Automatic tap changer controller for parallel transformers
Contents
1. PREG ar Automatic tap changer controller for parallel transformers Function block description PROTECTA HUNGARY IED EP Automatic tap changer controller for parallel transformers User s manual version information Version Date Modification Compiled by Preliminary 24 11 2010 Preliminary version without technical information Petri V1 0 13 12 2010 First edition for single transformers Petri V1 0 para 17 08 2012 Extension for parallel transformers Petri V1 1 20 12 2012 Corrected formula for complex compensation Petri V1 2 29 01 2013 Error codes added Petri VERSION 1 2 2 20 IED EP Automatic tap changer controller for parallel transformers CONTENTS 1 Automatic tap changer controlere suresini 4 a ey eee 9 Cetc 119 a eeee reer peer nere a err rrtees tree 4 1 2 Mode of operation to control a single transformer eeeeeeeeteeeeenteeeeeenaeeeeeeaeeeeeenaes 5 1 2 1 The scheme of the function block 00 0 eee ceeeeee sete eeeeeeeeeeeeteeeeeeeseneeeeeeeneaeeeeeeeaeees 5 1 2 2 Analog inputs of the Controller fUNCtION eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeteaeeeeeeeaeens 5 1 2 3 Internal checks before control Operation ceeeeeeeeeeeeeeeeeeeeeeeeeaeeeeeenaeeeeeeaees 5 124 sAULOMAtiG COMOl Modeen a sh a Oke eee eens 7 1 2 5 Manual contol MOOG ssar secupadpdcveebuaceueesesdis 9 1 2 6 Command generation and tap changer supervisi2. mode If all slave s Operation parameter is set to SlaveCmd mode then the slave device transmits the HIGHER or LOWER commands received via Ethernet connection from the master without comparing the tap changer position If the initial state of all tap changers assures the operation of the system without any circulating currents and the appropriate tap steps generate the same voltage regulation then this mode can be applied If there is a single failure in the operation of any of the tap changers then the error is not corrected automatically Operation in SlaveTap mode If all slave s Operation parameter is set to SlaveTap mode then the master device transmits the own tap position as the required tap position for all co operating controllers The slave devices generate the appropriate commands until this required position is reached If the tap position of a slave is identical with that of the master then the subsequent operation is performed according to the rule of the SlaveCmd mode There is a correction possibility for tap position adjustment if the tap changers are not of the same type the parameter setting Tap Offset can match the parallel running of the individual tap changers VERSION 1 2 12 20 IED EP Automatic tap changer controller for parallel transformers 1 3 3 Irregular modes of operation In case of certain errors the algorithm can override the mode of operation defined by para
3. ATCC_UHigh_Grl_ U High Voltage is high ATCC_ULow_Grl_ U Low Voltage is low ATCC_UBlock_Grl_ U Block Blocked state for too low voltage ATCC_IHigh_Grl_ High Blocked because of current limit ATCC_Locked_Grl_ Locked The supervision detected tap changer error the blocking can be released exclusively by the Reset impulse ATCC_VRed1_Grl_ Voltage Reduction 1 Controlling to reduced voltage 1 ATCC_VRed2_Grl_ Voltage Reduction 2 Controlling to reduced voltage 2 ATCC_HigherTimer_Grl__ HigherTimer Timer before generation Higher command is running ATCC_LowerTimer_Grl_ LowerTimer Timer before generation Lower command is running Extension for parallel transformers ATCC_RemHigher_Grl_ Remote Higher Signal of the slave indicating execution of the master command ATCC_RemLower_Grl_ Remote Lower Signal of the slave indicating execution of the master command ATCC_ComFail_ Grl_ Communication Error No connection with at least one of the configured devices ATCC_MasterError_Grl_ Master Error The slave device can not follow the master Table 1 9 Binary output status signals of the breaker failure protection function VERSION 1 2 18 20 IED EP Automatic tap changer controller for parallel transformers 1 5 4 Summary of the input signals Binary status signals The automatic tap changer controller function has binary input status signals The c
