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1. EURO UOT sr Setting guide for the distance protection function ila AAD Hac IED EP Setting guide for the distance protection function User s manual version information Version Date Modification Compiled by 16 12 2014 First edition Version 1 1 12 06 2015 Corrected explanation of the angles in the Seida Petri characteristics es ee es VERSION 1 1 2 43 IED EP Setting guide for the distance protection function CONTENTS 1 Setting of distance protection FUNCTION ccccccccccseeeecceceeeeceaeeeeeceeeeessaseaeeeeeeeeesssaaseeeeeees 4 1 1 Setting the polygon characteristics cccccccccsseseceeeceeeeeeeeeceeeeceeeesseeeeeeeeseeeeeeessneeeeees 4 1 1 1 Impedance characteristics of the distance ProteCtiOn cccccseeeeeeeeeeeeeeeeeeeeeees 4 1 1 2 The ANAS TSI S vs tes saeretiesa tacehsnenacentsnamennbaddansarenncenstennahennanbisiendaetshaeauniiansicaWshansanbaiandieesiss 5 1 1 1 Setting calculation ax teasissiencsichstnnrisinievantnntnusdenaiontssssmnaietisieetiticnvetiomeanbadendicessaciaentiakeacectadesaeatie 8 1 2 Binary signals influencing the operation of the distance protection function 20 1 2 1 Binary inputs of the distance function DIOCK ee ccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeaaees 20 1 3 The current conditions of the distance protection function cceeeeeeeeeeeeeeeeeeeees 24 1 3 1 The parameters of the current CONCITION ccccseeee2. Zexl 32041 _ o rl _ 3 0 12 s or 3erl 30012 Accordingly the required setting values are Zone Xo X1 3X1 0 5 Zonei Ro R1 3R1 0 5 Note In some applications the parameters Zone2 Xo X1 3X1 and Zone2 Ro R1 38R1 is considered to be equal to those of the Zone1 In this case this parameter cannot be seen in the group of parameters for the second zone Par Line Xm 3X1 Par Line Rm 3R1 In case of asymmetrical fault involving the ground the zero sequence current of the parallel line influences the impedance measurement To compensate this effect the zero sequence current of the parallel line is to be measured and the effect is compensated in the calculation using the zero sequence mutual compensation factors for the parallel line In the applied algorithm it is performed in the form of two real factors rm 3eri B xm aE Additionally to the given positive sequence reactance and resistance See the data of the example above per unit positive sequence reactance x1 0 41 Q km per unit positive sequence resistance r1 0 12 Q km the data of the mutual per unit impedances are also needed In this example they are supposed to be per unit mutual zero sequence reactance xm 0 70 Q km per unit mutual zero sequence resistance rm 0 15 Q km With these data VERSION 1 1 15 43 IED EP Setting guide for the distance protection function rmo 0 15 0 42 3sri 3012 xmo 0
3. Zone to be blocked by DIS21_PSDBIk2_BPar_ PSD Block Z2 e z Zone2 to be blocked by DIS21 PSDBIk3 BPar PSD Block Z3 a Zones to be blocked by DIS21_PSDBIk4 BPar_ PSD Block Z4 fo a Zone4 to be blocked by DIS21 PSDBIk5 BPar PSD Block Z5 oO i Zones to be blocked by Table 1 9 The Boolean parameters of the distance protection function Floating point parameters Parameter name Title Dim Min Max__ Default_ Table 1 10 The floating point parameters of the power swing detection function Integer parameters Parameter name Title Unit Min Definition of the ratio of the outside and inside rectangles of the characteristics for power swing detection DIS21_RRat_IPar_ PSD R_out R_in DIS21_XRat_ Par_ PSD X_out X_in Table 1 11 The integer parameters of the power swing detection function Timer parameters Parameter name Title Unit __ Min _ Max __ Step Default__ DIS21_PSDDel_TPar_ PSD Time Delay DIS21_PSDSlow_TPar_ Very Slow Swing 10000 DIS21_PSDRes_TPar_ PSD Reset 10000 DIS21_OutPs_TPar_ OutOfStep Pulse 10000 Table 1 12 The timer parameters of the power swing detection function 1 4 2 Setting Operation PSD The power swing is usually a three phase phenomena but in special application the line can operate also when one phase is switched off Set this parameter according to the application 1 out of 3 2 out of 3 3 out of 3 or using this parameter the blocking of the distance pr
4. by the saturation differences between the phase CT s and by the zero sequence error currents due to the asymmetrical arrangement of network elements as well Usually the two considerations above do not cause any difficulties in setting The setting range is 10 50 of the current transformer rated value The biasing is needed because the errors of the current transformers increases with increasing phase currents on fault The setting range is 5 30 of the current transformer rated value 1 3 3 Setting the starting current to limit line impedance calculation The impedance cannot be calculated with the required accuracy if the current value is too low To avoid errors limit current is to be set as follows IPhBase Sens Based on experiences the factory setting of this parameter usually assures correct operation of the function VERSION 1 1 25 43 IED EP Setting guide for the distance protection function 1 4 The embedded function block for power swing detection PSD On a relatively long transmission line the power swings can result low voltage and high current values Consequently the distance protection function can measure low impedance which is inside the tripping characteristic To avoid the trip command the power swing detection function can be applied Power swings can be stable or they can result in an out of step operation Accordingly the power swing detection function can block the distance protection functio
5. transients and the angle error of the measuring transformers the impedance contains inaccuracy too In this way the calculated impedance does not determine a single point on the impedance plane but several points which can cover a rather large area in the subsequent sampling sequence The characteristics must include this area as well Because of the effects mentioned above it is useful to open the characteristics The following fact however contradicts the opening The characteristics must exclude the impedance measured in the healthy loops The separation of the measuring loops based on the zero sequence current can exclude the measured impedance values of some loops but the remaining impedance values measured in healthy loops can approach the characteristics especially in case of heavy pre fault load An example is a close in single phase to earth fault in phase A when the impedance measured in the healthy loop B is close to the border of the characteristics Therefore it is useful to set the characteristics as closed as possible The requirements are in contradiction an engineering compromise is needed to set the slope based on the experience When making these considerations the mentioned VECTOR program of PROTECTA can help identifying the critical situations and investigating the effect of the actual parameters as well VERSION 1 1 11 43 IED EP Setting guide for the distance protection function This parameter can be
6. 1 28 43 IED EP Setting guide for the distance protection function This timer parameter is related with the time which is needed for the measured impedance to pass the defined impedance band If the measured time is longer than this parameter value then the power swing state blocks the trip command If the time is shorter which means that the measured impedance jumps inside the characteristic the fault is detected and trip command can be generated PSD Reset The setting of this parameter has two functions e Extending the duration of the blocked state e Limiting the duration of the Very Slow state signaling The power swing is expected either to return to a stable state of the system or the continuous change of the angle between the voltages results out of step operation of the systems at both line ends In both cases the measured impedance leaves the characteristics defined by the outer characteristic lines At the moment of leaving the band a timer is started which runs for the time defined by this parameter This means that the blocking state is kept additionally for PSD Reset time The other allocation of this parameter is explained below In heavily loaded state of the electric power system there is a chance that the measured impedance is within the power swing characteristic band for a long time To prevent continuous blocking there are two methods available One method is that the load encroachment ch
7. 70 057 3ex1 3 041 Accordingly the required setting values are Par Line Xm 3X1 0 57 Par Line Rm 3R1 0 42 This compensation factor is considered for Zone 1 only Zone Time Dela The first stage of the distance protection can be delayed The time delay of the first stage is to be set with this parameter in milliseconds The usual setting is 0 which means no additional time delay the protection function operates with the natural delay of the calculation time Operation Zonet The first stage of the distance protection can be disabled or can be directed forward or backward The parameter value can be Off Forward Backward accordingly The usual setting is forward supposing that the fault current flows toward the protected line Zone Start Onl The trip command of the first zone of the distance protection can be inhibited using this parameter If this Boolean parameter is set to 1 logic TRUE then the function is operable but the trip command is blocked Set 0 for Zone1 Start Only to generate also a trip command PSD Block Z1 The distance protection function includes the embedded function for power swing detection The role of this embedded function block is among others to block the trip command if the measured impedance is within the characteristic of the distance protection not because of fault but due to power swings If this Boolean parameter is set to 1 logic TRUE then the detec
