe ig OI 2 58 oe c Ul 5 Og g7 lt 58 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 26 00 TIME HOUR Z zx Figure 7 Measured and Predicted Conductor Temperatures and Weather Conditions at Remote Site Number 1 for June 30 1986 13 COMPARISON OF DYNAMP AND EXP TEMPS REMOTE SITE 2 EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 50 1986 MEASURED DYNAMP A AMB TEMP 4 CURRENT o wi o e e Qo T 9 d Do S NIB E o pp 2 220p On us 5 oon v e 2a444442454244242422 424422444442 4A 4 ARAM 0 AA44445444 aa 1
125. Wichita An EPRI weather station was installed within 25 feet of the transmission line at conductor height Problems were encountered with the weather station including induced voltage from the transmission line lightning damage This station was ultimately replaced by a weather station provided by Wichita State University Initial software problems data collection were also resolved Data were obtained from this site over a three day period The equipment was then relocated and data collected over three day periods at each of the next three sites 18 The transmission lines operated by KG amp E are not heavily loaded at the present time Therefore conductor temperatures below 50 C were commonly encountered even though the ambient temperature was frequently in excess of 33 C during the test period Switching was performed on the system to obtain higher currents and correspondingly higher temperatures After the test program at KG amp E was completed the line monitor was returned to Georgia Power Company October 7 1986 monitor was installed on the Forest Park test span to determine if any drift in the readings had occurred Monitor temperature data was collected over a two week period and the temperatures obtained were compared to surface conductor temperatures measured with thermocouples Figure 11 The data sets were randomly selected without regard to wind speed or direction Although differences of 10 C to 15 C
126. YNAMP s Predicted Temperatures for a Total of 24 700 Data Points DYNAMP PREDICTS EXACTLY AS MEASURED FOR 11 4 7 DYNAMP PREDICTS HIGHER THAN MEASURED FOR 61 5 Z DYNAMP PREDICTS LOWER THAN MEASURED FOR 27 1 2 MEAN TEMPERATURE ERROR IN DEGREES C DYNAMP gt MEASURED 4 5 4 5 MEAN TEMPERATURE ERROR IN DEGREES C DYNAMP MEASURED 3 6 3 7 NUMBER OF DATA POINTS DYNAMP gt MEASURED 15191 NUMBER OF DATA POINTS DYNAMP MEASURED 6692 NUMBER OF DATA POINTS DYNAMP MEASURED 2817 TOTAL DATA POINTS ANALYZED 24700 Table 6 Continued Over 61 of the data resulted in DYNAMP predicting a temperature greater than the measured conductor temperature Only 27 of the predicted temperatures were less than the measured value This behavior of over predicting the conductor temperature was intentional because the program was designed to on the conservative side The data Tables 7 and 8 contain the same data as shown in Table 6 except that Table 7 contains only those points for which DYNAMP over predicted the temperature and Table 8 shows only those cases where DYNAMP calculates a temperature lower than the measured value These values show that more accurate predictions occur at higher wind velocities see column labeled AV SPEED and when the wind is more in cross flow than parallel flow see column labeled AV ANGLE ERROR nm 29 40 Un amp W A m Up WW Ww CO CO GLO CO CO W PO AD A
127. a GEORGIA INSTITUTE TECHNOLOGY OFFICE OF CONTRACT ADMINISTRATION PROJECT ADMINISTRATION DATA SHEET ORIGINAL E REVISION NO Project No E 25 674 R5286 0A1 GTRI GEE DATE 9 19 84 Project Director Dr William Z Black 2 School CXi X ME Sponsor Electric Power Research Institute Type Agreement Agreement No RP254 6 1 27 7 Se Award Period From 7 1 84 739783 __ Performance 5 30 87 Reports Sponsor Amount This Change Total to Date Estimated 6 350 000 100 000 Funded 350 000 100 000 Cost Sharing Amount n a Cost Sharing No n a Title Conductor Temperature Research ADMINISTRATIVE DATA OCA Contact Lynn Boyd X4820 1 Sponsor Technical Contact 2 Sponsor Admin Contractual Matters Mr Vito J Longo Ms Virginia Hess or Ms Tommi Smith Project Manager Electrical Systems Dir Contract Negotiator 2 3412 Hillview Avenue 3412 Hillview Avenue P O Box 10412 P O Box 10412 Palo Alto CA 94303 Palo Alto CA 94303 Defense Priority Rating n a Military Security Classification cc NR or Company Industrial Proprietary n a RESTRICTIONS See Attached n a Supplemental information Sheet for Additional Requirements Travel Foreign travel must have prior approval Contact OCA in each case Domestic travel requires sponsor approval where total will exceed greater of 500 or 125 of approved proposal budget category Equipment Title vests with GIT if unit cost is
128. a consequence the program accuracy remained good throughout the test period Figure 17 illustrates two points First the program is capable of accurately predicting the temperature during large changes in conductor current Between 8 00 am and 9 00 am the current was reduced sharply from 1200 amps to zero and then returned to 1200 amps in a step fashion Even under this rapid change in current the program maintained reasonable accuracy Figure 17 also indicates the rather large conservative errors the program can make during periods of rain Between 2 00 pm and 5 00 pm rain occurred at the test site and the measured conductor temperature dropped to a value close to that of the air temperature Since the program does not consider the cooling effects of rain it continued to predict a temperature which assumes no evaporative cooling During this period the program over predicted the temperature by as much as 400C The period of rainfall can be easily identified by noting the change in weather conditions that accompany the rain The wind velocity increased during the rainfall period and the air temperature dropped during the same time COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 25 1986 m MEASURED DYNAMP A TEMP CURRENT 125 00 150 00 100 00 AM G rc 75 00 DEG C TEMP 50 00 25 00 c 0 00 8 2 00
129. ad Conductors which has been submitted for review and publication in the IEEE Transactions A copy of this paper is included in the appendix of this report E Evaluation of the Line Monitor The weather data and the conductor currents collected as part of the KEURP project were used to evaluate the accuracy of the line monitor and to compare the temperatures measured with the monitor to those values predicted by DYNAMP The data in Figures 23 through 27 show typical results collected over a period of one month for three different conductor sizes Figure 23 shows some of the best temperature comparisons between the monitor and program In general the comparison was not as good as indicated in Figure 23 and the differences between predicted and measured temperatures were far greater than the data collected in Georgia Weather conditions were somewhat different than experienced in Georgia because the Kansas wind velocity in general was much higher and fairly sustained compared to wind conditions in Georgia 46 COMPARISON OF DYNAMP AND EXP TEMPS GORDON EVANS EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO DRAKE CONDUCTOR ACSR 26 7 795 KCMIL JULY 31 1986 3 m MEASURED DYNAMP a AMB TEMP CURRENT amet 00 62 50 8 Oe o9 Re DA o z lt uh f 8 82 34 5 g a o 8 8 13 00 15 00 17 00 19 00 21 3 00 25 00 27 00 9 00 100 TIME HOUR WIND DIRECTION WIND
130. ahan Altman Lacefield Donahey Ithier L Porter Ramon Wilsky Title Transmission Engineer Manager Electric Engineering and Support Lead Transmission Planning Engineer Assistant Director Systems Planning Division Senior Energy Service Engineer Dept of Engineering Research Senior Electric Engineer Senior Operations Engineer Engineer Dept of Engineer Research Engineer Transmission Planning Engineer Overhead Transmission Supervising Electrical Engineer EE Department Engineer Transmission and Distribution Electric System Planning Engineer Transmission Engineer Manager Transmission Design Assistant Manager Systems Operations Principal Engineer Control Systems Manager Transmission Engineering Manager Transmission Planning Senior Engineer Control System Table 13 Continued Company Tennessee Valley Authority Berry Supervisor Estimate Specs and Procurement Services Wisconsin Electric Power Co Becker Transmission Planning Hesse Transmission Planning Nesbitt Operations Engineer System Operations Nichols Senior Project Engineer Transmission Design Schriener Systems Operator Wick Project Engineer Systems Operations Wisconsin Public Service Ellifson Associate Engineer Corporation Substation Transmission Dept Table 14 Utility Survey and Summary of Responses Date Name p M IIII C P
131. analog signal proportional to wind speed the wind speed was also sampled every two seconds and subsequently averaged for the five minute period before being recorded The data acquisition system samples the clock reading and performs the sampling averaging and recording The data was recorded on the HP floppy disk After each experiment was conducted the data was transferred for further processing to a floppy disk compatible with an IBM PC PACIFIC GAS amp ELECTRIC WIND TUNNEL Pacific Gas amp Electric used a wind tunnel to verify DYNAMP predicted conductor temperatures One ACSR conductor and one AAC conductor were placed in the wind tunnel and thermocouples monitored the temperature as the wind velocity wind angle and conductor current were varied DYNAMP was then run for the given test conditions and the predicted temperatures were compared with the measured values Since the tests were conducted in a wind tunnel where the conditions could be carefully controlled the variations in weather parameters usually experienced in outdoor tests were not present DRE mm LT COMPARISON OF PROGRAM RESULTS WITH MEASURED CONDUCTOR TEMPERATURES GEORGIA POWER TEST SPAN The temperatures predicted by DYNAMP have been carefully compared with the temperatures measured on the outdoor test span over a period of two and one half years Initially a Linnet ACSR conductor 26 7 336 kcmil was used and it remained in place for approximately one month during
132. and for reasonable weather conditions the maximum temperature difference that exists in stranded conductors is less than 109C However if conditions reach such a state that birdcaging in the conductor occurs then temperature differences within the conductor greater than 109C can easily result Conditions which provide for large convective heat losses from the surface of the conductor such as high wind velocities will produce large temperature differences in the conductor as long as the average conductor temperature remains constant Furthermore temperature differences increase as the current in the conductor increases for constant weather conditions The vast majority of the temperature drop in an ACSR conductor occurs in the conducting strands while the supporting steel strands are essentially isothermal Finally the results have shown that ampacity models based on the assumption of an isothermal conductor will provide accurate predictions of a conductor temperature that are between the center and surface temperatures Since the temperature of the center of a stranded conductor is usually only a few degrees Celsius above the temperature predicted by an isothermal model the errors introduced by the isothermal assumption should not detrimentally affect ampacity calculations UA IRAE y SECTION 5 PROGRAM VERIFICATION To give utility engineers confidence in the DYNAMP computer program an experimental program was devised to demonstrate th
133. at least in theory a much less demanding task If the temperature of a line is to be measured by thermal line monitors then the monitors can theoretically be located at the critical spans This approach would minimize the capital investment required to install a monitoring system Likewise if the conductor temperatures are to be predicted by using a computer model coupled with weather data measured along the route then the weather station can be located at the critical span Regardless of which technique for predicting the conductor temperature 1 eventually selected the concept of critical span will help minimize the equipment costs The wind velocity and direction conductor are known 2 3 to significant parameters in near the be two of the most regulating the conductor temperature This fact suggests that any span along the route of the line which has reduced wind velocity would be an obvious choice for a critical Span Lines that are routed through valleys tall stands of trees or other areas where the wind is inhibited from circulating freely over the conductor would be prime candidates for a critical span Furthermore wind which blows down the axis of the conductor is much less effective in cooling the conductor than wind which blows across the conductor Therefore spans which are oriented in a direction such that they are parallel to the predominant wind direction are also reasonable choices for critical spans While
134. ation and it will calculate steady state real time and predictive conductor temperatures for any realistic weather conditions and loading history The temperatures predicted by the program have been verified in a test program utilizing a full scale outdoor test span which has been operated for over four years The results of the experimental verification phase of the project have shown that the program can accurately predict the temperatures of a wide variety of conductor designs for any reasonable current and weather conditions MATHEMATICAL BASIS OF PROGRAM The thermal model that forms the basis for DYNAMP starts with a basic energy balance on a representative segment of the conductor The model considers convection and radiation from the surface of the conductor energy generation inside the conductor due to I R heating and storage of energy within the conductor due to its thermal capacitance All of these components are subject to time dependent variables such as wind speed and direction ambient temperature and line current so the solution is transient in nature The strands of the conductor are assumed to be in good thermal contact so that the temperature of all strands 15 identical Therefore the model is unable to predict the conductor temperature when the aluminum strands expand to such as extent that they are no longer contact with the steel core Under these conditions there can be significant temperature differences between
135. ature and the Celsius degree when specifying the conductor temperature One final area that received a unanimous vote concerned the way in which the responding utilities presently rate overhead conductors All companies rate their systems on the basis of a single winter and a single summer air temperature and all companies consider that the air flow across the conductor takes place perpendicular to the conductor With the exception of one company all those who responded to the survey indicated that they do not consider separate COMPANY City of Lakeland Electrical Utilities Florida Power amp Light Co Florida Power Corp Gainesville Regional Utilities Idaho Power Company Illinois Power Co Jacksonville Electrical Authority Madison Gas and Electric Co Niagara Mohawk Power Corp Orlando Utilities Commission Cm emo r s 5 o mas ee NAME H Curran Duffey G Raine Renowden Rhine Sooty Brown Watkins Hanson No and Wall Calhoun McPherron Spencer Trotter Dickinson Schuab Hipius R Zell TITLE Supervisor Substation Engineering Electrical Engineer Staff Engineer Systems Operations Principal Engineer Substation Transmission Design Principal Engineer Substation Transmission Design Senior Engineer General Engineering Senior Engineer Transmission Standards S
136. ature equally Some have a major impact on the conductor temperature while others have practically no influence The derivative process produces the seven sensitivity parameters listed in Table 9 A detailed derivation of the sensitivity parameters is given in Reference 37 The sensitivity parameters are convenient quantities which show how each variable influences the conductor temperature Therefore they will help to determine the location of critical spans For example the sensitivity parameter for wind velocity 8T 8V quantifies changes in the conductor temperature with changes in the wind velocity If the average value of 8T 8V is 10 C ft sec within a given range of operating conditions then that conductor will experience a temperature decrease of 10 C for a 1 ft sec increase in wind velocity Since wind velocities Table 9 Sensitivity Parameters xD T T E10 a Re 2a Re log k 1 194 sinw 0 194cos2u 0 368sin2u I OR 4eoxDT 09 2 3 ORA C OT 4eaxDT xDh 1 OR c T 4eorDT rDh _ DQ sun _ 4eonDT 1798 1 21 4 eoxDT gt Dh 1798 4 0 0 BI Lu 91 1288 4eorDT 5 I 8R c 8T 4ecxDT sDh Eq E 2 z E here h 5 10 16 A ag a logRe a logRe g7 0 070431 a 70 31526 0 035527 BRac Ry R a R R 20 a R R 20 R R a R 20 a R 20
137. average reading of the 16 thermocouples that were mounted on the line DYNAMP s predicted temperature was within 0 5 C for 2817 of the data points or 11 4 of the time Over half of the data points collected resulted in an error of 2 C and greater than 90 of the data points were within 8 of the correct temperature ERROR C NS M d d d mA RA RA CO F9 QOO I0 ONU CO F9 e 59 AD IEA Ch amp CO I 9 N CO CO C2 CO 0 0 0 UG I3 Ww TEMPERATURE NO PERCENT PERCENT AV ANGLE ANGLE PTS 2817 5423 4277 3123 2238 1628 1210 935 686 474 368 281 215 193 146 109 87 76 66 47 49 46 28 23 27 15 8 10 t SO Q t 0S A fms Table 6 BASE STATION RANK PERCENTAGES AV SPEED SPEED CONV REGIME 7 lt or DEG ST DV FT S ST DV FREE INTP FORCED 11 4 11 4 53 7 21 3 5 7 2 6 1 5 0 00 98 5 22 0 33 4 54 5 21 2 5 7 2 7 2 2 0 00 97 8 17 3 50 7 53 1 21 4 6 0 3 1 2 8 0 00 97 2 12 6 63 3 52 1 22 6 6 0 3 4 4 1 0 00 95 9 9 1 72 4 50 7 22 9 5 7 3 4 5 1 0 00 94 9 6 6 79 0 48 8 23 3 5 4 3 2 5 3 0 00 94 7 4 9 83 9 45 9 23 8 5 2 3 2 8 3 0 00 91 7 3 8 87 7 44 7 24 7 4 9 3 1 10 1 0 00 89 9 2 8 90 4 40 1 25 3 4 8 2 2 13 6 0 00 86 4 1 9 92 4 37 9 24 2 4 4 2 7 13 9 0 00 86 1 1 5 93 8 35 3 24 6 4 7 3 1 15 5 0 00
138. b Mar Apr May Jun Jul Aug Sep Oct Nov Forecast current year Lo fa fa fe ee fae Unbooked Forecast to Year s liabilily complete the 19 87 Forecast Please list dollar future year s 30 amount descrip tion of cosl and 2 Grand total of lines 1 2 3 4 expecied to be booked WO Remaining Years s Remaiks Comments on significant stems PREPARED BY Wm Z Black Print name EPRI CONTRACTOR COST PERFORMANCE REPORT EPRI 177 5B4A EPRI DIVISION NUMBER _ PERIOD OF PERFORMANCE 7 4 84 6 30 87 From ae eee to CONTRACTOR NAME ADORESS AND TELEPHONE NUMBER W Z Black 404 894 3257 School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 EPRI CONTRACT NUMBER 2 5 4 6 EPR PROJECT MANAGER For EPRI Use Only Hame Vito Longo Prior Year s Actual Note Instructions for completing this form are on the reverse side Ail figures are to be shown in U S dollars whole thousands only Show portion of the contract only Do not Include contractor cost sharing Actual booked cost In the Jan Feb current year 19 86 9 a jo Forecast to complete the Jan Feb May Jun Jul current year Il L L Unbooked Forecast to liability complete the 1987 Please list dollar future year s amount descrip 30 tion of
139. between the conductor axis and the wind velocity has been modified to eliminate improper round off errors In rare instances certain wind directions cause the program to attempt to calculate an angle whose sine was greater than one Code was inserted into subroutine HTC to prevent this occurrence 95 No significant programming errors have The changes in Version In two places in the program negative numbers were raised to the power 2 0 Fortran does not permit a negative number to be raised to floating point numbers It is however permissible to square a negative number by raising it to the integer 2 The decimal point was removed from two exponents the subroutine HTC and the other in the radiation subroutine called HTC In rare instances an arithmetic overflow occurred in the subroutine that calculates the incident solar load on the conductor For certain dates and times at certain latitudes and longitudes the program attempts to calculate an infinite value for the thickness of the atmospheric layer surrounding the earth that the sun must penetrate Several statements were inserted in the code to prevent that behavior and calculate the limiting value for the air mass rather than attempting to use the statement that causes the overflow condition The number of significant figures accepted in the input file for the variables of wind velocity AC resistance of the conductor time interval between weather data and time int
140. ble 3 The results in Fig 2 show the centerline and outer surface temperatures predicted by the Non Isothermal Model and the average conductor temperature predicted by the Isothermal Model These results were calculated for varying currents with fixed conductor properties and fixed environmental conditions which are specified in the figure Table 3 Physical and Electrical Characteristics of Typical ACSR Conductors From 23 Table 4 14A Name Size Stranding Dia Cond Dia Supp 00 kcmil Strands Strands in in Linnet 0 1137 0 0884 Hawk 0 1354 0 1053 Rook 0 1628 0 1085 Drake 0 1749 0 1360 Falcon 0 1716 0 1030 1 kemil 7 854 x 1074 in2 Conductor 1350 H19 Aluminum Supporting strands Galvanized steel The results of Fig 2 show that the maximum temperature difference across the cross section of a conductor increases as the current increases This temperature difference can be as high as 70 for the conductor sizes and current levels investigated The figure also shows that the ampacity values predicted by the Isothermal Model are very close to the ones predicted by the Non Isothermal Model In other words previous ampacity models which are based upon an isothermal conductor will provide satisfactory results and the slight increase in accuracy provided by a non isothermal ampacity model 15 not warranted when the additional complexity of the Non Isothermal Model is considered However it should be pointed out that
141. chnology School of Mechanical Engineering and Georgia Power Company Research and Test Laboratory July 1 November 30 1984 I GENERAL The contract between Georgia Tech and EPRI was formally started on July 1 1984 The subcontract with Georgia power Company was delayed and was eventually signed on October 22 As a result this report summarizes a 5 month effort for Georgia Tech and a one month effort for Georgia Power hree undergraduate students were hired on an hourly basis at Georgia Tech and their responsibilities were to check and optimize operation of the ampacity program An additional graduate student has been hired on a Research Assistantship to investigate the problem of internal temperature gradients inside the conductor This project will form the basis for the students Master s thesis requirement and his work will be completed in approximately six quarters II ORGANIZATIONAL MEETINGS A kickoff meeting was held in Atlanta at the Georgia Power Research and Test Laboratory in Forest Park on August 7 1984 During that meeting the capabilities and limitations of the program were outlined Numerous suggestions were made to modify the program so that it would be of greatest use to the utility industry The program is written in FORTRAN 77 language and it eventually will be incorporated into the EPRI Workstation Software as well as into the various utility mainframe computers During the kickoff meeting the utility survey was dis
142. city or 8T 0V quantifies changes in the conductor temperature with changes in the wind velocity If the average value of d8T dV 15 100C ft sec within a given range of operating conditions then that conductor will experience a temperature decrease of 10 C for a 1 ft sec increase in wind velocity Since wind velocities frequently can change on the order of several ft sec changes in conductor temperature are often in excess of 10 C simply as a result of uneven wind distribution along the route of the conductor oxd T m 1 4 2 QR C 9T 4eg DT aDh 4eanDT 8 i ah aD sun 1798 0T 4eo DT vDh Sensitivity Parameters In the graphs of the sensitivity parameters which follow many of the independent variables were maintained constant Unless specifically stated in the figures a standard reference set of values was adopted for this purpose and jis listed in Table 2 The correlation for convective heat transfer coefficient with velocity and direction was adopted from Reference 5 absorptivity 0 5 emissivity 0 5 ambient temperature 25 C sun radiation 1000 W m wind direction wind velocity conductor types 90 normal flow 2 ft sec 0 61 m s Curlew 54 7 1033 1 Linnet 26 7 336 kcmil 958 amps Curlew 492 amps Linnet current 75 C ampacity Table 2 Input Variable Refere
143. conditions at the five locations Since the program can accurately predict the conductor temperature of a span located at each site the predicted temperatures can be used to show the magnitude of temperature variations that will occur along a hypothetical transmission line that is routed past the five weather stations To illustrate how the conductor temperature can change from span to another the difference between the temperatures measured at the test span and those predicted at the other weather sites is plotted in Figure 20 These data show errors that could result when a weather station or line monitor located at one spot is used to predict the temperature of the conductor at another spot For example 50 percent of the weather data collected at the test span used in DYNAMP produced temperatures that were within 2 C of the actual measured conductor temperature If the weather station is moved one mile away then 50 percent of the time the program is within 6 C of the temperature of the conductor at the test span This type of information can be used to determine how closely spaced weather stations or monitors must be placed in order to produce a conductor temperature within a specified accuracy The weather data collected at the remote sites can also be used to show how various weather conditions will influence the predicted line 40 Remote Site Remote Site 2 Remote Site 3 Remote Site 4 Base Station Percent
144. consin Public Service Ellifson Associate Engineer Corp Sustation and Transmission Dept PARTICIPANTS IN UTILITY SURVEY daytime and nightime ratings None of the companies calculate a fault conditions ampacity value And finally none of the utilities consider magnetic heating evaporative cooling or a temperature gradient within the conductor when they calculate ampacity values Questions other than those mentioned in the previous paragraph received less than unanimous votes and as a result these results became somewhat more difficult to interpret For example several of the questions were formulated to determine whether most of the utilities would have the facilities to monitor weather conditions within their service area because a real time ampacity program would require up to date weather data as input Seventy five percent of the companies that responded to these questions stated that they had the capability to monitor weather conditions within their service area at least at one location It is probably safe to say that no company would presently have a sufficient number of weather stations to provide adequate input to a real time ampacity program In other words if a company wished to achieve a reasonable accuracy from a real time ampacity model over their entire service area they would certainly have to install a greater number of weather stations Seventy five percent of the utilities stated that they had the ability to calculate
145. crease in conductor current At 10 14 A M the temperature irzreases further because at that time the wind direction changes to blow down axis of the conductor And finally the conductor temperature drops starting it 10 49 when the ambient air temperature decreases by 10 C pU CBE Syene c AMP PrOGKRl 20 ete ncs dO litute of Tochnosrouv and Georg1a Power Companv UnaGer mwmFEZS543s1 aei sos andere GROMBTENT CALCULATIONS for LINNET Conductor Xo 3 Rule PTT ntek ALUM 125 STEEL CURE woe udio DIAMETER 7200 INCHES siete DME PCR 0 1120 S e wring O u 5554 INCHES Moe oe uc Si RANDE ze vw STRANDS 7 DAS UG E E BES C eee oO DHMS MILE hese 1 c 6 03 9 04 EASTERN whe Ju epee amp BEG Gee 84 1 DEG tebe etab HAT ON 90 0 DEG ok Sauce sese aar LAER DEG Viae sx we SEA LEVEL 1300 Fr x T aki cating VEL mL qom ELS s 4406 aa r i wh ao gg n 42 wound A e Ta S ams Tr Te i Y r As AL tJ TES CES a as 44 ENS 5 0 MINUTES Figure 4 3 Documented Input File for Transient Example zr cti 4 CAL i 2 lt u M jd aX liu
146. ctive case Each example includes a documented input file and the corresponding output file obtained by executing DYNAMP STEADY STATE OPTION To illustrate the steady state option consider the following example Calculate the temperature of a Linnet ACSR conductor 26 7 336 4 kcmils for a current of 350 amps ard the ampacity for a temperature of 100 C Perform the calculation for the Atlanta area on June 3rd at 9 04 A M conductor is horizontal and oriented in a north south direction The solar absorptivity and infrared emissivity of the conductor surface are 0 50 and 0 30 respectively The ambient air temperature is 25 C and the wind is from the west at 2 0 ft sec 10 assemble an input file for this particular problem the user can proceed hrough each input page and respond to the various prompts simplify input of conductor properties the user can specify the conductor code name LINNET for t is case and the program will automatically select the correct conductor sropert es The latitude and longitude for Atlanta are 34 2 and 84 1 espectively see Figure 2 1 and the mean altitude above sea level for Atlanta is oproximate y 1000 feet The inclination of the conductor is zero horizontal rd the conductor azimuth is also zero North South orientation The documented nput file for this particular example is shown in Figure 4 1 output file provided by DYNAMP for this exemple is shown in Figure 4 2 The fir
147. ctor area 211 10 lbs ft kg m Mass of conductor 210 10 in cm Strand diameter 210 10 in cm 0 0 of conductor 210 1 Lj Temperature 190 ft s m s Wind Velocity s 21 1 g ohms 1000ft Resistance 21 g 1 vote for knots SECTION II Steady State Ampacity Calculations 1 How do you presently determine steady state ampacity your overhead conductors 1 5 5 No Manufacturers tables In house program or tables 14 0 20 Aluminum Association Tables 8 4 From a Standard which one 201 100 Other specify 2 g 6 2 The form of your steady ampacity values is Yes No Tabular 16 O 2 L Graphical 70 50 Computer output 10 30 Other specify 7 0O Are your ampacity values based on a single summer and _ Yes No a single winter ambient temperature 16 LJ 40 What are the values used for ambient air temperature 25 C to 93 C summer 0 to 40 C winter Do you have separate daytime and nightime ratings Yes No 10 19 0 If yes how do the ambient conditions differ Does your steady ampacity model consider incident solar Yes No energy on the conductor 150 LJ If yes what is the value for solar energy Does it change with season Do you consider the direction of the conductor when considering the influence of sun on the conductor Yes No temperature 60 10 What values of infrared emissivity and solar absorptivity Er 0 5 to 0 75 do y