4. U U HighLimit Deadband Hysteresis UDeadband U Set U Deadband Deadband Hysteresis U Low Limit U Low Block Figure 1 2 Voltage level settings VERSION 1 2 8 20 IED EP Automatic tap changer controller for parallel transformers Time delay in automatic control mode In automatic control mode the first and every subsequent control command is processed separately For the first control command The voltage difference is calculated Udiff Ucontrol Uset If this difference is above the U Deadband value then depending on the setting of parameter T1 Delay Type three different timing modes can be selected e Definite this definite time delay is defined by parameter T1 e Inverse standard IDMT characteristic defined by the parameters o T1 maximum delay defined by the parameter o UDeadband is the width of the permitted range in both and directions o Min Delay minimum time delay Tdelay oa but minimum MinDelay akha e 2powerN Udiff Tdelay T1 5 1 waeaabana The binary parameters Fast Lower Enable and or Fast Higher Enable enable fast command generation if the voltage is above the parameter value U High Limit or below the U Low Limit In this case the time delay is a definite time delay defined by parameter T2 For subsequent control commands In this case the time delay is always a definite time delay defined by parameter T2 if the subse
5. current is above the value defined by the parameter I Comp Limit then in the formulas above this preset value is considered instead of the higher values measured The method is based on the experiences of the network operator Information is needed how much is the voltage drop between the busbar and the load center if the load of the network is the rated load The parameter R Compound Factor means in this case the voltage drop in percent NOTE if the active power flows from the network to be controlled to the busbar then in AbsoluteComp mode no compounding is performed e f the parameter Compensation is set to ComplexComp the calculation method is as follows In this method the vector positions are partly considered In the formula above the voltage drop is approximated with the component of the voltage drop the direction of which is the same as the direction of the bus voltage vector This is length component of the voltage drop the perpendicular component of the voltage drop is neglected Ucontrol Ubus UL1L2p jIL1L2 R CompoundF actor jXCompoundFactor Where R Compound Factor is a parameter value X Compound Factor is a parameter value VERSION 1 2 7 20 IED EP Automatic tap changer controller for parallel transformers The voltage of the load center of the network is controlled to be within a narrow range This assures that neither the voltage ne
6. secondary side of the transformer for voltage drop compensation IHV Maximum of the phase currents of the primary side of the transformer for limitation purposes The parameter U Correction permits fine tuning of the measured voltage 1 2 3 Internal checks before control operation In Figure 1 1 the block U I BLOCK performs the following checks before control operation e If the voltage of the controlled side UL1L2 is above the value set by the parameter U High Limit then control command to increase the voltage is disabled e If the voltage of the controlled side UL1L2 is below the value set by the parameter U Low Limit then control command to decrease the voltage is disabled e If the voltage of the controlled side UL1L2 is below the value set by the parameter U Low Block then the transformer is considered to be de energized and the automatic control is completely disabled e f the current of the supply side IHV is above the limit set by the parameter _overload then both automatic and manual controls are completely disabled This is to protect the switches inside the tap changer VERSION 1 2 5 20 IED EP Automatic tap changer controller for parallel transformers ULiL2 IHV IL1L2 Manual BIk BlkProc ManHigher Remote COMMUNICATION AutoBlk VRed1 VERSION 1 2 VRed2 6 20 Figure 1 1 The logic schema of the automatic tap changer controller ULow UHigh UBlock IHi
7. Xinc_FPar_ Factor o 0 0 15 0 1 5 0 Reduced set point 1 for voltage regulation priority related to the rated voltage See Chapter 1 2 4 Voltage ATCC_VRed1_FPar_ Reduction 1 0 0 10 0 1 5 0 Reduced set point 2 for voltage regulation related to the rated voltage See Chapter 1 2 4 Voltage o ATCC_VRed2_FPar_ Addai 2 o 0 0 10 0 1 5 0 Maximum current value to be considered in current compensation formulas See Chapter 1 2 4 ATCC_ICompLim_FPar__ Comp Limit A 0 00 150 0 1 Current upper limit to disable all operation See Chapter 1 2 3 ATCC_IHVOC_FPar_ Overload 50 150 0 100 Voltage upper limit to disable step up See Chapter 1 2 3 ATCC_UHigh_FPar_ U High Limit 90 0 120 0 1 110 0 Voltage lower limit to disable step down See Chapter 1 2 3 ATCC_ULow_FPar_ U Low Limit 70 0 110 0 1 90 0 Voltage lower limit to disable all operation See Chapter 1 2 3 ATCC_UBlock_FPar_ U Low Block 50 0 100 0 1 70 0 Time delay for the first control command generation ATCC_T1_FPar_ Ti sec 1 0 600 0 1 10 0 Definite time delay for subsequent control command generation or fast operation if it is enabled ATCC T2 FPar_ T2 sec 1 0 100 0 1 10 0 In case of dependent time characteristics this is the minimum time delay ATCC _MinDel_FPar_ Min Delay sec 1 0 100 0 1 10 0 After a control command if the voltage is out of the ra
