Analysis of VFTO in 1000kV GIS

With the development of UHV (Ultra High Voltage) transmission technology, GIS(Gas Insulated Substation) is usually used at all levels of substations, but it will produce VFTO (Very Fast Transient Overvoltage)when operating its isolating switch. It has the characteristics of large amplitude, high frequency and fast fluctuation. It is easy to cause safety problems such as electrical insulation breakdown of GIS and related equipment. In this paper, the VFTO generated in the GIS of the 1000kV UHV transmission system is taken as the research object. Aiming at this problem, the two suppression measures including metal oxide surge arrester and parallel brake resistance are analyzed and compared by using ATP-EMTP. The simulation result show that both of these measures can effectively suppress the impact of VFTO on the entire power system.