148. ctor temperatures in the upper curves for the identical time period The lower curves show a solid line representing the wind velocity in miles per hour and the wind direction data is plotted between 0 and 909 where flow perpendicular to the conductor is plotted as 900 The upper curves show DYNAMP s temperature prediction as a solid line and the average thermocouple readings are illustrated by the square data points The upper curves also include the measured air temperature and conductor current over the interval of the test Figure 12 for data collected on October 15 1986 shows typical weather and current variation and the corresponding measured and predicted line temperatures Differences between DYNAMP s predicted temperatures and the measured line temperatures average less than about 5 C over the 14 hours that data were collected The data for October 20th shown in Figure 13 was collected during a period of much higher current and during that period the conductor temperature exceeded 125 C Even at these high temperatures the trends predicted by DYNAMP remained excellent The data in Figs 14 and 15 give an indication of the relatively large errors that can result when the wind velocity decrease to zero and the wind direction is down the axis of the conductor Figure 14 for conditions on October 21 shows expected accuracy except for two brief periods Around midnight between 0 00 and 1 00 am the wind was very calm and the program predicted te
149. cuit that is used to access the weather data has been designed and built Also the computer program that stores weather data and calculates average wind direction and provides that data in a more convenient format has been approximately one half completed The thermocouples for measuring the conductor temperature and the wires for control of the conductor current have been installed control Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 An Equal Education and Employment Opportunity Institution A Unit of the University System of Georgia WZB maw wires for measurement of the conductor sag have also been reinstalled No new line monitors have been received although Niagara Mohawk has informed us that their model will be available for testing during the summer months Future Work A program will be written which will permit direct input of weather data and line conditions collected on tape at the Forest Park Facility into the DYNAMP program The program will serve as an interface between the Hewlett Packard Datalogger at Georgia Power and the CDC Cyber computer at Georgia Tech The present version of DYNAMP will be compiled on a IBM PC to determine if any modifications to the program must be made before the program can be executed on an IBM computer Once an IBM compatible version of DYNAMP is available a tape copy will be provided to EPRI DYNAMP will be used to generate typical am
150. current and er data for data line number 20 will appear on the screen 33 DYNAMP Current Weather Conductor current Camps s gg s B t ee Air temperature C a w 9 9 9 wee pg Wind 8 from north 98 from east Wind speed feet second e Choose One belete Previous Edit Jump Insert Me Select Leave rhe user can now modify current and weather data on line 20 After modifying the current and weather data for this set the user will again be given the eight ptions Choose One Delete Previous Edit Jump splayed at the bottom of the screen is process will continue unti the user is satisfied with the modifications to input data file When all desired modifications have been made the user uld select Leave from the eight options shown above or from the Input Page After selecting Leave the user will be prompted for the name of the file which the modified data is to be written DYNANP Write wodified data set Drive J Data name TRANS Press F1 Help Enter Next Field Esc Leave Fors 34 if tne user chooses to keep the same file name in this example TRANS then any orovicus output file called TRANS will be deleted However if the user chooses a different name for the new input file then no output will be deleted
151. current sensitivity parameter is plotted in Figure 24 These curves show how the current affects the temperature for a wide range of conductor sizes When a conductor at a given load has the current changed by a fixed amount the larger conductor will experience a smaller change in temperature while the temperature of the smaller conductor will change a greater amount At higher currents the sensitivity to a change in current is greater for all conductor sizes Therefore a heavily loaded small conductor will experience large temperature changes for relatively small changes in current Large lightly loaded conductors are less sensitive to changes in current The implication of the sensitivity parameters shown in Figures 22 23 and 24 can be applied to the task of predicting the location of a critical span The desire to locate a critical span will coincide with conditions that lead to a maximum conductor temperature A system operator would have the greatest need to know the location of a critical span when the current is greatest and the wind velocity is the lowest and in a direction down the axis of the conductor This combination of events maximizes the heat generated in a conductor and minimizes the convective PARTRIDGE 267 kcmil ROOK 636 kcmil lt 2 ee CURLEW 1033 kemil S 0 2 FALCON 1590 kcmil O I 500 looo 1560 2000 CURRENT Amps Figure 24 Current Sensitivity Parameter cooling of th
152. cussed and numerous modifications were suggested The suggestion was made to incorporate parts of a similar CIGRE survey into the questionnaire Initial plans were made to visit several utilities to discuss the objectives and goals of the conductor temperature research project and to complete the survey It was also recommended to review rating standards from as many companies as possible The rating standards are to be collected during the visits to each utility he section in the proposal entitled Alternate Site Recommendations was discussed At the present time work outlined in this section will be eliminated and all experimental work will be carried out at the Georgia Power Company Research Laboratory he work originally scheduled within this section will be replaced by an effort to assemble and evaluate all available conductor temperature monitoring equipment Equipment will be purchased and installed on the test span at Forest Park he equipment accuracy capabilities and limitations will be compared A quarterly organizational meeting has been scheduled to coincide with the New York IEEE Winter Power Meeting on February 3 1985 At that time a presentation on initial achievements will be made to the Overhead Ampacity Working Group and the Towers Poles and Conductors Subcommittee he kickoff meeting concluded with a tour of the Georgia Power Research and Test Laboratory which includes the instrumented overhead conductor test facil
153. d 34 the conservation of energy equations when applied to both materials become independent of each other with the results 0 for supporting strands 35 2 2 k dT I 554 5 Pl de dr lta T 293 S ms and 2 k dT I p z 4 T a a 0 for conducting strands 36 where T is measured in degrees Kelvin the subscripts s and c refer to properties of the supporting and conducting strands respectively p 15 the electrical resistivity at 20 C a is the temperature coefficient of resistance A is the cross sectional area including air gaps and is the cross sectional area of the metallic mater al excluding air gaps The solutions to Eqs 35 and 36 in terms of the four constants of integration Cj Co C3 and C4 are 1 i Lo 37 lE i J 38 where 6 m 39 and Jg and Yo are the zero order Bessel functions of the first and second kind The values for the constants through C4 Eqs 37 and 38 can be determined from the boundary conditions The four boundary conditions for the problem are a T 0 is finite 40 b Ts ros Tc ros 41 dT ks dr os Ke dr Uos 42 dT 1 QS un 43 These boundary conditions ensure that there is no thermal contact resistance between the supporting and conducting strands and they also ensure that the heat conducted up to the surface of the conductor is removed f
154. d for static rating schemes An analytical thermal model was used to predict radial temperature gradients in overhead conductors This analysis showed that temperature differences in overhead conductors rarely exceed a few degrees Celsius but under extremely high currents and high wind velocities the temperature differences may approach 10 C In general however temperature gradients in conductors are not large enough to adversely affect the accuracy of ampacity models which are based upon an isothermal conductor Several line monitors were selected for evaluation and one was attached to the Georgia Power test span and the Kansas Gas and Electric operating lines The difference between the temperatures measured by the monitor and the values recorded by the thermocouples attached to the test span was shown to be a function of line current wind velocity and wind direction Line monitors should be calibrated for different wind speeds and directions before they are attached to the line If the monitor is properly calibrated it will have the same relative errors as the ampacity model based on the computer program Line monitors are relatively new devices and they have not been extensively used by power companies the past As designs are improved and more experience is gained in using monitors on operating lines they will receive wider acceptance resulting in improved accuracy and reliability An experimental and analytical study of critical
155. d it should be completed in the next two weeks Documentation includes flow diagram interpretive comment cards and list of symbols including units Preparation is underway for a brief presentation to the Conductor Temperature Working Group and to the Towers Poles and Conductors subcommittee at the IEEE Winter Power Meeting in New York The presentation will summarize the program objectives and progress made to date Sincerely Wm 7 Black Professor WZB maw AN EQUAL EDUCATION EMPLOYMENT OPPORTUNITY INSTITUTION 25 67 GEORGIA TECH 1885 1985 DESIGNING TOMORROW TODAY April 17 1985 Mr Vito J Longo Project Manager Electrical Systems EPRI 3412 Hillview Ave 0 Box 10412 Palo Alto CA 94303 Dear Vito Here is a brief summary of our progress during the period mabe 15 through April 15 1985 on Project 2546 1 Utility Survey One additional utility survey has been received from Guive Nabet Senior Engineer Electrical Engineering Dept Baltimore Gas and Electric Co His responses have been incorporated into the master questionnaire This brings the total number of engineers participating in the utility survey to 46 representing 21 utilities No further responses are expected 2 Development of DYNAMP The verification and checking of DYNAMP has been completed Flow diagrams and descriptions of all subroutines are practically finished 3 Forest Park Test Span Facility The digital cir
156. d velocity near the conductor ft sec This value must be between 0 and 85 feet per second DESCRIPTION OF INPUT VARIABLES TRANSIENT CALCULATIONS in response to the input of the Run Type the user may specify the transient rogram option For this option the program calculates transient real time conductor temperatures based on a set of weather conditions and conductor currents hat change with time ren the transient program option is selected the input variables to the program re identical to those described above for steady state calculations except for changes The user must specify a series of weather conditions and conductor irrents instead of a single value for each and the user must specify a time terval for the data by selecting values for the Transient Variables These ditional input values are described below Transient Vartabies gt first of these two variables ts used to determine the time interval between h set of weather and current data second variable determines how quently the transient temperature of the conductor is printed Time Interval The time interval between each set of current and weather Minutes conditions This value must be between 1 and 30 minutes 15 Printing Interval The time interval between the printing of each conductor Minutes temperature This value must be between 1 and 30 minutes It is usually desirable aithough not necessary to have this value equal the Time Interval
157. d which system of units was preferred when using an ampacity program All companies expressed a desire to use the English system of units except the unit for temperature Most preferred to use the Fahrenheit degree when measuring the air temperature and the Celsius degree when specifying the conductor temperature One final area that received a unanimous vote concerned the way in which the responding utilities rated their overhead conductors All companies rated their systems on the basis of a single winter and a single summer air temperature and all companies considered that the air flow is perpendicular to the conductor With the exception of one company all those who responded to the survey indicated that they do not consider separate daytime and nightime ratings None of the companies calculated a fault condition ampacity value And finally none of the utilities considered magnetic heating evaporative cooling or a temperature gradient within the conductor when they calculate ampacity values Questions other than those mentioned in the previous paragraph received less than unanimous votes and as a result these results became somewhat more difficult to interpret For example several of the questions were formulated to determine whether most of the utilities would have the facilities to monitor weather conditions within their service area because a real time ampacity program would require up to date weather data as input Seventy five percent of
158. de contractor cost sharing Current mST EE oe 1 Current Year Actual Future Forecast to 97 Remaining Year s complete the Years s Forecast future year s 57 4 Grand total of lines 1 2 3 4 498 Remarks Comments on significant items PREPARED BY Print _ Title CONTRACTOR COST PERFORMANCE REPORT PHI I EPRI 177 5 b4R EPRI CONTRACT NUMBER William 7 Black AND TELEPHONE NUMBER illiam Z Black ne 2 5 4 6 EE School of Mechanical Engineering PERIOD OF PERFORMANCE Georgia Institute of Technology Atlanta GA 30332 EPR DIVISION NUMBER For EPRI Use Only EPRI PROJECT MANAGER Vito L _ 1784 0 6 30 87 404 894 3257 AE c M Prior Note Instructions for completing this form are on Ihe reverse slde Year s Actual All figures are to be shown In U S dollars whole thousands only e Show EPRI portlon of the contract only Do not include contractor cost sharing Currenl Aclual booked Year current year 7 fe Year Forecast Forecast to complete the Jan Feb Mar Apr May Jun current year m e Unbooked Forecast to Remaining Year s liability complete the 19 BZ Years s Forecasl future year s Please list dollar of cost and 498 Grand tolal of lines 1 2 3
159. did exist the least square curve fit shows that on average the monitor and measured temperatures compared well A comparison of the calibration results obtained before and after use at KG amp E indicates that no significant drift in the readings of the device occurred The effects of wind direction on the accuracy of the monitor were then evaluated The test span 1 oriented in a north south direction and the monitor was installed with the jaw opening facing to the east Figures 12 15 indicate that errors do exist which are a function of wind direction The monitor reads high when the wind is from the west because the jaws are sheltered from the wind by the monitor housing The average monitor temperature is low when the wind blows from any of the other three quadrants 0x2 Final Calibration Check of Line Monitor x Installed on Forest Park Test Span Data Collected 10 14 86 to 10 24 86 Monitor Temperature C 110 90 70 20 30 30 40 20 60 70 80 Measured Surface Temperature C 90 100 110 Figure 11 Calibration of Line Monitor after Use in KG amp E Project 120 130 LINE MONITOR CALIBRATION CHECK NORTH WIND LEGEND 200 MONITOR SURFACE TEMP Avg Monitor Temp 89 0 C Avg Surface Temp 97 6 C Avg Ambient Temp 13 5 C Last Calibration Avg Error 9 0 C AE WA c ET RRR N 5132 S338930 dN31 180 16
160. dit Create input data Edit or Create E After the file name is entered the Input Data Selector Menu appears DYNAMP Edit Create input data Edit or Create E C nput data selector Conductor Properties Date amp Time Line Location Radiation Properties Current Weather LERUE Edit Press F1 Help Space Bar Next Choice Enter Select Choice ince current and weather data are to be edited the user selects the Current x Weather page by pressing Enter when the appropriate title is highlighted following series of prompts then appears 30 DYNAMP Date Time 221 Month JULY Input data selector gt Run Type Conductor Properties Date amp Time Line Location Radiation Properties Transient Variables amp woather LEAVE Edit eh ns vs le en R Which set of Current Weather Conditions 1 thru 25 Press Fil Help Space Bar Next Choice Enter Select Choice The user must respond by entering a number between and the total number of sets 25 in this example of current and weather data In this example assume the user wishes to modify data in set number 14 Thus the user responds to the prompt by entering 14 After a moment the current and weather data for set number 14 appears on the screen as
161. e AN EPRI CONTRACTOR COST PERFORMANCE REPORT 177 SibARn CONTHACT NUMBER 21s 4 6 o 1 EPRI PROJECT MANAGER EPRI DIVISION HuMBER La PERIOD OF 7 1 84 0 6 30 87 For EPAI Use Only CONTNACTOR NAME ADDRESS AND TELEPHONE NUMBER School of Mechanical Engineering Georgia Institute of Technology Atlanta GA 30332 Prior Year s Actual Hole Instructions for completing this form are on the reverse side All figures are to be shown U S dollars whole thousands only Show portion of the contract only Do not Include contractor cost sharing 27 Current Actual booked Year cost In the Jan Feb Aug Sep Nov Dec Actual died year 8 19 95 1 28 58 18 25 198 Current Forecast to Year complete the Jan Feb Aug Sep Oct Nov Dec Forecast current year 19 x Future Unbooked Year s liability Years s Forecast Please list dollar amount descrip tion ol cosl and monih year in which costs are expected lo be booked Forecast to 87 complete the 192222 19 future year s Grand total of lines 1 2 3 4 Remarks Comments on significant tems PREPARED BY Wm Z Black Print name 1 4 EPRI CONTRACT NUMBER DIVISION NUMBER For EPRI Use Only CONTRACTOR NAME ADDRESS AND
162. e ey ewe eee wee ee 4 ee ee ACSA ALUM 1350 COND STEEL CORE AL DUTSIDE DIAMETER 0 2200 INCHES TONLUCTOR STRAND DIAMETER 0 1137 INCHES STRAND DIAMETER 0 9884 INCHES NUMBER OF CONDUCTOR STRANDS 6 NLUmasER OF CORE STRANDS 7 mESISTANCE 25 Deo 0 2750 HnS MILE u jane Location Variabies JATE AND TIM 6 03 9 04 EASTERN cm PT TUDE 24 2 UNO Tube 54 1 DEG CUNDUCTOR INCLINATION 0 0 CONDUCTOR AZIMUTH 0 0 DEG i EVATIUON ABOVE SEA LEVEL 000 Iad3iation Froperties ILAR aBSODRFETIIVITY MISSiIv11Y tansi ent variables 1 ASUREMENT TIME INTERVAL MINUTES SIMI IND TIME INTERVAL G MINUTES eaaa Vari abies EPFLOAD CURRENT 750 MITING TEMFEFATURE 100 02 DEG C Figure 4 6 Output File for Predictive Example UYManmo c AMP acini Fiuiohht lub omoia of fechas vw arab ara Power Company tinder REZ lt en 1 OK LINNET Conguc to sf PREDICTIVE CALCUL it 42 at feta hE TOR 6 3171 LES FY QE MASS 0 1455 LLb Fi UNDUCIOR PAAD 1 iH LIRE AREA 0 043G t0 EN gt Lu weet CLI ve 1 otartina SEAS Fe UH AIR WIND WIND COND OYRLOAD OVKLOAD ELFSD L UCAL COND TEME DIR SPEED TEMr CURRENT TEMP TIME i Mt A
163. e Run Type ige ter the user has selected a page of data to edit more menus and prompts wil pear allowing the user to modify data on that page of input The user should swer the menus by selecting a choice with the space bar and then pressing the terj key Prompts should be answered by enter ng the desired values in the stds following the questions After a page of input data has been edited and of the prompts have been answered the following menu will appear at the tom of the screen Select One Previous Edit Select LEAVE menu allows the user to perform one of five possible tasks If the user wishes to edit data on the page that exists prior to the present page of data Previous should be selected from the menu 28 25 If the user wishes to continue editing the present page of data Ed t Should be selected da If the user wishes to edit data on the page immediately following the present page WEXT should be selected 4 If the user desires to return to the Input Data Selector Se ect should pe used 5 Jf the user has completed al editing of the input data file LEAVE should be selected The editing of each page of data is relatively simple However two of the data groups presented in the Input Data Selector Conductor Properties and Current and Weather may give some difficulty to the first time user To reduce potential difficulties an explanation of the editing procedu
164. e Fe de He He He se HEH He He He CALCULATION OF PROPERTIES AS A FUNCTION OF THE AVERAGE C TEMPERATURE AND THE ELEVATION de Ae He He Fe PR 0 71 2 7628E 08 TAVE 2 7 2316E 05 TAVE 2 3681E 02 VISC 3 954E O8 TAVE 17 456E 06 DENS DENSTY Z TAVE GBETA 9 807 TAVE 273 0 VISC DENS 2 C VAIR FVAIR TIME PSI FPSI TIME GM GAMMA PI 180 PS PSI PI 180 1 5708 ASIN ABS COS GM SIN PS COS PS SIN GM 1 194 SIN W 0 194 COS 2 W 0 368 SIN 2 W CCo e fef fe de C CALCULATION OF THE NUSSELT NUMBER FOR FREE CONVECTION Fe Fe de He Fe He He He ae He He Ie He de He He He He He He Ze He Fe Fe Ie Me He Fe He Te He Fe He Fe He He He He He He He He He ak GR GBETA DIA 3 ABS TEMP TAIR A LOGIO GR PR LNU AO Al A A2 A 2 A3 A X 3 NU 10 LNU C RE VAIR DIA DENS VISC C IF RE LT 100 0 RE 100 0 C Ce Fe Fe He Fe de ve ae He Ie Fe ae ae ae Ae He He de He He Fe ae He He ae He He ae He He de Hee He He Hk He C CALCULATION OF THE NUSSELT NUMBER FOR FORCED CONVECTION se ak He He He He ee dk Ie Hee ve He de de Fe He de He He He de He He He He He ae ae He Fe se Fe He Fe He He Ae He He Fe He He He He He He Hk LNU BO B1 LOGIO RE B2 LOGIO RE 2 NUO 10 LNU 2 0 WCAL He He He Fe He He Ie C CALCULATION OF THE I
165. e accuracy of the program Actual experimental data under varying load and weather conditions were recorded during tests conducted at three different locations Outdoor verification was obtained at the Georgia Power Research Center Test Span where conductor temperatures were measured with thermocouples Additional outdoor experimental results were obtained at Kansas Gas and Electric on four types of energized conductors using an on line monitor to measure conductor temperatures The DYNAMP program was also evaluated under controlled conditions in the Pacific Gas and Electric wind tunnel A description of these three test programs and the results obtained during these tests is presented below GEORGIA POWER TEST SPAN Initially an experimental span of 336 kcmil ACSR Linnet conductor was constructed at the Research Center field site in Forest Park The 213 meter 700 ft span was constructed using 65 foot poles and installed with system line hardware according to Georgia Power specifications Figure 8 Two conductors were installed and were spaced horizontally 0 46 meters 18 inches apart The conductors were oriented in a north south direction The Linnet conductor was later replaced with a 1033 kcmil ACSR Curlew conductor The poles were heavily guyed to reduce pole movement A critical component of the test system was the main power circuit This circuit consisted of a power supply system and an impedance matching system Figure 9 The curren
166. e contractor cost sharing Current Year Jan Feb Actual Mar Apr May Jun Jul Current Year Forecast Future Forecast to complete the future year s Year s Forecast Grand total of lines 1 2 3 4 Deliverable 43 PREPARED BY Print name Title Georgia Institute of Technology A UNIT OF THE UNIVERSITY SYSTEM OF GEORGIA SCHOOL OF MECHANICAL ENGINEERING ATLANTA GEORGIA 30332 October 2 1984 Mr Vito J Longo Project Manager Electrical Systems EPRI 3412 Hillview Ave Box 10412 Palo Alto CA 94303 Dear Vito Here is my first informal monthly report on the conductor temperature project he Utility Survey Questionnaire has been completed and mailed to all those on the advisory committee The final form of the questionnaire has incorporated input from the CIGRE survey as well as comments from the advisory committee The survey was taken to Illinois Power on August 20 1984 and to Wisconsin Electric on August 21 1984 Seven completed questionnaires have been received from these two utilities Two future trips are now in the planning stages Tampa Electric on October 25th and a western trip to Idaho Power and PG and E on October 15 17th Two graduate programmers have been hired to revise and document the program They have completely documented three of the 23 subprograms in the existing computer code Work is underway to document two additional subprograms an
167. e dece e Ye dece ye dee Yee kkk CHECK FOR PURE OR STEEL REINFORCED CONDUCTOR kkkkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk IF ISTEEL EQ 2 THEN IF ICOND EQ 1 RCOND IF ICOND EQ 2 RCOND ELSE RESST RHOST ARST IF ICOND EQ 1 RCOND RESST RESAL RESST RESAL IF ICOND EQ 2 RCOND RESST RESCU RESST RESCU END IF RESAL RESCU RAC RCOND SKIN END sb FUNCTION RMCP Purpose his subprogram calculates the product of the conductor mass per unit length and the specific heat of the conductor as a function of the conductor temperature Input TEMP the conductor temperature in c Qutput RMCP the product of conductor mass per unit length and specific heat in J cm C Common Blocks Computer Symbols and Description of Variables Symbol Description Units CPCOND Specific heat at constant pressure for the conductor J kg K CPST Specific heat at constant pressure for the steel J kg K RMST Mass per unit length of steel kg m 506 o FUNCTION RMCP START COMMON Statements DATA Statements Y Compute CPCOND a Compute CPCOND b Compute CPST Compute RMCP RETURN m FUNCTION RMCP TEMP 3 e e e e e e ee e e fe e e ee e e fe THIS FUNCTION SUBPROGRAM CALCULATES THE PRODUCT OF THE CONDUCTOR MASS PER UNIT LENGTH WITH THE SPECIFIC HEAT AS A FUNCTION OF THE CONDUCTOR TEMPERATURE TEMP IN DEG C THE RESULT IS IN JOULES
168. e is shown graphically Figure 2 2 The theory behind this calculation stems from the desire to give operating engineer a single value of time so that he can quickly take rective action in the event of an emergency current overload If this dicted time is very short say between a few seconds or a few minutes then the rator knows he is dealing with a heavily loaded line with practically no spare rmal capacity If an emergency overload occurs on that particular line then tching of current to other circuits will be necessary or otherwise the zuit will quickly become overheated On the other hand if the program cts an emergency time that is closer to an hour or greater then the line is er lightly loaded and it has a relatively large capacity to respond to an load in current without reaching a dangerous temperature level E T Z INITIAL CURRENT PRIOR TO EMERGENCY CURRENT I5 OVERLOAD CURRENT 7 CONDUCT OR gt USER SPECIFIED EMERGENCY TEMPERATURE LIMITING TEMPERATURE CALCULATED EMERGENCY TIME TIM Figure 2 2 Predictive Calculational Scheme Used by DYNAMP of the input variables arstent calculations are eration In addition to described for steady state calculations and for required when the user selects the predictive mode of these input values the user must also select one citional input variable when the predictive program
169. e previous line to the current and weather data set displayed on the screen in this example line number 13 22 Edit is selected to edit the current and weather data set displayed on the screen 4 Next is selected to edit the current and weather data set on the following line to the one displayed on the screen in this example line number 15 32 5 Jump is selected to aliow the user to jump over to a set of Current and weather Data not adjacent to the one displayed rn Insert is selected to insert a new data either before or after the data set displayed 7 Serect is used to return the user to the Input Page Menu 8 Leave is selected to close the editing session n tne present example assume the user wishes to modify current and weather data line number 20 The user should then select The user will then be asked to enter the deta line number through a prompt appearing on the screen image shown below DYNAMP Current amp Weather 14 of 25 uA carm m t vpn a Conductor current amps Air temperature Wind 8 from north 98 fron east Mind speed feet second are 25 sets of Current and fmbient Conditions set to jump to Choose One lete Previous Edit Next Insert Select Leave entering 20 in response to the prompt as shown above the
170. e proper input properties This program feature streamlines the program operation and helps prevent user errors in the conductor data input information The operation of DYNAMP 1 described in a separate document 33 This document is a users manua that provides detailed instructions on how to run the program and how to interpret the results DRAFT LL SECTION 4 TEMPERATURE GRADIENTS WITHIN OVERHEAD CONDUCTORS Early ampacity models used to calculate the relationship between the current in an overhead conductor and the conductor temperature ignored radial temperature variations that may have existed within the conductor This assumption could easily be accepted because overhead conductors are relatively small and they consist of materials that have very high thermal conductivities As a result the internal resistance to the conduction of heat across the cross section of a conductor is extremely small and temperature gradients if they exist should be negligible More recent work in the ampacity area 38 has revealed that the isothermal assumption may not be justified under all conditions and some experimental measurements have suggested that temperature differences in a conductor may reach as high as 5 15 Naturally if such temperature differences do exist the question of how they may affect previous ampacity calculations is an important one This section addresses that question and the thermal model proposed here will permit