8. ap changer to the same position as the transformer assigned to the master controller Up to 4 transformers may be involved Individual EuroProt controllers are assigned to each of them and these devices co operate with each other The method of co operation depends on the selected mode as set by the Operation parameter Usually the devices must be connected to the same Ethernet communication network characterized with the same GroupID This must be selected by parameter setting identical for the co operating devices The Device Address must be set unique for the devices within the group for two transformers 0 and 1 etc The GroupID can be applied also for VLAN identifier To do this the parameter UseVLAN must be set to logic 1 The messages sent via Ethernet network are similar multicast messages to the GOOSE messages according to the IEC 61850 communication standard but they are device specific commands The MAC address of these multicast messages is 01 0C CD 07 GroupID 1 3 1 Minimizing the circulating currents This mode of operation is selected if the Operation parameter is set to CircCurrMin To perform the related algorithm communication is needed among the controllers The co operating controllers must be identified by each device by checking the parameters Address 0 InUse Address 1 InUse Address 2 InUse Address 3 InUse For minimizin
9. ar to the busbar is too high nor the voltage at far away points of the network is too low The method is based on the estimated complex impedance between the busbar and the load center The parameter R Compound Factor means in this case the voltage drop in percent caused by the real component of the rated current The parameter X Compound Factor means in this case the voltage drop in percent caused by the imaginary component of the rated current Voltage checking in automatic control mode In automatic control mode the calculated Ucontro voltage is checked to see if it is outside the limits The limits are defined by parameter values U Set is the setting value defining the centre of the permitted range U Deadband is the width of the permitted range in both and directions Deadband Hysteresis is the hysteresis decreasing the permitted range of the U Deadband after the generation of the control command If the calculated Ucontrol voltage is outside the limits then timers are started In an emergency state of the network when the network elements are overloaded the Uset value can be driven to two lower values defined by the parameters Voltage Reduction 1 and Voltage Reduction 2 U Set is decreased by the parameter values if the binary inputs Voltage Reduction 1 or Voltage Reduction 2 enter into active state These inputs must be programmed graphically by the user
10. ar_ Fast Lower Enable 0 Enabling fast lower control command Extension for parallel transformers ATCC_ChinUse1_BPar_ AddressO InUse 0 O priority level is used in the system ATCC_ChinUse2_BPar_ Address1 InUse 0 1 priority level is used in the system ATCC_ChinUse3_BPar_ Address2 InUse 0 2 priority level is used in the system ATCC_ChinUse4_BPar_ Address3 InUse 0 3 priority level is used in the system ATCC_UseVLAN_ BPar_ UseVLAN 1 VLAN identifier is used for the communication Table 1 5 The Boolean parameters of the automatic tap changer controller function Integer parameters Parameter name Title Unit Min Max Step Default Code value of the minimum position ATCC MinPos Par_ Min Position 1 32 1 1 Code value of the maximum position ATCC_MaxPos _ Par_ Max Position 1 32 1 32 Extension for parallel transformers VLAN Identifier for the group of cooperating controllers ATCC_VLAN_ Par_ GroupID 0 4095 1 0 Device address within the group of cooperating controllers ATCC Addr _ Par_ Device Address 0 3 1 3 Setting the tap offset position in master slave SlaveTap mode ATCC_Offset_IPar_ Tap Offset tap 5 5 1 0 Table 1 6 Integer parameters of the automatic tap changer controller function Timer parameters Parameter name Title Unit Min Max Step Default Time limit for tap cha
