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1. 4 o 55 5 5 2 5235 w e Q gt 3a Ka ag og co H e o G 5 p e D 9 5 5 8 Sa o gt you a ia L e S pm e ces E S 251 S ok o NG 8 w Sy Hi 3 93 E E S e 5 be oO fe o E o 2 S wi E E D w o S o o a 4 Constant Pass if gt a 9999 5 Constant 2 Pick Up 3 Threshold a 0 5 Drop Out 1 Input Signal Figure 2 2 Block diagram of over current voltage frequency power etc protection Date 12 01 2012 Page 7 MIS RTU WP3 Scilab Models 120110 V0 doc COOPERATION PEGASE COOPERATION Block Description 6 number 1 Input signal current voltage frequency power etc 2 The hysteresis block for pick up and drop out settings As soon as monitored signal exceeds pick up value binary 1 value appears at the output of the hysteresis element relay picks up On the other hand relay drops out as soon as signal decreases below drop out value 3 The switch block passes through the first top input or the third bottom input based on the value of the second middle input 4 Constant 1 is chosen so that the numerical value of the output of the integrator 6 corresponds to the time that has passed since the start of the integration process 5 Constant 9999 is necessary to reset quickly the integrator 6 to zero 6 This block is an integrator The output y is the integral of the input u at2. generators motors etc beyond the nameplate rating can cause a rise of temperature of these devices above permissible level As a result the insulation will deteriorate resulting in accelerated loss of life of the equipment The thermal overload protection is used to avoid it 1 7 Thermal overload function is available in modern numerical protection relays This function depending on the protected object and specific implementation in the relay uses some combination of ambient temperature oil temperature and measured current to detect the presence of an over temperature condition The block diagram of thermal overload protection is presented in Figure 4 1 Most of it is similar to the diagrams discussed in previous sections except that it has additional alarm stage The first part of diagram models the heating equation 4 1 2 dH I nr H 4 1 dt i where Symbol Unit Description H 90 Heat rise For example if H 120 the oil or winding of the protected object overheat by 20 in relation to its nominal operation I A Actual load current Imax A Maximum permissible current or full load current T min Thermal time constant of the protected object Equation 4 1 is in accordance with IEC 60255 8 8 and is used to track a first order thermal image replica based on the measured current The thermal replica model calculates a maximum temperature rise based on the measured cur
3. that are scheduled by parameter period in seconds The starting date of events generation can be set in seconds with the initialization time parameter 22 The scope block displays its input with respect to simulation time Table 2 1 Description of individual blocks Some additional possible applications of the considered model are presented below Dynamic cold load pickup function Sometimes it may be necessary to dynamically increase the pick up values if during starting certain elements of the system show an increased power consumption after a long period of zero voltage e g air conditioning systems heating installations motors Thus a general raise of Date 12 01 2012 Page 8 MIS RTU WP3 Scilab Models 120110 V0 doc PEGASE COOPERATION pick up thresholds can be avoided taking such starting conditions into consideration A number of manufacturers have implemented such feature in their relays 2 3 4 5 The dynamic cold load pick up feature can be simulated by blocking one over current protection model and releasing the other when necessary Switch onto fault SOTF logic The instantaneous high current switch onto fault protection function is usually provided to disconnect immediately and without delay feeders that are switched onto a high current fault It is primarily used as fast protection in the event of energizing the feeder while the earth switch is closed but can also be used every time
