Simulation of Short Circuit and Lightning Transients on 110 kv Overhead and Cable Transmission Lines Using ATP-EMTP

Transcription

1 Simulation of Short Circuit and Lightning Transients on 110 kv Overhead and Cable Transmission Lines Using ATP-EMTP Predrag Maric 1, Srete Nikolovski 1, Laszlo Prikler 2 Kneza Trpimira 2B 1 Faculty of Electrical Engineering, Croatia Osijek, Croatia 2 Department of Electrical Engineering, Hungary srete@etfos.hr, pmaric@etfos.hr Műegyetem rkp H-1111 Budapest, Hungary prikler@vmt.bme.hu Abstract This paper presents calculation and simulation of a three phase short circuit, single line to ground fault and lightning stroke transients on a 110 kv cable-overhead transmission line that connects the new 110/20 kv transformer station Djakovo 3 with the existing TS 400/110 kv Ernestinovo and TS 220/110 kv Djakovo. Calculation and simulation of short-circuit transients are made using the EMT DIgSILENT Power Factory module. Simulations of a lightning stroke are compared using the ATP-EMTP software and EMT DIgSILENT module. Using the composite DSL (DIgSILENT Simulation Language) model, the Direct lighting stroke has been represented as the Double-exponential function and the return stroke as the Heidler function. Using the ATP-EMTP model, the lightning stroke has been represented as the Heidler function. Lighting stroke simulations are made with and without the presence of ZnO polymer-housed surge arrester model in both simulation tools. Keywords: Short circuit, lightning stroke, cable, overhead transmission line, simulation, DIgSILENT software, ATP-EMTP software. 1 Introduction A new transformer station 110/20 kv Djakovo 3 has been incorporated in the Slavonian transmission system between the existing TS 400/110 kv Ernestinovo and TS 220/110 kv Djakovo. Conjunction with the 6- phase 110 kv Ernestinovo-Djakovo overhead line is realized with two parallel 110 kv NEXANS type cables lying in the same canal. The DIgSILENT model used in the simulation includes the whole Slavonian transmission system with the newly incorporated facilities, while the ATP-EMTP model includes a detailed overview of new facilities. According to IEC (published in 2001) norm, short-circuit RMS and EMT values have been calculated and simulated on every 10% of length of the considered lines and cables. A lightning stroke has been simulated at the conjunction point of the 6-phase overhead line and two parallel 110 kv cables. 2 DIgSILENT model description Short circuit values and diagrams have been calculated and simulated using the EMT DIgSILENT module, while the lighting stroke has been simulated using the same EMT

2 module incorporating the DSL composite model. 400/110 kv ERNESTINOVO POLE 57 NEW TS 110/20 kv DJAKOVO 3 220/110 kv DJAKOVO Figure 2.1 A new transformer station incorporated in the existing Slavonian transmisson network, one-line diagram in DIgSILENT Direct ligthing stroke has been modeled within the DSL composite model as the Doubleexponential function : I(t)= A ( e -α + e β ) with parameters A=100 ka, α=1500, β= 5 * 10 6 ; and Heidler function I( t) A H ( t, A, A ) B H (1, B, B ) t -t 1 H(1,, ) 2 e t 2 e with parameters A= ka, τ 1 =1,5 μs, τ 2 = 61.7 μs, η = 7.

3 Returning lighting stroke has been modeled as the Heidler function with parameters : A= - 15 ka, τ 1 = 0,5 μs, τ 2 =70 μs, η = 5. Figure 2.2 Double-exponential function used for direct lightning stroke Figure 2.3 Heidler function 8/20 µs used for returning lightning stroke Three 1000 A current sources behind the reactances of 20 mh that represent a lighting stroke reactance are also involved in the DSL model. A ZnO surge arrester is modeled according to manufacturer s documentation: Table 2.1 Technical data for the ZnO arrester Nominal discharge current (IEC) IEEE/ANSI 10 ka peak Classifying current (ANSI/IEEE) 10 ka peak Rated voltage 360 kv Max system voltage 420 kv Line discharge class (IEC) 3