11. enable further operation the input Reset must be programmed for an active state by the user 1 2 7 Error codes The On line information includes a variable ErrorCode ATCC_ErrCode_ISt_ indicating different error states These states are binary coded any of them causes Locked state of the controller function The explanation of the individual bits in the code value is explained in the Table below Bit Value Explanation 0 1 Drive started without control command 1 2 Drive did not start after control command 2 4 Drive did not stop in due time 3 8 Invalid position signal 4 16 Position signal did not change value In case of multiple error states the values are added in the ErrorCode VERSION 1 2 10 20 IED EP Automatic tap changer controller for parallel transformers 1 3 Mode of operation to control parallel transformers This mode of operation is selected if the Operation parameter is set to one of the following values e CircCurrMin for operating the controllers of the parallel connected transformers to minimize the circulating current e Master for selection one of the controllers of the parallel connected transformers to be the master to transmit commands to the slave controllers e SlaveCmd for selection the controller to operate in slave mode and follow the UP and DOWN commands e SlaveTap for selection the controller to operate in slave mode and drive the t
12. escribed limits The most common mode of voltage regulation is the application of transformers with on load tap changers When the transformer is connected to different taps its turns ratio changes and supposing constant primary voltage the secondary voltage can be increased or decreased as required Voltage control can take the actual load state of the transformer and the network into consideration As a result the voltage of a defined remote point of the network is controlled assuring that neither consumers near the busbar nor consumers at the far ends of the network get voltages out of the required range The voltage control function can be performed automatically or in manual mode of operation the personnel of the substation can set the network voltage according to special requirements The automatic tap changer controller function can be applied to perform this task Depending on the selected mode of operation this version of the controller can be applied to regulate a single transformer or to control parallel transformers When transformers are connected parallel i e they are connected to the same busbar section on the primary side and also on the secondary side of the transformer then these transformers must be regulated together to avoid circulating current among the transformers This circulating current causes additional losses and the generated additional heat could overstress the transformers The Operation parameter f
13. g the circulating current the following information is needed from each co operating devices e Calculated voltage drop Ug see below e Current real and imaginary components relative to the common bus voltage e Sn Drop calculated internally from parameters Transformer Sn and Transformer Drop e Connected or disconnected state of the transformer to the busbar of the regulated voltage level Based on this information the current vectors are transformed into a common coordinate system defined by the common voltage vector The sum of these currents is the total load current I In i The transformers disconnected from the busbar of the regulated voltage level are not involved in this calculation The current according to the impedance relationship is calculated by Sni Ei li I ey VERSION 1 2 11 20 IED EP Automatic tap changer controller for parallel transformers The difference of the measured Ir current and the current I due to the current division is the circulating current Icci Iri Thi This circulating current causes a voltage drop which is equivalent to the voltage difference caused by the tap changer position Eicon Ua Uai IMUcci F In this formula a special drop value is applied Eicon called control drop and can be set as parameter Control Drop If this value is set different as compared with the setting value of the parameter Transformer Drop then
