Calculation of Very Fast Transient Overvoltages in GIS

This paper refers to 500kV gas insulated substation (GIS) of the Tian Huangping pumped storage power station in East China Power System. With the current Electro-magnetic Transient Program (EMTP) in world, we simulate and calculate the very fast transient overvoltages (VFTO) caused by operating of disconnect switch (DS), and the factors that influenced overvoltages. Otherwise we analyze the reason why the discharge counters of surge arrester acted frequently and the harm to transformer done by VFTO.