Shell circulating current and transient ground potential rise in 220 kV GIS

In recent years, GIS(Gas Insulated Switchgear) become more and more important in the power grid. The distance between GIS shell and its internal conductor is short, which cause a strong electromagnetic coupling between these two parts. A travelling wave will occurred when the GIS isolating switch and circuit breakers are closed or broken down, which will cause a high frequency oscillation electrical signal called VFTO (Very Fast Transient Voltage), and finally lead to GIS shell circulating current and TGPR(Transient Ground Potential Rise). The principle of PEEC method is briefly introduced in this paper, and an equivalent circuit of GIS metal shell, bus conductor and grounding grid is built according to the PEEC method. Based on the model of GIS shell and grounding circulating current, the theoretical calculations of the shell and grounding circulating current are taken by using the ATP-EMTP simulation software. According to the result, the possible influencing factors of shell circulating current and TGPR(Transient Ground Potential Rise) are analyzed, and some reasonable control measures are proposed.