14. gh Higher Command Lower Command MaxPosReached MinPosReached Locked Manual AutoBlocked VRed1 VRed2 IED EP Automatic tap changer controller for parallel transformers 1 2 4 Automatic control mode Voltage compensation in automatic control mode The module AUT in Figure 1 1 gets the Fourier components of the busbar voltage and those of the current e UL1L2p and ULIL2m e IL1L2p and IL1L2m In automatic control mode the voltage of the controlled side UL7L2 is compensated by the current of the controlled side L1L2 This means that the voltage of the load center of the network is controlled to be constant in fact within a narrow range This assures that neither the voltage near to the busbar is too high nor the voltage at far away points of the network is too low The voltage of the load center i e the controlled voltage is calculated as Ucontrol Ubus Udrop There are two compensation modes to be selected by setting the Compensation parameter AbsoluteComp and ComplexComp e f the parameter Compensation is set to AbsoluteComp the calculation method is as follows In this simplified method the vector positions are not considered correctly the formula above is approximated with the magnitudes only Ucontrol Ubus Udrop Ubus Udrop x Ubus I R CompoundFactor Where R Compound Factor is a parameter value If the I
15. here is no interconnection with the device on address 1 4 Ox4 There is no interconnection with the device on address 2 8 Ox8 There is no interconnection with the device on address 3 256 Ox100 Invalid address 512 Ox200 Master error indicated by the slave device 1024 Ox400 Error in the topology e g a transformer seems to be connected to more than one bus section 2048 Ox800 There is another master with higher priority in the system indicated by the master device 4096 Ox1000 Address error more then one device with the same address In case of multiple error the assigned code values are added Table 1 1 Parallel error code values 1 3 5 Disabled state The devices are blocked in CircCurrMin mode if the communication fails with any of the co operating devices or any of them is blocked VERSION 1 2 13 20 IED EP Automatic tap changer controller for parallel transformers 1 4 Manual mode of operation When programming the graphic logic there are some important inputs to select the mode of operation Binary status signal Title Explanation ATCC Local _GrO_ Local Local state of the manual operation ATCC Remote _GrO_ Remote Remote state of the manual operation ATCC _BIk_GrO_ Blk Blocking of the function ATCC _AutoBlk_GrO__ AutoBlk Blocking of the automatic function ATCC Manual _GrO _ Manual Manual mode of operation ATCC_ManHigher_GrO__ ManHigher Manual command for increasing the v
16. isc Disconnector closed for Bus2 ATCC _Bus3Disc_GrO _ Bus3Disc Disconnector closed for Bus3 ATCC_MTO GrO_ MTO Slave is enabled to take over the master role Table 1 10 Binary input signals of the breaker failure protection function VERSION 1 2 19 20 IED EP Automatic tap changer controller for parallel transformers 1 5 5 The symbol of the function block in the graphic editor The names of the input and output signals are parts of the Binary status signal names listed in the previous paragraph VERSION 1 2 20 20
17. meter setting as follows e Forced Single mode The mode of operation is changed to Single mode and at the same time the operation is disabled in case of any of the following errors o Contradiction in addresses o Topology error o If the device set to Master mode finds another master with higher priority connected to the same bus section o In Master mode or in CircCurrMin mode the voltage measurement is missing e Forced Master mode The slave with the highest priority can enter to this mode of operation if the MTO input is active and the former Master is not available The device displays the actual mode of operation in the On line menu of the LCD and also in the WEB interface 1 3 4 Operation in case of errors For correct operation the following conditions must be fulfilled e The devices to control parallel transformers must be connected to the same Ethernet network e The status signals indicating the busbar configuration must be correct and e Also the parameter setting of the co operating controllers must be correct In case of any errors the On line window of the controller function shows an error code The configured code vales of the Parallel error field are summarized in the Table below Error code Error code Explanation Decimal Hexa 0 Ox0 No error 1 Ox1 There is no interconnection with the device on address 0 2 Ox2 T