4 Figure 2.4 Manufacturer s ZNO arrester V-I protective characteristic The calculated residual voltage for current impulse 10 ka, 8/20 µs entered in the DIgSILENT surge arrester model is represented in Table 2.2. Table 2.2 The calculated residual voltage for 10 ka, 8/20 µs impulse according to manufacturer s data I [ka] V [kv] I [ka] V [kv] I [ka] V [kv] I [ka] V [kv] I [ka] V [kv] 0,10 176,26 0,40 187,57 0,80 193,22 4,00 212,43 30,00 264,40 0,20 183,06 0,50 189,83 1,00 194,35 7,00 221,46 40,00 277,97 0,30 185,32 0,60 190,96 2,00 203,40 10,00 226,00 50,00 289,26 0,40 187,57 0,70 192,09 3,00 207,92 20,00 248,60 60,00 298,32 The residual voltage of kv for current impulse 10 ka, 8/20 µs is a lighting protective level obtained with this surge arrester. The highest withstanding lightning voltage for the 110 kv facility (according to VDE) is 550 kv, the ratio of the highest withstanding lightning voltage for the 110 kv facility and the residual voltage on the surge arrester is 550 kv/226 kv = 2.43 (>1.4) which provides appropriate overvoltage protection. 3 ATP Model description A more detailed overview of the new facility with the corresponding switching equipment has been modeled in the ATP-EMTP software. The lightning stroke has been modeled as the Heidler function with cable and overhead line parameters frequency dependence appreciation using the JMarti frequency-dependant model. A few overhead line spans nearby the conjunction point with cables are presented in detail from both sides of the 6-phase overhead line including grounding inductances and impulse resistances, as well as tower wave

5 impedances. Figure 3.1 Overhead-cable transmission line in ATP-EMTP - detailed model 4 Simulation results The calculated three phase short-circuit RMS current values along the 110 kv line between the new 110/20 kv transformer station Djakovo 3 and 400/110 kv transformer station Ernestinovo are presented in Table 4.1 and Figure 4.1. Table 4.1 Three phase short-circuit RMS current values along the 110 kv line ''Ernestinovo- Djakovo3'' Line location Sk3'' [MVA] Ik3'' [ka] angle [ ] 10% 3156,36 16,57-80,15 20% 2722,19 14,29-78,72 30% 2443,28 12,82-77,79 Ernestinovo -Djakovo 3 40% 2259,75 11,86-77,16 (pole 57) 50% 2141,19 11,24-76,74 60% 2071,41 10,87-76,47 27,441 km 70% ,72-76,32 80% 2049,68 10,76-76,27 90% 2095,28 11,00-76,33 100% 2182,92 11,46-76,48

6 Figure 4.1 Distribution of 3 phase short-circuit currents along the 110 kv line ''Ernestinovo-Djakovo3'' Single line to ground fault analysis considers calculation and distribution of RMS current values along the 110 kv lines nearby the new facilities, as well as the EMT simulation. The calculated single phase to ground RMS current values along the 110 kv line between the new 110/20 kv transformer station Djakovo 3 and 400/110 kv transformer station Ernestinovo are presented in Table 4.2 and Figure 4.2. Table 4.2 Single phase to ground RMS current values along the 110 kv line ''Ernestinovo- Djakovo3'' Line Ernestinovo location Sk1'' [MVA] Ik1'' [ka] angle [ ] Z0 [Ω] I0 [ka] 10% 916,6 14,43-77,78 3,21 4,81 Djakovo 3 (pole 57) 20% 727,49 11,46-76,62 3,26 3,82 27,441 km 30% 627,51 9,88-76,04 3,32 3,29 40% 572,16 9,01-75,76 3, % 544,38 8,57-75,68 3,49 2,86 60% 537,3 8,46-75,76 3,63 2,82 70% 549,34 8,65-75,99 3,82 2,88 80% 583,2 9,18-76,43 4,13 3,06 90% 647,56 10,2-77,16 4,7 3,4 100% 762, ,4 6,04 4

7 DIgSILENT Figure 4.2 Distribution of single phase to ground fault currents along the 110 kv line Ernestinovo-Djakovo3 The single phase to ground fault with 0 Ω impedance has been initiated at t=100 ms, whereas at t=300 ms the fault has been cleared. Figure 4.3 presents a single phase to ground current diagram at the middle of the 110 kv line ''Ernestinovo-Djakovo 3'' [s] Ernestinovo-stup57: 3*I0 in ka struje_ern_djakovo Date: 4/21/2009 Annex: /1 Figure 4.3 The single phase to ground current diagram at the middle of the 110 kv overhead line ''Ernestinovo-Djakovo 3''