171. e surface of the conductor Unfortunately the sensitivity parameters show that the same set of circumstances can cause a large variation in conductor temperature along the route of the line Therefore when there 1 the greatest need to locate a critical span conditions are such that the task of predicting the location of a critical span becomes the least likely to succeed Periods when the wind velocity is relatively high and sustained increase the convective cooling and reduce the chance of overheating an overhead conductor During this type of weather the location of a critical span is most likely to remain fixed and the probability of predicting that location becomes greater While the convective mode of heat transfer plays the dominate role in controlling the conductor temperature it is by no means the sole factor influencing the selection of a critical span or spans Radiation also influences the temperature because the conductor emits radiant energy and it also absorbs incident solar energy Therefore any change radiative conditions such as variation in cloud cover along the route of the conductor will influence the selection of a critical span Obviously the extent and variation in cloud cover is in a practical sense unpredictable and the sun s influence on the conductor temperature makes the job of locating a critical span solely on the basis of radiative effects a very difficult one The effect of radiative properties of the c
172. ears in Section 9 DRAET ORAFT SECTION 2 ASSESSMENT OF STATE OF THE ART SEMINARS A review of the state of the art in the dynamic rating of overhead lines revealed an unusual situation On one hand a utility survey conducted at the beginning of the project see next section indicated that there was considerable research ongoing in the area of real time ampacity determinations On the other hand most utilities either had not initiated a real time rating system or they lacked the expertise to formulate a transient ampacity model for their transmission and distribution systems To present the latest in real time rating research and to disseminate information on ampacity schemes a two day seminar was held The joint ampacity seminar sponsored by EPRI Georgia Power Company Georgia Institute of Technology and the Aluminum Association of America was held in Atlanta May 20 21 1986 An excellent group of engineers and scientists performing research in or involved with the line rating area volunteered to present technical papers on their work These seminars were held to stimulate interest in dynamic line ratings and to bring together individuals working these areas Over one hundred people attended Forty one utilities were represented by individuals in Electrical Engineering System Operations Planning and Operation and Maintenance Fourteen different manufacturers were represented Also in attendance were several consultants several enginee
173. eather station increases Measured and Predicted Temp CC Wind Angle deg Figure 11 Errors in Predicted Conductor Temperature as a Function of Wind Direction SUMMARY The sensitivity analysis the weather data collected at the five weather sites and the computer predicted temperatures for the five locations all confirm the following conclusions 1 It is unlikely that a single critical span exists in a transmission line Multiple critical spans are more likely and the location and number of critical spans move from one spot to another as a function of time 2 location and number of critical spans is predominantly dictated by weather factors 3 On calm days the number of critical spans increases and their movement from span to span becomes more frequent 4 Mind that blows down the axis of a conductor causes an increase the number of critical spans and promotes movement in the critical span from one location to another 5 Thermal line monitors and weather stations coupled with computer programs will be least successful in predicting the cr tical temperature of a transmission line when the average wind velocity is low when the wind blows down the axis of the conductor and when the current levels in the circuit are high 6 Line current and weather conditions which produce the greatest thermal demand on the system resulting the highest average conductor temperature are identical to those that ma
174. ecrease in program or monitor accuracy as the wind blows down the axis of the conductor As expected the variation in conductor temperature increases as the distance to the weather station increases The sensitivity analysis the weather data collected at the five weather sites and the computer predicted temperatures for the five locations all confirm the 30 REMOTE SITE 2 REMOTE SITE REMOTE SITE 3 10 REMOTE SITE DIFFERENCE IN MEASURED AND AND PREDICTED TEMPERAT URE C TEST SPAN 60 90 30 WIND ANGLE Degrees TET dus Figure 32 Errors in Predicted Conductor Temperature as Function of Wind Direction for Five Weather Stations following conclusions 1 It is unlikely that a single critical span exists in a transmission 2 2 line Multiple critical spans are more likely and the location and number of critical spans move from one spot to another as a function of changing weather conditions The location and number of critical spans is predominantly dictated by weather factors line orientation and terrain On calm days the number of critical spans increases and their movement from span to span becomes more frequent 4 Wind that blows down the axis of a conductor causes an increase in the number of critical spans and promotes movement of the critical span from one location to another 5 Thermal line monitors and weather stations coupled with computer programs will be least
175. ed to be booked Jong h EPR DIVISION NUMBER CONTRACTOR COST PERFORMANCE REPORT EPRI 177 5 84R For EPRI Use Only CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER School of Mechanical Engineering PERIOD OF PERFORMANCE ia Georgia Institute of Technology Atlanta GA 30332 Prior Note instructions for completing this form are on the revorse side Year s All figures are to be shown In U S dollars whole thousands only Actual Show EPRI portilon cf the contract only Do not inciude contractor cost sharing Jan Feb o Mar Apr May Remarks Comments on signilicant items Current Jun Jul Year Current Year Future Year s Forecast Forecast to complete the future year s Grand total of tines 1 2 3 4 PREPARED BY Print name Mm 2 Black 22 1 CONTRACTOR T PERFORMANCE oe 077 S iL C MEM oem For Use Only COMTAACTON HAME SA ARD VIAE PIONI VONDEN ui 2 15 14 6 011 School of Mechanical Engineering Pree Cary D x ee RE Georgia Institute of Technology Eo PROJECT MANAGER PERIOD OF Atlanta GA 30332 9 Vito Longo ENS From 7 1 84 lo 6 50 8722 m a a Prior Hote Instructlons for completing thts form are on the reverse side Year s All figures are to be shown in U S
176. elect core strand diameter that is between 0 and 0 5 inch but less than the 0 5 of the conductor Select a conductor strand Number of Conductor diameter that is between O and 0 5 inch but less than the 0 0 of the conductor Select an integer value that is positive but less than 300 Select an integer value that is positive but less than 300 Select a positive value Please Check Input Value of ALC Resistance np C Resistance sale 7 JAnrealnsric Input Latitude ya ue for Latitude unrealistic Input Longitude value for Longitude Input Value for the Azimuth af Conductor Unreatistic Input Value af Angle of Conductor with ee a MM M a M aM Conductor Azimuth Conductor Inclination ee A Skin calculated from input values of resistance and calculated value of D C resistance is outside of reasonable range Check A C resistance value and adjust w Select a value between 0 and 909 M Select a value between 0 and 3600 Select a between 0 and 1809 Select a value between 90 and 9
177. emperature increases with wind velocity and for a 30 mph 13 4 m s wind velocity the maximum temperature difference within the conductor is approximately 16 C This is a rather large temperature gradient ina conductor but it exists under an unusually strong wind and unusually high current load over 2 2 times the 750C ampacity value for a Drake conductor at 2 ft sec wind conditions These results illustrate that weather conditions which result in a large convective heat loss from the surface of the conductor high wind velocity and flow normal to the conductor axis are ones which translate into the largest temperature gradients within the conductor However high currents must accompany the high wind velocities in order for the large temperature gradients to exist Therefore conductors loaded at normal 2 ft sec 75 C ampacity values will be practically isothermal at high wind conditions 88 0 860 T center 840 82 0 80 0 o DRAKE CONDUCTOR 72 4 78 0 90 25 76 74 T surfoce en Tee en Lee ane I Messen 12 95 50 150 200 25D AIR VELOCIT Y mph Figure 7 Temperature as a Function of Air Velocity for a Constant Outer Surface Temperature for a Drake Conductor Several general conclusions can be drawn from the result presented in this section For typical conductor constructions energized to current levels which produce conductor temperatures less than 100 C
178. enior Engineering Assistant Engineer Transmission Dept Supervisor Power Operations Electronics Design Engineer Supervisor Transmission Design Supervisor Transmission Planning Director Transmission and Distribution Design Manager of Engineering ransmission Supervisor Transmission Engineer Lead Transmission Planning Engineer Assistant Director Systems Planning Division PARTICIPANTS IN UTILITY SURVEY COMPANY NAME TITLE PG and E Agboativala Senior Energy Service Engineer Dept of Engineering Research S Baishiki Senior Electric Engineer Bunten Senior Operations Engineer J Hall Engineering Dept of Engineering Research Lai Engineer Transmission Planning Lee Engineer Overhead Transmission T Morgan Supervising Electrical Engineer EE Dept Solloway Engineer Transmission and Distribution Seminole Electric Co op Altman Transmission Engineer Southwestern Electric Power Co A Lacefield Tampa Electric Co Donahey Assistant manager Systems Operations Ithier Principal Engineer Control Systems L Porter Manager Transmission Engineering Ramon Manager Transmission Planning Wilsky Senior Engineer Control Systems Wisconsin Electric Power Co Becker Transmission Planning Hesse Transmission Planning Nesbitt perations Engineer Systems perations Nichols Senior Project Engineer Transmission Des ign Schriener Systems Operator Wick Project Engineer Systems Operation Wis
179. eport concerning the KG amp E Field Site Study Finally we would like to acknowledge the many valuable contributions made by Vito Longo who expertly guided our work from the beginning He assembled an excellent Project Review Team which provided technical assistance and guided our research efforts NOMENCLATURE Symbol Description A cross sectional area Cp specific heat at constant pressure D diameter Gr Grashof Number g acceleration of gravity h convective heat transfer coefficient I current Jo zero order Bessel function of the first kind k thermal conductivity Ks skin effect m mass of the conductor per unit length N number of strands Nu Nusselt number Pr Prandtl Number Q radiant energy incident on conductor per unit area Re Reynolds number R electric resistance per unit length of conductor or gas constant r radius SE skin effect T temperature t time V velocity Y age of conductor in years Yo zero order Bessel function of the second kind 2 elevation above sea level Greek Symbols Description a atmospheric lapse rate solar absorptivity of conductor surface or ag temperature coefficient of resistance P thermal coefficient of expansion of air ET infrared emissivity of conductor surface E 9 ov v Subscripts AC C conv DC dif dir gen rad sun dynamic viscosity of air kinematic viscosity of air quantity defined Eq 39 resistivity or density Stefan Bol
180. erature and weather conditions were recorded Wind speed wind direction and ambient temperature were also recorded at four remote sites ranging from 1 to 25 miles away from the test site The weather data from the remote sites was compared to the data from the test span The recorded conductor current and weather data from each site were then used by DYNAMP to predict the temperature of the transmission line conductor based on weather data from each site The computer predictions using data from each remote site were compared to the measured line temperatures Remote site number one was located one mile from the test span at the High Voltage Laboratory of the Research Center This site was assembled from weather station sensors obtained from the Georgia Power Telecommunications Department an Apple IIe computer system and HP data acquisition system belonging to the Research Center The sensors were Ejus installed on a 70 foot transmission pole Cables were run into the High Voltage Lab where the computer and data acquisition system were located Software was written to read the sensors once each minute and to average those readings for each five minute period data was printed and then stored in the input format of DYNAMP on the Apple IIe disk drive The data was later transferred to an IBM PC over an RS 232 data link and stored on IBM compatible disks to be read directly by DYNAMP Remote site number two was located at the south campus
181. eratures were calculated for conditions at the five sites Since the computer program can accurately predict the conductor temperature of a span located at each of the sites the data can be used to show the types of temperature variations that will occur along the route of a transmission line The data shown in Figure 28 and 29 are representative of the remote site weather data and the temperature predictions of DYNAMP Figure 28 shows the weather conditions measured at the test span Base Station and the corresponding computer predicted conductor temperatures Figure 29 shows temperatures for the same time but for data collected at Remote Site 1 For this particular day the wind velocity was fairly strong averaging about 9 ft sec 2 7 m s As a result the difference in predicted temperature of the two spans located 1 mile 1 6 km apart was reasonably small and rarely exceeded 159C However on days when the wind was quite calm variations in conductor temperature from one weather site to another ranged as high as 509 C This type of variation was predicted by the sensitivity parameter 8T OV To illustrate how the conductor temperature can change from one location to another the difference between the temperatures measured at the test span and those predicted at all of the weather sites 15 plotted for the Base Station and each of the remote weather stations in Figure 30 These data show errors that could result when a line monitor at o
182. erms of the Grashof number Gr and the Prandtl number Pr or Nu f Gr Pr 14 where Nu hD k 15 3 gA T T D Gr MEAE 16 5 pc Pr 22 17 For common sizes of overhead conductors and for surface temperatures between 00 and 100 C it can be shown that 104 lt GrPr lt 109 18 and for this range of GrPr the Nusselt number for free convection to air from horizontal cylinder is given by 27 Nu 0 53 GrPr 1 4 19 A computational difficulty exists in free convection that does not exist in the case of forced convection Equations 16 and 19 show that the free convection heat transfer coefficient depends upon the temperature of the conductor However the temperature of the conductor cannot be calculated until the value of h is known Therefore the problem requires iterative solution involving repeated calculations of h and T until convergence is satisfied This difficulty does not arise forced flow because the convective heat transfer coefficient is independent of conductor temperature as long as thermodynamic properties of air are assumed to be independent of temperature When the wind velocity across the conductor 15 not zero the heat transfer to the air occurs by forced convection and the relationship of the Nusselt number becomes a function of both the dimensionless Reynolds and Prandtl numbers or Nu f Re Pr 20 where _ VD Re 5 21 For forced convection from a ho
183. ers and planners on the other hand were not concerned about the simplicity of the output but they expressed a desire that the program be general enough to handle all types of conductors and all possible weather conditions that could possibly exist within their service area Even though none of the utilities surveyed are presently measuring the temperature of any of their conductors and even though only two out of eleven companies that were surveyed said they had any future plans to install temperature measuring devices on their energized lines seventy percent of the utilities said that they would purchase line monitoring equipment if it were reliable and readily available at a cost between 10 000 to 15 000 number of devices that these utilities would purchase ranged between two and twelve The most commonly used reason for purchasing this type of equipment was to have a means of checking the accuracy of a real time ampacity computer model Most people felt that when the instruments had proven the accuracy of the model they would not continue to use the devices on their system When asked whether an on line instrument or a computer model would provide the greatest confidence is knowing the temperature of an overhead conductor the response was equally split It appears that design engineers place more confidence in a computer model while planners and operating engineers seem to feel more confident with an on line monitor The questions re
184. erval between output information were all increased The dimension of the variables called NAME and ANAME were increased from 15 to 20 This change was 26 necessary so that the IUF portion of the program was able to recognize the bird name for ACSR conductors g The array size of two variables in the subroutine QRAD were reduced from 62 to 14 h The common blocks in all subroutines were checked and reduced by placing many of the variables previously that were in common blocks into the argument lists i Several repetitive calculations have been eliminated in order to decrease the run time of the program Version 1 2 first became available in August 1986 The program along with a revised users manual has been mailed to six users No comments have been received regarding the operation of Version 1 2 of All additional weather data collected since the June 1986 meeting have been run through DYNAMP No unusual conditions have been observed and DYNAMP continues to predict the measured line temperature to within approximately 10 C for temperatures up to 125 C A statistical analysis of all data collected to date and a comparison of DYNAMP s accuracy is given in the next section of this report Several typical curves of measured and predicted conductor temperatures for some of the more recent data are shown in Figures 16 through 19 Figure 16 for data collected on October 15 1986 shows typical results similar to those
185. es seventy percent of the utilities said that they would purchase line monitoring equipment if it were reliable and readily available at a cost between 10 000 to 15 000 The number of devices that these utilities would purchase ranged between two and ten The most commonly used reason for purchasing this type of equipment was to have a means of checking the accuracy of a real time ampacity computer model Most people felt that when the instruments had proven the accuracy of the model they would not continue to use the devices their system When asked whether an on line instrument or a computer model would provide the eJ se greatest confidence in knowing the temperature of an overhead conductor the response was equally split It appears that design engineers place more confidence in a computer model while planners and operating engineers seem to feel more confident with an on line monitor The questions regarding the concept of critical span and how the industry views this concept seem to indicate that most utilities either do not subscribe to the concept of a critical span or if they do they are not sure how to utilize the concept when rating their transmission network Only thirty percent of the comapnies utilize the concept of a critical span in determining the real time rating of their network Of these companies some had difficulty defining what actually constitutes a critical span but the most frequently given definition of a critical
186. esented at the Real Time Ampacity e Participants in Utility 5 Responses to Utility 5 ACKNOWLEDGEMENTS Several Georgia Tech graduate and undergraduate students were supported on Research Assistantships from funds provided by this project To a large degree the analytical portion of this work is a summary of their efforts and it could not be completed without their help Acknowledgement is given to Bruce McWhorter Jeffrey Jerrell John Savoullis Stuart Collins and Patricia Woodward for their excellent work We would also like to acknowledge the contributions of several other key people who contributed to the results of this report Bill Eisinger and Dick Wall of Idaho Power Company were instrumental in providing support for the Critical Span study T C Champion III and T J Parker of Georgia Power Company provided assistance in the collection and storage of data from the five weather stations used in the Critical Span analysis Kurt Forester of the Kansas Electric Utilities Research Program provided additional funding for the Alternate Site Study performed at Kansas Gas and Electric Paul Mauldin and Jim Hall of Pacific Gas and Electric provided technical assistance and made available research results obtained from the PG amp E San Ramon wind tunnel tests Gary Thomann of Wichita State University provided assistance in writing the portion of this r
187. eter Inches 6 8606 Diameter of individual conductor strands inches 8 80606 Diameter of individual core strands inches 8 8608 Member of conductor 6 EX B B 9 9 B B 9 4 a b 3 s e 4d 9 9 gt P Press F1 Help Enter Next Field Leave Form In response to this form the user may enter the code name of the desired conductor and the conductor properties will be automatically entered If the user wishes to enter properties for a non standard conductor then those properties 932 must be entered manually Assuming for this example case it is desired to use a CURLEW conductor the following form will appear after CURLEW is entered in esponse to the conductor code name prompt DYNAMP Conductor Properties Conductor code CURLEW Conductor ACSR Total conductor outside diameter inches 41 2458 Diameter of individual conductor strands inches 8 1383 Diameter of individual core strands inches 6 13863 Mumber of conductor 4 4 Select One Edit LEAVE 5 in the case for the run type option the user selects Next to go to the next ata group To continue editing the Conductor Properties Ed t
188. for rating conductors on a real time basis Section IV considers the problem of monitoring conductor temperatures with instrumentation and the identification of critical spans A response should be given to all questions If a particular question could be answered one way by say an operating engineer and another way by a design engineer be sure to enter both answers and identify the individual responsible for each answer Responses to all questions will be compiled and a summary of the results will be provided in the final report to EPRI A copy of the final report will be made available to participants Thank you for your participation in this important project Your responses to these questions are important in forming the framework of the ampacity program If you have difficulty in interpreting or answering any of the questions please contact W Z Black at 404 894 3257 7 84 rev 9 84 Date Name Position Title Company Affiliation Address Telephone SECTION I Operation of Your Transmission and Distribution System 1 List the principal bare overhead conductor sizes you use on your system Designation eg Drake Linnet tranding 8 For the following parameters your preference for units are Conductor area Mass of conductor Strand diameter 0 0 of conductor Temperature Wind Velocity Resistance kcmi lb ft L in in d ft s mi hr L
189. g the ten day period that the monitor was in operation weather data was also being collected This procedure allows a direct comparison of the monitor results the DYNAMP predictions and the temperatures measured by the line thermocouples In general both the monitor and the DYNAMP program gave good correlations although periods did exist where the monitor temperatures differed from the measured conductor temperatures by 20 C These comparisons are shown in Fiaures 35 40 t MONITOR TEMPERATURE C 30 30 MEASURED SURFACE TEMPERATURE C Figure 33 Initial Monitor Calibration Check 90 MONITOR TEMPERATURE C 130 90 LEAST SQUARES CURVE FIT 50 30 40 50 60 70 80 90 100 120 130 MEASURED SURFACE TEMPERATURE Figure 34 F nal Monitor Calibration Check Similar data was collected on October 17 and is shown in Figures 37 and 38 For this particular time period DYNAMP gave good correlations while the monitor read approximately 20 C low at 8 00 At this time the wind was blowing parallel to the conductor This figure implies that the errors experienced from the monitor are a function of the wind direction On October 23 at 19 00 the DYNAMP program predicted temperatures 20 C higher that those measured as shown in Figure 39 This error corresponds to a time period where the wind velocity was under the wind velocity sensor threshold of 0 5ft sec The wind speed input to DYNAMP was
190. garding the concept of critical span and how the industry Views this concept seem to indicate that most utilities either do not subscribe to the gt concept of a critical span or if they do they are not sure how to utilize the concept when rating their transmission network Only thirty percent of the companies utilize the concept of a critical span determining the real time rating of their network Of these companies some had difficulty defining what actually constitutes a critical span but the most frequently given definition of a critical span was simply the span which had the highest temperature Most of those who subscribed to the concept of a critical span simply said that a critical span was one that had experienced thermal problems in the past and a few people said that a critical span could be identified by locating those lines that had experienced exceptional load growth in the past DRAFT DRA p y SECTION 3 DEVELOPMENT OF DYNAMP INTRODUCTION Steady state models for conductor ampacity have been widely used throughout the electric power industry and they remain the backbone for most design and operating decisions relating to the thermal behavior of overhead systems These models assume that each change in conductor current is immediately followed by a corresponding change in conductor temperature In reality the temperature of the conductor changes gradually over a period of time after a change in current This delay is a resu
191. hat has been used to help predict those weather and line operating conditions that will aid in locating a critical span To verify the predictions of the sensitivity parameter analysis an experimental program was devised REMOTE WEATHER STATION SITES The remote site program consisted of the test span located at Forest Park See Section 5 and four other weather stations placed at various distances from the Forest Park test site as shown in the map in Figure 27 The Forest Park test span will be referred to as the Base Station and the other weather stations will be called Remote Sites NORTH SI SHENANDOAH HWY 34 DEKALB I 285 JUNIOR COLLEGE FOREST PARK N BASE STATION TEST SPAN C HIGH VOLTAGE LAB CONYERSYXO SITE 1 85 I 75 ATLANTA AREA SCALE 1 UNIT 5 MILES Figure 27 Location of Tcst Span and Remote Sites Weather data was collected at the Base Station and at the four Remote Sites during the same time intervals At the same time the test span was operated and the temperature of the conductor was measured with the array of thermocouples located along the test span DYNAMP was then run with the five sets of weather data one set collected at the Base Station and four sets from the Remote Sites The output from DYNAMP therefore could be used to predict the temperature of a hypothetical line located at each of the four remote sites as well as the temperature of the real line located at the base
192. he control of all incoming data to magnetic tape and eliminating the need to manually key in line data when running the thermal modeling program The proposed software changes are necessary to handle the magnetic recording of data and to provide an averaged wind speed for the proposed five minute sampling interval Initial plans have been made to select a larger conductor for the Forest Park test facility Although additional calculations are still necessary to verify final equipment modifications a preliminary analysis indicates a 1033 ACSR conductor will meet both the requirement and the physical constraints of the existing system proposed at the project kick off meeting held in Atlanta Final design calculations should be completed by the end of the year A summary of the ampacity curves provided by the dynamic thermal line program for 1033 ACSR conductor are shown in Figures 1 and 2 Factors affecting the specific conductor choice will be 1 maximum anticipated conductor temperature during the test program 2 expected average weather conditions in the Atlanta area during the period of system operation 3 stranding of the test conductor and 4 power limitations imposed by the existing line driving and impedance matching equipment 595 Ig 7 amps CURRENT 1600 1400 200 800 700 FIGURE 2 FOREST PARK TEST SPAN CURLEW CONDUCTOR 54 7 1033 kcmil
193. he shield grounding on the thermocouples to tie through at the thermocouple junction box and 4 replacing a hard wire analog data link with an equivalent fiber optic cable Replacement of the thermocouple extension wire is necessary due to dig in damage to the existing buried conductors and to clear construction which is currently in progress under the test span The accuracy of the ampacity program is directly dependent upon the accuracy of the weather data that is used as input to the program The utility survey indicates that very few companies have the capability to monitor weather conditions and many utilities may be forced to resort to weather data that is collected miles from the location of the transmission 38 lines To check the accuracy of the program when weather data is collected at a remote weather station initial plans have been made to obtain weather data from the Atlanta airport which is approximately five miles from the Forest Park facility Both weather data from the airport and weather parameters measured by the station located at the test site will be put into the program and the differences in predicted conductor temperatures will be used to assess the influence on the accuracy of the ampacity program A review of commercially available on line conductor monitors is in progress Monitors will be obtained for installation on the transmission span in Forest Park Linfo Line Monitor manufactured in Sweden has bee