18. nction 1 5 2 Summary of the parameters Enumerated parameters Parameter name Title Selection range Default Control model according to IEC 61850 ATCC_ctIMod_EPar_ ControlModel Direct normal Direct enhanced Direct SBO enhanced normal Select before operate class according to IEC 61850 ATCC_sboClass_EPar_ sboClass Operate once Operate many Operate once Parameter for defining the mode of operation of the function ATCC_Oper_EPar_ Operation Off Single CircCurrMin Off Master SlaveCmd SlaveTap Parameter for time delay mode selection ATCC_T1Type_EPar_ T1 Delay Type Definite Inverse 200werN Definite Selection for compensation mode ATCC_Comp_EPar_ Compensation Off AbsoluteComp ComplexComp Off Tap changed supervision mode selection ATCC_TCSuper_EPar__ TC Supervision Off TCDrive Position Both Off Decoding of the position indicator bits ATCC_CodeType EPar CodeType Binary BCD Gray Binary Selection range extension for parallel transformers Table 1 4 Enumerated parameters of the automatic tap changer controller function VERSION 1 2 15 20 IED EP Automatic tap changer contro Boolean parameters ller for parallel transformers Parameter name Title Default Explanation ATCC_FastHigh_BPar_ Fast Higher Enable 0 Enabling fast higher control command ATCC_FastLow_BP
19. nge operation ATCC_TimOut_TPar_ Max Operating msec 1000 30000 1 5000 Time Command impulse duration ATCC Pulse _TPar_ Pulse Duration msec 100 10000 1 1000 Time overbridging the transient state of the tap changer status signals ATCC_MidPos_TPar Position Filter msec 1000 30000 1 3000 Select before operate timeout according to IEC 61850 ATCC_SBOTimeout_TPar_ SBO Timeout msec 1000 20000 1 5000 There are no additional timer parameters for extension with parallel transformers Table 1 7 Timer parameters of the automatic tap changer controller function VERSION 1 2 16 20 IED EP Automatic tap changer controller for parallel transformers Float parameters Parameter name Title Unit Min Max Digits Default Factor for fine tuning the measured voltage ATCC _Ubias FPar_ U Correction 0 950 1 050 3 1 000 Set point for voltage regulation related to the rated voltage Valid at l 0 ATCC_USet_FPar_ U Set 80 0 115 0 1 100 0 Dead band for voltage regulation related to the rated voltage ATCC_UDead_FPar_ U Deadband 0 5 9 0 1 3 0 Hysteresis value for the dead band related to the dead band Deadband ATCC_DeadHyst_FPar_ Hysteresis o 60 90 0 85 Parameter for the current compensation See Chapter 1 2 4 l R Compound ATCC_URinc_FPar_ Factor o 0 0 15 0 1 5 0 Parameter for the current compensation See Chapter 1 2 4 X Compound ATCC_U
20. nge within the reclaim time then the command is generated after T2 time delay ATCC_Recl_FPar_ Reclaim Time sec 1 0 100 0 1 10 0 Extension for parallel transformers Transformer drop for the circulating current mode of operation ATCC_Drop_FPar_ o 1 0 30 5 0 Transformer rated power for the circulating current mode of operation ATCC Sn FPar_ Transformer Sn MVA 1 0 500 40 0 Drop for weighting the influence of the circulating current for the circulating current mode of operation ATCC_ControlDrop_FPar Control Drop 1 0 50 10 0 Table 1 8 Float parameters of the automatic tap changer controller function VERSION 1 2 17 20 IED EP Automatic tap changer controller for parallel transformers 1 5 3 Summary of the generated output signals The binary output status signals of the breaker failure protection function are listed in the table below Binary status signal Title Explanation ATCC_AutoBlocked_Grl_ Auto Blocked ext Automatic control blocked ATCC_Manual_Grl_ Manual Signaling the manual mode of operation ATCC_HigherCmd_Grl_ Higher Command Command for increasing the voltage ATCC_LowerCmd_Grl_ Lower Command Command for decreasing the voltage ATCC_MaxReached_Grl__ Max Pos Reached Signaling the maximal position ATCC_MinReached_Grl_ Min Pos Reached Signaling the minimal position
21. oltage ATCC _ManLower_GrO__ ManLower Manual command for decreasing the voltage Table 1 2 Inputs to select the mode of operation If the input Manual is programmed by the user and set to logic 1 then the automatic modes are disabled and the device transmits the commands from the inputs ManHigher or ManLower to the tap changer Manual commands can be generated using the local means or they can be received from the communication channels If in manual mode the input Local is programmed by the user and set to logic 1 then the local LCD of the device can be the source of the command If the input Remote is programmed by the user and set to logic 1 then the communication channels can deliver the manual commands The function can be blocked by binary signal if the input BIk is programmed by the user and set to logic 1 The input AutoBlk can block the automatic control functions only VERSION 1 2 14 20 IED EP Automatic tap changer controller for parallel transformers 1 5 Technical summary 1 5 1 Technical data Function Range Accuracy Voltage measurement 50 lt U lt 130 lt 1 Definite time delay lt 2 or 20 ms whichever is greater Inverse and 2powerN time delay 12 lt AU lt 25 lt 5 25 lt AU lt 50 lt 2 or 20 ms whichever is greater Table 1 3 Technical data of the automatic tap changer controller fu