8. Therefore the most important setting aspect to be considered is to avoid faulty start on high power transmission on the line and on a power swing This stages can also serve special purposes e g two second stages with two time delays and setting values in case of short outgoing line from the far away busbar reverse zones generation of inhibition signals for some tele protection schemes to detect faults in reverse direction etc Of course this description cannot cover all network configurations but the examples above show that the setting of a protection must be co ordinated with all other protections of the network When determining the setting values a great care must be taken A too high setting value for the third stage is not advised The same statement is valid for all higher stages as well The time delay of these stages has an additional selective time step The parameters for the stages 3 4 5 are as follows See the explanation for the first stage setting The time delay of these stages is given in milliseconds the value is usually the delay time of the second stage plus at least one selective time step The value can be determined only knowing the total protection system The backward stages can form a natural bus bar protection for the substation If the time delay is shorter than that of the distance protection second stage at the far away line end then the nearest circuit breakers will be disconnected on bu
9. be accordingly longer Location of the protection Figure 1 13 Distance measurement on lines with three terminals According to Figure 1 13 the measured impedance is Z I4 Ipg measured ZA Zc lA This value is higher than the impedance Z 4 Zc proportional with the distance The correct impedance setting for the second zone is Z l 1 A gt measured Zi a A B ZL l l TIp Here the highest possible feeding distortion factor on different network conditions must be considered VERSION 1 1 32 43 IED EP Setting guide for the distance protection function 1 7 2 Distortion caused by parallel lines If two line systems are mounted on the same tower then the zero sequence current flowing in the parallel line through the zero sequence inductive coupling will result zero sequence induced voltage in the line to be protected This induced voltage will distort the measured impedance in case of earth faults The direction of the induced voltage in the protected line depends on the zero sequence current direction on the parallel line The smallest possible impedance measured in case of fault at the end of the line must be determined and the first stage of the differential protection must be set accordingly I VARN min L a E e lt is a smaller value than the needed setting without parallel effect The highest impedance must be similarly determined and the setting of the second stage of the differ
10. calculated as Angle 4th Quad ArcTan X R deg Here the ratio defines the slope only X and R have no relationship to the positive sequence impedance data of the line The unit of this parameter is degrees For example in case of a 120 kV transmission line the proposed setting value is Angle 4th Quad 15 deg The greatest possible opening is 30 deg If needed this setting can be modified The proposed seiting Angle 4th Quad 15 deg This angle is common for all five zones Angle 2nd Quad Slope of the characteristics border line S arctg R X in the negative resistance area see Figure 1 1 When setting this parameter similarly to the setting of the slope Angle 4th Quad the following considerations are to be made The principal border of the possible impedance values is the impedance of the line The points of this line are measured in case of solid faults along the line The characteristics must include these points In case of close in faults the voltage will be a very small value which cannot be sufficient when calculating the fault direction In this case the voltage values stored in the memory are to be applied to calculate the direction During a fault the power flow can change largely as compared to the flow during normal operation of the network and the voltage during fault is rotated as compared to the healthy voltage This phase shift depends on the impedances and on the power flow To decide a correct
11. direction it is useful to open the inclination of the characteristic line Due to the inaccuracy of the algorithm the measuring errors caused by the short circuit transients and the angle error of the measuring transformers the impedance contains inaccuracy too In this way the calculated impedance does not determine a single point on the impedance plane but points which can cover a rather large area in the subsequent sampling sequence The characteristics must include this area as well Because of the effects mentioned above it is useful to open the characteristics The following fact however contradicts to the opening The characteristics must exclude the impedance measured in the healthy loops The separation of the measuring loops based on the zero sequence current can exclude the measured impedance values of some loops but the remaining impedance values measured in healthy loops can approach the characteristics especially in case of heavy pre fault load An example is a close in double phase fault in phases B and C when the impedance measured in the healthy loop AB is close to the borders of the characteristics Therefore it is useful to set the characteristics as closed as possible The requirements are in contradiction an engineering compromise is needed to set the slope based on the experiences When making these considerations the mentioned VECTOR program of PROTECTA can help identifying the critical situ
12. is 27 64 Theta P R distortion of x Line A al Hf Re lm a LineX a Q Hs Beta 25 004639 i ssden a J gt 1 2636090 0 4065394 K Ssidex af fie UR 2305400 fo R side F zide 1 H us 20329491 97 616455 prot R side X 4 heg Beta 25 004639 ume a 400 Ze aga 13 6086 PiMw a 995 IF 8 2807 110 3364 RF ho IFS 1 2692 1 5163 UFS 25 5294 E 8 7904 UFPrat fi 83 7655 78 8261 Re IFProt 2 5328 E 1097 ZProt 4g 4297 52 7799 Theta 27 6407 END Figure 2 4 Screenshot of the simulation software for three phase fault When operating the sliders in the simulation software the influence of different factors can be studied and as a result diagrams can be dawn The Table and the diagrams below show examples p pmm wowo w x f o t p p e qa a ha pa pa pa p ha a7 P MW Average Figure 2 5 Calculated results for three phase fault Based on the calculated results the following diagram can be drawn See Figure 2 6 VERSION 1 1 38 43 IED EP Setting guide for the distance protection function Parameter is the Beta angle Top to bottom 25 20 15 10 5 0 Tilting angle O 9 n E a E a E a T a E 0 10 20 30 40 50 60 Fault resistance Ohm Figure 2 6 Diagram for three phase fault Figure 2 6 shows that the required tilting angle changes relatively small in the function of the fault resistance Consequently it is justified to calculate the avera
13. is needed due to the measurement distortion of the fault resistance then the load resistance can be within the extended characteristic Consequently the correct R load setting is important VERSION 1 1 13 43 IED EP Setting guide for the distance protection function This primary resistance 133 Q is to be calculated to the secondary side of the measuring transformers If at the relay location also a relatively small amount of reactive power is measured then load encroachment area is opened using the Load Angle parameter The method of calculation is aS an example with 20 reactive load Load Angle ArcTan Qmax Pmax ArcTan 0 20 11 3 degli12 deg Zone Reduction Angle The algorithm of the distance protection calculates fault distance based on the measured reactance value If the fault resistance at the fault location cannot be neglected and before fault inception there is considerable power transfer on the protected line the calculated reactance value consequently the calculated distance to fault is distorted This distortion means overreaching or under reaching of the distance protection Overreaching can result operation also in case of fault outside the protected zone resulting unselective tripping To compensate this distortion of the measured distance the X border line of the polygon shaped characteristic can be tilted downwards or upwards depending on the amount and direction of the pr