4. the current time step t Upper and lower limits can be set Together with 3 4 and 5 elements it forms resettable integrator This block performs logical comparison of its two inputs Time delay setting of the protection If the releasing input is not used then the binary 1 is connected to the second logical operator 10 Blocking input is supplemented with logical NOT operator so that received binary 11 0 corresponds to no blocking state 12 The logical operator block performs the specified logical operation on its inputs If pick up condition is maintained for a time period equal or greater than the time delay setting 8 the binary 1 value appears at the output of the logical operator relay trips Otherwise the output of resettable integrator 6 does not reach in time the value corresponding to the time delay setting 8 13 The block performs addition of its inputs 14 The hysteresis element 14 is intended to hold output signal for a fixed amount of time Hysteresis element is switched off at 0 5 The switch off is achieved by the help of resettable integrator 18 15 Constant 1 16 The switch block 17 Constant 9999 18 This block is an integrator Together with 15 16 and 17 elements it forms resettable integrator 19 This block performs logical comparison of its two inputs 20 Minimum trip signal duration setting 21 The unique output of this block generates a regular train of events
5. D ee D D D e PEGASE BEES d PAN EUROPEAN GRID ADVANCED SIMULATION AND STATE ESTIMATION Scilab models for some protection and automation devices WP5 Proprietary Rights Statement This document contains information which is proprietary to the PEGASE Consortium Neither this document nor the information contained herein shall be used duplicated or communicated by any means to any third party in whole or in parts except with prior written consent of the PEGASE Consortium Grant Agreement Number 211407 implemented as Large scale Integrating Project Coordinator GDF SUEZ Project Website http Awww fp7 pegase eu PEGASE Document Information Document Name Scilab models for some protection and automation devices ID MIS RTU WPS Scilab Models 120110 V0 doc WP 5 Task Revision 0 Revision Date 10 01 2012 Author V Strelkovs Diffusion list Approvals ane company EN KY V Strelkovs Task Leader WP Leader aa history 10 01 2012 First version of the document V Strelkovs Date 12 01 2012 Page 2 MIS RTU WP3 Scilab Models 120110 V0 doc PeGASe p Table of content Scilab models for some protection and automation devices 1 WP5 1 di Introduction dadaan EE E EE 4 2 Over current voltage frequency power etc protection ceeeeeeeeeeeeeeeeeeeeeeeeeeee 5 3 Under current voltage frequency power etc protection eceeeeeeeeeeeeeeeeeeees 10 4 Thermal ov
6. ay as with the protection tripping time the alarm time can be estimated 4 3 ng ES Hi pit max I 2 z Halarm max The calculated value will show how much time has left until the actual heat content H will exceed the set alarm level Hajarm Halarm 80 for instance assuming that the load current talarm T In min 4 3 I will remain constant The calculation of the heat content H is based on the fact that the temperature in the windings or oil is proportional to the square of the current and that the temperature increases and decreases exponentially with a certain time constant 1 2 3 4 The part of the model that represents the equation 4 1 includes blocks 1 to 8 see Figure 4 1 Date 12 01 2012 Page 13 MIS RTU WPS Scilab Models 120110 V0 doc COOPERATION Bums wely 27 S O HO YMS 0 UO YIYMS TE wins LE doe ge F oner kejag au 0 pegsuog ST X90019 LE 0 pur samo OO yur sadd S 4 UONEIMES BT SOZ B PIOUSAIUL pZ wu lt Seed juegsuoo ez S O HO YIYIMS adoos 9E SO UQ YMS TZ 49019 SE ANY do e2160 Aejag awl JO EL UBYSUOD TI ONY do jeo1607 qUBYSUOD LL Buas dul OL 0 pur samo 001 pur d n sa uopeiny s gL qUBYSUOD A1 nG lt H SSEd S0 e P oysaJy Ob jue su09 el 0 a
7. cuit breaker is open Cascaded events The model should be able to operate in case of cascaded consecutive events Pick up drop out ratio Pickup of the relay can be stabilized by setting the dropout value the pickup condition is maintained until the signal falls below the drop out value thus securing that the function does not drop out too fast 2 3 4 5 The hysteresis or difference between pick up and drop out signals results in operation that is similar to a Schmitt trigger Pick up and drop out ratio varies widely from relay to relay and is settable or specified by manufacturers Drop out ratio is mostly around 0 95 for new digital protection devices For older electromechanical devices it is lower for instance 0 8 Blocking releasing input Very often protection is blocked or released according to some external criterion Protection can be blocked in case of power swings or during automatic re closure cycle It can be released for instance if voltage decreases below a preset value very often it is employed for over current protection To account for these blocking releasing schemes it is necessary to supplement the model with digital blocking and releasing inputs Previously mentioned operating principles and requirements are implemented in the model that is presented in Figure 2 2 with the description of individual blocks in Table 2 1 The presented model is relatively simple yet it is multi purpose and can be a