22. on sessseesseessesssesssr seernes 10 1 2 7 ENON COOGS iori E A eee es 10 1 3 Mode of operation to control parallel transformers ssseseesesessesesseerrenrerrssrernenns 11 1 3 1 Minimizing the circulating currents seeeeeeeeserrserrrssrrrnsrirrssrinnnnrinnssreenns 11 1 3 2 Master slave mode of operation eecececeeeeteeeeeeeneeeeeeeeeeeeeaeeeeesaeeeereaeeeenes 12 1 3 3 Irregular modes Of operation ssseesseeeesrressernesssnnesrennnsrnnnnstnnnnnnnnnnnnnnnnnnnnnnna 13 1 3 4 Operation in Case Of errors ecceceeeceeeeeeeeeeeeeeeceeeeecaeeeeaaeeeeeeeseeeesaeeeeeeeesaees 13 1 3 5 Disabled State i sec iii ceded aa a aE aaa EEE 13 1 4 Manual mode Of Operator sesgos E EE 14 15 Technical SUMMALY nnn R R 15 1 5 1 Tecnnical dala sspe cette a A hated eer dele 15 1 5 2 Summary of the parameters sssssessssnessnssrnssrtesenesstnssrnssrnnstenstnnsnnnsnnnnnnnennn nt 15 1 5 3 Summary of the generated output signals ccccceeeeeeseeceeeeeseeeeeeeeeeeeneeteaees 18 1 5 4 Summary of the input Signals ccccccececeeeeeeeeeceeeeeceaeeeeaeeeeeeeseeeeseaeeseaeeeeeees 19 1 5 5 The symbol of the function block in the graphic editor n 20 VERSION 1 2 3 20 IED EP Automatic tap changer controller for parallel transformers 1 Automatic tap changer controller 1 1 Application One of the most important criteria for power quality is to keep the voltage of selected points of the network within the pr
23. onditions are defined by the user applying the graphic equation editor The binary input status signals of the automatic tap changer controller function are listed in the table below Binary status signal Title Explanation ATCC _Local_GrO_ Local Local state of the manual operation ATCC_Remote_GrO _ Remote Remote state of the manual operation ATCC _Blk_GrO_ Blk Blocking of the function ATCC_AutoBlk_GrO__ AutoBlk Blocking of the automatic function ATCC Manual GrO_ Manual Manual mode of operation ATCC_ManHigher_GrO__ ManHigher Manual command for increasing the voltage ATCC _ManLower_GrO_ ManLower Manual command for decreasing the voltage ATCC _BitO GrO_ Bito Bit 0 of the position indicator ATCC Bit1_GrO_ Biti Bit 1 of the position indicator ATCC Bit2 GrO_ Bit2 Bit 2 of the position indicator ATCC Bit3 GrO_ Bit3 Bit 3 of the position indicator ATCC Bit4 GrO_ Bit4 Bit 4 of the position indicator ATCC BitS GrO_ Bit5 Bit 5 of the position indicator ATCC_TCRun_GrO_ TCRun Running state of the tap changer ATCC Reset GrO_ Reset Reset to release from blocked state ATCC_BIkProc_GrO_ BlkProc Blocking signal from the tap changer ATCC_VRed1_GrO__ VRed1 Reduced voltage 1 is required ATCC _VRed2_GrO _ VRed2 Reduced voltage 2 is required Extension for parallel transformers ATCC _Bus1Disc_GrO _ Bus1 Disc Disconnector closed for Bus1 ATCC _Bus2Disc_GrO _ Bus2D
24. or selection of the operating mode has several choices e Off for disabling the control function e Single for regulation a single transformer only e CircCurrMin for operating the controllers of the parallel connected transformers to minimize the circulating current e Master for selection one of the controllers of the parallel connected transformers to be the master to transmit commands to the slave controllers e SlaveCmd for selection the controller to operate in slave mode and follow the UP and DOWN commands e SlaveTap for selection the controller to operate in slave mode and drive the tap changer to the same position as the transformer assigned to the master controller In any of the active modes of operation the controllers can be set to the Manual or to Automatic control command generation VERSION 1 2 4 20 IED EP Automatic tap changer controller for parallel transformers 1 2 Mode of operation to control a single transformer This mode of operation is selected if the Operation parameter is set to Single 1 2 1 The scheme of the function block Figure 1 1 shows the scheme of the function block simplified for single mode of operation 1 2 2 Analog inputs of the controller function The automatic tap changer controller function receives the following analog inputs UL1L2 Line to line voltage of the controlled secondary side of the transformer IL1L2 Difference of the selected line currents of the