194. he symbol Qcony represents the rate of heat removed from the surface of the conductor to the ambient air by the convection mode This term is a function of the conductor temperature and the instantaneous weather conditions which are functions of time The generation term in Eq 1 is calculated from Quen Rap T 2 g The AC resistance of the conductor 15 assumed to be a linear function of the conductor temperature and accounts for the skin effect and line reactance The sun s energy which is absorbed per unit length of conductor Qsyn 15 attributed to two distinct sources The first is energy directly incident on the conductor and the second is due to solar energy which first reflects from the surroundings before striking the line The total rate at which solar energy 15 absorbed by a unit length of conductor is then m Da 4 521 3 where D is the conductor diameter and is the solar absorptivity of the line The direct incident solar flux Qdir and diffuse incident solar flux Qq are functions of date time of day latitude and longitude of the line orientation of the line and amount of cloud cover For the purposes of formulating a computer program to calculate both of these terms it was found 20 that the standard solar flux equations given in Ref 16 were satisfactory in estimating the total amount of solar energy corrected for atmospheric absorption that is incident on the line The conducto
195. hole thousands only Actual Show EPRI portion of the contract only Do not Include contractor cost sharing Current Year Jan Feb Mar Apr May Jun Jul Aug EN Oct Nov Dec Actual Current Year Jan Fob Mar Apr May Jun Jul Aug Sep Nov Forecast Future Year s Forecast Forecast to complete the future year s Remaining Years s Grand total of lines 1 2 3 4 2 PREPARED DY Print name Taila CONTRACTOR COST REPORT EPRI 177 san CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER William Z Black School of Mechanical Engineering Georgia Institute of Technology EPRI CONTRACT NUMOER EPRI DIVISION NUMBER For EPRI Use Only 1 EPRI PROJECT MANAGER PERIOD OF PERFORMANCE es Atlanta peo die 30332 Name Vito Lon From TBA to __ 6 20 87 _ aq Prior Note Instructions for completing this form are on the reverse side Year s figures are to be shown In U S dollars whole thousands only Actual e Show EPRI portion of Ihe contract only Do not Include contractor cost sharing Current Actual booked Year mE 2 0 fo fs fo fs jim Current Forecast to Year complete the Jan May Jun Jul Forecast current year me Fy a Pe Ls Fulure Unbooked Forecast to 87 Remaining Year s liability complete the 9 Years s Forecast future year s Please l
196. idual conductor strands inches 6 1383 Diameter of individual core strands inches 8 1383 Mumber of conductor 54 Member of core JAMES A C resistance at 25 C mile Select One Previous Edit Select LEWE f the user desires to manually enter the conductor properties the Enter key is essed in response to the code name prompt and the highlighted block will sceed to the field of Conductor ter the modifications are made to the file the user should select L amp AVE to ose the edit session At this time the user wil be prompted for the new input le name as shown earlier in the current and weather example After the new file ne is specified the Module Menu will return to the screen GE OUTPUT DATA ONLY purge output data the user should select Purge Output Data Oniy from the ule Menu The following prompts will appear DYNAMP Purge output data only a Press Fi Help Enter Next Field Esc Leave Form Tae use should respond by entering the drive letter and the name of the output ile to be purgec A DATA SET gt rename a set of data the user should select Rename a Data Set from the cdule Menu The following prompts will appear DYNANP Rename a data set s
197. ind travel Therefore the number of output pulses in a minute is equal to wind speed in mi hr The wind direction sensor generated an output of 0 5 V representin3 0 to 360 degrees measured clockwise from north A zero volt output represented a wind direction of magnetic north The sensors described above were not used during the measurements on the Flamingo conductor VA320 combination hot wire anemometer and wind direction sensor which had analog voltage output directly proportional to wind speed was used for the ud week However it failed as a result of a lightning strike after the first conductor measurements were complete All air temperatures were obtained from the National Weather Service NWS Hourly readings of air temperature were obtained and a linear interpolation was used to obtain values between the hourly readings The NWS air temperature sensor is located at the Wichita airport which is just southwest of the city Current transformers used to measure line current were already in place at the substations Connections to these sensors were provided by KG amp E personnel SPEED DIRECTION EMPERATURE PULSE ACCUM if RRENT SAMPLE RECEIVER DIGITIZE DIGITAL HP MICRO VOLTMETER COMPUTER Figure 11 Block Diagram of Data Acquisition and Control System at Test Span Line temperature was measured with a line monitor placed on the energized conductor The calibration of this device was checked on the
198. interval and the print time interval The weather and current data are listed at the bottom of the file To make the weather and current array a reasonable length only a few representative values which range saver the desired values were selected wind speed is varied from 1 to 10 ft sec for the first 5 data sets 20 minute time interval and it is then held constant for the remainder of the data set The next variable that is changed is the current which is increased from 350 to 410 amps while all other conditions lt unchanged At 10 14 A M the wind changes from perpendicular flow to axial flow and it remains at zero degrees for the remainder of the data set At 10 49 A M the air temperature decreases from 25 C to 15 C he output corresponding to the input file in Figure 4 3 is shown in Figure 4 4 The first portion of the output file is identical to the steady state output with the calculations consisting of mass and cross sectional for both the conducting and supporting strands and the skin effect The last lines of the output file show the time current weather conditions along with the calculated conductor temperature The trend in the conductor temperatures as a function of time shows the expected results considering the input values for current and weather conditions The temperature first decreases dramatically as a result of the increase in wind velocity At 9 44 A M the temperature begins to increase secause of the in
199. ion is an absolute requirement 2 Loss of strength less than 102 3 Creep when considered 1 Calculated dt 60 operates uctor temperature SECTION 111 Real Time Ampacity Calculations Does your company at the present time have the ability to 5 Yes predict the real time rating of your overhead system C If no would you plan to implement a real time rating Yes program if it were available 40 Where do you feel the greatest input a real time Planning rating system would be within your company Operations Design If a real time conductor temperature program were available how accurate would it have to predict the conductor temperature before you would 196 596 10 consider using it 130 31 20 What is the priority of real time ampacity program High within your transmission and distribution division Moderate Low If a real time rating program were available would your company install the program on main frame computer Yes or a personal computer If yes state the type of computing equipment 5 4 mainframe 6 personal computer 9 both 0 neither
200. is 0 degrees gt Radiation Properties The user must specify two radiative properties of the conductor material solar absorptivity and infrared emissivity Solar Absorptivity The fraction of incident solar radiant energy that 15 absorbed by the conductor surface This value should be between 0 and 1 Recommended values are given in tables below ee aa ALUMINUM CONDUCTORS Years in Line Voltage Service Infrared Emissivity fhe ratio of infrared radiant energy emitted by the conductor surface to the infrared radiant energy emitted by a blackbody at the same temperature This value should be between 0 and 1 Recommended values are given In tables below COPPER CONDUCTORS ALUMINUM CONDUCTORS Years in Line Voltage Service xidation Emissivity Level None 0 03 Light 0 3 Normal 0 5 Heavy 0 8 242 6 current and Weather Conditions The conductor current in amperes is the first input value in this set It is foliowed by three weather parameters wiich are ambient air temperature wind direction and wind velocity When steady state conditions are specified only a Singie set of current and weather conditions is permitted Current Line Current in amperes camps Air Temperature Air temperature between 50 and 50 Deg C degrees Celsius wind Direction Wind direction in degrees measured clockwise degrees from due north between 0 and 350 degrees Wind Velocity Win
201. is type of model has been raditionally referred to as the House and Tuttle method The second program ption consists of a transient model for real time conductor operation and it alculates instantaneous conductor temperatures when the conductor experiences arying current levels and weather conditions The third program option provides edictive temperature calculations based on emergency situations that can arise om a sudden current overload on the line real time calculations are based upon ambient weather conditions and are equently updated so that real time values of wind speed wind direction and the sient temperature are used as input data The effect of the changing weather iditions and conductor current 1 incorporated into the thermal analys s by ounting for the thermal capacitance of the conductor The contribution of the loading on the conductor temperature 1 automatically considered in a separate routine which calculates the clear sky incident solar energy at the specified ation of the conductor program has the capability of predicting real time temperatures for seven ferent types of conductors Composite conductors such as ACSR as well as conductors consisting of either all aluminum or all copper strands can be modeled A single parameter is used to specify the type of conductor The program execution is simplified by the use of a property program that automatically enters five physical constants of the conductor when the user s
202. ist dollar amount descrip 57 month year in Grand total of IInes 1 2 3 4 which costs are expected to be booked tion ol cost and e Remarks Comments on significant items Based on total authorized expenditures through Dec 31 1986 of 400 000 plus 41 000 proposed new funds for final quarter of 1986 PREPARED 8 Bills that have accured from Georgia Power s ub contract but have not been paid by Georgia Tech through August Ent nan 1986 total 33 118 Title EPHI flame Actual booked costin the 19 _8 Forecast to complete the current year 19 _ 86 Unbooked hability Please fist dollar amount descrip tion ol cost and month year in which costs are expected to be booked NTRHACT 2 is tate l i MANAGER CONTRACTOR COST PERFORMANCE EPRI 177 5 3 EPREDIVISION NUMUER PERIOD OF PERFORMANCE Fron 71184 ____ CONTRACTOR NAME ADDRESS ARD TELEPHONE NUMDER Z Black 404 894 3257 School Of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 For EPRI Use Only to 30 87 ito Longo Prior Year s Actual Note Instructions for completing this form are on the reverse side figures are to be shown U S dollars whole thousands only Show EPRI portion of the contract only Do not Inclu
203. ithm IEEE Trans PAS Vol 102 No 6 pp 1858 64 June 1983 Stephen D Foss Sheng Lin Howard Stillwell and Roosevelt A Fernandes Dynamic Thermal Line Ratings Part II Conductor Temperature Sensor and Laboratory Field Test Evaluation IEEE Trans PAS Vol 102 No 6 pp 1865 76 June 1983 W Z Black and W R Byrd Real Time Ampacity Model for Overhead Lines IEEE Trans PAS Vol 102 No 7 pp 2289 93 July 1983 R A Bush W Z Black T C Champion III W R Byrd Experimental Verification of a Real Time Program for the Determination of Temperature and Sag of Overhead Lines IEEE Trans PAS Vol 102 No 7 pp 2284 88 July 1983 Robert L Rehberg High Temperature Ampacity and Sag Model for ACSR Conductors M S Thesis School of Mechanical Engineering Georgia Institute of Technology Atlanta GA Dec 1983 Aluminum Electrical Conductor Handbook Second Edition The Aluminum Association Washington D C 1982 Engineering Data Electrical Characteristics of Bare Aluminum Conductors Kaiser Aluminum and Chemical Sales Oakland CA W S Rigdon H E House R J Grosh and W B Cottingham Emissivity of Weathered Conductors After Service in Rural and Industrial Environments AIEE Trans Vol 82 pp 891 96 Feb 1963 C S Taylor and H E House Emissivity and its Effect on the Current Carrying Capacity of Stranded Aluminum Conductors AIEE Trans Vol 75 Part III pp 9
204. ity III UTILITY SURVEY Task I A survey was formulated for the purpose of providing utility input in the early developmental stages of the computer program The responses to the questions in the survey were used to provide direction so that the computer program will eventually receive the greatest possible use throughout the industry Ihe questions used in the survey came from a combination of sources Some questions were taken from a survey conducted by CIGRE Others were inserted into the survey for the purpose of determining how the industry will ultimately want the computer program designed The survey is subdivided into four sections Section I Operation of Transmission and Distribution System Section II Steady State Ampacity Calculations Section III Real Time Ampacity Calculations Section IV Ampacity Instrumentation and Critical Span Analysis A copy of the questionnaire is provided in the appendix to this report The survey was mailed to the utilities that have an interest in a project of thermally rating overhead lines In addition five companies were visited to conduct discussions on the project and to collect the completed surveys All discussion periods were recorded on tape Rating manuals have been collected for most of the companies At this time the following utilities have been visited Illinois Power Company on August 20 Wisconsin Electric Company on August 21 Pacific Gas and Electric Company on October 15 Idaho Powe
205. ke the location of the critical spans most difficult to predict 7 very calm days line monitors and weather stations must be closely spaced probably no more than 1 2 miles apart for the type of terrain in this study to assure accurate conductor temperatures When selecting monitor locations each utility should consider its own terrain and evaluate how the spacing will affect the accuracy of real time line monitoring system On days in which the wind velocity is high and sustained an accurate conductor temperature can be obtained from much more widely spaced monitoring equipment ACKNOWLEDGEMENTS The authors would like to acknowledge the financial support of EPRI through project 2546 and the technical assistance of Vito J Longo Project Director Also funding from Idaho Power Company for the alternate weather site phase of this work is greatly appreciated Finally the assistance of Patricia Woodward deriving the sensitivity parameter expressions 15 acknowledged REFERENCES 1 Jerrell Jeffrey Critical Span Analysis of Overhead Lines M S Thesis George W Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia April 1987 2 Black Z and Byrd W R Real Time Ampacity Model for Overhead Lines Trans IEEE Vol PAS 102 No 7 pp 2289 93 July 1983 3 Bush A Black 7 Champion T C and Byrd W R Experimental Verification of a Real Time P
206. kkkkkkkk THIS FUNCTION COMPUTES THE DENSITY OF ATMOSPHERIC AIR IN KG PER CUBIC METER AS A FUNCTION OF THE ELEVATION Z IN METERS AND THE AMBIENT TEMPERATURE TEMP IN DEG x deese desee fee dede fe fefe PARAMETER 9 807 TEMPSL 15 0 PRESSL 101 3 R 0 287 PARAMETER ALPHA 0 0065 400 0 TMIN 40 0 PARAMETER ZMIN 0 0 2 11000 0 IF Z LT ZMIN OR Z GT ZMAX THEN PRINT UNREALISTIC INPUT DATA FOR ELEVATION PRINT PLEASE CHECK YOUR INPUT DATA PROGRAM IS TERMINATED RETURN END IF IF TEMP GT TMAX OR TEMP LT TMIN THEN PRINT 44 TEMP IS OUT OF RANGE OF RESISTIVITY EQUATIONS PRINT 22 SINCE TEMPERATURE IS TEMP DEG C 22 FORMAT 2X A F5 1 A PRINT 44 HOWEVER CALCULATIONS WILL CONTINUE 44 FORMAT 2X A END IF 3 s se e e ee fe e e e e e fe fe ee e efe fe e fee fee e ee fee e fe fee e e efe e fe ee eee fe efe eee ee CALCULATION OF ATMOSPHERIC PRESSURE VARIATION WITH ELEVATION gt EXPONT R ALPHA 1000 0 DLESST TEMPSL 273 15 ALPHA Z TEMPSL 273 15 PRESR PRESSL DLESST EXPONT ee e e efe fe de fee e fee efe e fe e fee efe fe efe e dee ee efe efe e fee e fee defe e fee dece dee e fee fee dee fefe efe dee fee CALCULATION OF ATMOSPERIC DENSITY USING IDEAL EQUATION OF STATE e de se de de e e e e de e e e de e de de de de Je e
207. l time conductor temperature The computer program provided predicted span temperatures at the five locations In addition a statistical analysis of the temperature data was used to examine the location of a critical span under various weather conditions Temperature data collected at the test span weather data from the five sites and the results of the sensitivity analysis all confirm the difficulties in locating critical spans particularly when they are governed to a large degree by local weather conditions that are highly variable and practically impossible to predict NOMENCLATURE Cp specific heat at constant pressure D conductor diameter h convective heat transfer coefficient I current k thermal conductivity of air conductor skin effect m mass of a unit length of conductor incident solar energy per unit area RAC AC resistance of conductor Thomas J Parker Research Center Georgia Power Company R1 DC resistance of conductor material R DC resistance of core material R 20 DC resistance of conductor at 20 C 01 conductor material temperature coefficient of resistance at Ty a2 core material temperature coefficient of resistance at 2 T conductor temperature To air temperature t time wind velocity a solar absorptivity of conductor surface infrared emissivity of conductor surface kinematic viscosity of air p density 0 Stefan Boltzmann constant angle between conductor axis and wind velocity vect
208. ld realize that there 15 considerable spare thermal capacity beyond the capacity predicted by DYNAMP whenever rainfall occurs at the location of the conductor The initial conductor temperature predicted by DYNAMP is a result of a steady state energy balance on the conductor assuming that the first set of weather data does not vary with time Mathematically this assumption is necessary to calculate an initial condition for the differential equation Eq 30 When the first set of weather conditions is very close to the weather conditions that preceded it the predicted initial temperatures are very accurate However occasionally the first set of weather conditions is different from the previous data sets and in these instances the program accuracy is poor until sufficient weather data has been reported which truly represents the average conditions in the vicinity of the line This behavior of the program should not be considered a serious disadvantage because the program must be started only once Once the program has been initiated and sufficient weather data has been accumulated the starting errors if they exist will disappear The next few pages shows several selected comparisons of measured line temperatures and DYNAMP s predicted temperatures Each curve has been selected to illustrate a particular point All are displayed ina similar fashion with the wind conditions shown in the lower curves and the current air temperature and condu
209. le Menu the following prompt will appear DYNANP m Directory Listing re rt a rl Press F1 Help Enter Next Field Esc Leave Form ihe user should respond by entering the drive letter in which the files are located After entering the drive letter the directory listing will appear which will be similar to the following listing DYNAMP 2 Ray Input du vL NOR er PREDCT STEADY TRANS VITO NEWDAT ag Documentation of Input Report Optian aun NONE FOUND MENDA Output Ama ee mee VITO nd of report Escl Leave PgUpl Preu PgDnl Mext End Bottom 4 gt END he data files will be listed in one of three categories Raw Input Documented Input Output 40 If the listing occupies more than one screen the Pg0n PgUp Home and End keys can be used to move through the listing return to the Module Menu press the Esc key REVIEW INPUT DATA Occasionally it is desirable to review input data files before executing the program This can be accomplished by selecting Review Input Data from the Module Menu After making this selection the following prompt will appear on the screen DVNAMP Reviow input data Data name Press F1 Help Enter Next Field Esc Leave Fore The user should re
210. les Westinghouse Electric Journal Pittsburgh Pa April 1923 REFERENCES A General Formula for Calculating the Temperature of Electric Heated Wires The Electric Review Vol 95 No 2405 pp 989 90 Dec 1923 J C Wood Heating Large Steel Cored Aluminum Conductors AIEE Trans Vol 43 pp 1258 62 1924 M Woll and J Gable Current Carrying Capacity of Bare Cables The Electric Journal Vol 23 No 1l pp 557 59 Nov 1926 A V Zeerleder and P Bourgeois Effect of Temperatures Attained in Overhead Electric Transmission Cables Journal Inst of Metals Vol 42 pp 321 27 1929 0 R Schurig and C W Frick Heating and Current Carrying Capacity of Bare Conductors for Outdoor Services General Electric Review Schenectady N Y Vol 33 No 3 pp 141 57 March 1930 H A Enos Current Carrying Capacity of Overhead LLL Electric World New York N Y pp 60 63 1943 J Waghorne and V E Ogorodnikov Current Carrying Capacity of ACSR Conductors AIEE Trans Vol 70 Part II pp 1159 62 1951 H E House and P D Tuttle Current Carrying Capacity of ACSR AIEE Trans PAS Vol 78 Part III pp 1169 78 Feb 1959 Earl Hazen Extra High Voltage Single and Twin Bundle Conductors Electric Characteristics and Conductor AIEE Trans Vol 78 pp 1425 34 Dec 1959 G M Beers S R Gilligan H W Lis and J M Schamberger Transmission Conductor Ratings
211. les group and Predictive Variables group are not necessary when transient calculations are called for only the values for the Predictive Variables are not required When predictive calculations are specified the user must provide input values for each of the eight groups of data DESCRIPTION OF INPUT VARIABLES STEADY STATE CALCULATIONS The first item of input information the user is asked to supply when first running the program is the Run Type If the steady state option is selected then the user wii be sequentially led through the remaining input information necessary to operate the steady state program option This section briefly describes the required input information for steady state calculations 1 If the steady state program option is selected the user will be asked to supply iimitiag conductor temperature The program will then calculate the conductor ampazitv for this limiting temperature and the specified weather conditions Limiting emperature This temperature should be the maximum conductor Degrees C temperature in degree Celsius The selected value should be between 209C and 200 C 2 Conductor Properties The user can select the conductor properties in one of two ways If the code name of the conductor is specified and it corresponds to one cataloged in a properties subprogram al properties of that conductor will be automatically loaded into the program If a conductor name is not specified
212. less than 25 000 Title vests with EPRI if the unit is greater than 25 000 00 see Article 11 COMMENTS Budget forwarded to accounting ahead Deliverable Schedule will b forwarded at a later date due to ne d c clarificatjonvof report requirements COPIES TO Project Director Procurement EES Supply Services GTRI Research Administrative Network Research Security Wim Library Research Property Management Reports Coordinator OCA Project File Accounting Research Communications 2 Other I Newton FORM OCA 4 383 DX efe ku ll aA ORGIA INSTITUTE OF TECHNOLOGY OFFICE OF CONTRACT ADMINISTRATION 2 SPONSORED PROJECT TERMINATION CLOSEOUT SHEET E Date 9 15 87 ject E 25 674 School 5 ME sludes Subproject No s N A ject Director s Dr W 2 Black TR onsor Electric Power Research Institute ERRI Conductor T nD en aeu no 2S fective Completion Date9 30 87 Performance 9 30 87 Reports ant Contract Closeout Actions Remaining None Final Invoice or Final Fiscal Report Closing Documents Final Report of Inventions Sent questionaire to P I Govt Property Inventory amp Related Certificate Classified Material Certificate UU S OU Other ntinues Project No Continued by Project No PIES TO jject Director Library search Administrative Network GTRC search Property Management Research Communications 2 counting Project File icure
213. limiting ampacity values should ultimately be set on the basis of clearance and other factors should play only a very minor role in dictating operating temperatures of the conductor Several utilities had experienced splice failures throughout their overhead network and they were being forced to face the problem of replacing or upgrading numerous splices These particular utilities obviously placed a greater emphasis on selecting a limiting temperature that would protect the integrity of their splices and they placed very little importance on the clearance as a factor which should dictate maximum operating temperatures While practically all of those companies that were surveyed had the ability to calculate steady state ampacity values very few of the utilities have the capability to predict real time ampacity values Only one fourth of the utilities at the present time are capable of calculating real time ampacity values All companies would use a real time ampacity program if it were available and they would expect that program to predict the conductor temperature to within 59C of the actual temperature Two companies placed a high priority on developing a real time ampacity program seven felt that they had a moderate priority for such a program and four placed a low priority on such a program The highest priority for the development of a real time ampacity program came from the operating engineers followed by planning engineers and the design engi
214. llars are to be shown in exact amounts specifying type of currency Actual Figures In U S dollars are to be shown In whole thousands Show portion of the contract only Do not Include contractor cost sharing Actual booked mee current year fo I Current Year Actual Forecast to enm v Year complete the Jan Feb Forecast current year Future Unbooked Forecast to Remaining Year s ltability complete the Year s Forecast Please list dollar future year s amount in whole thousands descrip tion of cost and Grand total of lines 1 2 3 4 487 month year in which costs are expected to be booked Remarks Comments on significant items PREPARED SY Print name _ Title EPRI CONTRACT NUMBER ap 2 5 4 6 EPRI PROJECT MANAGER Vito Longo Name Actual booked cost In Ihe currenl year 19 87 Forecast to complete Ihe current year 19 87 Unbooked liability Please list dollar amount descrip lion of cost and month year in which costs are expecied to be booked Co CONTRACTOR COST PERFORMANCE REPORT EPRI 177 S 24R DIVISION NUMBER __ PERIOD OF PERFORMANCE 7 1 84 rom CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER W Z Black 404 894 3257 School of Mechanical E
215. lt of the thermal capacitance of the conductor which is a function of environmental and physical factors Real time ampacity models account for conductor capacitance and they therefore can reveal increased system capacity particularly under emergency loading conditions that would otherwise remain unutilized when a steady state ampacity model is employed The energy stored in the conductor during the time of the transient is often sufficient to provide the operator time to make more effective load management decisions before the conductor reaches a predetermined limiting temperature Armed with a real time ampacity model an operating engineer can efficiently and safely distribute energy over the transmission network without exceeding sag limits or without jeopardizing the strength of the conductors A real time ampacity model can provide other advantages to an operating engineer Steady state ampacity models based on a set of conservative weather parameters may often predict that major tie lines between utilities operate at their ultimate capacity If a real time rating program is applied to the same lines it will frequently reveal a strikingly different conclusion By using actual weather conditions and by accounting for the thermal capacity of the line the real time program can show a reserve capacity for transmission of power and thereby provide the operator with a potential to generate increased revenue A real time ampacity program helps n
216. lysis is shown in Tables 4 through 6 These tables include a total population of 24 700 data points out of the 26 400 points collected The difference in these two numbers represents the data collected during periods of rain and the first few minutes at the beginning of each new collection period At both of these times DYNAMP is known to be inaccurate because it does not S93 account for the evaporative cooling that occurs during rainfall and it is not able to predict the real time temperature when it is given only a single weather data point at the beginning of a run Therefore these points were removed from the statistical package so that a true picture of the program accuracy would emerge The data in Table 4 shows the errors that resulted with DYNAMP for the total population of 24 700 data points collected over the 15 month period the test span was in operation with the Curlew conductor The errors which appear in the table are defined as the difference between DYNAMP s predicted temperature and the average reading of the 16 thermocouples that were mounted on the line DYNAMP s predicted temperature was within 0 5 C for 2817 of the data points or 11 4 of the time Over half of the data points collected resulted in an error of 2 C and greater than 90 of the data points were within 8 C of the correct temperature Over 61 of the data resulted in DYNAMP predicting a temperature greater than the measured conductor temperature Only
