The Simulation Model and Analysis of Transient Grounding Potential Rise in GIS Under VFTO

Abstract

In recent years, gas-insulated substations (GIS) have been widely used in power systems. However, because of its compact structure, very fast transient overvoltage (VFTO) with frequencies up to tens or even hundreds of megabytes can easily occur when switching devices such as disconnectors and circuit breakers are operated. Through research, it has been found that the generation of VFTO can often cause the GIS shell circulation and transient ground potential to rise, resulting in significant losses.This paper takes a GIS test field as the object of analysis and proposes a distribution parameter analysis model for the transient process of such equipmentCby establishing a transient ground network model that takes into account the mutual inductance between grounding bodies, the potential change of the grounding grid and the change of the transient current at the point of entry are analyzed.The results show that the VFTO voltage of the key nodes in the GIS is affected by the external conditions of the GIS equipment. Changing the external conditions of GIS equipment, the GIS shell transient ground potential rise will also change. Based on this characteristic, this article discusses how to suppress transient ground potential rise in GIS.