Investigation of Transient Overvoltages on GIS Busbars and External Enclosures

Fast Front Transient Overvoltages and Very Fast Transient Overvoltages in a 380kV gas-insulated substation (GIS) located in Jeddah City have been studied and analyzed using PSCAD Software. The Gas insulated substation (GIS) components and equipment's inside substation have been modeled using their equivalent circuits and distributed parameter lines that take into account during transients. Two Lighting events leading to the generation of possible Fast Transient Overvoltages are analyzed and discussed: i) Direct Strike, ii) Back Flashover. One switching operation event leading to the generation of possible Very Fast Transient Overvoltages inside GIS is analyzed and discussed: i) disconnector switching of outgoing diameter. Transient ground potential raise has also been investigated. Keywords: Fast Transient Overvoltages, Very Fast Transient Overvoltages, PSCAD softwar