Surge Arrester Placement for Substation Lightning Protection. Qianxue Xia

Transcription

1 Surge Arrester Placement for Substation Lightning Protection Qianxue Xia 1

2 Agenda Introduction Modelling Results Conclusions 2

3 Introduction 3

4 Introduction Most utilities install surge arresters at both the entrance of the substation and the terminal of the transformer. Due to the high installation cost of surge arresters, some utilities like Salt River Project (SRP) only install the surge arrester at the transformer side. 4

5 Two major concerns: Critical point Introduction maximum recommended length of the transmission line before an arrester needs to be applied Performance for different surge arrester configurations 5

6 Introduction Definition of critical point Lightning strokes are applied at different distances from the entrance point. The corresponding lightning stroke location of the maximum voltage at the entrance of the substation or the terminal of the transformer is defined as the critical point. X Y Z 6

7 Introduction Four different surge arrester configurations for substation lightning protection are considered: C1: No installed surge arrester on the substation C2: Surge arresters are installed at the entrance of the substation and at the terminal of the transformer respectively. C3: Surge arresters are only mounted at the entrance of the substation; C4: Surge arresters are installed on the terminal of the transformer. 7

8 Modelling 8

9 Modelling Fast front transient model for : a practical SRP kv substation (with real field data) a few spans of the 230kV transmission line This Model is developed using PSCAD SRP denotes Salt River Project which is a utility located in Arizona. 9

10 Modelling Simulation procedures : Step 1. Model 230kV transmission line and the connected substation in PSCAD using the field data. Step 2. Changing the distance from the lightning stroke location to the entrance of the substation. Step 3. repeating step (2) for different protection configurations. X Y Z Peak voltage amplitude (kv) phase A -phase B UY-phase C -phase A -phase B -phase C Distance to Point X (m) (d) C4- One surge arrester on Point Z 10

11 Results 11

12 C2 : surge arresters are installed at both the entrance of the substation and the terminal of the transformer. Direct stroke Phase B is hit by the lightning stroke Voltage (kv) Phase A Phase B Phase C Voltage (kv) Phase A Phase B Phase C Arrester Voltage Energy (kj) Time (µs) Phase A Phase B Phase C (i) Energy (kj) Time (µs) Phas e A Phas e B Phas e C (i) Arrester Energy duties Current (ka) Time ( µs) (ii) Phase A Phase B Phase C Curren t (ka) Time (µs) (ii) Phase A Phase B Phase C Arrester Current Time (µs) (iii) (a) Entrance of the substation Time (µs) (iii) (b) Terminal of the transformer Lightning stroke distance = 20m 12

13 Voltage-distance curves Peak voltage amplitude (kv) Peak voltage amplitude (kv) Critical Point Distance to Point X (m) -phase A -phase B UY -phase C -phase A -phase B -phase C (a) C1-No installed surge arrester UY-phase A -phase B -phase C - phas e A - phas e B UZ- phas e C Distance to Point X (m) (c) C 3- One surge ar rester on P oint Y Peak voltage amplitude (kv) Peak voltage amplitude (kv) Distance to Point X (m) - phas e A - phas e B - phas e C UZ-phase A UZ-phase B -phase C (b) C2- Two surge arrester on both Point Y and Z -phase A -phase B UY-phase C -phase A -phase B -phase C Distance to Point X (m) (d) C4- One surge arrester on Point Z X The voltages on phase A and phase C are far less than the voltage on phase B. Most critical points are the closest point to the line entrance of the substation Y 13 Z

14 U max / BIL (%) U max / BIL (%) CP=920 m 28% 15% CP=160m 183% 70% CP=920mCP=700m 31% 25% 15% 12% CP=20 m 194% 85% CP=840m 27% U A,Y U B,Y U C,Y U A,Z U B,Z U C,Z (a) C1 CP=20 m U A,Y U B,Y U C,Y U A,Z U B,Z U C,Z (c) C3 U max / BIL (%) U max / BIL (%) CP=2 0M 19% 14% 16% 0 Results 73% 79% 19% 12% 16% 12% 71% 70% 15% U A,Y U B,Y U C,Y U A,Z U B, Z U C,Z (b) C2 CP=2 0m 15% U A,Y U B,Y U C,Y U A,Z U B, Z U C,Z (d) C4 Phase A and phase C voltages can only reach up to 31% of the BIL value Without surge arrester, the voltage at the transformer can reach up to 194% of the BIL value. C3 has the highest voltage at the transformer terminal among C2, C3, C4 14

15 Voltage-distance curve for Phase B Peak voltage amplitude (kv) ,800 1,500 1, P 1 P C1 -C1 -C2 -C2 -C3 -C3 -C4 -C Distance to Point X (m) C3: UY < UZ C4: UY > UZ UY - voltage at the entrance of the substation UZ - voltage at the terminal of the transformer C3: Surge arresters are only mounted at the entrance of the substation; C4: Surge arresters are installed on the terminal of the transformer. 15

16 Voltage-distance curve for Phase B Peak voltage amplitude (kv) ,800 1,500 1, P 1 P C1 -C1 -C2 -C2 -C3 -C3 -C4 -C Distance to Point X (m) C3: UY < UZ C4: UY > UZ PP 1 is the point of intersection of UZ C3 aaaaaa UY CCC UY denotes the voltage at the entrance of the substation UZ denotes the voltage at the terminal of the transformer C3: Surge arresters are only mounted at the entrance of the substation; C4: Surge arresters are installed on the terminal of the transformer. 16

17 Voltage-distance curve for Phase B Peak voltage amplitude (kv) ,800 1,500 1, P 1 P C1 -C1 -C2 -C2 -C3 -C3 -C4 -C Distance to Point X (m) C3: UY < UZ C4: UY > UZ PP 1 is the point of intersection of UZ C3 aaaaaa UY CCC PP 2 is the point of intersection of UZ C3 aaaaaa UZ CCC UY denotes the voltage at the entrance of the substation UZ denotes the voltage at the terminal of the transformer C3: Surge arresters are only mounted at the entrance of the substation; C4: Surge arresters are installed on the terminal of the transformer. 17

18 Peak voltage amplitude (kv) 1,800 1,500 1, Voltage-distance curve for Phase B P 1 P C1 -C1 -C2 -C2 -C3 -C3 -C4 -C Distance to Point X (m) C3: Surge arresters are only mounted at the entrance of the substation; C4: Surge arresters are installed on the terminal of the transformer. C3: UY < UZ C4: UY > UZ PP 1 is the point of intersection of UZ C3 aaaaaa UY CCC PP 2 is the point of intersection of UZ C3 aaaaaa UZ CCC UY C4 is always high UY denotes the voltage at the entrance of the substation UZ denotes the voltage at the terminal of the transformer 18

19 Conclusions 19

20 Conclusions The voltage distance curve provides a good visual depiction of the simulation results. For most cases, the overvoltage increases when the distance from the lightning stroke location to the line entrance of the substation decreases. Critical points are typically close to the line entrance of the substation. Installing surge arresters either on the entrance of the substation or at the terminal of the transformer are sufficient for lighting protection Installing surge arrester only at the terminal of the transformer in the SRP kV substation is proved to be both adequate and efficient with respect to the lightning performance. 20

21 Qianxue Xia 21