25. quent need for regulation with the same direction is detected within the Reclaim time defined by parameter The automatic control mode can be blocked by a binary signal received via binary input AutoBlk and generates a binary output signal AutoBlocked ext 1 2 5 Manual control mode In manual mode the automatic control is blocked The manual mode can be Local or Remote For this mode the input Manual needs to be in active state as programmed by the user In the local mode the input Local needs to be in active state The binary inputs ManHigher or ManLower must be programmed graphically by the user In the remote mode the input Remote needs to be in active state as programmed by the user In this case manual commands are received via the communication interface VERSION 1 2 9 20 IED EP Automatic tap changer controller for parallel transformers 1 2 6 Command generation and tap changer supervision The software module CMD amp TC SUPERV is responsible for the generation of the HigherCmd and LowerCmd command pulses the duration of which is defined by the parameter Pulse Duration This is valid both for manual and automatic operation The tap changer supervision function receives the information about the tap changer position in six bits of the binary inputs Bit0 to Bit5 The value is decoded according to the enumerated parameter CodeType
26. the calculated effect of the circulating current can be influenced With this U voltage drop the measured busbar voltage U to be controlled is modified Up Up Uai This modified busbar voltage is applied as the Ubus voltage in paragraph 1 2 4 and using this value the controller perform the task as if the transformer would be alone see Single mode of Operation in Paragraph 1 2 The result of this mode of operation is that additionally to the required control of the load center voltage the circulating current is minimized Based on the calculated U voltage drops the controller with the highest U calculated value starts generating the required control command the operation of all other controllers are delayed This method prevents the possibility to regulate quickly up and down subsequently due to the mutual influence of tap changer operations 1 3 2 Master slave mode of operation This mode of operation is selected if the Operation parameter of one of the co operating devices is set to Master and for all other devices it is set either to SlaveCmd or to SlaveTap The not consistent setting is signaled as setting error In this mode of operation the master is controlling the assigned transformer as if it would be alone and transmits the HIGHER and LOWER commands and the tap changer position to the slaves The slave devices react according to the parameter setting Operation in SlaveCmd
27. the values of which can be Binary BCD or Gray During switchover for the transient time defined by the parameter Position Filter the position is not evaluated The parameters Min Position and Max Position define the upper and lower limits In the upper position no further increasing command is generated and the output Max Pos Reached becomes active Similarly in the lower position no further decreasing command is generated and the output Min Pos Reached becomes active The function also supervises the operation of the tap changer Depending on the setting of parameter TC Supervision three different modes can be selected e TCDrive the supervision is based on the input TCRun In this case after command generation the drive is expected to start operation within one quarter of the value defined by the parameter Max Operating Time and it is expected to perform the command within Max Operating Time e Position the supervision is based on the tap changer position in six bits of the binary inputs BitO to Bit5 It is checked if the tap position is incremented in case of a voltage increase or the tap position is decremented in case of a voltage decrease within the Max Operating Time e Both in this mode the previous two modes are combined In case of an error detected in the operation of the tap changer the Locked input becomes active and no further commands are performed To
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