8 DIgSILENT DIgSILENT Voltages on the end terminals of the 110 kv overhead line ''Ernestinovo-Djakovo 3'' follow the current waveforms during the fault. Peak voltage sags values are up to 30 kv [s] Stup 57 DJK: Voltage Phasor, Magnitude in kv [s] Stup 57 ERN: Voltage Phasor, Magnitude in kv naponi2 Date: 4/21/2009 Fig. 4.4 Voltages on the end terminals of the 110 kv overhead line ''Ernestinovo-Djakovo 3'' Annex: /6 The single phase to ground fault current phase A simulated at the middle of the cable from ''Pole 57 Djakovo 3 (section from TS Ernestinovo) is presented in Figure [s] Stup57-Djakovo3-Ern: 3*I0 in ka Ernestinovo_Djakovo3-kabel Date: 4/21/2009 Annex: /5 Figure 4.5 The single phase to ground fault current phase A simulated at the middle of the cable from ''Pole 57 Djakovo 3 (section from TS Ernestinovo)

9 DIgSILENT DIgSILENT The single phase to ground fault peak values simulated at the middle of the cable from ''Pole 57 Djakovo 3 (section from TS Ernestinovo) are approximately 1.5 times the simulated single phase to ground current peak values at the middle of the 110 kv overhead line ''Ernestinovo-Djakovo 3'' due to lower cable direct, inverse and zero component reactances than overhead line reactances. The lightning stroke has been simulated at the conjunction point 110 kv overhead line cable (pole 57) with the ZnO surge arresters modeled on both tower terminals. According to residual voltage-current surge arrester characteristics (Table 2.2), the 50 ka resistive current value has been achieved on the surge arrester electrically closer to the point of lightning stroke, while the 3 ka value has been obtained on the farther tower terminal [s] ZNOodvodnik 1: Current Phasor, Magnitude in ka [s] ZNOodvodnik 2: Current Phasor, Magnitude in ka udar_munje ZNO-2 Date: 5/12/2009 Annex: /3 Figure 4.6 Surge arrester resistive current values on both tower terminals [s] Stup 57 DJK: Voltage Phasor, Magnitude in kv [s] Stup 57 ERN: Voltage Phasor, Magnitude in kv naponi2 Date: 5/12/2009 Figure 4.7 Surge arrester residual voltage on both tower terminals Annex: /2

10 The simulated results differ due to model differences in both simulation tools especially overhead line parameters frequency dependence appreciation using the JMarti frequencydependant model, grounding inductances, tower wave impedances and more accurate tower geometry presentation in the ATP-EMTP model. The complete lightning stroke model has been presented as the Heidler function in ATP- EMTP Figure 4.8. Figure 4.8 The Heidler function as the lightning stroke model in ATP-EMTP Figure 4.9 Voltages on the tower terminals after lighting stroke simulation

11 Figure 4.10 Surge arrester residual voltage- arrester further from the lightning stroke location Figure 4.11 Surge arrester resistive current

12 Figure 4.12 Surge arrester residual voltage- arrester closer to the lightning stroke location Figure 4.13 Voltages on the 110 kv busbars of the new TS 110/20 kv Djakovo 3 after lighting stroke simulation

13 Residual voltage differences on surge arresters closer and further from the lightning stroke location are negligible as expected due to more accurate tower geometry model in ATP- EMTP which is the advantage of this simulation tool. 5. Conclusion The paper presents lightning stroke simulation, as well as calculation of short circuit transients along the 110 kv cable-overhead transmission line. Cable and overhead transmission line has been presented as frequency-dependant model in DIgSILENT and ATP- EMTP software. Lightning stroke model consisted of direct stroke and returning stroke components in DIgSILENT results in somewhat different transient shape than in the ATP- EMPT software where the same model consists only the direct stroke component including grounding inductances and impulse resistances, as well as tower wave impedances in a few spans nearby the conjunction point with cables. In both simulation tools, the ZNO surge arrester has been modeled with related non-linear characteristic. The ATP-EMTP software provides better and more accurate lightning stroke analysis results. References [1] IEC Standard Short-circuit Currents in Three-phase A.C. Systems - Part 0: Calculation of Currents, IEC July 2001 [2] Z. Feizhou, L. Shange A New Function to Represent the Lightning Return-Stroke Currents'', IEEE Transaction on Electromagnetic Compatibility, vol. 44, No.4, Nov [3] ABB document 1HSM en Edition Protection Characteristic of Surge Arrester 110 kv PEXLIM-Q2, ABB, [4] NEXANS High Voltage Cables and Systems Cable data Al 110kV Al-PE sheath A2XS(FL)2Y+ 1x1000RM/95 64/110 (123) kv, Nexans ref.: C