8. erload protection EEN 12 5 FGETS EE 15 Date 12 01 2012 Page 3 MIS_RTU_WP5_Scilab_Models_120110_V0 doc PEGASE COOPERATION Introduction The purpose of the current report is to comply with the following recommendation by European Commission specified in the 2 EC technical review Recommendation 4 some of the models developed in Scilab under WPS could be made available on the PEGASE website It is considered reasonable to have a few representative models in open access version Three models that are developed with open access software Scilab 5 3 3 http www scilab org are presented in the report These models are applicable for a wide range of protective relaying functions Date 12 01 2012 Page 4 MIS RTU WP3 Scilab Models 120110 V0 doc is PEGASE Cg go COOPERATION pa Over current voltage frequency power etc protection When a fault occurs in a power system the fault current is almost always greater than the pre fault load current in any power system element A very simple and effective relaying principle is the one using current magnitude as an indicator of a fault Over current relays can be applied to protect practically any power system element i e transmission lines transformers generators or motors The operating principle of a relay can be defined as follows 1 IZI gt Tri set p 2 1 I lt Iet Do not trip The quantity La is known as the pickup setting of the relay Equation 2 1 desc
9. pplied in a number of simulation scenarios 1 It can be applied as over current over load protection for different power system elements transformers lines generators busbars etc 2 Wide range of other input quantities are applicable as well therefore many protection functions can be modeled 3 Two or more operating stages can be easily simulated applying several separate models each for one stage 4 It can be used as I phase 2 phase or 3 phase protection respectively employing 1 2 or 3 models 5 The protection operation can be instantaneous by setting time delay 0 or time delayed 6 Output signal can be applied for circuit breaker tripping as well as for alarming releasing and blocking purposes Date 12 01 2012 Page 6 MIS RTU WPS Scilab Models 120110 V0 doc PEGASE 7 Model can be used as a building block for complex protection and automation SPS schemes that involve over current over voltage over frequency etc criterion 8 It is applicable for all time scales steady state quasi steady state transient and dynamic 9 It is applicable for different objectives for off line and real time studies of the ETN as well as for dispatcher training simulations 21 Clock 22 Scope 0 5 14 Switch On 0 5 Switch Off 13 Sum Relational Logical op AND op amp 20 Time Delay o E v2 o 5 SE 5 S a a amp gs E E 5 a
10. rent the thermal time constant and the maximum permissible current of the protected object The biggest advantage of using a thermal replica for temperature protection is the ease of implementation The function involves only settings in the relay with no need to physically install and connect temperature sensors However this method does not account for ambient temperature and provides only a simple representation of oil or winding temperatures due to load but is not truly the temperature of interest oil top oil winding or hot spot temperature Functionally therefore this is essentially an over current function with an asymptotic time delay Thermal replica based protection elements typically include several threshold settings to alarm and trip on increasing temperature conditions The thermal replica model is widely used it is incorporated in many protection devices by different manufacturers and it can be applied to different power system elements Date 12 01 2012 Page 12 MIS RTU WPS Scilab Models 120110 V0 doc ZC PEGASE B Protection tripping time can be easily calculated for model verification purposes only assuming the protected object is loaded with constant current I 4 2 1 7 8 WW ES Hinit max 2 Lmax The calculated value will show how much time has left until the actual heat content H will exceed the set overload level Hip Hip 100 min 4 2 ttrip T In In a similar w