217. m a a i e lt 2 aS g7 co L p 3 11 00 12 50 14 00 15 50 17 00 18 50 20 00 21 50 23 00 2430 TIME HOUR Figure 17 Measured and Predicted Conductor Temperatu for October 20 1986 30 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL OCT 21 1986 MEASURED DYNAMP AMB TEMP 4 CURRENT 8 Sp D a 8 s p AM ee um 8 a Q o ow J ar ma 2 B HS 2 a 0 00 2 00 4 00 8 00 10 00 12 00 14 00 16 00 TIME HOUR 2 pj WIND DIRECTION WIND SPEED Oo ul e 28 DG V 9 Eg um FUE m lt B a 90 00 2 00 4 00 6 00 16 00 8 00 10 00 TIME HOUR Figure 18 Measured and Predicted Conductor Temperatures for October 21 1986 EE 200 00 175 00 50 1 125 00 100 00 CURRENT AMPS 75 00 3 tao 4 00 8 00 12 00 MPH IND SPEED 00 W 185 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 9 OCT 22 1986 5 m MEASURED DYNAMP a AMB TEMP 4 CURRENT g 8 i AA Ad d 8 a amp di o e 5 Ol Ar 4 ar moe bab e d a gt Lug 3 9 82 O e 5 00 00 0 00 2 00
218. mation that the variables contain The input information is subdivided into eight groups with each variable n a single group providing a similar function The eight groups are 1 Run Type One variable which selects major program options suci as steady state transient and predictive calculations of the conductor temperature and one variable which specifies the limiting temperature used in both the steady state and predictive program options 2 Conductor Properties Seven variables which specify the geometry of the conductor 3 Date and Time Four variables used to specify the time sequence for calculation of the solar input to the conductor 4 Line Location Five variables that specify the location and orientation of the conductor 5 Radiation Properties Two variables used to specify the radiative properties of the conductor 6 Transient Variables Two variables used to control the transient operation of the program 7 Predictive Variables One variable used to control the predictive operation of the program B Current and Weather One value for conductor current and three variables which describe the weather conditions at the location of the conductor One value for each quantity is required for steady state calculations while a series of currents and weather properties is expected for real time and predictive calculations when the user specifies steady stete ampacity calculations input values for both the iransient Variab
219. me at 404 894 3257 if you need additional information concerning our meeting The agenda for the meeting is as follows A Discussion of Progress 1 Development of Ampacity Program DYNAMP Accuracy of Program Comparison with Test Line Data Preliminary Feedback from Utilities on Program Usage Results of Test Facility Modifications Results of Line Monitor Evaluations Fvaluation of Collected Test Data Discussion of Critical Span Analysis SD 4 C9 PO B Future Work 1 Further Developments for DYNAMP 2 Further Work on Test Facility 3 Proposed Work for Critical Span Analysis 4 Planning for 1986 Symposium on Effects of Elevated Temperatures Operation on Overhead Conductors Revisions to the DYNAMP program have delayed its availability However preliminary copies of DYNAMP along with a user s manual will be available at the meeting maw Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 An Equal Edueatien lt lt venen A Unit of the University System of Georgia EPRI RP 2546 CONDUCTOR TEMPERATURE RESEARCH TASK FORCE MEMBERS J J Hipius Niagara Mohawk Power Corporation 300 Erie Boulevard West Syracuse NY 1320 315 428 5783 Lacefield Southwestern Electric Company P 0 Box 21106 Shreveport LA 71156 318 222 2141 G J Ramon Tampa Electric Company P O Box 111 Tampa FL 33601 813 228 4469 R W Wall Idaho Power
220. mensionless group Substitution of Eqs 2 3 4 and 5 into the basic energy balance equation Eq 1 results in mc 12 0 Da Qu t yy 01 6 t sbh IT which is the fundamental differential equation solved by DYNAMP for the conductor temperature T This equation is a first order ordinary non linear differential equation Since Eq 6 15 non linear it is not reasonable to expect a closed form analytical solution for the conductor temperature as a function of time However Standard numerical techniques such as a Runge Kutta method 32 can be used to provide a value for the conductor temperature at discrete time intervals The numerical techniques to solve this equation is discussed in more detail in a later section Conductor Properties Equation 6 contains five properties of the conductor mass per length m specific heat at constant pressure Cp electric resistance per unit length Rac infrared emissivity and solar absorptivity The program calculates each one of these properties from given input information or it requires the user to provide the properties as input information The mass per unit length of the conductor is calculated from the number of strands N diameter D of each of the strands and the density p af the conductor material The mass per unit length of the conductor is determined from see Nomenclature for definition of symbols 2 S C
221. ment GTRI Supply Services Other search Security Services Sorts Coordinator jal Services RM OCA 69 285 EPHI CONTRACTOR COST PERFORMANCE REPORT EPIRI 127 SUR CONTRACT HUGEN 215416 EPRI PROJECT MANAGER EPRI DIVISION HUDER La PERIOD OF PERFORMANCE Erw 2 1 8 to 6 30 87 For EPRI Use Only CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER School of Mechanical Engineering Georgia Institute of Technology Atlanta GA 30332 TEN Nama Vito Longo Prior Year s Aclual Note Instructions for completing this form are on the reverse side All figures are to be shown In U S dollars whole thousands only Show EPRI portion of the contract only Do not Include contractor cost sharing Current Actual booked Year cost In the Jan Feb Jun Jul Aug Sep Oct Nov Dec Aclual current year ES ls 19 3 1 28 25 9 58 18 2 2 25 Current Forecast to Year complete the Jan Feb Jun Jul Aug Nov Dec Forecast current year S Fulure Year s Unbooked Forecast to 87 liability complete the 19 19222 Forecast Please list dollar future year s amount descrip 30 30 tion of cost and month year in PAM Grand total of Iines 1 2 3 4 486 expected to be booked Years s Remarks Comments significant tems PREPAREO BY Wm Z Black Print nam
222. misuse of the prczgram and prevents the program from performing calculations that are cutside of acceptable ranges These error criteria are continually applied to calculated values and input variables and when error is detected the user is warned by an appropriate message that appears on the screen The table below shows the error messages which can appear and the response which wiil eliminate the errcr List of Error Messages and Recommended Solutions r P Error Message Variable Checked Solution to Problem Conductor Select an 0 D of the Unrealistic Input Value for Conductor Diameter Diameter conductor which is greater than zero but less than the diameter of an individual core or conductor strand 0 D of conductor must be Core Strand Unrealistic Input Value for Core Strand Diameter unrealistic Input value for Conductor Strand Diameter unreatistic Input value for Number of core Strands inrea istic Input Value or Number of Conductor realistic Input ue for esistance wn Diameter Diameter Number of Core Strands Strands A Resistance A i re gt M e M naa 60 M less than 3 0 inches S
223. mperatures that were at times both high and of the measured values As the wind velocity began to increase after 1 00 am the usual accuracy of the program returned and it remained excellent with the exception of one brief period at approximately noon At that time the wind was blowing down the axis of the conductor wind angle 0 and the program briefly predicted a temperature that was about 30 C higher than the measured temperature Once wind direction changed and the wind angle increased the program accuracy returned COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL 8 OCT 15 1986 g m MEASURED DYNAMP AMB TEMP CURRENT 8 8 e e 8 jo 9 2 2 VS 3 _ gt va ay CP mid gt lt 35 5 o 2 Rl E 8 0 00 2 00 4 00 6 8 00 10 00 1200 1400 1600 16 TIME HOUR g m WIND DIRECTION WIND SPEED 5 ey oS 581 SE i 58 5 lt 2 8 i 0 00 2 00 4 00 1200 14 00 16 00 1800 8 00 10 00 TIME HOUR Figure 12 Measured and Predicted Conductor Temperatures for October 15 1986 150 00 125 00 DEG C 75 00 100 00 TEMP 50 00 25 00 0 00 11 00 12 50 14 00 15 50 0 00 OND DEG 60 00 50 00 00 WIND ANGLE WITH C 11 00 12 50 14 00 15 50 COMPARISON OF DYNAMP AND EXP TEMPS
224. n ordered by Georgia Power for installation at the site This device is being loaned for the duration of the EPRI project Thermo Tector manufactured by A B Chance has been purchased This inexpensive device 1s held with a hot stick against an energized overhead line The temperature is read from an LCD display mounted on the device Negotiations are underway to purchase line monitors offered by Creative Power Systems and Niagara Mohawk These systems require the use of radio signals to transmit data 39 APPENDIX COPY OF UTILITY SURVEY UTILITY SURVEY CONDUCTOR TEMPERATURE RESEARCH EPRI PROJECT 2546 INTRODUCTION Georgia Institute of Technology and Georgia Power Company are currently developing a real time ampacity model for overhead conductors under the sponsorship of EPRI Project 2546 An initial phase of this project involves surveying several representative utilities who will ultimately utilize the ampacity model on their operating systems The purpose of this survey is to provide utility input in the early stages of the model design and to provide direction to the model so that it receives the greatest possible utilization by the Transmission and Distribution engineer The survey is separated into four sections Section I deals with your particular transmission network Section II asks questions relating to how your utility handles the steady state ratings of your system Section III concerns the capability your utility has
225. nal Utilities R C Matkins Georgia Power Company Don Smith Gulf Power Company J A Babbitt Idaho Power Company Hanson Noland Wall Illinois Power Company Calhoun McPherron Spencer Trotter Jacksonville Electrical Authority Dickinson Title Senior Electrical Engineer Senior Engineer Electrical Engineering Department Supervisor Substation Engineer Electrical Engineer Staff Engineer Systems Operation Principal Engineer Substation Transmission Design Principal Engineer Substation Transmission Design Senior Engineer General Engineering Senior Engineer Transmission Standards Senior Engineering Assistant Transmission Planning Manager Supervisor of System Planning Engineer Transmission Dept Supervisor Power Operation Electronics Design Engineer Supervisor Transmission Design Supervisor Transmission Planning Director Transmission and Distribution Design Manager of Engineering Transmission Supervisor Company Madison Gas and Electric Company Mississippi Power Company Niagara Mohawk Power Corp Orlando Utilities Commission Pacif c Gas and Electric Rochester Gas amp Electric Company Seminole Electric Co op Southwestern Electric Power Company Tampa Electric Co Table 13 Continued E Schuab S Hewes J Hipius Zell C Agboativala S Baishiki Bunten Hall Lai Lee T Morgan Solloway Call
226. nce Set The graph of the wind velocity sensitivity parameter Figure 1 illustrates that the conductor temperature is far more sensitive to changes 1n wind velocity when wind conditions are nearly calm At high wind velocities a change in velocity has only a minor effect the conductor temperature Under normal conditions it is far more common for the wind velocity to show large variations when Linnet Perpendicular Curlew Perpendicular Linnet Parallel Curlew Parallel 0 10 20 30 Wind Velocity 275 Figure 1 Wind Velocity Sensitivity Parameter 0 2 4 8 10 Ls conditions are calm Therefore calm weather conditions promote large variations in the local conductor temperatures as a result of variations in wind velocity from point to point along the route of the transmission line As the wind velocity increases the conductor temperature becomes less sensitive to changes in wind velocity and the temperature becomes more uni form The graph of the wind direction sensitivity parameter shown in Figure 2 confirms that the conductor temperature 1s more sensitive to changes in wind direction as the wind blows down the axis of the conductor This result implies that a wind oriented along the axis of the conductor will be accompanied by larger swings the conductor temperature than when the wind blows across the conductor Therefore when the wind blows down the axis of the conductor the location
227. nction of 600 volts Since the maximum induced voltage on the line was under 300 volts the thermocouples could be used quite satisfactorily Occasionally a thermocouple would fail and have to be replaced It is expected that conductor strand movement caused shear to the thermocouples causing the wires to break Sixteen thermocouples were placed along 90 foot sections of both conductors at center span The sheathed thermocouples were purchased to meet ANSI error limits A Meathertronics meteorological system was installed at center span at conductor height The station consisted of an ambient temperature thermistor sensor a relative humidity sensor a barometer a tipping bucket rain gauge a solar sensor a micro response anemometer and a micro response wind direction vane review of the effects of each meteorological condition on conductor temperature revealed that data from some sensors was not necessary as input to the program Changes in either the relative humidity or barometric pressure have negligible impact on conductor temperature Also the radiation measurements were not recorded because the program was designed to calculate the maximum radiation at the line location This decision elminated the need to know the solar energy flux which is a difficult and expensive measurement to obtain It was also decided to omit the rainfall as an input to DYNAMP Therefore the program ignores the significant evaporative cooling that can occur during pe
228. nd incidence angle Forced convection Nusselt number Prandtl number for air Wind direction from south radians Wind direction from south degrees Reynolds number of air Slope of interpolation calculations Ambient air temperature Average of TAIR and TEMP mE Wind velocity 5 3 Dynamic air viscosity Ws m Correction parameter for wind incidence angle Correction parameter for forced convection elevation m s 5 FUNCTION HTC START Compute TAVE Y PRINT Error Message Compute K VISC GBETA PS W WCAL GR A LNU NU RE Compute LNU NU2 Interpolation Between NU free and NU2 forced at RE 100 Compute RE and NU ME Compute HTC zc FUNCTION HTC TIME TEMP Ae He Fe He He Fe He He He Fe He He He He Fe He Te e He Ae Ae He Fe He C THIS FUNCTION SUBPROGRAM CALCULATES THE FREE AND FORCED C CONVECTION HEAT TRANSFER COEFFICIENT FOR A CYLINDER IN C WATTS PER METER SQUARED DEGREES C AS A FUNCTION OF C CONDUCTOR TEMPERATURE IN DEGREES C REAL LNU 02 COMMON BDIA DIA Z BLG BETA GAMMA C DATA A0 A1 A2 A3 12724 02238 042030 0025973 DATA B0 B1 B2 PI 070431 31526 035527 3 14159 C TAIR TAVE TEMP TAIR 2 C IF TAVE GT 300 THEN PRINT TEMP IS OUT OF RANGE OF PROPERTY EQUATIONS ENDIF C He ae ae He vee ae Fe He de He Me He He e He He He He He He He Fe He Fe He He H
229. ne location to another as weather and operating conditions vary or does the location remain constant 10 4 What criteria would you use in selecting a location to install a limited number of line temperature monitors Locations known to have thermal problems in the past Locations on critical spans A critical span on a line that is experiencing exceptional load growth Other locations specify If reliable line monitoring equipment were readily available in the range of 10 000 15 000 would you consider installing it on your system If yes approximately how many devices would you install 11 Yes QUARTERLY PROGRESS REPORT EPRI PROJECT 2546 CONDUCTOR TEMPERATURE RESEARCH George W Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 and Georgia Power Company Research Center New Orleans February 1 1986 NOTICE This report was prepared by the organization s names below as an account of work sponsored by the Electric Power Research Institute Inc EPRI Neither EPRI members of EPRI the organization s names below nor any person acting on behalf of any of them makes any warranty express or implied with respect to the use of any information apparatus method or process disclosed in th s report or that such use may not infringe privately owned rights or b assumes any liabilities with respect to the use of or f
230. ne location is used to predict the temperature at another location For example 50 percent of the weather data collected at the test span and run through the program produced temperatures that were within 2 C of the actual line temperature If the weather station was moved away 1 mile Remote Site 1 then 50 percent of the time the program would be within 6 C of the conductor temperature at the test span Moving the weather station further from the test span would produce further reductions in accuracy The remote site weather data can also be used to verify the predictions of the sensitivity parameter study In Figure 31 the difference between the computer predicted temperature and the measured conductor temperature is shown for the four remote weather stations and the base station Weather data was collected at the five sites for the same period of time All five sets of data were put into DYNAMP and the predicted temperatures were compared with the measured temperatures for different wind velocities When the weather data was collected at the location of the test span the accuracy was quite good and it averaged less than 6 C As the weather data was collected further from the test span the accuracy was reduced because the weather at the remote sites rarely coincided with that at the test site Also the accuracy decreased as the wind velocity decreased because the line temperature COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION EPRI PROJ
231. neers felt they would be the ones who would be least likely to use the program When asked what type of computing equipment would be most likely used to run the program the response showed an even split between a mainframe computer and a personal computer The form of the output information provided by the computer program seems to depend greatly upon who will be using the program The operating engineers made a very strong case for a program output that is very simple and easy to interpret They are not particularly concerned about a program that is very general or one which will apply to the broadest range of conductor geometries and weather conditions When asked how the program should convey real time information to the user the operating engineer showed a strong preference for the output of a single value that would predict the time a conductor would reach a predetermined limiting temperature The designers and planners on the other hand were not concerned about the simplicity of the output but they expressed a desire that the program be general enough to handle all types of conductors and all possible weather conditions that could possibly exist within their service area Even though none of the utilities surveyed are presently measuring the temperature of any of their conductors and even though only two out of eleven companies that were surveyed said they had any future plans to install temperature measuring devices on their energized lin
232. ngineering Georgia Institute of Technology Atlanta GA 30332 For EPRI Use Only 6 30 87 lo Prior Year s Actual Note Instruclions for completing this form are on the reverse side All figures are to be shown in U S dollars whole thousands only Show portion of the contract only Do nol Inciude contractor cost sharlng 422 Currenl Year Jan Feb Actual Current Year Forecast Fulure Forecast to complele the fulure year s Year s Forecast Grand tolal of lines 1 2 3 4 Remarks Comments on significant items PREPARED BY Print name CONTRACTOR COST PERFORMANCE REPOR EFRI EPRI EPRI CONTRACT NUMBER EPRI DIVISION Use Only 2 5 4 6 CONTRACTOR NAME ADDRESS AND TELEPHONE NUMBER W Z Black 404 894 3257 School of Mechanical Engineering d DM Peon rt cre are Georgia Institute of Technology Name Vito Longo From 1784 to 6 20 87 Atlanta GA 30332 Nole instructions for completing this form are on the reverse side Ma Ali to be shown in U S dollars whole thousands only Aclual Show EPRI portion of the contract only Do not Include contractor cos sharing 225 1 225 Curreni Actual booked Y uu Current year 19 87 E Current Forecast to Yeat om om om om om om om a current year a ER
233. nt temperature differences can exist in a conductor To obtain an expression of the temperature variation within a composite conductor a governing differential equation was derived which assures conservation of energy within the conductor To simplify the resulting equation the following assumptions were made a The conductor current 1 steady and the weather conditions are independent of time b The temperature of the conductor is only a function of radial position c The thermal conductivity of the conductor materials is constant d The electrical resistance of the conductor varies linearly with temperature e The I R heat is generated uniformly throughout each material of the conductor Applying these assumptions the differential equation for the local conductor temperature within a conductor carrying a current I is See Ref 27 page 50 r SE 1 0 32 six eo lt where the conductor material has a cross sectional area A a resistance per unit length of R and a thermal conductivity of k In a composite conductor such as in an ACSR conductor the majority of the current is carried by the low resistance conducting strands and only a small fraction of the total current circulates through the high resistance supporting steel strands A sketch of a typical composite conductor consisting of centrally located supporting strands surrounded by conducting strands is shown in Fig 1 If the total current pa
234. nt temperature of 34 5 C The DYNAMP prediction is consistently within a few degress of the measured core and surface conductor temperatures The same Marigold conductor was subjected to a series of Six step changes in current over a period of two hours to evaluate the time response of the DYNAMP program and the results are plotted in Figure 21 The conductor was placed at a direction perpendicular to the wind at a velocity of 4 5 mph The ambient temperature was 30 4 C Again the DYNAMP predicted temperatures are within a few degress of the measured surface and conductor temperatures The tests carried out in the PG amp E wind tunnel verified the accuracy of DYNAMP for both steady state and real time calculations under conditions that can be much more accurately and precisely controlled than outdoor tests As a result the comparison of predicted and measured temperatures showed much smaller differences than existed during outdoor tests where weather conditions particularly wind speed and direction cannot be regulated or controlled 7O 65 60 p Marigold Conductor E BO V 4 4 mph 90 m To 34 5 C 8 45 A o 35 30 TIME MINUTES Figure 20 Comparison of DYNAMP and PG amp E Wind Tunnel for Marigold Conductor AFter a Step Change from 300 to 1200 Amperes 180 CENTER 150 DYNAMP 7O SURFACE 120 O 60 AN 3 STEP CURRENT CHANGES 9
235. nt to Georgia Tech Conditions have been recorded for a minimum of three days for four different line sizes Gary Thomann has used some the data in DYNAMP and he has compared DYNAMP s predictions with the CPS line monitor measurements worked satisfactorily through all these checks according to Gary omann The line monitor has been returned from Kansas and it has been placed on the Georgia Power test span for recalibration The line monitor was operated for three weeks during October before the line was disassembled Preparation for 1986 Summer Meeting Jeff Jerrell Tom Parker and I are in the initial phases of putting together a paper for the Summer Meeting It will deal with the subject of critical spans and it will base its conclusions on the remote site weather data and how DYNAMP s accuracy varies with distance between the span and the weather station Jeff has also finished his analysis of the sensitivity parameters and he has then plotted for typical operating parameters We plan to use the sensitivity parameters to back up our conclusions about critical spans Sincerely Wiliam Z Black Professor WZB maw cc Stan Harper Rick Bush GEORGIA TECH 1885 1985 DESIGNING TOMORROW TODAY June 24 1985 Vito J Longo Project Manager Electrical Systems EPRI 3412 Hillview Ave P 0 Box 10412 Palo Alto CA 94303 Dear Vito Here is a brief summary of our progress during the period May 15 through June 1
236. nta at the downtown Days Inn The seminar on the Effects of Elevated Temperature Operation on Overhead Conductors will be held on May 20 1986 and the seminar on Real Time Ampacity Ratings of Overhead Conductors will take place on May 21 1986 The seminars are being coordinated with the Aluminum Association and both the South Eastern Electric Exchange and IEEE have been contacted for appropriate mailing lists of possible participants 5 Operation of Test Facility Several additional weeks of temperature data has been collected for the Curlew conductor The data acquisition program has been modified so that data on time intervals of two minutes can be obtained These data will be used to determine the effect of data frequency on the accuracy of real time ampacity calculations 6 Line Monitor Equipment The Linfo device has had a failure in the receiving equipment and at the present time it is being repaired The Creative Power System s Real Time Temperature Device will delivered next week and it will be checked out and installed on the test line when it is received Sincerely yours William 4 Black Professor WZR pat Attachment THE GEORGE W WOODRUFF SCHOOL GEORGIA TECH 1885 1985 MECHANICAL ENGINEERING DESIGNING TOMORROW TODAY ae Pe 54 November 5 1986 Mr Vito J Longo Project Manager Electrical Systems EPRI 3412 Hillview Ave P O Box 10412 Palo Alto CA 94303 Dear Vito Here s
237. number of switching relays and a counter The input from each sensor was connected to a relay except for the pulse producing output of the anemometer which was connected to the counter The relays were sequentially connected to the digital voltmeter The digital voltmeter was a Fluke 8840A model and its output was connected to one of the computer input ports An HP integral personal computer was connected to the customer board through its RS 232 port The computer custom board digital voltmeter and receiver were located in an air conditioned trailer supplied by KG amp E The trailer environment protected the instruments and also provided a comfortable place for working on the software and hardware and monitoring the experiment operation The computer controlled the relay switching recorded values from the voltmeter and it read the wind speed counts from the custom board The computer clock was used to time the experiment Every 5 minutes readings of line current and line temperature were taken by closing the appropriate relay briefly and recording the digital voltmeter output Because wind direction is highly variable a single reading every five minutes was not taken Instead wind direction was sampled every two seconds and an average value over the five minute period was recorded Also at the end of each five minute period the wind speed counter output was read and recorded During the first week when the hot wire anemometer was producing an
238. o the time the first set of data is recorded The decrease in program accuracy as the wind velocity decreases to zero and as the wind blows down the conductor axis is a result of increasing temperature sensitivity to these two weather conditions This same phenomena also makes the measurement of a conductor temperature with a line monitor more subjected to error when the wind velocity is low and down the conductor axis While normal operating temperatures rarely exceed 1250C even under emergency conditions the program accuracy was checked under conditions which lead to temperatures in excess of 200 C The results showed that DYNAMP was able to predict conductor temperatures to within 10 C at temperatures up to 125 C but its accuracy decreased at higher temperatures In general the program averaged within 200C for temperatures up to 225 C but there were conditions usually low wind velocities where the program errors exceeded 20 C for brief periods of time The heat transfer model used to formulate DYNAMP does not consider the evaporative cooling that occurs during periods of rain Since the evaporation of moisture on the surface of a conductor represents significant cooling effect the program will over predict the conductor temperature during periods of rain This trend 15 not considered to be a serious weakness of the program because the predicted temperature is always conservative when the conductor is wet However the user shou
239. od by IBM PC and sorted on diskettes in the DYNAMP format Table 2 is a summary of information gathered at each weather station The equipment at all sites had been calibrated within three months when data collection began Figures 1 5 contain sketches of all weather station sites showing the location of the sensors surrounding objects which could affect the weather data Table 1 gives the time periods that data was collected at the base station and at the four remote sites The weather data from each site was read into the DYNAMP program to determine how well the predictions would match the line temperatures measured at the base station A typical set of data generated on June 30 1986 is shown in Figures 6 10 Between 8 00 am and 6 00 pm 1800 hours steady wind conditions prevailed and DYNAMP predicted line temperatures fairly accurately with weather data collected at stations up to twenty five miles away from the base station After 6 00 pm the wind direction remained fairly steady but the wind speed decreased at all weather stations The accuracy of the DYNAMP predictions began to fall using data from all sites farther than a few miles from the base station Remote site 1 which is one mile from TABLE 2 WEATHER STATION DESCRIPTIONS MM M s X UM a M UM ac pa Hom UND cuum UND uem ee c A crs cp um Cae com cm m cdi PEE anam dium cu dium paie pude ry umm
