A Calculation Method of Transient Field under Very Fast Transient Over-voltage in Gas Insulated Substation (GIS)

摘要

This paper presents a calculation method for the analysis of transient fields under very fast transient over-voltages (VFTO) in gas insulated substation (GIS). Differential equations of transient fields are established, in which relative permittivity expression ε~* considering relaxation polarization is deduced. Discrete Fourier Transform (DFT) is introduced to decompound very fast transient over-voltage (VFTO) caused by disconnector switching offloaded short bus bar in GIS. Three main frequency components are obtained, which are regarded as boundary excitation. As an example, a typical spacer of GIS is calculated based on this method. Some distinguishing features of the transient field are also discussed.