14. miniature circuit breaker in the voltage transformer secondary circuit is shown for common contact in Figure 1 6 for individual auxiliary contacts in Figure 1 7 This mode of application generates a logic TRUE signal if the contacts are closed This signal is connected to a binary input of the device Another possibility for supervision is the application of the voltage transformer supervision VTS function block See the details in the manual Voltage transformer supervision and dead line detection function block description Depending on the setting this function block generates a signal if the detected asymmetry of the three phase currents differs from the type of asymmetry measured in the three phase voltages These signals are connected in the graphic logic editor to the VIS input of the distance protection function block DIS 21 See Figure 1 8 VERSION 1 1 20 43 IED EP Setting guide for the distance protection function VT 2211 6 luise s fuse VT 2211 Name U L1 gt U L1 lt 2 3 U L2 gt 4 U L2 lt 5 pe utse pe lus S 0O12 2101 3 Bln_ 03 o A ep Figure 1 7 Individual auxiliary contacts for the VT miniature circuit breakers VERSION 1 1 21 43 IED EP Setting guide for the distance protection function VTS_Line gt gt AR_run Blk Fail Figure 1 8 Example Blocking of the distance protection function due to voltage measurement error Detail Block Z1 5 If needed the i
15. the switch onto fault logic The parameters of the SOTF function are explained in the following tables Enumerated parameters Parameter name Title Selection range Default Parameter for selecting one of the zones or high speed overcurrent protection for the switch onto fault function SOTF Off Zone1 Zone2 Zone3 Zone4 Zone5 Table 1 14 The enumerated parameters of the SOTF function Integer parameters Parametername__ Title Unit__ Min Max Step Default __ Definition of the overcurrent setting for the switch onto fault function for the case where the DIS21_SOTFMd_EPar_ SOTF Zone parameter is set to HSOC Table 1 15 The integer parameters of the SOTF logic 1 6 2 Setting The general condition to generate a trip command in case of switch onto fault is that the dedicated input SOTF COND of the distance protection function block should be active This signal indicates that in dead state a close command is performed See Chapter 1 2 and an example in Figure 1 9 The second condition is that additionally a fault is detected The fault can be detected by any of the distance protection zones or by the high speed overcurrent HSOC function The selection is the user s choice wit setting the SOTF Zone parameter SOTF Zone This parameter selects either one of the distance protection zones or the high speed overcurrent protection function When selecting a distance zone e g Zone
16. 3 see Table 1 14 then the additional condition for the trip command is the start signal of this zone For the decision the directional parameter of this zone is considered NonDirectional independently on the setting See Table 1 1 When selecting HSOC then the additional condition for the trip command is the operation of the embedded function HSOC This high speed overcurrent protection function operates within one network period if the measured current is above the setting value SOTF Current Set this current safely above the highest load current considering the possible inrush currents in healthy operation but possibly below the lowest short circuit current which can be expected after a close command No time delay setting is applied VERSION 1 1 31 43 IED EP Setting guide for the distance protection function 1 7 Setting in some special applications 1 7 1 Setting for a transmission line with more than two terminals If the line connects more than two substations then the setting of the first stage of the protection at busbar A in Figure 1 13 should be based on the shortest distance of AC or AB If the shortest distance is AB then the setting is Z Z ap l E As the protection cannot measure the exact distance between A and the fault in case of fault between T and C due to the problem caused by the feeding distortion of the intermediate third supply the setting of the second stage must
17. 5 the protection measures a larger impedance than the impedance proportional with the distance because of the distorting effect of the z short circuit current component delivered by a third line The measured impedance will be greater than the real one which means that the border of the impedance stage is withdrawn It is possible that the fault in the second zone and the protection trips only in the subsequent third stage which means an additional time delay Setting the second stage as an overreaching stage Application of overreaching stage with co operation of an external automatic reclosing device can be effective to overcome the problems caused by the delayed fault clearing in case of faults near the far line end Another application of overreaching is the tele protection see Chapter 7 4 in detail In case of overreaching the setting will cover completely the protected line but the faults at the beginning of the outgoing line as well The formula for setting is OVERREACH gt Z V l 8 VERSION 1 1 18 43 IED EP Setting guide for the distance protection function 1 1 1 3 Setting the higher impedance stages The role of these stages of the distance protection is to give back up protection to the following lines outgoing from the far busbar or reverse backup protection so it has not a main protection role Due to the feeding distortion mentioned above explained with Figure 1 5 this task cannot be fully achieved
18. 91 45 A132 i D 4 6405 Agra a uw Fiside Al a Aside FisideRO R side soa ie LIFPrat 191 3978 FFrot 0 5775 i a on 14 4851 oo lard r BUE 1 2638090 0 4065394 osamo fo 20929491 97 516455 EEEF 127207 sso hass fams E fams o 2272 perz pass jire 144891 31 2978 83 1274 hama formo 815673 57 5369 a 5813 0 1710 UN kM a Ej PiMw Prot 191 5673 57 5369 Theta 13 1807 RF EPE Figure 2 11 Screenshot of the simulation software for phase to ground fault Summary In a given application the required tilting of the characteristic can be calculated using the method above The dynamic tilting of the algorithm applied in the EuroProt devices results less overreaching or underreaching if the pre fault power transfer is high on the protected line VERSION 1 1 43 43
19. FPar Zones X DIS21_Z4X_FPar Zone4 X DIS21_Z5X_FPar Zoned X ohm Load encroachment setting DIS21_LdR_FPar R Load ohm Zero sequence current compensation factors for the five zones individually DIS21_Z1aX_FPar_ Zonet Xo X1 3X1 OSS DIS21_ZiaR_FPar_ Zonet Ro R1 3R1 OT i DIS21_Z2aX_FPar_ DIS21_Z2aR_FPar_ 5 DIS21_Z3aX_FPar__ Zone3 Xo X1 3X1 l0 J5 i DIS21_Z3aR_FPar_ Zone3 Ro R1 3R1 oo 5 Ji DIS21_Z4aX_FPar_ DIS21_Z4aR_FPar_ DIS21_Z5aX_FPar_ Zoned Xo X1 3X1 DIS21_Z5aR_FPar_ Zoned Ro R1 3R1 Parallel line coupling factor DIS21_a2X_FPar_ Par Line Xm 3X1 DIS21_a2R_FPar_ Par Line Rm 3R1 Data of the protected line for displaying distance DIS21_Lgth FPar_ Line Length 1000 100 DIS21 LReact FPar_ Line Reactance Table 1 3 Floating point parameters for the distance protection ohm ohm 1 ohm 1 ohm ohm 0 0 ohm 10 ohm ohm ohm O0 pO 0 100 0 x F ohm 1 Integer parameters The integer parameters in Zone Reduct Angle parameter is valid for Zone 1 only Table 1 4 show the fine tuning parameters of the polygon characteristics For explanation see Figure 1 1 VERSION 1 1 7 43 IED EP Setting guide for the distance protection function Parameter name ___ Title S Unit _ Min Max Step Default _ DIS21_dirRX_IPar__ Angle 2nd Quad ss fdeg O 30 1 15 DIS21_dirXR_IPar__ Angle 4thQuad_ sf deg o 30 1 15 Definition of the Zone 1 reduction ang
20. The resistance value of the line section to be protected calculated with the factor 1 1 must be within the polygon In case of electric arc at the fault location which is approximated with a resistance value added to the impedance of the line section This increases the total resistance value which must be within the polygon too Remember Warrington formula for calculation the arc resistance caused by J RMS current and d arc length fe _ 28700 dl arc g o gaa For example d 1 m and 7 500 A Rarc 4 78 Q If 1000 A this value decreases to 1 81 Q primary value VERSION 1 1 9 43 IED EP Setting guide for the distance protection function In case of earth fault the earth resistance at the fault location must be taken into consideration If the steel towers are interconnected with each other with the earth wire this resistance can be small The sum of the mentioned resistance line resistance arc earth resistance must be within the polygon The calculated impedance contains errors because of the inaccuracy of the algorithm the amplitude and phase errors of the VI s and CT s the measuring errors caused by the short circuit transients The sequence of calculated impedances is not a single point on the impedance plane but they will cover a certain area The characteristics must be set to include this area as well The power supply from the far end of the protected line distorts the measured resistance magnitude and als
