VFTO inhibitory effect analysis of overhead line in GIS substation

In order to suppress the very fast transient overvoltage( VFTO) caused by switching operation in GIS substation,a simulation model based on electromagnetic transient simulation software ATP-EMTP was built,and a VFTO suppression method which used overhead line to connect GIS output bus bushing and main transformer was also proposed. Owing to the larger geometrical inductance in overhead line per unit length and the corona of overhead line,VFTO amplitude and wave-head steepness were suppressed,and the safe operation of GIS substation was guaranteed. Simulation results showed that,with about 20 m overhead line,the VFTO wave-head steepness could be suppressed in the allowed range. The suppression method has a great practical application value.