Lightning overvoltage studies of Siahbishe 400 kV Gas Insulated Substation

Lightning surge overvoltages are generally related to two cases, direct lightning stroke and back-flashovers. Lightning overvoltage waves travel on the transmission line and then enter a substation. High voltage equipment in a substation can be affected by transient overvoltage. This paper investigates the influences of lightning surge with fast front wave on Siahbishe 400 kV Gas Insulated Substation (GIS) located in the north of Iran. The fast transient overvoltages induced in major parts of GIS are investigated due to the first and subsequent direct lightning strokes and back-flashovers. We also show the relationship between the lightning surge current and the overvoltage induced at the entrance of the substation. In addition, the proper arc distance value for 400 kV transmission line string insulators is obtained.