21. aracteristic set by the parameters R Load and Load Angle discloses the impedances measured in heavily loaded state of the electric power system The other method is that this parameter limits the duration of the blocked state At the moment of power swing is detection a timer starts If the impedance vector is continuously within the power swing detection characterisrics this timer runs for the time defined by this parameters and then Slow Swing is detected At the same time the blocking state is reset Set this parameter to cover the expected longest swing time period only OutOfStep Pulse This parameter defines the duration of the pulse indicating out of step operation of the systems at both line ends VERSION 1 1 29 43 IED EP Setting guide for the distance protection function 1 5 The distance to fault calculation FAULT LOCATOR The distance protection function selects the faulty loop impedance its positive sequence component and calculates the distance to fault based on the measured positive sequence reactance and the total reactance of the line This reference value is given as a parameter setting Line Reactance The calculated percentage value facilitates displaying the distance in kilometers if the total length of the line is correctly set by the parameter Line Length 1 5 1 The parameters for distance to fault calculation Floating point parameters Parameter name Title Dim Para
22. ase of a three phase fault in all six measuring loop the result of the calculation is the positive sequence impedance of the line between the relay and the fault location Let us select the L1 N loop Here TT Vepror ee N ot tJAproe leproe komp 319 prot The zero sequence current compensation factor would be g komp a VERSION 1 1 36 43 IED EP Setting guide for the distance protection function In case of a three phase fault however the zero sequence current component is le 0 When drawing the impedance of the line and the calculated impedance in the same coordinate system the distortion of the impedance can be evaluated and the required tiling of the characteristic with a angle to compensate the distortion can be seen See Figure 2 3 X Xprot 9 tg iiia Figure 2 3 Distortion of the measured impedance VERSION 1 1 37 43 IED EP Setting guide for the distance protection function 2 2 Calculation example The example below shows the method of calculation for a three phase fault The data of the network correspond to a 400 kV transmission line These can be identified on the screenshot of the simulation software in Figure 2 4 The screenshot shows that the angle between the voltages at the line ends is 25 Beta which results 995 MW pre fault power transmission If in this state the fault resistance is 10 ohm then the required tilting of the X characteristic line
23. ations and investigating the effect of the actual parameters as well This parameter can be calculated as Angle 2nd Quad ArcTan R X deg Here the ratio defines the slope only X and R have no relationship to the positive sequence impedance data of the line The unit of this parameter is degrees For example in case of a 120 kV transmission line the proposed setting is Angle 2nd Quad VERSION 1 1 12 43 IED EP Setting guide for the distance protection function 15 deg This is the inclination from the X axis 15 deg to the left The greatest possible opening is 30 deg If needed this setting can be modified The proposed seiting Angle 2nd Quad 15 deg This angle is common for all five zones R Load Load Angle When setting the impedance stages it has to be taken into account that the setting should be well below the impedance measured in maximum power operating condition If however extremely high temporary load can be expected and at the same time the zone reach in R direction is set to a high value then the load encroachment property of the distance protection function can help in case of high load to exclude the measured impedance from the distance characteristic There are two parameters to serve tightening the characteristic R Load and Load Angle The effect of these parameters is shown in Figure 1 1 The application of these parameters supposes that the power transfer along the line is mostly acti
24. ce protection The distance protection function calculates the positive sequence impedance in six measuring loops The calculated R and X aL co ordinate values define six points on the complex impedance plane The protection function compares these points with the polygon characteristics of the distance protection shown in Figure 1 1 The main setting values of Zone R and Zone X refer to the positive sequence impedance of the fault loop The resistance value includes the positive sequence fault resistance of the possible electric arc and in case of a ground fault the positive sequence resistance of the tower grounding as well Angle 2nd Quad Zone Reduct Angle Line Angle R Figure 1 1 The polygon characteristics of the distance protection function on the complex plane Example Zone1 If a measured impedance point is inside the polygon shown in Figure 1 1 then the algorithm generates the true value of the related output binary signal The distance protection has six zones applying polygon characteristics each of them have independent parameter setting values VERSION 1 1 4 43 IED EP Setting guide for the distance protection function 1 1 2 The parameters The parameters needed in the polygon evaluation procedure of the distance protection function are explained in the following tables Enumerated parameters The enumerated parameters of the zones according to Table 1 1 serve disabling of the
25. e fault power transfer on the protected line Figure 1 1 shows tilting downwards the zone reduction angle is clockwise The tilting is performed dynamically in five sections depending on the extent of the pre fault power transfer The setting of the tilting angle needs technical consideration This method of calculation is explained in the Appendix P Pn Full Zone reduction angle downwards 0 75 0 95 Half Zone reduction angle downwards 0 No tilting 0 25 Half Zone reduction angle upwards 0 75 Full Zone reduction angle upwards Figure 1 4 Dynamic sections of the Zone reduction The result of this correction is that for fault at the zone reach point the behavior of the distance protection is practically independent on the pre fault load state of the protected line or cable VERSION 1 1 14 43 IED EP Setting guide for the distance protection function Zone Xo X1 3X1 Zonet Ro R1 3R1 In case of faults involving the ground the algorithm applies formulas for the impedance distance calculation where the phase currents are compensated with the zero sequence current o Uphase Iphase x 3lo The a zero sequence current compensation factor is applied in the algorithm of the distance protection function in the form of two real factors Both of them are calculated from the data of the protected line With the data given above for the 120 kV line _ o x1 4 03 0 41 gg Oe Se a x
26. e measuring impedance error so its setting value must be less than the total positive sequence impedance of the protected line The equation for selective setting the first stage is z lt e Where Z the setting value of the first impedance stage ZL the positive sequence impedance of the line to be protected E the security factor usually 0 15 VERSION 1 1 8 43 IED EP Setting guide for the distance protection function Example for setting the first impedance stage For the setting procedure the following data are necessary Data 120 kV overhead line Line length length 40 km Per unit positive sequence reactance x1 0 41 Q km Per unit positive sequence resistance r1 0 12 Q km Per unit zero Sequence reactance xo 1 03 Q km Per unit zero Sequence resistance ro 0 30 Q km Voltage transformer turns ratio au 120 kV 0 1 kV Current transformer turns ratio al 600A 5A Calculation Zonet X Ohm Setting of the reactance is calculated according to the classical setting formula I lt X pine e The parameter values are to be given in secondary Ohm units The primary reactance to be set Xprim length x1 1 40km 0 41 Q km 1 0 15 14 26 Q Transformed to secondary value Xsecond ai au Xprim 600 5 120 0 1 14 26 Q 1 426 Q The value to be set Zone1 X Xsecond 1 426 Q Zone1 R Ohm When setting the resistance the following considerations must be made
27. ed from the decision To decide the presence or absence of the zero sequence current biased characteristics are applied which avoid starting on phase to phase faults with high current The minimal setting current IRes Base Sens and a percentage biasing IResBias is to be set See Figure 1 11 VERSION 1 1 24 43 IED EP Setting guide for the distance protection function 3lo In 100 IResBias Ilmax In IRes Base Sens Imax In Max IL1 IL2 IL3 In Figure 1 11 Zero sequence current detection with biased characteristics IRes Base Sens The correct setting needs the following considerations The zero sequence current detection setting should be sensitive enough to detect the smallest possible zero sequence current in case of a phase to earth fault or a double phase to earth fault The selectivity is needed mainly in case of faults in the base zone which is the first stage and the second stage of the distance protection i e the line to be protected So the smallest zero sequence current must be determined with a series of short circuit calculations lt is necessary to calculate faults in the reverse zone as well The setting value is limited by the zero sequence currents which can be detected in case of faults without earth Principally there are no zero sequence currents in these kinds of faults even so zero sequence current can be detected They are caused for example by the current and phase errors of the current transformers
