Surge Arrester Placement for Substation Lightning Protection Qianxue Xia qxia11@asu.edu 1
Agenda Introduction Modelling Results Conclusions 2
Introduction 3
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
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
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
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
Modelling 8
Modelling Fast front transient model for : a practical SRP 500-230 kv substation (with real field data) a few spans of the 230kV transmission line 4.6.0. This Model is developed using PSCAD SRP denotes Salt River Project which is a utility located in Arizona. 9
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) 700 500 300 200 100 -phase A -phase B UY-phase C -phase A -phase B -phase C 0 200 800 1000 Distance to Point X (m) (d) C4- One surge arrester on Point Z 10
Results 11
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) 200 0 Phase A Phase B Phase C Voltage (kv) 200 0 Phase A Phase B Phase C Arrester Voltage Energy (kj) 200 0 40 80 120 160 Time (µs) Phase A Phase B Phase C (i) Energy (kj) 200 0 40 80 120 160 Time (µs) Phas e A Phas e B Phas e C (i) Arrester Energy duties Current (ka) 0 18 12 6 0 0 40 80 120 160 Time ( µs) (ii) Phase A Phase B Phase C Curren t (ka) 0 18 12 6 0 0 40 80 120 160 Time (µs) (ii) Phase A Phase B Phase C Arrester Current 0 40 80 120 160 Time (µs) (iii) (a) Entrance of the substation 0 40 80 120 160 Time (µs) (iii) (b) Terminal of the transformer Lightning stroke distance = 20m 12
Voltage-distance curves Peak voltage amplitude (kv) Peak voltage amplitude (kv) 1800 1 1 1200 1000 800 Critical Point 200 0 200 800 1000 800 700 500 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 300 200 100 0 200 800 1000 Distance to Point X (m) (c) C 3- One surge ar rester on P oint Y Peak voltage amplitude (kv) Peak voltage amplitude (kv) 700 500 300 200 100 700 500 300 200 100 0 200 800 1000 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 0 200 800 1000 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
U max / BIL (%) U max / BIL (%) 200 160 120 80 40 0 80 60 40 20 0 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 (%) 80 60 40 20 0 80 60 40 20 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
Voltage-distance curve for Phase B Peak voltage amplitude (kv) 800 700 500 1,800 1,500 1,200 900 P 1 P 2 50 100 150 200 250 300 -C1 -C1 -C2 -C2 -C3 -C3 -C4 -C4 300 0 100 200 300 500 700 800 900 1000 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
Voltage-distance curve for Phase B Peak voltage amplitude (kv) 800 700 500 1,800 1,500 1,200 900 P 1 P 2 50 100 150 200 250 300 -C1 -C1 -C2 -C2 -C3 -C3 -C4 -C4 300 0 100 200 300 500 700 800 900 1000 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
Voltage-distance curve for Phase B Peak voltage amplitude (kv) 800 700 500 1,800 1,500 1,200 900 P 1 P 2 50 100 150 200 250 300 -C1 -C1 -C2 -C2 -C3 -C3 -C4 -C4 300 0 100 200 300 500 700 800 900 1000 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
Peak voltage amplitude (kv) 1,800 1,500 1,200 900 Voltage-distance curve for Phase B 800 700 500 P 1 P 2 50 100 150 200 250 300 -C1 -C1 -C2 -C2 -C3 -C3 -C4 -C4 300 0 100 200 300 500 700 800 900 1000 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
Conclusions 19
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 500-230kV substation is proved to be both adequate and efficient with respect to the lightning performance. 20
Qianxue Xia qxia11@asu.edu 21