240. of Data 0 10 20 30 40 50 60 Differencein Measured and Predicted Temperature Figure 20 Program Accuracy as a Function of Distance Between Weather Station and Conductor Location zdj temperatures For example Figure 21 shows how the difference between predicted and measured line temperatures at the five locations vary with the wind velocity While the magnitude of the differences would change for different values of average line current the trend shown in Figure 21 would still be the same This figure shows that the difference in line temperature that exists between the five locations increases as the average wind velocity decreases Therefore if a single station or monitor is expected to predict the temperature of another span one mile away remote site 1 during calm wind conditions errors that average 15 C can be expected If a span is between 7 and 25 miles away remote sites 2 3 and 4 then differences in temperatures in excess of 30 C can be expected The curves in Figure 22 are similar to those that appear in Figure 21 except that the temperature differences are plotted as a function of wind angle instead of wind velocity These curves show the general decrease in program or monitor accuracy as the wind blows down the axis of the conductor he data in Figures 20 21 and 22 show that weather stations 2 and 3 have a poorer correlation than weather station 4 even though these two stations are closer to the test span than
241. of temperature Conversion factor between inches and cm Maximum limiting temperature for which calculations are valid Minimum limiting temperature for which calculations are valid Electrical resistance of a unit length of the composite conductor Resistance of a unit length of aluminum conductor Electrical resistance of a unit length of copper conductor Electrical resistance of a unit length of steel conductor Electrical resistivity of the aluminum conductor Electrical resistivity of the copper conductor Electrical resistivity of the steel conductor 23 The program considers ACSR copper conductors length of conductor in Units ohg 9 2 cm 2 cm cm ohm cm 9C ohm cm me PE ohm cm ohm cm ohm cm ohm cm ohm cm ohm cm ohm cm FUNCTION RAC START COMMON Statements DATA Statements Compute ALAR CUAR STAR PRINT Y Compute RHOAL RHOCU RHOST RESAL RESCU Y N Compute RESST R Y IRCOND RESAL Y N Compute RCOND Y N RCOND RESCU Compute RCOND bet Compute RAC RETURN FUNCTION RAC TEMP kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk THIS FUNCTION SUBPROGRAM CALCULATES THE A C RESISTANCE FOR FOUR DIFFERENT CONDUCTOR TYPES ACSR ACAR COPPER CONDUCTOR STEEL REINFORCED AND SOLID COPPER CONDUCTOR THE A C RESISTANCE IS CALCULATED IN OHM CM AND THE ONLY INPUT TO THE FUNCTION IS THE T
242. olar energy 15 used as part of the energy input to the conductor DYNAMP automatically calculates sunrise and sunset times for the specified latitude and longitude of the line DYNAMP contains a number of warning and error messages to assure that the program is used properly and it can accurately predict the conductor temperature Various error and warning messages will appear on the screen if input values cause the program to attempt unreasonable calculations The execution of DYNAMP from the operators standpoint has been simplified as much as possible A user friendly front end program written Professional Applications Development Language PADL has been developed by Power Computing Company PCC and it greatly simplifies the program operation The PADL interactive program is similar in format to other programs that are part of the TLWorkstation software Incorporated into the user interface program is a series of help files that are designed to aid the user when problems arise with the program operation The input information to DYNAMP has been simplified as much as possible The program contains a separate subroutine that can provide conductor properties for a wide variety of conductor designs Each property set is designated by the code name that is frequently used to specify different types and designs of conductors By simply specifying the conductor code the program will search the conductor property file and select th
243. om the use of any information apparatus method or process disclosed in this report Prepared by Georgia Institute of Technology Atlanta Georgia ACKNOWLEDGEMENTS This report reflects the efforts of a number of people Bruce McWhorter graduate student at Georgia Tech played a major role in documenting the program and in writing portions of the manual Rich Bush a Research Staff Engineer at the Georgia Power Company Research Center supervised the experimental portion of this project which verified the results of the computer program Gary Thomann Professor of Electrical Engineering at Wichita State University organized the KEURP funded Kansas Gas and Electric project which gathered line monitor data used to verify the computer predictions And finally Vito Longo Project Manager for EPRI not only guided the overall direction of the research work but also was the motivating force behind the program that provides a user friendly interface for DYNAMP CONTENTS section 1 INTRODUCTION 2 PROGRAM INFUT General Information Description of Input Variables Steady State Calculations Description of Input Variables Transient Calculations Description of Input Variables Predictive Calculations 3 OPERATION General Menus Prompts Data Files Getting Started fdit Create Input Data General Creating an Input File Editing Input Data F les General Editing Current and Weather Data Editing Conductor Pr
244. onductor surface on the temperature are shown by the sensitivity parameters 8T 8a and 9 Figures 25 and 26 emissivity sensitivity parameter is negative because an increase in e decreases the conductor temperature The sensitivity to increases as the incident solar energy increases causing the conductor temperature to increase and enhancing the importance of radiation emitted from the conductor The absorptivity sensitivity parameter shown in Figure 26 is always positive because an increase in a always produces an increase in conductor temperature Under the extreme conditions of 1000 W m of incident solar energy the conductor temperature will increase by about 10 C if the conductor changes from a perfect reflector to a perfect absorber of solar energy change of a from 0 to 1 These two sensitivity parameters give an indication of the changes conductor temperature that could be achieved by coating the outer surface of the line with a low absorptivity high emissivity material 5 9 C SER 5 _ 2 Q un W m 25 750 W m 500 Wnt 250 Wnt 30 W m Q2 04 06 08 EMISSIVITY _ Figure 25 Emissivity Sensitivity Parameter 20 1000 w m 15 750 W m 2 10 500 W m N eo 5 250 W nf Pa 0 wim 2 2 0 4 06 08 LO ABSORPTIVITY a Figure 26 Absorptivity Sensitivity Parameter The sensitivity parameter is a mathematical concept t
245. operties Purge Output Data Cnly Rename a Data Set Copy a Data Set Delete a Data Set Directory Listing Review nput Data Execute DYNAMP 15 16 18 18 18 19 19 20 21 21 22 27 27 29 39 37 38 38 39 40 4 42 DYNSMP Reports DYNAMP Help Facility Leave DYNAMP 4 EXAMPLE PROBLEMS Steady State Option Transient Option Predictive Option APPENDIX A Troubleshooting APPENDIX B List of Conductor Code Names 43 45 45 46 46 50 55 60 63 Section 1 INTRODUCTION This User s Manual describes the operation of a computer program which models the transient ampacity of overhead conductors he program was developed at the Georgia Institute of Technology and its accuracy has been verified by comparing the predicted conductor temperatures with values measured at Georgia Power Company s Research Center and temperatures measured in a separate study sponsored 5y Kansas Electric Utilities Research Program and carried out by Kansas Gas and Electric Company The resulting program is called DYNAMP for DYNamic AMPacity of overhead conductors YNAMP can perform both steady state and transient ampacity calculations There are three program options The first program option involves a steady state mode vhich calculates a single value of the conductor temperature for constant weather onditions and a constant line current The program also calculates ampacity for given value of conductor limiting temperature Th
246. or angle between normal to conductor and wind velocity vector INTRODUCTION In order to more fully utilize the capacity of existing overhead lines many major utilities are implementing techniques to determine conductor temperatures in real time If a utility chooses to measure the temperature of a line by installing thermal line monitors it is faced with determining how many monitors should be used and where they should be located Likewise if the utility chooses to use computer modeling coupled with weather data to predict the conductor temperature the number and location of weather stations need to be determined The emphasis on determining the real time temperature of overhead conductors has lead to the introduction of the term critical span A critical span is an individual span possibly several spans overhead transmission line that has the highest conductor temperature The critical span therefore represents a thermal chokepoint which limits the amount of power that can be delivered by the circuit The concept of a critical span 1 particularly attractive one to an operating engineer who has the responsibility of economically and safely operating a transmission network because it identifies the thermal weak link in each transmission line By loading the system on the basis of the limiting critical span the complex job of making load flow decisions without exceeding sag or loss of strength limits becomes
247. or damages resulting from the use of any information apparatus method or process disclosed in this report Prepared by Georgia Institute of Technology Atlanta Georgia and Georgia Power Company Atlanta Georgia II III TABLE OF CONTENTS EXPERIMENTAL PHASE Deor coegi Es EVA ice A Operation of Forest Park Test 5 B Weather Data Collection at Remote Sites 544 295 eee CU A ae THEORETICAL 5 P m A Additional Developments with 1 Version EE de 2 Interactive Version of B Statistical Analysis of DYNAMP s Predictions C Analysis of Remote Weather Data qm D Critical Span 1 ee ere rae E Evaluation of Line Monitor d ew ss APPENDIX s Rv MT P Puig pum Critical Span Analysis of Overhead Conductors m md a N amp gt I 25 25 25 33 33 40 46 54 55 I EXPERIMENTAL PHASE During the past six months the experimental phase of the project has progressed satisfactorily The test span operated by Georgia Power Company and located at their Research Center in Forest Park has continued to collect weather data conductor currents and conductor temperatures Since the last report the test span was operated for nearly 50 days
248. or if one is and it does not correspond to one with stored properties then the user must manually enter each property A list of all conductor code names contained in the property subprogram is included in the Appendix Code Name The code name specifies a particular conductor Typical example code names are DRAKE FALCON MARIGOLD etc Conductor Type Must be one of the seven types listed in the table below 1 5 AAC AAAC ACAR Copper Alumoweld AAAC Note Conductor Diameter Inches Conductor Strand Diameter Inches Core Strand Diameter Inches Number of Conductor Strands Number of Core Strands Sa ee vem ee Conductor Material Core Material 1350 H19 Aluminum 1350 H19 Aluminum 6201 181 Aluminum Steel 1350 H19 Aluminum 6201 T81 Aluminum 1350 H19 Aluminum 6201 181 Aluminum Hard drawn Copper Hard Drawn Copper 1350 H19 Aluminum Alumoweld 5005 H19 Aluminum 5005 H19 Aluminum Composite conductors such as ACSR conductors cons st of two layers of different materials The inner supporting material is referred to as the core material The outer current carrying material is referred to as the conductor material The outside diameter of the conductor Must be greater than the strand diameter and less than 3 0 inches The diameter of individual conductor strands Must be greater than zero but less than 0 5 inches
249. or location for the time zone chosen e g if the conductor is located in Hawaii and if calculations are desired for noon Hawaii time then the time that should be us d if the Pacific time zone is chosen would be 14 00 NOTE Values for the time variables are needed so that the program can correctly calculate the solar heat added to the conductor For real time calculations these values specify the time for the initial set of weather and current values For steady state calculations the time variables specify the time at which a single steady State conductor temperature is calculated Line Location Latitude The latitude of the conductor location in Degrees degrees north from the equator This value should be spl Longitude Degrees Elevation Feet Conductor Azimuth Degrees Conductor Inclinaticn Degrees between 0 and 90 degrees See map shown in Fig 2 1 for values The longitude of the conductor location in degrees east of Greenwich England This value should be between 0 and 360 degrees See map shown in Figure 2 1 for values The elevation of the conductor above mean sea level This value should be between 0 and 25 000 feet The conductor azimuth is the angle in degrees measured clockwise from a vector po nting north to the vector which is the horizontal projection of a line passing through the axis of the conductor The conductor azimuth must be between 0 and 180 degrees Examples a conductor o
250. osition Title Company Affiliation Address Telephone SECTION I Operation of Your Transmission and Distribution System 1 List the conductor sizes you use on your system Type MCM Stranding kV ACSR ACAR etc Area Designation Manufacturer Comments T o EE Does your company have the capability to calculate its own Yes Steady state ampacity values 16 Does your company measure the temperature of any of its Yes energized conductors DN 2 Does your company have the ability to monitor weather Yes conditions such as air temperature wind speed and wind 15 direction throughout your service area If yes how many weather stations do you have what is their location and what is the size of your service area If you do not measure the weather conditions do you Yes routinely collect data from another source If yes what is the source What is the form of that data Printed on tape etc In your service area do you have unusual operating or weather conditions for your overhead network such as Yes unusually high ambient temperatures extremely high winds 3 isolated or sheltered lines Explain the unusual conditions Area Subject to hurricanes The peak power demand in your service area is Summer 15 No 17 O No 40 No O N 9 0 Winter 40 8 For the following parameters your preference for units are kcmil cm Condu
251. ot only the operating engineer but it also provides a useful and valuable tool for planning and design engineers If a planner or designer has a knowledge of the transient thermal behavior of the overhead network he is better able to make capital intensive decisions For example a real time ampacity model could greatly influence the decision between purchasing additional right of way and installing a new line or simply utilizing an established line coupled with resagging reconductoring or rebuilding the existing towers The initial work on the steady state ampacity models first appeared in the 1920 s 1 5 even though extensive work had been completed prior to that time on the convective heat transfer from cylinders to air Thermal models for the calculation of the conductor temperature became more sophisticated 6 12 and naturally more complicated to use Real time ratings of overhead conductors were introduced 13 21 in the 1960 s 4 the present time most transient ampacity models are so complex that they require the aid of a digital computer for their solution The numerical complexity associated with a real time rating program is a distinct disadvantage and it will obviously discourage some from attempting to use real time rating results i This report describes a user friendly computer program that will overcome the problems with the complexities of previous real time ampacity models The program requires a minimum amount of input inform
252. ou use in your ampacity model 0 5 to 1 0 Do you consider only a single wind velocity in your 15 65 0 steady ampacity model If yes what is the value V 1 to 4 4f sec If no what is the minimum and maximum value rds ft sec for wind velocity and what dictates the selection between the two values dass ft sec 9 Do you assume the wind is always oriented Yes No perpendicularly to the conductor 210 If no what is the angle of wind relative to the axis of the conductor degrees 10 Do you calculate conductor ratings for Yes No Normal Conditions 200 00 Emergency Operation 40 40 Fault Conditions 00 10 Emergency If yes for emergency operation and fault time T conditions give estimates for t me that Fault you would expect ampacity values to be valid time 11 Does your steady ampacity model consider the following factors Yes No Magnetic heating 2 O 60 Temperature gradient in the conductor Evaporative cooling 0 12 How is your ampacity information made available to your operating engineer Yes No CRT display 120 40 Tables 90 00 Standards Manual 10 4 Other specify 0 13 What are the maximum conductor temperatures your company considers for the following conditions Normal Values ranged between 70 C and 120 C T Values ranged between 80 C and 140 T gt Fault Values ranged between 90 C and 100 C ___ 14 Are
253. ow changes in temperature and elapsed time when the air temperature wind ection wind velocity and current change 55 ilg dE OrNami AMPamitw 4 Version 1 20 Lovelia Sv Georgia of Technology and Georgia Fower Company Under 40 ivi DATA FREDIE LIVE tALCULALIUNS tor LINNET Conductor D es ductor Froperties 19 ACSR ALUM 1350 COND STECL CORE OUTZIDE DIAMETER CONDUCTOR STRAND DIAMETER Q 1137 JMCHES STRAND DIAMETER 0 OBRA INCHES NUMBER OF CONDUCTOR STRANDS 26 NUMIER OF STRANDS 7 Sets RESISTANCE 1393 DEG O 27 10 OHMS i1iLt w am em m n 2 we e e ne me wo ye am 0 722700 INCHES Location variables a o v w A m Ro p M Sg umite AND TIME rel i TUDE 54 2 BEG UNG TUDE 84 1 PEG INLLINATION PEG UuNDUCTOR AZIMUTH 6 0 PEG b obve TON G6BOVE SEA LEVEL 1000 gt 3 04 EASTERN Radiation Progerties o ABSORPTIVITY re me ee oe 0 50 30 anZient Variables gt ME GSUPOMENT TIME INTERVAL SINTING TIME INTERVAL em ae
254. pacity curves expected for common conductor sizes when subjected to typical weather conditions These curves will also be used as a check of all of the options within DYNAMP Whenever possible the curves will be compared with existing and accepted ampacity data The guy wires and the load cell for the test span will be installed in the next two weeks It is anticipated that the Linnet conductor will be re energized and temperature data will be collected in the latter part of April Sincerelv Wm 7 Black Professor EDS 474 GEORGIA TECH 1885 1985 P i M P DESIGNING TOMORROW TODAY May 24 1985 Mr Vito J Longo Project Manager Electrical Systems Div EPRI 3412 Hillview Ave P 0 Box 10412 Palo Alto CA 94303 Dear Vito Here is a brief summary of our progress on the Conductor Temperature project for the period April 15 through May 15 1985 1 Development of DYNAMP DYNAMP is currently being modified so that it will compile on an IBM PC This task is far more involved than originally anticipated and it should be completed in 2 or 3 weeks if no further complications develop The scope of DYNAMP is being changed so that it can calculate conductor temperatures for a greater diversity of conductor types The present version of the program will only consider three different conductor types while the new version will consider six different types of conductors They are
255. pecifies the conductor code name Most of the common overhead conductors are included in this property subcrogram and its use greatly simplifies the input of conductor data into the program The main program and all subprograms contain numerous checks on internal calculations performed within the program If the program encounters unusual values for calculated quantities or for input variables a series of diagnostic messages are printed on the screen In addition a series of help files are appended to the program to alid the user in interpreting the use and operation of the program DYNAMP is designed to operate on an an it is part of the TLWorkstation software The user interacts with the program through a user friendly front end program written by Power Computing Corporation This program facilitates the operation of DYNAMP and it simplifies the program instructions The remainder of tis manual describes the commands necessary to operate the real time ampacity program Section 2 PROGRAM INPUT GENERAL INFORMA T ION Input to DYNAMP consists of 24 variables when steady state calculations are required 26 variables when transient or real time ampacity values are required and 27 variabies when the predictive program is specified This section briefly describes each of these input variables It is not necessary that the user know the variable names te execute the program but he should be familiar with the type Lf infor
256. r Company on October 17 Tampa Electric Company on October 25 a An additional discussion period is being planned to coincide with the IEEE Winter Power Meeting in New York It is hoped that representatives of Ontario Hydro Rochester Gas and Electric Niagaria Mohawk and Boston Edison will attend this meeting and also complete the questionnaire Thus far 41 people representing 16 different companies have either participated the group discussions and have completed the questionnaire See Table below The survey has also been mailed to interested parties at TIVA Georgia Power Mississippi Power Gulf Power and Alabama Power Responses from these companies will be compiled when the surveys are returned The questions in the utility survey concerning present practice used by the various utilities revealed several unanimous points None of the utilities respnding to the survey presently have the capability to measure the temperatures of their overhead transmission conductors and yet every company expressed a desire to utilize a real time ampacity program to predict actual conductor temperatures when such a program becomes available Another question receiving a unanimous vote was the one which asked which system of units was preferred when using an ampacity program All companies expressed a desire to use the English system of units except the unit for temperature Most preferred to use the Fahrenheit degree when measuring the air temper
257. r than wind which blows across the conductor Therefore spans which are oriented ina direction such that they are parallel to the predominant wind direction are also reasonable choices for critical spans While the concept of a critical span is quite simple unfortunately it is difficult to put into practice The temperature of an overhead conductor is a complex function of a wide variety of parameters including conductor size current electric resistance weather conditions line location and orientation localized sheltering of the conductor and radiative properties of the surface of the conductor Any computer model or line monitoring equipment must successfully account for all of these factors if they are expected to accurately predict the conductor temperature SENSITIVITY PARAMETERS In order to predict the location of the critical span one must know how sensitive the conductor temperature is to the numerous parameters which influence it This requirement leads to the definition and derivation of sensitivity parameters which will help determine whether a critical span can be located with any accuracy and repeatability Expressions for each of the sensitivity parameters are obtained by taking derivatives of temperature with respect to each of the independent variables that occur in Equation 6 Equation 6 shows that the conductor temperature is a complex function of many factors Obviously not all of the parameters affect the conductor temper
258. r will emit radiant energy from its surface to the surroundings and this heat loss per unit length of conductor is given by the term Qrag in Eq 1 Since the conductor has relatively low temperature the predominant portion of the emitted radiant energy is in the infrared wavelength range Therefore the correct line radiative property to be used in calculating the emitted energy is the infrared emissivity Assuming the portion of the surroundings that has view of the line has the same temperature as the ambient air the net radiant energy exchange between the conductor and the surroundings per unit line length 15 Quan o T TL 4 where is the Stefan Bolzmann constant and T is the absolute temperature of the conductor The convection term in Eq 1 must account for free convection when the wind velocity is zero and for forced convection effects when wind exists The heat removed from the surface of the conductor per unit length by convection to the ambient air in terms of the convective heat transfer coefficient h is Quas 7 D A t Cr T 0 5 The convective heat transfer coefficient is a complex function of conductor temperature air temperature wind velocity and wind direction For still air conditions the convective heat transfer coefficient is a function of the Prandt number and Grashof number and for forced convection the Reynolds number replaces the Grashof number as the significant di
259. rands is an excellent insulator and has a very low thermal conductivity The appropriate thermal conductivity values to be used in Eqs 37 and 38 are effective values that consider the fact that the heat generated in the metal must be conducted through a composite material consisting of both air layers and the cylindrical metallic strands Therefore the appropriate thermal conductivities to be used in Eqs 37 and 38 are the effective conductivities of metallic strands interspersed with encapsulated air layers located between the strands Douglass 36 has compiled a number of effective conductivity values for ACSR conductors from a number of sources Effective thermal conductivity values range from 1 2 to 5 6 W me C depending upon the size of conductor tension in the conductor stranding and state of the thermal environment Values of effective conductivity seem to center around a value of 2 W me C for aluminum strands and 1 5 for steel strands These values will be used in the results presented in the next section Table 2 Values of Thermal Conductivity at 20 C from 23 pg 24 and 27 pgs 511 and 520 Material _k W me C Copper 410 Aluminum 1350 H19 234 6063 T6 201 Galvanized Steel 40 Air A computer program was developed to determine the temperature distribution in the conductor Input variables to the program include geometric thermal and electric properties of both the supporting and conducting strands and the total cur
260. re of these two data Jroups is given below Editing Current and Weather Data DYNAMP must be given the conductor current ind weather conditions in order to make temperature calculations If the steady state mode is selected only one set of current and weather data is needed that s only one value of steady state conductor current ambient temperature wind rection and wind speed is needed However if the transient or predictive odes are selected several sets of current and weather data are required Each et corresponds to a particular time and date and each set is separated from diacent sets by a time equa the value for Time Interval specified in the ransient Variables menu s an example suppose it is desired to change current and weather data in a file illed TRANS After selecting Edit Create Input Data from the Module Menu following prompts appear DYNAHP Edit Create input data Edit or Create 1 BB Data name A ers eae AA O ee eo ee ee ee eee Press Fi Help Mext Field Esc Leave Form 29 The user should respond by typing an E for edit in the first prompt Assuming the data files are stored on drive C the user enters C in response to the second prompt Since the file name is called TRANS the user enters TRANS in response to the third prompt as shown below DY NAMP E
261. rent in the composite conductor Additional input parameters include values which quantify the thermal environment of the conductor such as wind velocity and direction solar flux and ambient air temperature Using the mathematical model described in this section the temperature in an overhead conductor can be calculated as a function of radial position Then by comparing the temperature current relationship for this model with one like DYNAMP which assumes an isothermal conductor at any instant in time it is possible to determine whether temperature gradients inside the conductor will have an influence on the ampacity of a conductor To distinguish between the two models the one based on Eqs 37 and 38 will be referred to as the Non Isothermal Model because it accounts for radial temperature gradients in the conductor The model described in the previous section and based on the DYNAMP program will be designated as the Isothermal Model because it assumes the conductor is uniformly at a single temperature The Non Isothermal Model has been applied to a wide variety of ACSR AAC and all copper conductors A few of the more important conclusions that can be drawn from these results are illustrated in the figures presented this section A more extensive set of results is provided in Ref 35 Figure 2 illustrates some of the typical results for five ACSR conductors with widely varying sizes Characteristics of these conductors are given in Ta
262. rfaces 0 30 for lightly oxidized surfaces 0 03 for polished new surfaces The incident radiant energy on the conductor lies predominantly in the wavelength range from the visible portion of the spectrum into the near infrared Therefore the parameter which dictates the percent of the total incident solar energy that is absorbed by the conductor is the solar absorptivity The trend in the solar absorptivity can be predicted with some reliability by observing the color of the conductor Surfaces which are highly corroded and dark color tend to have values of solar absorptivity which approach 1 0 More polished and highly reflecting surfaces have much lower absorptivities Values for the solar absorptivity for both aluminum and copper conductors can be approximated by using the results presented in Ref 29 ag 0 2 13 with the restriction that lt 1 0 Convection An accurate model for determining the convective heat transfer coefficient is imperative for an accurate prediction of the thermal behavior of an overhead conductor Unfortunately the convective heat transfer from a conductor is a complex phenomena that does not easily lend itself to a simple analysis As the wind velocity approaches zero the heat transfer from the conductor occurs by free convection and the convection heat transfer coefficient in terms of the Nusselt number Nu is given by a functional relationship which can be written in t