28. eeccceeeceseeseeeeeeeeeeseeeeeeeeeeeeseseeeeeeeeeeeaaas 34 2 1 1 Model of the pre fault power transfer cecccccseeeceeeeeeeeeeeeesseeeeeeeseeeeeeeeesaaees 35 2 1 2 Modeling a three phase fault COMPONENT eee eeceeeeeeeeeeeeeeeeeeeeaeeeeeeesaeeeeees 36 2 1 3 The superposition for three phase fault ee ceccsseseeeeeeseesseeeesseaseeeeesseseees 36 2 1 4 Impedance calculation cccccssssscecccsesseeeeccsessececcceueeeecseeaseeeesseseeeesssaeeees 36 2 2 Calculation CxAMple cccccccsseeeeccceceeeeeeeeecceeeeeesaeeeeeeeeeeeseueeeeeeeeeesessueaeeeeeeeeesaaas 38 2 3 Influence of asymmetrical faults ccc ccccceeeccceeeeeeeeeeeeeeeseeeeeeseeeeeeeaeeeeseeeeensaeeeeeas 40 2 3 1 Modeling a the pre fault component cccceeceeecseeeeeceeeeeeceaeeeeeeeeeeeesaeeeeesaaaees 40 2 3 2 Modeling a single phase to ground fault component ccccseeeeeeeeeseeeeneeeees 40 239 WINS superpositiON ccssanecisneaxanenesuinnavitsesacattaensendiauenteranenies Eaa iiaeie a 40 2 3 4 Impedance calculation ccccccssseeceeeceeeeeceecceeeeeeeecaaueeeeeesaaaeeeeessaaeeeeeessaeeees 41 2 4 Calculation example ccccccssssccccccseeceeeceeseceesceeeeeeeeeseeaeeeeeeseeaseeeesseeageeeesssseeeesenas 41 VERSION 1 1 3 43 IED EP Setting guide for the distance protection function 1 Setting of distance protection function 1 1 Setting the polygon characteristics 1 1 1 Impedance characteristics of the distan
29. eeeeeseeeeeeeeeesaeeeeesaeeeeesnees 24 1 3 2 Setting the zero sequence Current detection ccceeeceecseeeeeeeeeeeeeeeeeeeesaeeeeeens 24 1 3 3 Setting the starting current to limit line impedance calculation ccee 25 1 4 The embedded function block for power swing detection PSD 26 1 4 1 The parameters for power SWING CeteCtiONn ccccceeeeseeeeeeeeeeeeeeeeeeeaeeeeeeeeas 26 Me RS ices E E O 27 1 5 The distance to fault calculation FAULT LOCATOR cc ceeeeeeeeeeeeeeeeeeeeeeees 30 1 5 1 The parameters for distance to fault calculation cccccceecccseeeceeeeeeeeeeeeaeees 30 Be CUA ieee stents ne eens occ E E E E E E AE 30 1 6 The high speed overcurrent protection function with switch onto fault logic HSOC SOTE ee E cee gevee sbebere T E EE E E E E 31 1 6 1 The parameters for the switch onto fault lOQIC ccccseeseeeceeseeeeseeeeeseeeeeeeeeees 31 LOL GEUN aaia R E E E EE 31 1 7 Setting in some special applications eee ccccseeeeceecceeeeeeeeccaeseeeeeeeseaeeeeesseaeeeessaaess 32 1 7 1 Setting for a transmission line with more than two terminals c ccseeeeeees 32 1 7 2 Distortion caused by parallel lines 2 0 0 ceececceeceeeeeeeeeeeeeeeeeeeseeeeeeeeesseaeeeeeeas 33 2 Appendix Compensation of the distance distortion due to the power transfer and the TEU WC SIS ANG E E TE E E T E E E E E E E ET 34 2 1 Calculation for three phase fault cc ceccc
30. en the voltages at the line ends is 25 Beta which results 995 MW pre fault power transmission If in this state the fault resistance is 10 ohm then the required tilting of the X characteristic line is 27 64 Theta This is the same as the result for three phase fault PY Z1F_R distortion LineRT af LineX1 4 wj ee 25 004639 LineRO LinexXO aj SsideR1 Ssidex1 E3 25 004639 Sside RU aj 5 side lt 0 al w 1 2636090 E m m 230 94010 Ea on Ph IIF 09 29451 J i 0 9021 10 39021 3 6086 13 6086 P T D 7 2 7602 R side All 4 at 1 2692 R side X1 al w R side Raaj F side lt Da wf E LIFProt 183 7655 4455 7m ow 1 5163 7 wn yet aya ia 25 5294 18 7904 70 826 IFProt 25328 1 1097 UNIKS a j Pw 4 eProt 149 4297 04065394 Bo 37 616455 1 36088 3 E 7304 B2733 i af hdd Theta 27 6407 Ee Figure 2 9 Screenshot of the simulation software for phase to ground fault VERSION 1 1 41 43 IED EP Setting guide for the distance protection function lf data that are more realistic are set the zero sequence impedance is four times positive sequence impedance then the results slightly deviate In the example below with 25 voltage angle Beta the power transfer is 995 MW A 10 ohm fault resistance results the need of 26 79 Theta tilting of the X characteristic line See Figure 2 10 Z1F_R dist
31. ensate this distortion of the measured distance the X border line of the polygon shaped characteristic can be tilted downwards or upwards depending on the amount and direction of the pre fault power transfer on the protected line The angle value of tilting needs technical consideration This method of calculation is explained below 2 1 Calculation for three phase fault For the calculation the power system is reduced to two points the protected line is located between these points fed by two equivalent generators The calculation is performed with the application of the superposition The following two components are superposed e The first component is the pre fault steady state where the pre fault voltage at the fault location is calculated e The fault is added by connection the pre fault voltage multiplied by 1 at the fault location of the deactivated network The sum of the two components results the faulty state during power transfer on the line The superposed results of the calculation result the voltages and currents at the location of the protection These values are substituted in the measuring equations of the distance protection algorithm When comparing the measured impedance with the impedance of the protected line the distortion can be evaluated This distortion is to be compensated by tilting the reactance line of the distance protection When explaining the method of calculation below the several influe
32. ential protection is to be set as follows lt is a higher value than the needed setting without parallel effect As the second stage in case of measured Zmeas min may reach far into the next line the time delay must be increased if necessary by two selective time steps The disadvantage of the additional time delay can be avoided using a teleprotection scheme whose result is quick fault clearing along the protected line As an option the zero sequence current compensation for parallel lines can be considered If so the current flowing in the parallel line must be connected to the dedicated input of the device and the parameters Br and b must be set accordingly See section 1 1 1 1 VERSION 1 1 33 43 IED EP Setting guide for the distance protection function 2 Appendix Compensation of the distance distortion due to the power transfer and the fault resistance The algorithm of the distance protection calculates the fault distance based on the measured reactance value If the fault resistance at the fault location cannot be neglected and before fault inception there is considerable power transfer on the protected line then the calculated reactance value consequently the calculated distance to fault is distorted This distortion means overreaching or underreaching of the distance protection Overreaching can result operation also in case of fault outside the protected zone resulting unselective tripping To comp
33. fault the faults detected in the individual zones generate also a trip command For special applications the trip command can be blocked Note if also the start signals need to be blocked the switch the selected Operation parameters Table 1 1 to Off Parameter name __ Title _ Default Explanation DIS21_Z1St_BPar_ Zone1 StartOnly 0 Ofor Zonet to generate trip command DIS21_Z2St_BPar_ Zone2 StartOnly 0 _ 0 for Zone2 to generate trip command DIS21_Z3St_BPar_ Zone3 Start Only 0 O for Zone3 to generate trip command DIS21_Z4St_BPar_ Zone4 Start Only 0 0 for Zone4 to generate trip command DIS21_Z5St_BPar_ Zone5 Start Only 0 0 for Zone5 to generate trip command Table 1 2 Boolean parameters of the phase selection logic VERSION 1 1 6 43 IED EP Setting guide for the distance protection function Floating point parameters The floating point parameters of the zones according to Table 1 3 serve setting the main sizes of the polygons for the zones one by one See Figure 1 1 These parameters can be calculated if the parameters of the protected lines or cables are known The calculation methods are demonstrated in Appendix 1 Parameter name _ si Title ___ Dim _ R and X setting values for the five zones individually DIS21_Z1R_FPar Zonei R DIS21_Z2R_FPar Zone2 R DIS21_Z3R_FPar Zone3 R DIS21_Z4R_FPar Zone4 R DIS21_Z5R_FPar Zoned R DIS21_Z1X_FPar Zone X DIS21_Z2X FPar Zone2 X DIS21_Z3X_
34. ge value for each Beta angle and to draw a diagram which shows this average value as the function of the Beta angle This diagram is shown in Figure 2 7 tlagos d nt s 1000 1200 Figure 2 7 Average tilting angle for three phase fault When setting the required tilting angle in the parameter set of the protection the maximum angle calculated for the rated power can be selected In case of moderate power transfer the algorithm proportionally decreases in 3 steps the actual tilting angle For reverse power direction however the slope of the X characteristic line is positive increasing the operating area of the impedance plane VERSION 1 1 39 43 IED EP Setting guide for the distance protection function 2 3 Influence of asymmetrical faults This chapter discusses a single phase to ground fault to find general conclusions 2 3 1 Modeling a the pre fault component The pre fault power transfer does not depend on the type of fault Consequently the first component of the superposition is the same as described in Chapter 2 1 1 2 3 2 Modeling a single phase to ground fault component The schema for calculation of the second component of the superposition is shown in Figure 2 8 RF Zso lFso Zi ZRO a gt i bos RF i Zs1 lFsi Z ZRI fe a i FS1 Zs2 lFs2 Z ZR2 t FS2 Figure 2 8 Model for single phase fault component calculation This model includes the inactivated positive negative and zero sequence