11. ribes an ideal relay operating characteristic as shown in Figure 2 1 The relay does not operate operating time is infinite as long as current magnitude is less than Le If current magnitude exceeds La relay operates taking a definite time delay to close its contacts Operating zone t gt H r I gt Bs I Figure 2 1 Example of tripping characteristic of two stage over current protection function The same operation principle is true for other input signals as well e Current positive seq negative seq zero seq residual e Voltage phase line positive seq negative seq zero seq residual e Frequency frequency rate of change of frequency e Power active reactive apparent positive seq negative seq zero seq I phase 3 phase e Speed e Etc Let us add some typical requirements to the previously mentioned operating principles so that the developed model imitates more precisely real world devices Fixed length of tripping impulses Date 12 01 2012 Page 5 MIS_RTU_WP5_Scilab_Models_120110_V0 doc PEGASE COOPERATION It is advisable to avoid inconsistent length of tripping impulses and to provide the possibility to define their length In practice the trip command duration must be set longer than the maximum time taken by the circuit breaker to trip following initiation of a trip command time from start of trip command until circuit breaker auxiliary contacts indicate that the cir
12. the feeder is energized in other words also following automatic re closure 2 3 4 5 If necessary the SOTF function can be easily modeled by releasing for a short period of time the over current protection model during feeder energization Date 12 01 2012 Page 9 MIS_RTU_WP5_Scilab_Models_120110_V0 doc PEGASE COOPERATION Under current voltage frequency power etc protection These protections are used to protect equipment against an abnormally low current voltage frequency etc They can also be used for instance 1 e To monitor the operation of voltage regulators e To load shed the non priority consumer network when an overload occurs e To monitor the voltage before sources to carry out a power supply transfer The protection in its simplest form is activated when the input signal decreases below the pre set threshold Suggested block diagram of under current voltage frequency etc protection is presented in Figure 3 2 When modeling this type of protection it should be noted that the drop out setting of the protection has larger value than the pick up setting therefore standard hysteresis Schmidt trigger element cannot be applied In order to model the pick up drop out feature the logic depicted in Figure 3 1 can be used if the operating point is below pick up setting then 2 is set at the output of the block 12 in Figure 3 2 and the relay picks up If operating point is above the drop out se
13. tting then 2 is set and the relay drops out In case of O relay waits for further signal changes The rest of the model is the same as in previous chapter Voltage Drop out Drop out setting Pick up setting Time Figure 3 1 Pick up and drop out moments during transient process Date 12 01 2012 Page 10 MIS_RTU_WP5_Scilab_Models_120110_V0 doc z 8 adoos EE 42019 TE S O HO YMS S0 UO YMS SZ Wns E A x dug NS EZ Kejag aw LE ez DE 8 do leuonejay LON ZZ ME SU0 VC p 20 Pog any o do je21507 JUEYSUOD OZ aseaj y JUB SU0 9L Aejag awil ei 6666 0 pur samo OO pur sadd JB lt JI SSEd ez HL SAA UOHEINES ZL SO JB PlOUSPIUL GL UBYSUOD pL queYSUOD BZ 6666 0 pun Jamo7 001 pur addr uP lt JI SSEd S34 UOWBINIES GC S0 e PIOUSAJUL LZ MAA WUEYSUDD o S V NO YMS S UO YMS EL Ng wns CL JUBYSUOD LL I Bu lt H SSEd 0 e pIOysaJy OL HILIMS ee wno doudb queysuog g Bu lt H SSEq 0 8 ploysasy 2 LE 3 ENER He uf ynduy 10n f under current voltage frequency power etc protect iagram o Block di Figure 3 2 MIS RTU WPS Scilab Models 120110 V0 doc Page 11 Date 12 01 2012 ec PEGASE ee paa ee ap COOPERATION 4 Thermal overload protection Overloading transmission lines cables transformers
14. ys Eu g jueysuog am Z apina g DAD en ly apna E T Sumas paang Z teubis ynduy Figure 4 1 Block diagram of thermal overload protection MIS RTU WP3 Scilab Models 120110 V0 doc Page 14 Date 12 01 2012 PEGASE COOPERATION 5 References 1 m Christophe Preve Protection of Electrical Networks ISTE Ltd 2006 ISBN 10 1 905209 06 1 2 SIPROTEC Multi Functional Protective Relay with Local Control 7SJ62 64 V4 7 Manual Siemens MiCOM P141 P142 P143 Feeder Management Relays Technical Guide Areva F650 Digital Bay Controller User manual Firmware version 3 7X GE Multilin 2007 MiCOM P125 P126 P127 Directional Non directional Relay Version 6D Technical Guide Areva Scilab v5 3 3 Help Rich Hunt Michael L Giordano Thermal Overload Protection of Power Transformers Operating Theory and Practical Experience 59th Annual Protective Relaying Conference Georgia Tech Atlanta Georgia April 27th 29th 2005 TEC 60255 8 Electrical Relays Thermal Electrical Relays Second Edition 1990 mo op nn E w Ed d ch a3 oo oo iS Date 12 01 2012 Page 15 MIS RTU WP3 Scilab Models 120110 V0 doc
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