263. rienced with the Linnet conductor although the program consistently overestimates the conductor temperature by approximately 10 C Additional measured temperatures have been collected on disc for the Curlew conductor but the data has not been analyzed with DYNAMP 3 Temperature Gradients in Conductors A detailed analytical study of the temperature gradients that occur within conductors has been completed Stuart Collins recently completed his master s degree requirements and a copy of his thesis is enclosed The analysis allows calculation of the temperature gradients in ACSR AAC and all copper conductors operating under all types of weather conditions The results show that ampacity calculations can be accurately made without considering the temperature differences in the conductor even though in extreme conditions the temperature differences that may exist in ACSR conductors can be as high as 10 15 Georgia Institute of Technology School of Mechanical Engineering Atlanta Georgia 30332 te te am ee M An Equal Education and Employment Opportunity Institution A Unit of the University System of Georgia Mr Vito J Longo 2 September 12 1985 4 Planning for Seminars Planning for the two Spring seminars is proceeding satisfactorily Announcements will be mailed within the next two weeks Both seminars will be held in Atla
264. riented from the northwest to the southeast has an azimuth of 135 degrees An east west line has an azimuth of 90 degrees The azimuth of a north south line can either be 0 degrees or 180 degrees Note The end of the conductor used to determine the azimuth will also be used to determine the conductor inclination The conductor inclination is the angle in degrees between a line through the conductor axis and the horizontal plane This angle should be between 90 0 and 90 0 degrees If the end of the conductor used to determine the conductor azimuth lies below the horizontal plane then the conductor inclination is negative If the end of the conductor used to determine the conductor azimuth lies above the horizontal plane then the conductor inclination is positive Examples If the end of the conductor is 33 degrees below the horizon then the inclination angle is 33 degrees If the end of the 12 2 A Lv x T gt A DA 7C M UN 2 Uu tow c ae x s 6 MT m d SN gt 4 Qu 0 th 14 Se x Ax 0 pe ee QU k DM uM E A tU s p 7 a UM Pi 6 v7 gt gt E z 7 Se eee a 3 i gt 2 G 4 gt Ph TRACTU ox 2 D wg EE s T we A p uz Peete ub MEE EC 7 o 7 a a hd xw vs mS Cha b
265. riods of rain This assumption leads to conservative results and during rainfall the program can over estimate the conductor temperature These last two assumptions greatly Simplify the otherwise complex task of collecting weather data for input to the program As a result the inputs required for the DYNAMP program are simply the wind speed wind direction and ambient air temperature The thermistor sensor used for ambient temperature measurement is accurate to within 0 1 C The threshold velocity of the anemometer is 0 5 mph The accuracy of the anemometer is 0 15 mph or 1 of the full scale reading whichever is greater The cup anemometer gives two contact closures per revolution so that the number of counts per minute is proportional to the wind speed The threshold response of the wind vane is 0 5 mph and the resolution is one degree The output from the microprocessor based weather station is optically isolated and sent to the data acquisition system via an RS 232 data link The weather station was calibrated at Weathertronics to standards that are NBS traceable The calibration of the wind speed output was then checked in three month intervals using a constant speed motor to drive the shaft of the cup anemometer Practically no drift of the sensors occurred during the time the test span was in operation All load control and data collection for the test span were performed using the HP3054 data acquisition system The system consisted of a
266. rizontal cylinder to air flowing perpendicular to the axis of the cylinder the Nusselt number correlation can be estimated by the expression See Ref 16 10 0 07043 0 3153 logRe 0 03553 1ogRe 22 For wind directions other than perpendicular to the conductor Eq 22 can be corrected by using the expression 16 1 194 sinw 0 194cos2w 0 36851 2 23 where w is the angle between the normal to the surface of the conductor and the direction of the air flowing across the conductor denominator in Eq 23 Nu w 0 is the Nusselt number for perpendicular flow Properties of Air The Nusselt Prandtl Grashof and Reynolds numbers contain properties of air that are functions of the average air temperature The program calculates these properties at a film temperature which is the average temperature of the ambient air and the conductor or OTT Te 24 thermal conductivity W m C of air at the film temperature in C fs 0 023681 7 232 x 10 5 Tf 2 763 x 10 8 Tg 25 The dynamic viscosity in Jes m of air at the film temperature in C is p 17 456 x 1076 3 954 x 1078 26 The property group gf v in the Grashof number 15 gf 9 807 2 y E 27 where the film temperature is and the property group has units of K lm 3 The density of the air used in this group is a function of the air temperature and elevation of the conductor If
267. rlew Conductor Ocrober 23 OSG occ oes cS EP CCCII S v9o9999909 Comparison of Monitor and DYNAMP Predictions for Curlew Conductor on October 23 1986 10 11 12 13 14 TABLES Electrical Resistivity and Temperature Coefficient of Resistivity of Common Conductor Materials Values of Thermal Conductivity at 200 m Physical and Electric Characteristics of Typical ConduCtOrs iv Reo ACA eee as Physical and Electric Characteristics of Typical AAC Conductors Ve Eg re er XX y dax deep ee KG amp E Field Site Conductor Characteristics ccccscecece Statistical Analysis of DYNAMP s Predicted Temperatures for a Total of 24 700 Data Points Statistical Analysis of Data Points where Predicted Temperature is Greater than Measured ERE RA cues ware bes Statistical Analysis of Data Points Where Predicted Temperatures are Less than Measured 1 Sensitivity Parameters Input Variable Reference 5 Weather Station Site 5 VERA CIR Title of Presentations at the Real Time Anpacity Semina Ss AN Yu eis Participants in Utility Survey iss ah reer Utility Survey and Summary of Responses Peleus i RART DRAET SECTION 1 INTRODUCTION Historically most electric utilities have thermally rated their overhead transmi
268. rogram for the Determination of Temperature and Sag of Overhead Lines Trans IEEE Vol PAS 102 No 7 pp 2284 88 July 1983 4 Black Z and Rehberg R H Simplified Analysis for Steady State and Real Time Ampacity of Overhead Conductors Trans IEEE us PAS 104 No 10 pp 2942 53 October 1985 5 Davis M A New Thermal Rating Approach The Real Time Thermal Rating System for Strategic Overhead Conductor Transmission Lines Part II Steady State Thermal Rating Program Trans IEEE Vol PAS 96 No 3 pg 812 815 May June 1977 TLWorkstation DYNAMP Version 1 2 Research Project 2546 Computer Code Manual June 1987 Prepared by School of Mechanical Engineering Georgia Institute of Technology Principal Investigator William Z Black Prepared for Electric Power Research Institute 3412 Hillview Avenue Palo Alto California 94304 EPRI Project Manager Vito J Longo Overhead Transmission Lines Program Electric Systems Division Notice This report was prepared by the organization s named below as an account of work sponsored by the Electric Power Research Institute Inc EPRI Neither EPRI members of EPRI the organization s named below nor any person acting on behalf of any of them makes any warranty express or implied with respect ts the use of any information apparatus method or process disclosed b assumes iabilities with respect to the use of or for damages resulting fr
269. rom the surface by convection and radiation to the surroundings The analysis assumes that the sun creates an incident radiant flux on the outer surface of the conductor equal to The portion of this incident solar energy that is absorbed by the conductor is dictated by the absorptivity a of the conductors surface The emissivity of the conductor is and the surroundings are assumed to be radiatively black at the ambient air temperature which is equal to Tw values for both Qgy and h are calculated using the procedure outlined in the previous section Application of these four boundary conditions results in four non linear algebraic equations that can be used to solve for the four constants of integration in Eqs 37 and 38 Details of these equations and the solution by Bairstows method 32 are given in Ref 35 Once the values for the four constants are determined as a function of conductor properties current in both materials and the state of the thermal environment of the conductor Eqs 37 and 38 can be used to calculate the radial temperature distribution in both the supporting and conducting strands One remaining factor that must be addressed before the local temperatures in the conductor can be calculated is the proper value for the thermal conductivity of the strands The thermal conductivity of solid conductors are quite high as can be seen from the values in Table 2 On the other hand the air that exists been the st
270. rs The program predicts a temperature that is consistently above the monitor temperature although the trend in the two temperatures is nearly identical Figure 27 shows the data collected on September 25 1986 with a Rail conductor This particular figure shows the worst correlation between the program and monitor for all the data collected Over a brief period of time the program predicted temperatures that were over AB COMPARISON OF DYNAMP AND EXP TEMPS WEAVER EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO HAWK CONDUCTOR ACSR 26 7 477 KCMIL SEP 16 1986 MEASURED DYNAMP A AMB TEMP CURRENT 9 00 35 00 3 59 9260 _ 23 00 19 00 o 5 00 8 00 10 00 12 00 14 00 16 00 TIME HOUR WIND DIRECTION WIND SPEED o7 M OND DEG 60 00 30 00 WIND ANGLE WITH C lt 0 00 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 TIME HOUR Figure 24 Comparison of DYNAMP and Line Monitor for KG amp E Hawk Conductor on September 16 1986 49 75 00 62 50 50 0 25 00 37 CURRENT AMPS 12 50 1800 24 00 16 00 8 00 IND SPEED 5200 COMPARISON OF DYNAMP AND EXP TEMPS WEAVER EPRI PROJECT 2546 DATA COLLECTED BY KANSAS POWER CO RAIL CONDUCTOR ACSR 45 7 954 KCMIL SEP 23 1986 amp m MEASURED DYNAMP TEMP CURRENT m 8 N N 8 So d c 29 5
271. rs in academic positions and a few members of the press The proceedings of the seminars entitled Effects of Elevated Temperature Operation on Overhead Conductors and Accessories and Real Time Ratings of Overhead Conductors are available from EPRI as a special publication The titles of the individual papers are given in the Appendix UTILITY SURVEY In the initial stages of the project a survey was written to solicit input from a broad cross section of utility engineers The survey was specifically formulated to determine how the various utilities would ultimately use a real time ampacity program It was also designed to provide utility input in the early development stages of the ampacity program The responses to the questions in the survey were then used to provide direction in writing the program so that it would receive the greatest possible use throughout the industry A copy of the survey and the responses to all questions is placed in the Appendix The questions in the survey came from a combination of sources Some questions were taken from a survey conducted by CIGRE others were formulated to determine the present state of ampacity models used in the industry while other questions were inserted to determine needs for future ampacity models Some questions were specifically inserted to determine the interest in and the demand for line instrumentation which could be used to predict real time conductor temperatures e The survey wa
272. s 59 58 T C 57 DRAKE CONDUCTOR 1 Amps V 5 6mph 0 90 26 Teo 25 5 0 5 I O ae GEN oo loc Figure 3 Temperature as a Function of Radius for a Drake Conductor at 1100 amps Figure 4 shows results similar to the ones in Fig 2 except for four AAC conductors The physical and electrical characteristics of these conductors are summarized in Table 4 These results show that temperature differences in AAC conductors rarely exceed 70C even for conductor temperatures as high as 1000C The Isothermal Model again predicts temperatures extremely close to the temperature of the outer surface of the conductor and the Isothermal Model 1 able to accurately predict ampacity values under the conditions stated in the figure When the Non Isothermal Model is applied to all copper conductors the predicted temperature differences between the centerline and surface of the conductor are about one half the values for AAC and ACSR conductors 35 DAISY 20 MISTLETOE MAGNOLIA CARNATION 100 80 6 T C 4 b N 4 SURFACE SOTHERMAL MODEL 20 500 1000 1500 2000 I Amps Figure 4 Temperature as a Function of Current for Several AAC Conductors Table 4 Physical and Electrical Characteristics of Typical AAC Conductors From 23 Table 4 5 Size Strands Dia of 00 11 Strands Daisy 266 8 e 0 1953 0 586 Mistletoe 556 5
273. s Fence Row 26 High Power Pole Hardwoods Remote Site 3 Conyers Figure 4 Plan View of Remote Weather Station Number 3 es cep oux Scale 1 inch 60 Feet Figure 5 C CS Colle C C PAPA C ECT Building CRM SA OSES 65 ele ae ee ag e x 8 Foot Fence small building 13 Feet above Roof 63 weather station pole 8 feet above on corner Power Plant 17 Feet High Remote Site 4 Shenandoah Plan View of Remote Weather Station Number 4 COMPARISON OF DYNAMP AND EXP TEMPS BASE STATION PROJECT 2546 DATA COLLECTED BY GEORGIA POWER CO CURLEW CONDUCTOR ACSR 54 7 1034 KCMIL JUNE 30 1986 5 m MEASURED DYNAMP a AMB TEMP 4 CURRENT 2 E 6 9 3 O 5 pu t E viv de 2 ay ux Tr TEE ds Nom 3 m 4 oS 2 gi zh MARS g in lt 3 am 5 wv e 5 98 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 HOUR Zo WIND DIRECTION WIND SPEED cy V gt Us LJ Oo 25 lt 98 00 10 00 12 00 14 00 15 00 18 00 20 00 22 00 24 00 TIME HOUR lt Figure 6 Measured and Predicted Conductor Temperatures and Weather Conditions at Base Station for June 30 1986 12 200 00 175 00 150 00 407 125 00 CURRENT AMPS 12 00 520 00 75 00 100 00 8 00 IND SPEED MPH 4 00
274. s for completing this form are on the reverse side All figures are to be shown In U S dollars whole thousands only Show EPRI portion of the contract only Do not include contractor cost sharing Current Actual booked Year cost In the Jan Mar Apr May Jun Jul Aug Oct Nov Dec Actual io BO year x Ld NM MEME Current Forecast to Year complete the Jan Feb Mar Apr May Jun Jut Aug Sep Nov Forecast 19 Op year Unbooked Forecast to gt Remaining liability complete the 19 87 19 Years s Please list dollar future year s amount descrip 30 tion ol cost and nm Grand total of tines 1 2 3 4 which costs are i expected to be booked Future Year s Forecast Remarks Comments on significant items EPRI Actual booked cost In the current year 19 86 Forecast to complete the Current year 19 86 Unbooked liability Please list dollar amounl descrip of cost and month year in which costs are expected to be booked CONTRACT NuMDER e 215 g 6 _ PROJECT MANAGER 27259 dinge From 7 1 84 6 30 87 Atlanta GA 30332 Prior Note Instructlons for completing this form are on the reverse slde Year s All figures are to be shown In U S dollars whole thousands only Actual AN CONTRACTOR COST PERFORMANCE REPORT EPRI 177 5 b4A EPRI DIVISION NUMUER _ PERIOD OF PERFORMANCE
275. s subdivided into four parts Section I Operation of Transmission and Distribution Systems Section II Steady State Ampacity Calculating Section III Real Time Ampacity Calculations Section IV Ampacity Instrumentation and Critical Span Analysis In addition to the survey five companies were selected for site visits and discussions were held concerning real time ampacity models 11 discussions at these site visits were recorded on tape During these visits rating manuals were collected and compared The five companies visited were Illinois Power Company Decatur Wisconsin Electric Company Milwaukee Pacific Gas and Electric Company San Francisco Idaho Power Company Boise Tampa Electric Company Tampa A list of people who either participated in the discussions during the site visits or completed the questions on the survey are listed in the Appendix The list includes 48 engineers representing 23 different companies As expected the response to the survey revealed a broad range of interest in a few areas but there were several items that received unanimous opinions None of the utilities responding to the survey had the capability to measure the temperatures of their overhead transmission conductors and yet every company expressed a desire to utilize a real time ampacity program to predict actual conductor temperatures when such a program becomes available Another question receiving a unanimous vote was the one which aske
276. span was simply the span which had the highest temperature Most of those who subscribed to the concept of a critical span simply said that a critical span was one that had experienced thermal problems in the past and a few people said that a critical span could be identified by locating those spans that had experienced exceptional load growth in the past ll Purpose Input Qutput Common Blocks Computer Symbols and Symbol ALPHA DENSTY DLESST EXPONT G PRESSL R TEMPSL TMAX TMIN FUNCTION DENSTY This function subproyram calculates the density of atmospheric air at the ambient air temperature and local atmospheric pressure Z elevation in meters TEMP local atmospheric temperature in C DENSTY density of air in kg m Description of Variables Description Lapse rate of the atmosphere Density of air Dimensionless constant he value of the exponent in calculations Acceleration to gravity Pressure at sea level Ideal gas constant Temperature at sea level Maximum temperature for which calculations are valid Minimum temperature for which calculations are valid Units C m kg m m s KPa oc FUNCTION DENSTY PARAMETER Statements Y PRINT Statements Smp Y PRINT Temp Tmin Statements Compute EXPONT DLESST PRESR Calculate DENSTY 14 FUNCTION DENSTY Z TEMP kkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
277. specifying the conductor code The conductor code names that are contained in the subprogram are listed cenw for each of six different conductor types ACSR Aluminum Conductor Steel Reinforced JOREE FALCON MARTIN BLUEJAY HAWK amp INGFIZHER NUTHATCH BITTERN FINCH HEN CLUEBIRDO PARROT PHEASANT ORTOLAN CHICKADEE HULKAR BOBOL INK BUNTING CURLEW BRANT AFW ING PLOVER GRACKLE NONAME 1815 RNCRAKE DIPPER GReBE ROOK LARK ae CRANE CROW GOOSE MERLIN JCOUE STILT GROSBEAK WIDGEON TERN STARLING EGRET LINNET TURBIT REDWING SCOTER TURKEY GANSER PUFFIN BUTEO DUCK BRAHMA ANS TONE CONDOR GULL PEACOCK DORKING E CUCKOO FLAMINGO SQUAB PARTRIDGE DRAKE GANNET TEAL PENGUIN MALLARD SWIFT WOODDUCK QUAIL ARY SKIMMER K INGBIRD OSPREY RAVEN SPATE ORIOLE GUINEA PARAKEET ROBIN i PHOEBE LEGHORN THRASHER SPARROW GADWALL MINORCA KIWI SPAKATE OSTRICH PETREL JUNCO SWAN N GROUSE PIGEON SWANATE ES WAXWIhG COCH _N DOTTEREL ACSR EHS 63 DE 1585 H19 Aluminum Core and Conductor 2 ESUNNET CATTAIL HAWTHORN mia PETUNIA MARIGOLD NASTURT EUM LARKSPUR SUN PL IOLET BLUEBELL JE FLAG HAWKWEED lt gt 515 VERBENA CAMELLIA weed seus ORCHID GOLDENROD CARMA TON MEADOWSWEET MAGNOLIA COLUMSINE MISTLETOE SNAPORAGON NARCISSUS HYACINTH COCKSCOMB ZINNIA CROCI S 5005 H19 Aluminum Core and Conductor SOLAR 2 R KOPE
278. spond by entering the drive letter and the name of the input data file that is to be reviewed After responding to the prompts the following menu will appear on the screen DYNAMP Review input data Drive Input data selector Conductor Date amp Time Line Location Radiation Properties Current amp Weather Edit Press F1 Help Space Bar Next Choice Enter Select Choice E ENS This menu allows the user to select the data group input page that is to be reviewed After that selection is made the input page will be displayed with the following menu iocated at the bottom of the screen Select One Previous Select LEAVE If the user desires to go to the previous input page Previous should be selected is selected if it is desired to go to the next input page return to the Input Page Menu use Select To return to the Module Menu select Leave EXECUTE OYNAMP When the user wishes to execute the DYNAMP program Execute DYNAMP is selected rom the Module Menu This procedure will produce an output file with the same name as the raw input file As stated earlier the two files are referred to as a data set and this data set will have the same name as the input and output files ifter selecting Execute DYNAMP the user will be asked to enter the raw input lata file name with the following prompt PYMAHP Execute
279. ssing through the composite conductor is I then the current through the conducting strands with a resistance of and the current through the supporting strands Ig with a resistance Rg are RADIATION TO SURROUNDINGS Qrad m 2 CONDUCTING STRANDS SUPPORTING STRANDS Conv CONVECTION TO SURROUNDINGS CONDUCTOR PROPERTIES m Mass Specific Heat Resistance Gs Solar Absorptivity Infrared Emissivity T Temperature Figure 1 Energy Balance on Conductor TE P 33 S t Rot Ro 34 C t Rot Re The results of Eqs 33 and 34 illustrate that the current distribution in one material of the composite conductor 1 function of the temperature of both materials because the resistances are functions of temperature Therefore the determination of the temperature distribution in both the supporting and conducting materials becomes an exercise of simultaneously solving Eq 32 when it is applied to both materials To simplify matters without a significant loss in accuracy values for the two currents and Ig can be approximated by using values of the two resistances in Eqs 33 and 34 evaluated at an approximate temperature This assumption has shown 35 to produce errors in the current distribution in the two layers of conductor that are less than 2 even if errors in the assumed temperature are as high as 30 C Using the current distribution given by Eqs 33 an
280. ssion and distribution lines on the basis of a desired maximum operating temperature and an assumed set of conservative fixed weather conditions As result most lines are thermally underutilized for a majority of the time Recently more utilities have recognized the significant economic benefits associated with the ability to determine conductor temperatures and line clearances based on existing weather conditions A real time thermal line model can therefore reveal excess current carrying capacity and it can permit safe system operation without exceeding temperature and ground clearance limits The objective of this project was to develop an experimentally verified computer program that is capable of predicting the real time ampacity of overhead conductors The result is a program for modeling conductor DYNamic AMPacity DYNAMP which is part of the TLWorkstation software package DYNAMP solves the basic energy balance on a unit length of conductor and it includes convection and radiation from the surface of the conductor energy generation inside the conductor due to I R heating and storage of energy within the conductor resulting from the thermal capacitance of the conductor mass The details of the energy balance and the mathematical techniques used to solve for the conductor temperature as a function of weather conditions and current are outlined in Section 3 The temperatures predicted by DYNAMP have been verified by a test program u
281. st calculates the mass and cross sectional area for both the conductor id core strands It also calculates the skin effect of the composite conductor using the input value for A C resistance and a calculated value for the D C sistance The final line of output contains the time for which the ampacity and mperature calculations are carried out the conductor current and the weather nditions Also on this line of output is the calculated conductor temperature 3 9 C for this example which exists for the given current and weather ditions The final calculated value this line of output is the 100 C sacity value which is 596 amps for the given conditions 46 Dy NOME ViNamic owibecitv FROGRAM Version 1 20 2222 22 29 Georala Institute of Technologv and Georaia Fower Company Under EFRI 2246 1 oT eni STATE CALCULATIONS for LINNET Conductor vus iuf ae weer 1 Lune facinus Auai ALUM 1350 COND STEEL CORE amna Asia dua arbos DIAMETER 0 7200 INCHES STRAND DIAMETER 222227 INCHES JEKE STRAND DIAMETER 0 0884 INCHES CF CONDUCTOR STRANDS 26 IF COSE STRANDS Fi ow a MESTSETSANCE 25 DEG 2720 OHMS MILE wei l dubi doa f 6 04 9 04 EASTLRN 3 254 2 DEG ie Oe eae 84 1 DEG Rr 1 0 0 GEG Tue Dazu MP X NOR CPG DS 0 0 DEG nk SEO LEVEL LOCO 2 n dd a aa 9 9
282. st span was operated for this project the Curlew conductor was in place for about 15 months During that time over 26 400 data points of weather conditions current and conductor temperature were collected and recorded on diskette This number represents nearly 92 days of continual operation All of these data points have been analyzed with DYNAMP and a statistical analysis of the program accuracy has been performed The result of the statistical analysis 1 shown in Tables 6 through 8 These tables include a total population of 24 700 data points out of the 26 400 points collected The difference in these two numbers represents the data collected during periods of rain and the first few minutes at the beginning of each new collection period At both of these times DYNAMP jis known to be inaccurate because it does not account for the evaporative cooling that occurs during rainfall and it fs not able to predict the real time temperature when it is given only a single weather data point at the beginning of a run Therefore these points were removed from the statistical package so that a true picture of the program accuracy would emerge The data in Table 6 shows the errors that resulted with DYNAMP for the total population of 24 700 data points collected over the 15 month period the test span was in operation with the Curlew conductor errors which appear in the table are defined as the difference between DYNAMP s predicted temperature and the
283. stance at an arbitrary temperature T per a unit length of conductor is calculated from the expression 2 p 20 1 a T 20 Re D 240 9 02 4 and the lay factor values from Ref 30 have been used to correct for the length of strands for a unit length of conductor The A C resistance can be calculated from the known skin effect SE Rac T SE Rpc T 10 Equation 10 is used to calculate the electric resistance of both the supporting and conducting strands The resistance for a unit length of the composite structure is then calculated from i Ro T R T RO ROT because the two materials form a parallel resistance to the flow of the total current The resistivity and temperature coefficient of resistivity for the various conductor materials are given in Table 1 Table 1 Electrical Resistivity and Temperature Coefficient of Resistivity for Common Conductor Materials From Ref 23 Material p 209C x 106 a x 103 ohmecm ohmecm C 1350 H19 Aluminum 6201 T81 Aluminum 5005 H19 Aluminum Hard Drawn Copper Alumoweld Stee The two radiative properties needed in the thermal model Eq 6 are the solar absorptivity and infrared emissivity of the surface of the conductor The emissivity is the ratio of the radiant energy emitted by a surface to the radiant energy emitted by a black surface at the same temperature The emissivity depends upon the material of the emitting surface its
284. subscripts Number of data points X value at which interpolation for the Y value is desired The x coordinate variable manipulations Variables used in the interpolation The y coordinate variable FUNCTION YINT Y PRINT Error Message PRINT Error Message RETURN ze FUNCTION YINT cont QLoop 10 Y N 1 MO M 1 pe N a WHT ey N FUNCTION YINT cont MO t I 1 XP I X L XQ I X L YY I Y L YY J XX J YINT Y Y M RETURN Ed FUNCTION YINT X Y N M P He He He He te He te He He He te He He He He He He eee eee dee ee He eK e dede HH THIS FUNCTION SUBPROGRAM IS USED TO INTERPOLATE WITHIN A SET OF TABULAR VALUES 3 s eee e eee He dee He He eee ee Heke KH AHHH AH H e dee ee dee deese eee deese DIMENSION X N XX 10 XP 10 XQ 10 10 IF P LT X 1 P GT X N THEN WRITE 7 9 P RETURN END IF IF N LT M OR N LE 2 THEN WRITE 7 7 RETURN END IF 7 FORMAT 44HINTERPOL IS IMPOSIBLE DATA ARRAY TOO SMALL 9 FORMAT 29HINTERPOL IS IMPOSSIBLE P E12 4 C 12HOUT OF RANGE IF M GT 10 THEN M 10 ELSE IF M LT 2 THEN M 2 END IF Ml 2 DO 1 I 1 N IF P LE GO TO 2 1 CONTINUE 2 IF P LE 0 5 X I X I 1 AND GT 2 THEN I
285. successful in predicting the critical temperature of a transmission line when the average wind velocity is low when the wind blows down the axis of the conductor and when the current levels in the circuit are high Line current and weather conditions which produce the greatest thermal demand on the system resulting in the highest average conductor temperature are identical to those that make the location of the critical spans most difficult to predict On very calm days line monitors and weather stations must be closely spaced probably no more than 1 2 miles apart for the type of terrain in this study to assure accurate conductor temperatures When selecting monitor locations each utility should consider its own terrain and evaluate how the spacing will affect the accuracy of a real time line monitoring system On days in which the wind velocity is high and sustained an accurate conductor temperature can be obtained from much more widely spaced monitoring equipment DRAPP eue A survey was undertaken to determine what line monitors were commercially available A total of four types of monitors were obtained Of these only one was found to be sufficiently reliable or accurate to evaluate This monitor measures line temperatures and after this measured temperature is corrected for the influence of local wind conditions and heat sink effects it sends a radio signal to a ground station The monitor was installed on the test span