35. ime setting has to be delayed with two selective time steps If the busbar at the far end of the line protected supplies a transformer the second stage of our protection may not overreach the transformer even if the measuring has a positive error Ie Ly Lig e Z second stage impedance setting ZTR impedance of the transformer Zv positive sequence impedance of the line to be protected E the security factor usually 0 15 The parameters to be set are as follows Operation Zone2 Zone2 Start Only PSD Block Z2 one2 X Zone2X Zone2 Xo X1 3X1 Zone2 Ro R1 3R1 Zone2 time delay See the explanation for setting the first stage VERSION 1 1 17 43 IED EP Setting guide for the distance protection function Note In some applications the parameters Zone2 Xo X1 3X1 and Zone2 Ro R1 38R1 is considered to be equal to those of the Zone1 In this case this parameter cannot be seen in the group of parameters for the second zone The time delay of the second stage is to be set in milliseconds the value should be usually one selective time step If however the far away line is too short it is possible that the second stage of our protection intersects the second stage of the far away line distance protection characteristics In this case the time setting is delayed with two selective time steps Figure 1 5 Distortion caused by power supply at the far line end If a fault occurs on a next outgoing line Figure 1
36. le of the polygon characteristic on the impedance plane DIS21_Cut_IPar_ Zone Reduct Angle deg O 40 1 0 Definition of the load angle of the polygon characteristic DIS21_LdAng_ Par__ Load Angle deg 0 45 1 30 Definition of the line angle Definition of the line angle SS O DIS21_LinAng_IPar_ Line Angle deg 45 9 1 75 Zone Reduct Angle parameter is valid for Zone 1 only Table 1 4 Integer parameters for the POLY logic Timer parameters The timer parameters together with the basic zone settings in Table 1 3 serve selectivity of the whole protection system These setting values must be coordinated with all other protection settings of the system Usually the operation in zone 1 has no additional time delay Zone1 Time Delay is set to 0 Between the subsequent time delay setting values the difference is the selective time step For these values please check the practice of the application Parameter name Title Unit Min Max Time delay for the zones individually Delay Delay Delay Delay Table 1 5 Timer parameters of the distance protection function 1 1 1 Setting calculation 1 1 1 1 Setting the first impedance stage The role of the first impedance stage is usually to protect the most of the line or cable The first stage is not allowed to operate together with the protections located on the outgoing lines of the far end bus bar even if the protection has positiv
37. meter name Title Dim Min Max__ Default DIS21_Lgth_FPar_ Line Length DIS21_LReact_FPar_ Table 1 13 The floating point parameters 1 5 2 Setting Example for setting the line data For the setting procedure the following data are necessary Data 120 kV overhead line length length 40 km per unit positive sequence reactance x1 0 41 Q km voltage transformer turns ratio au 120 kV 0 1 kV current transformer turns ratio ai 600A 5A Calculation Line Length Set Line Length 40 km Line Reactance The primary reactance to be set Xprim length x1 40km 0 41 Q km 16 4 Q Transformed to secondary value Xsecond ai au Xprim 600 5 120 0 1 16 4 Q 1 64 Q The value to be set Line Reactance Xsecond 1 64 Q VERSION 1 1 30 43 IED EP Setting guide for the distance protection function 1 6 The high speed overcurrent protection function with switch onto fault logic IHSOC SOTF The switch onto fault protection function can generate an immediate trip command if the function is enabled and switch onto fault condition is detected The condition of the operation can be the starting signal of any distance protection zone as it is selected by a dedicated parameter or it can be the operation of the high speed overcurrent protection function The high speed overcurrent protection function operates if a sampled value of the phase current is above the setting value 1 6 1 The parameters for
38. n in case of swings This function can also generate a trip command if the system operates out of step See Figure 1 12 1 4 1 The parameters for power swing detection PSD Xinner Stable swing Stable swing Out of Step PSD Rinner R Load Load Angle Ratio of the outer characteristics related to the inner one is set by PSD R_out R_in PSD X_out X_in The load encroachment setting for the polygon inside is the same as for the distance characteristic R Load Load Angle The polygon outside can be calculated by shifting the load encroachment points parallel to the R axis by the ratio PSD R_out R_in Figure 1 12 Characteristics of the power swing detection function The parameters of the power swing detection function are explained in the following tables Enumerated parameters Parameter name Title Selection range Parameters for power swing detection with out of step detection concerning the number of the involved phases DIS21 PSD EPar_ ne Off 1 out of 3 2 out of 3 3 out of 3 Parameter enabling out of step function Oper pise1_outePa PR Toon Table 1 8 The enumerated parameters of the power swing detection function VERSION 1 1 26 43 IED EP Setting guide for the distance protection function Boolean parameters for the individual zones to be blocked by the Power Swing Detection PSD function Parameter name Title Default Explanation DIS21_PSDBIki_BPar_ PSD Block Z1 oO
39. ncing factors can also be evaluated To derive the information for practical purposes a software is prepared for fault simulation The diagrams published in this description are the results calculated by this simulation software VERSION 1 1 34 43 IED EP Setting guide for the distance protection function 2 1 1 Model of the pre fault power transfer The model with the parameters is shown in Figure 2 1 S R Zs Z R jX ZR Us Uel Ur Ue Figure 2 1 Model of the pre fault power transfer In this model the reference voltage is the voltage of the R receiving end of the protected line Here ny Uy y3 This R point will be the fault location The protection is located at the S sending line end In the pre fault steady state the power transfer can be calculated using the following simplified formula U2 sin f P x Note When calculating with line to line voltages the power is the three phase power substituting phase to ground voltages the single phase power is calculated The approximation of this formula is neglecting the power loss of the line but this approximation is acceptable The X reactance is measured between two points where the voltage angle difference between them is 6 In some calculation these two points are the internal points of the equivalent Thevenin generators In this application however these points are the R and S ends of the line the X reactance is consequently
40. ndividual zones of the distance protection function can be blocked by user defined signals These signals are connected in the graphic logic editor to the Z_Blk inputs of the distance protection function blocks The individual signals can be edited by the user according to special requirements Block PSD The distance protection function includes the embedded function for power swing detection The role of this embedded function block is among others to block the trip command if the measured impedance is within the characteristic of the distance protection not because of fault but due to power swings The operation of this embedded function can be blocked with this input signal The conditions for blocking can be edited by the user using the graphic logic editor of the EuroCap configuration software SOTF COND The distance protection function needs to decide the direction of the fault This decision is based on the angle between the voltage and the current In case of close up faults however the voltage of the faulty loop is near zero it is not sufficient for a directional decision If there are no healthy phases then the voltage samples stored in the memory are applied to decide if the fault is forward or reverse If the protected object is energized the close command for the circuit breaker is received in dead condition This means that the voltage samples stored in the memory have zero values In this case the deci
41. network equivalents in serial connection via RF fault resistance Based on this schema the procedure of the calculation is as follows e Calculate the resulting impedances of the symmetrical component networks e Calculate the positive negative and zero sequence current component on the fault location e Calculate the component currents at the relay location e Calculate the component voltages at the relay location e Calculate the phase currents at the relay location e Calculate the phase voltages at the relay location 2 3 3 The superposition The superposition means in this case adding the pre fault voltages and currents and the single phase to ground fault voltages and currents at the relay location VERSION 1 1 40 43 IED EP Setting guide for the distance protection function 2 3 4 Impedance calculation In the formula for impedance calculation in the phase to ground fault loop the superposed voltage and current is substituted including the zero sequence current compensation to calculate the fault impedance 2 4 Calculation example The example below shows the method of calculation for a phase to ground fault The data of the network correspond to a 400 kV transmission line with the modification that the zero sequence impedances are supposed to be identical with the positive sequence impedances These can be identified on the screenshot of the simulation software in Figure 2 9 The screenshot shows that the angle betwe
42. o phase angle Because of the mentioned effects the characteristics must be widened in R direction The following facts however contradict this requirement The role of the R setting is to exclude the calculated impedance in case of high load of the line The small normal impedance during heavy load is not allowed to start the protection see the setting of the load by R Load and Load Angle explained below The unwanted operation during power swings without fault on the protected line has to be avoided if possible See the power swing setting explained below In case of a fault during heavy load the impedance calculated for the healthy phase s approaches the borders of the characteristics The phase selectivity requires a proper R setting value which excludes these impedance values Because of the contradiction of the requirements an engineering compromise has to be applied the setting must be selected based on experiences For example in case of a 120 kV transmission line the compromise Zone 1 R Zone1 X can be an adequate setting The primary value 14 26 Q can include the 40 km 0 056 km 1 0 15 1 95 Q resistance of the line arc resistance earth resistance as well If needed this value can be corrected according to the experience The value of parameter Zone 1R is the same as that of parameter Zone 1X secondary values Zone1 R Zonel X 1 426 Q The influence of this parameter is to set the slo
43. ortion LineR1 Io Line x1 oats 25 004639 Line x0 4 E o Sside A aj Ssidext hg Sside RO al 5 side x0 4 w S z ah 2 R side Al lt ae Reidext fis ah aS r 10 jlm 4065354 E m m 230 94010 DD Ep 09 29451 3 00463 0 3021 13 6086 14 3206 3 4265 1 1576 7 ow 13 4762 4 Fie 25 004635 2635050 osn aoa 29401 25004635 EAN foso zas pasz fesses e2 e731 14 1231 R side RO a R side xO 4 wj umg ajo a00 PIM 4 995 UIFPrat 93 4933 FFrat 0 7510 yee a ag Prot r 8204 54 3000 F Theta 26 7911 a m gt Figure 2 10 Screenshot of the simulation software for phase to ground fault VERSION 1 1 42 43 IED EP Setting guide for the distance protection function When changing other parameters in the simulation the calculation seems to be more sensitive As an example the short circuit power at the far line end R side has considerable influence on the results See Figure 2 11 These parameters are results of a network reduction they include the effect of large number of network components and the network configuration Z1F_R distortion Line R1 al tol Line x1 a gt 25 004639 Line RO al m Line i a wf Sside R aj Ssidext 25 004639 Seide AO al m 5 side XO a 26365090 Z n 230 94010 E on 209 29491 97 616455 J a ere 3 90
44. otection can be disabled Off Example when the selection is 3 out of 3 then all three phase to ground measuring loop is required to detect power swing to block the distance protection Oper OutOfStep The out of step detection is a by product of the function If the power swing is not asymptotic to a final load angle but the voltage on one end of the protected line continuously revolves as VERSION 1 1 27 43 IED EP Setting guide for the distance protection function compared to the voltage at the other end then this function generates a status signal This signal can be enabled On or disabled Off using this parameter PSD Block Z1 If this Boolean parameter is set to logic TRUE 1 then the detected power swing blocks the trip command of Zone NO SD Block Z SD Block Z SD Block Z SD Block Z These parameters have the same effect to higher zones as the parameter PSD block Z1 to Zone 1 Note Consider that higher zones have usually high time delay setting 500 2500 ms The slowest power swing in a stable network is not lower than 2 Hz It means that the impedance within 500 ms performs a whole period of the swing consequently the trajectory of the impedance leaves the impedance zone again the timer of the impedance zone cannot reach the tripping state Consequently these zones need not be involved in power swing blocking 5 ee D ai Ql PSD Xinner PSD Rinner These parameters define characteri
45. pe of the rightmost line of the impedance characteristic as it is shown in Figure 1 1 Usually it is set according to the given data of the protected line Line Angle ArcTan x1 r1 Using the data given for the 120 kV line per unit positive sequence resistance 0 12 Q km per unit positive sequence reactance 0 41 Q km Line Angle ArcTan 0 41 0 12 73 69 The setting een Ine Angle k VERSION 1 1 10 43 IED EP Setting guide for the distance protection function NOTE1 The line angle intersects the point of the horizontal line of the distance protection See Zone1 X setting where the Zone Reduction Angle parameter starts to modify the shape of the characteristic Related to the setting of the parameter Zone Reduction Angle see the consideration in Appendix below NOTE2 To cover better the increased measured resistance in case of faults near to the far line end this parameter can also be set to a lower value Angle 4th Quad Slope of the characteristics border line a arctg X R in the negative reactance area see Figure 1 1 When setting this parameter the following considerations are to be made The principal border of the possible impedance area is the R axis since negative reactance Is not possible in case of fault on the line The impedance is on the R axis when the fault is exactly at the current transformer and the fault resistance is measured The characteristics with safety margin must include
46. sbar fault Since this stage must detect close in faults as the busbar fault the impedance setting must be appropriately small In this role the impedance setting of the reverse stage can be safely smaller than the setting of the protection for the shortest line VERSION 1 1 19 43 IED EP Setting guide for the distance protection function 1 2 Binary signals influencing the operation of the distance protection function 1 2 1 Binary inputs of the distance function block The binary inputs of the distance protection function block are signals influencing the operation These signals are the results of the logic schema graphically edited by the user Binary input signals Signal title Explanation Blocking signal due to error in the voltage DIS21_Z1Blk_GrO_ Block Z1 Blocking of Zone 1 DIS21_Z2Blk_GrO_ Block Z2 Blocking of Zone 2 DIS21_Z4Blk_GrO_ DIS21_Z5Blk_GrO_ Block Z5 DIS21_PSDBlk_GrO_ DIS21_ SOTFCond GrO_ SOTF COND aie a indicating switching onto fault Table 1 6 Binary input signals influencing the operation of the distance protection function block Block from VTS If there is no voltage for impedance calculation then the distance protection function must be blocked The blocking signal can be generated from e the auxiliary contact of the miniature circuit breaker in the voltage transformer secondary circuit or e the voltage transformer supervision VTS function block The application of the auxiliary contact of the
47. sion on the trip command is based on the programming of the protection function for the switch onto fault condition This switch onto fault detection function prepares the conditions for the subsequent decision See the details in the manual Switch onto fault preparation function block description The manual close command is an input binary signal The drop off of the output signal ManSOTFE is delayed by a timer with timing set by the user VERSION 1 1 22 43 IED EP Setting guide for the distance protection function The application of this input is shown in Figure 1 9 Autos OTF Bin sos ManSiTrF Figure 1 9 Example Application of the SOTFCond function block Detail VERSION 1 1 23 43 IED EP Setting guide for the distance protection function 1 3 The current conditions of the distance protection function The distance protection function can operate only if the current is sufficient for impedance calculation Additionally a phase to ground fault is detected only if there is sufficient zero sequence current The setting values in this chapter support these preliminary decisions 1 3 1 The parameters of the current condition Integer parameters Parameter name Title Unit_ Min Max__ Step _ Default Definition of minimal current enabling impedance calculation DIS21_Imin_IPar___ IPh Base Sens Definition of zero sequence current characteristic enabling impedance calculation in phase to ear