286. t to the line was determined by adjusting the output from a 480 volt power transformer This transformer fed a series of current transformers which were used to induce current through the conductor at low voltage The current was measured by running the conductor through a meter grade current transformer The impedance matching system was used to couple capacitance to the line so that the self inductance of the conductors was offset A capacitor bank was attached 2 to the high side of a step up transformer which was connected to the line By switching an optimum number of capacitors into the circuit a maximum current output of 1800 amperes could be obtained on the Curlew conductor ANEMOMETER CONDUCTOR WIND VANE M THERMOCOUPLES Figure 8 Diagram of Test Span TEST SPAN 15 LI VARIABLE CURRENT IMPEDANCE CAPACITOR AUTOTRANSFORMER LOADING MATCHING BANK TRANSFORMER TRANSFORMER Figure 9 Power Circuit Schematic Thermocouples were connected directly to the conductor to measure the conductor temperature measurements Type T sheathed thermocouples with ungrcunded junctions were installed Holes were drilled into the outer strands as well as into the steel core so that the inserted thermocouples could be used to measure core temperatures and surface temperatures The thermocouple sheaths were 34 mils in diameter and they had a breakdown voltage between the sheath and the thermocouple ju
287. tant conclusions regarding critical spans can be drawn from the sensitivity parameter study and the conclusions are verified by the data collected from the remote weather stations On calm days the number of critical spans increases and their movement from span to span becomes more frequent Also when the wind blows down the axis of a conductor the number of critical spans and the movement of a critical span increases These two facts imply that a thermal monitoring scheme can be expected to be the least accurate when the wind velocity is low and when the wind direction 1 down the conductor Therefore when weather and operating conditions place the greatest thermal demand on the system the task of predicting the location of a critical span 1 most difficult On days when the conductor is coolest that is on days with relatively high wind speed flowing across the conductor the critical span is easiest to locate 45 Finally the weather data collected at the base station and the four remote sites has shown that on very calm days line monitors and weather stations must be closely spaced probably no more than one or two miles apart to assure accurate conductor temperatures On days in which the wind velocity is high and sustained an accurate conductor temperature can be obtained from much more widely spaced monitoring equipment The results of the critical span study have been summarized in a paper entitled Critical Span Analysis of Overhe
288. te 1 200 00 150 00 100 00 12500 CURRENT AMPS 10 75 00 0 00 26 00 12 00 MPH 4 00 WIND SPEED 90 00 100 Z7 BASE STATION ET REMOTE SITE 7 REMOTE SITE2 60 REMOTE SITE 3 q REMOTE SITE 4 q Q 5 c mn QO a 20 lO 20 30 40 50 60 DIFFERENCE IN MEASURED AND PREDICTED TEMPERATURE C Figure 30 Errors in Predicted Conductor Temperature as a Function of Distance Between Span and Weather Station became more sensitive to changes in the wind and the small variations in wind velocity from location to location produced large changes the conductor temperature The data in Figure 31 shows that if a single monitor is expected to predict the temperature of another span about 1 mile away remote site 1 during conditions of no wind average errors of about 15 C can be expected If it is expected to predict the temperature of a span between 7 and 25 miles away average errors in excess of 30 C can be expected m sec ED 30 REMOTE SITE 2 REMOTE SITE 4 DIFFERENCE IN MEASURED AND PREDICT 4 6 8 10 WIND VELOCITY ft sec Figure 31 Errors in Predicted Conductor Temperature as a Function of Wind Velocity for Five Weather Stations The curves in Figure 32 are similar to those which appear in Figure 31 except that the temperature differences are plotted as function of wind angle instead of wind velocity These curves show the general d
289. temperature surface condition and wavelength distribution of the emitted energy Since the temperature of a conductor rarely exceeds 1500C the emitted energy lies predominantly in the infrared wavelength ranges As a result the appropriate emissivity for use in the emitted radiated energy term is the infrared emissivity Two studies 25 26 considered a large number of ACSR samples removed from service The results showed that the emissivity of the aluminum ranged between 0 23 for a new conductor to 0 98 for an aged heavily oxidized surface As expected the measured emissivity data showed a significant amount of scatter Nevertheless the emissivity values can be predicted with enough accuracy for the purposes of an approximate ampacity model The recommended curve from Ref 25 for ACSR conductors energized above 15 kV in most industrial as well as rural atmospheres is 25 0 70 Y where Y is the age of the conductor in years For ACSR conductors energized below 15 kV the emissivity variation with conductor age was determined to be 251 75 5 Y 12 for 0 Y 95 Like aluminum conductors the infrared emissivity for copper conductors is a function of the surface contamination and the extent of oxidization of the conductor surface The following values are recommended 23 and 27 for use in ampacity calculations utilizing copper conductors 2 0 80 for black heavily oxidized surfaces 0 50 for normally oxidized su
290. teps for creating and editing input files wil be described below INPUT DATA senera The dit Create feature allows the user to either make changes to edit an existing input data file or to create a new input data file After selecting Fait Create input Data from the Module Menu the following form will appear Dy N MP Edit Create input data Edit or Create E C Fae amp P ada p Press F1 Help Enter Next Field Esc Leave Form e user is now presented with three prompts The first prompt asks the user to ter an E or C The user may choose to edit an existing input data file by tering E or the user may choose to create a new input data file by entering After entering either E or C the user is asked to select the letter responding to the computer drive unit The user is then asked to specify the ie of the data file that is to be edited or created Note that at any time the r may press Fi for help or press the Esc key to return to the Module Menu ee Creating an input File 1f the user chooses to create an input file the drive letter and the name of the new nput file must be specified name that is not already assigned to a file can be used After entering the file name the user wil be allowed to create input data by responding to a sequence cf prompts and menus For example suppose it is desired to create a steady state
291. terminated and restarted numerous times in the middle of a set of transient input data and the temperatures have always converged to measured temperatures 1 55 than ten minutes of real time CAPABILITIES OF DYNAMP DYNAMP is a very versatile program with broad capabilities It can determine both steady state ampacity values as well as transient or real time temperatures of overhead conductors In addition it has a predictive mode of operation that permits the user to calculate the temperature of the conductor in a future time when the conductor is subjected to a step change in current The predictive mode of operation is designed to help a operator who wants to anticipate the temperature of the conductor when it experiences current transients that are typical during emergency operation DYNAMP is capable of predicting temperatures for seven different types of conductors 1 ACSR 2 AAC 3 6201 81 4 ACAR 5 All copper 6 1 1 7 AAAC 5005 H19 Properties of these conductors are automatically entered by the program once the user specifies the conductor type The program can calculate the conductor temperature for any reasonable set of weather and current conditions Wind velocities can range from zero to 58 mph 85 ft sec and air temperatures can be between 500C and 50 C The program calculates a clear sky incident solar energy for any location on the surface of the earth and the value for s
292. the atmosphere is assumed to be stagnant ideal gas with a linearly varying temperature then the density as a function of film temperature Tf elevation z lapse rate of the atmospheres a acceleration of gravity g gas constant of air R sea level temperature Tg and sea level pressure Pg is 31 P T a2 g aR Pt ome 28 f f where 0 0065 K m Pg 101 3 kPa 288 K n 9 807 m s 0 287 kPaem3 kgeK 7 R The units of both Tg and in this expression are and p is in kg m The final air property needed to evaluate the convective heat transfer coefficient 1 the Prandtl The program assumes a constant Prandt number over the entire range of normal film temperatures 27 Pr 0 71 29 Radiation The final parameter in Eq 6 that influences the ampacity and transient rating of an overhead conductor is the rate of solar energy per unit area incident on the surface of the conductor This parameter is a complex function of the orientation of the line relative to the position of the sun the extent of cloud cover and the composition of the atmosphere A detailed discussion of these parameters is presented in Ref 16 The incident solar energy external to the atmosphere is approximately 1353 W m The solar radiation that reaches the surface of the earth is partially attenuated by the atmosphere and it is composed of a direct or beam component and a diffuse component as can be seen in Eq 6 The program utili
293. the companies that responded to these questions stated that they had the capability to monitor weather conditions within their service area in at least one location It is probably safe to say that no company would presently have a sufficient number of weather stations to provide adequate input to a real time ampacity program In other words if a company wished to achieve a reasonable accuracy from a real time ampacity model over their entire service area they would certainly have to install a greater number of weather stations Seventy five percent of the utilities stated that they had the ability to calculate their own steady state ampacity value The form of the steady state ampacity values that are used by the various utilities were quite different Ampacity values were primarily in the form of tables and they appeared to be fairly evenly split between the Aluminum Association tables manufacturer s tables and tables that were developed with internally generated computer programs The most frequently mentioned program was one based on the House and Tuttle method The conditions used the ampacity tables are fairly consistent among those utilities that have steady state ampacity programs Two thirds of those who responded report that they calculate their ampacity values for a constant wind velocity of 2 ft sec The remainder used a velocity of 4 4 ft sec with the exception of one company which calculated ampacity based on a zero wind velocity
294. the determination of the precise form and magnitude of the temperature differences that exist in stranded conductors Furthermore the model will illustrate the errors produced in ampacity calculations as a result of assuming the conductor 1 isothermal The thermal model is used to calculate the temperature differences that exist in a stranded conductor as function of current conductor construction and weather conditions Even though a stranded conductor is composed of materials with high thermal conductivities the composite conductor has effective thermal conductivity which is significantly less than the value for a solid metallic material due to the air encapsulated between the strands Also the effective thermal conductivity is a strong function of any factor which influences the amount of air trapped between adjacent strands For example it would be natural to expect that the existence of temperature differences in a conductor would be strongly dependent upon the conductor construction compact ACSR or ACSR TW as opposed to normal stranded ACSR and the conductor tension Furthermore the effective conductivity of a stranded conductor can be a strong function of the conductor temperature because excessive temperatures could produce a situation known as birdcaging in which adjacent strands actually do not touch each other Under these extreme conditions the effective thermal conductivity of the conductor can be quite low and significa
295. the initial stages of the contract This one month period of data was supplemented by data collected during an 18 month period proceeding the contract The Linnet conductor was removed and replaced with a Curlew ACSR conductor 54 7 1033 kcmil and it remained on the test span throughout the duration of the project Over 27 000 separate sets of weather and current data were collected and used as input condition to DYNAMP These data were collected on five minute intervals over a period of two and one half years These data represent nearly 94 days of continuous operation of the line and weather station All data was statistically analyzed to determine the accuracy of the program and the results of the statistical analysis is discussed in the next section In general DYNAMP is capable of predicting the conductor temperature to within 10 C for temperatures up to 1250C The program 1 known to predict the conductor temperature more accurately under certain weather conditions See the discussion on Critical Span Analysis Section 8 The program accuracy is known to decrease for the following conditions Wind velocities that are close to zero Wind directions that are nearly down the axis of the conductor Currents and weather conditions that produce conductor temperatures in excess of 150 C 4 Periods of rainfall Weather conditions for the initial set of input parameters which are drastically different from the conditions that exist prior t
296. the limitations for the maximum operating temperature dictated by Yes No Clearance 19 O 00 Loss of strength 140 70 8 Degradation of terminations splices 8 3 Economic LJ 70 Other specify 01 70 ACSR clearance is primary concern AAC and AAAC loss cf strergth is primary concer 100 hrs at 850C 30 hrs at 1000 15 minutes short time rating 24 heurs long Time rating Aluminum at 110 C for 4 hours cr 115 C for 15 minutes cthers between 10 minutes and 4 hours If yes do you consider a critical span to vary from one location to another as weather and operating conditions vary or does the location remain constant If reliable line monitoring equipment were readily available in the range of 10 000 15 000 would you consider Yes No installing it on your system 120 40 If yes approximately how many devices would you install 3 votes for 3 4 remainder between 2 and 12 SECTION IV Ampacity Instruction and Critical Span Analysis Does your company at the present time measure the conductor temperature on any of its energized lines If yes how many instruments are installed If yes what type of instrumentation do you use made in house or manufactured by others Briefly describe these devices Does your company have any future plans to install temperature mesuring devices on energized lines What criteria would you use in selecting a location to install a limited
297. thermocouples have been removed from the Linnet conductor in preparation for installation on the 1033 conductor of the two poles that will be used in conjunction with the measurement of support deflection has been installed and the modifications necessary for the relaying of the new conductor have been started 5 Planning for Symposium The Aluminum Association has been contacted and notified of our intent to offer a symposium on the operation of overhead conductors at elevated temperatures The Electrical Division of the Aluminum Association has agreed to co sponsor this event 6 Planning for Quarterly Meeting The next quarterly progress meeting will be held at Georgia Power Research and Test Laboratory in Forest Park Georgia on Tuesday July 30 1985 An attached agenda of the meeting will be mailed to each member of the Task Force Respectfully submitted lm Z Black Professor WZB maw Enclosure GEORGIA TECH 1885 1985 DESIGNING TOMORROW TODAY June 24 1985 MEMORANDUM TO EPRI Task Force for Conductor Temperature Project FROM Wm Z Black Project Director SUBJECT Task Force Meeting on July 30 1985 This memo is a reminder that the EPRI Task Force for the Conductor Temperature Research Project Project 2546 will meet on Tuesday July 30 1985 at 9 00 am at Georgia Power s Research Center in Forest Park Georgia A map indicating the route from the Atlanta Airport to the Research Center is enclosed Call
298. tilizing a full scale outdoor instrumented test span The test span was operated over a four year period and temperatures were measured by thermocouples attached to two different conductor sizes The experimental effort to verify the program results appears in Section 5 As part of a critical span analysis weather data were collected at four remote weather stations within a twenty five mile radius of the test span The remote station weather data were used in DYNAMP and the predicted line temperatures at each remote site were compared to the temperatures measured at the test span The results were statistically analyzed to show how different weather conditions can produce variations in span to span conductor temperatures These data were also used in conjunction with a sensitivity analysis that predicts those weather and operating conditions that have the greatest influence on the location of a critical span A final objective of this project was the evaluation of available line monitors that attach to the conductor and measure temperatures in real time Several monitors were collected and evaluated at the outdoor test span One monitor was attached to the conductor and temperatures measured with this monitor were compared with thermocouple measurements and DYNAMP s predicted values In addition this monitor was also mounted several energized lines in Kansas as part of a project funded by KEURP A detailed discussion of the line monitors app
299. ty of economically and safely operating a transmission network because it theoretically identifies the thermal weak link in each transmission line By loading the system on the basis of the limiting critical span the complex job of making load flow decisions without exceeding sag or loss of strength limits becomes at least in theory a much less demanding task If the temperature of a line is to be measured by thermal line monitors then the monitors can theoretically be located at the critical spans Likewise if the conductor temperatures are to be predicted by using a computer model coupled with weather data measured along the route then the weather station can be located at the critical span Regardless of which technique for predicting the conductor temperature is eventually selected the concept of critical span will help minimize the equipment costs The wind velocity and direction near the conductor are known 20 21 to be two of the most significant parameters in regulating the conductor temperature This fact suggests that any span along the route of the line which has a reduced wind velocity would be an obvious choice for a critical span Lines that are routed through valleys tall stands of trees or other areas where the wind is inhibited from circulating freely over the conductor would be prime candidates for a critical span Furthermore wind which blows down the axis of the conductor is much less effective in cooling the conducto
300. types of data files 1 raw input data 2 documented input data 3 output data input data files are created and maintained through features under Data agement and Ut t es in the Module Menu These data files contain the raw ut data that will be used when the DYNAMP program is executed This raw input a consists of the vartfable groups discussed fn earlier sections of this manual user cannot print raw input data to a printer but will be able to edit raw it data files by using editing and creating procedures to be described later atted input data files are formatted versions of raw input data c These data s are not used to execute the DYNAMP program They are used to display the ents of raw input data files either by printing to the screen or to the 27192 orinter The procedure used to create and print formatted input will be described Output data files contain DYNAMP program results An output data file is created ny execution of the DYNAMP program This file contains not only the thermal analysis output cut also the formatted input data of the raw input data file that was used executing the DYNAMP program these cata files are automatically grouped into data sets Fach data set wil contain one and only one raw input data file Each data set may also contain a formatted input data file and or an output data file Each formatted input data rile and output data file will correspond to the raw input data
301. tzmann constant angle between the wind direction and the axis of the conductor angle between wind direction and normal to conductor Description alternating current conductor strand property convection direct current diffuse solar contribution direct solar contribution film value generated heat inside conductor area excluding air gaps between strands sea level value radiation supporting strand property relates to solar value total value ambient conditions 10 11 12 13 14 15 16 October 20 1986 FIGURES Energy Balance on TT X Temperature as a Function of Current for Several ACSR Conductors Temperature as a Function of Radius for a Drake Conductor at 1100 amps er Temperature as a Function of Current for Several Conductor S ses uersa e VER RECEN RSEN KEY ERE Temperature as a Function of Effective Thermal Conductivity of the Outer Conducting Strands Temperature as a Function of Air Velocity for a Drake Conductor at Constant Current T Temperature as a Function of Air Velocity for a Constant Outer Surface Temperature for a Drake T Diagram of Test 5 Power Circuit Schematic Block Diagram of Data Acquisition and Control System at Test 5
302. uctor construction They have established relatively low values for emergency temperatures for hard drawn copper conductors and progressively higher acceptable values for AAC and ACSR conductors The reasons that the various utilities gave for selecting the maximum limiting conductor temperature were split among the following factors clearance loss of strength creep degradation of splices and economic factors The two factors that did receive a slightly greater consideration were clearance and loss of strength Several of the utilities that were interviewed made the statement that limiting ampacity values should ultimately be set on the basis of clearance and other factors should play only a very minor role in dictating operating temperatures of the conductor Several utilities had experienced splice failures throughout their overhead network and they were being forced to face the problem of replacing or upgrading numerous splices These particular utilities obviously placed a greater emphasis on selecting a limiting temperature that would protect the integrity of their splices and they placed very little importance on clearance as a factor which should dictate maximum operating temperatures While practically all of the companies that were surveyed had the ability to calculate steady state ampacity values very few had the capability to predict real time ampacity values One fourth of the utilities have programs to calculate real time ampacity
303. unction of Distance from Span Figure 9 m sec 0 2 3 Co 20 Difference in Measuredand Predicted Wind Velocity ft sec Figure 10 Errors in Predicted Conductor as a Function of Wind Velocity accuracy was quite good and it averaged less than 6 As the weather data was collected further from the test span the accuracy was reduced because the weather at the remote sites rarely coincide with that at the test site Also the accuracy decreased as the wind velocity decreased because the line temperature became more sensitive to changes in the wind and the small variations in wind velocity from location to location produced large changes in the conductor temperature The data in Figure 10 shows Difference in that 1f a single monitor is expected to predict the temperature of another span about 1 mile away remote site 1 during conditions of no wind errors of about 15 C can be expected If it is expected to predict the temperature of span between 7 and 25 miles away errors in excess of 30 C can be expected The curves Figure 11 are similar to those which appear Figure 10 except that the temperature differences are plotted as a function of wind angle instead of wind velocity These curves show the general decrease in program or monitor accuracy as the wind blows down the axis of the conductor As expected the variation in conductor temperature increases as the distance to the w
304. values All companies would use a real time ampacity program if it were available and they would expect that program to predict the conductor temperature to within 5 C of the actual temperature Two companies placed a high priority on developing a real time ampacity program seven felt that they had a moderate priority for such a program and four placed a low priority on such a program The highest priority for the development of a real time ampacity program came from the operating engineers followed by planning engineers The design engineers felt they would be the ones who would be least likely to use the program When asked what type of computing equipment would be most likely used to run the program the response showed an even split between a mainframe computer and a personal computer The form of the output information provided by the computer program seemed to depend greatly upon who would be using the program The operating engineers made a very strong case for a program output that was very simple and easy to interpret They were not particularly concerned about a program that was very general or one which would apply to the broadest range of conductor geometries and weather conditions When asked how the program should convey real time information to the user the operating engineer showed a strong preference for the output of a single value that would predict the time a conductor would reach a predetermined limiting temperature The design
305. weather station 4 Weather data at remote sites 2 and 3 was stored on strip charts and had to be manually averaged and recorded In addition the data at remote site 2 could only be recorded on 15 minute intervals resulting in larger errors for that particular site The best correlations resulted for those stations that have automatic data acquisition systems base 42 Difference in Predicted Temp C Wind Velocity ft sec Figure 21 Program Accuracy as a Function of Wind Velocity for the Five Weather Stations 43 Measured and Predicted Temp C Difference in Wind Angle deg Figure 22 Program Accuracy as a Function of Wind Direction for the Five Weather Stations 44 station and remote sites 1 and 4 because these stations were free of the errors that enter as a result of manual manipulation of the data D Critical Span Analysis During the last six months the study of the critical span concept has continued Sensitivity parameters derived previously and reported in the last quarterly report have shown that the location and number of critical spans is dictated predominantly by weather conditions such as wind direction and wind speed It has also been shown that it is unlikely that a single critical span exists along the length of a transmission line Multiple critical spans are more likely and the location and number of critical spans move from spot to spot as a function time Several impor
306. wide range of conductor temperatures the most common value being 759C The maximum temperature used for a normal rating is 120 C while some companies provide for different ratings depending upon the construction of the conductor Of those companies that consider emergency ratings the most commonly mentioned limiting time for an emergency rating was two hours Other values for a limiting time during which an emergency overload would be tolerated ranged between 30 minutes and 4 hours and one company permitted emergency conditions to exist for up to 500 hours per year The temperatures that were acceptable during the emergency current overload ranged between 80 C and 140 C with the most commonly mentioned figure being 93 C Some companies have established different acceptable values for emergency ampacity calculations depending upon different types of conductor construction They have established relatively low values for emergency temperatures for hard drawn copper conductors and progressively higher acceptable values for AAC and ACSR conductors he reasons that the various utilities give for selecting the maximum limiting conductor temperature is evenly split among the following factors clearance loss of strength creep degradation of splices and economic factors The two considerations that did receive a slightly greater consideration were clearance and loss of strength Several of the utilities that were interviewed made the statement that
307. zes the line orientation date time of day and location of the conductor on the surface of the earth to calculate the clear sky diffuse and direct radiant energy incident on the conductor The program utilizes the equations developed in 16 and calculates both the direct and diffuse solar energy incident on the conductor Numerical Methods Before Eq 6 can be solved for the conductor temperature a single initial temperature must be determined program assumes that the initial condition for the differential equation is the steady state temperature corresponding to the first set of conductor currents and weather conditions Therefore the initial condition 1s T To 0 30 where Tg is the steady state temperature of the conductor corresponding to the solution of the equation 12 t Rac T asD Qdir t 091002 Dro T4 Tot t sDh t T 0 31 Since this equation is algebraic but non linear it can be solved using a traditional Newton Raphson numerical technique 32 Once the initial temperature has been determined the real time conductor temperature can be calculated from Eq 6 by using a Runge Kutta 32 numerical scheme This technique is very efficient and it has been used for a wide variety of weather conditions and current distributions which vary with time The solution for the conductor temperature has always been numerically stable and is strictly convergent in al cases The program has been

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