48. stic of power swing detection See Figure 1 12 The required setting of these parameters is in close relationship with the selection PDS Block_x These values should be set higher than the setting of the selected impedance zones Example if the Zone 3 has the highest impedance setting among the zones to be blocked by the power swing then the recommended setting Is PSD Xinner gt kx Zone3 X PSD Rinner gt kr Zone3 R Where Zones X is the X setting for Zone3 Zones R is the R setting for Zone3 kx is a security factor in X direction at least 1 2 kr is a security factor in R direction This factor should be selected high enough to exclude the upper right corner in this example of the Zone 3 distance characteristic PSD Rinner 1 2 Zone3 R Zones X ctg Line Angle 1 2 15 Ohm 10 Ohm ctg 78 21 67 Ohm L 22 Ohm PSD Xinner 1 2 10 Ohm 12 Ohm PSD R_out R_in PSD X_out X_in These two parameters with the parameters PS Rinner and PSD Xinner define an impedance band The time needed for the measured impedance to pass this band is decisive for the power swing detection If this time is short then a fault is detected the trip command may not be blocked If however the time is above the PSD Time Delay setting then power swing is detected the trip command is blocked Consequently these parameters have to be considered together with the parameter PSD Time Delay VERSION 1
49. ted power swing state blocks the trip command VERSION 1 1 16 43 IED EP Setting guide for the distance protection function 1 1 1 2 Setting the second impedance stage The second impedance stage is usually delayed with a selective time step This stage has certainly to operate in case of a fault at a small section on the far end of the line which is not covered by the first stage The operation has to be achieved even if the protection measures with a negative error Zz gt l e Where 2 is the setting of the second impedance stage If the outgoing lines from the far end busbar are protected with distance protection as well then the second stage of our protection may not operate together or instead of the second stage of the protection on the shortest outgoing line No overlapping of the characteristics is allowed even if the far away protection operates with negative measuring error and our protection has a positive measuring error Z jae er ee gt lt Zy l E Z e e e Where zZ setting of the second stage Zv positive sequence impedance of the line to be protected the security factor usually 0 15 Z k setting values of the far away line distance protection ZK positive sequence impedance of the far away line lf the far away line is too short it is possible that the second stage of our protection overlaps the second stage of the following line distance protection To avoid the non selective trip the t
50. th loops DIS21_loBase_ Par_ IRes Base Sens DIS21_loBias_ Par_ Table 1 7 Integer parameters for the current conditions module The current is considered to be sufficient for impedance calculation if it is above the level set by parameter IPh Base Sens To decide the presence or absence of the zero sequence current biased characteristics are applied see Figure 1 10 The minimal setting residual current IRes Base Sens and a percentage biasing IRes Bias must be set The biasing is applied for the detection of residual current in the case of increased phase currents 3lo In 100 IResBias Ilmax In IRes Base Sens Imax In Max IL1 IL2 IL3 In Figure 1 10 Percentage characteristic for earth fault detection 1 3 2 Setting the zero sequence current detection The zero sequence current detection is needed to separate earth faults and faults without earth contact This separation prevents for example that in case of close in A N phase to earth fault the measured impedance in the phase to phase loops CA or AB could disturb correct decision If considerable zero sequence current is detected then the results calculated for phase to phase loops are not taken into consideration Another example can be a fault between phases B and C when small impedance is detected in phase to earth loops B N and C N as well but in case of BC fault there is no zero sequence current so the measured values for phase to earth loops can be exclud
51. the reactance of the line Another approximation can be to consider the magnitude f the voltages at both line ends to be the same Consequently the power transfer is determined by the angle only When substituting a given power the required angle is B arcsin PX 73 If the reference voltage is the R side voltage then the voltage at the S line end this is the pre fault voltage at the relay location is Us Uel At this location the pre fault current is 7 UEF 1 s z VERSION 1 1 35 43 IED EP Setting guide for the distance protection function 2 1 2 Modeling a three phase fault component For the simple explanation let us start with a three phase fault The second component of the superposition is calculated using the schema of Figure 2 2 Figure 2 2 Model for three phase fault component calculation seen from the fault location the resulting impedance of the network is 7 Cs Z ZR gt editia The current at the fault location is fj R Ip g The fault current component at the relay is calculated by current division les i PZo Z Zpg The fault voltage component at the relay location is Urs 0 Z5 175 2 1 3 The superposition for three phase fault With summation of the two components calculated above the voltage and the current measured by the relay are Urprot Us Urs leprot ls Irs 2 1 4 Impedance calculation It is well known that in c
52. this measured point The power supply from the far end of the line can distort the voltage of the fault resistance The impedance is calculated with the measured Ir current and the Up voltage at the relay location The Ur voltage includes the voltage drop on the fault resistance too If before the fault there was a heavy power transfer on the line this voltage drop caused by the far end equivalent voltage source has a different vector position than the voltage drop caused by the voltage source at the relay location The voltage on the resistance can have a considerable phase shift In case of unfavorable direction it can turn the measured impedance point out of the characteristics The protection against this effect is the opening of the inclination of the characteristics In case of a close in fault the voltage can have a very small value which cannot be sufficient when calculating the fault direction In this case the voltage values stored in the memory are applied to calculate the direction During a fault the power flow can change largely as compared to the flow during normal operation of the network and the voltage during a fault is phase shifted as compared to the healthy voltage This phase shift depends on the impedance and on the power flow To decide a correct direction it is useful to open the inclination of the characteristic line Due to the inaccuracy of the algorithm the measuring errors caused by the short circuit
53. ve power only Based on the supposed maximum current or thermal load limit in overload operation the load resistance can be calculated 2 R Cr ee Cee load X V3 PER STA where loper max is the highest possible overload current Soper max is the thermal load limit three phase power This consideration is especially important in high voltage systems For the 120 kV example above the thermal load limit of the line is Soper max 11 0 MVA The calculated resistance in case of max load is R Ce a 120kV oad S 110MVA oper max 130Q primary value As compared with the proposed Zone 1 R setting 14 26 Q this results 130 Q 14 26 Q 0O 9 times margin Consequently in case of a relatively long 120 kV line the load has no influence on the setting of the characteristic parameters This primary resistance 130 Q is to be calculated to the secondary side of the measuring transformers R load Second ai au R toad prim 600 5 120 0 1 130 Q 13 Q This setting may influence the shape of the characteristic in higher zones and the shape of the characteristic for power swing detection For a 200 km long 400 kV line however the proposed setting is Zone 1 R Zone 1 X 200 km 0 32 O km 1 0 15 55 65 Q U ine to tine ried 400kV E S 1200MVA oper max R 133Q primary value 133 QO 55 65 Q O 2 3 times margin If large Zone 1 R setting value
54. zones one by one or setting the direction e Forward the orientation of the polygon is according to Figure 1 1 e Backward the orientation of the polygon is according to Figure 1 2 e NonDirectional the extended polygon is according to Figure 1 3 NOTE Zone 1 cannot be NonDirectional It is the free user s choice to select the required directionality Selection range Default Parameters to select directionality of the individual zones DIS21_Z1_EPar_ Operation Zone1 Off Forward Backward Off Forward Backward DIS21_Z2 EPar_ Operation Zone2 NonDirectional Off Forward Backward DIS21_Z3_EPar_ Operation Zone3 NonDirectional Forward l Off Forward Backward DIS21_Z4 EPar_ Operation Zone4 NonDirectional Forward Off Forward Backward DIS21_Z5 EPar_ Operation Zone5 NonDireciional Backward Table 1 1 Enumerated parameters for the POLY logic Figure 1 2 The polygon characteristics of the distance protection function with Backward setting Example Zone1 VERSION 1 1 5 43 IED EP Setting guide for the distance protection function Figure 1 3 The polygon characteristics of the distance protection function Zones 2 5 with NonDirctional setting Boolean parameters for the individual zones are listed in Table 1 2 These parameters define if the operation of the function in the zones generate trip command 0 or indicate starting only 1 The usual setting is the de
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