The Influence of Gas Conductivity on the Surface Charge Accumulation Characteristics of DC-GIS/GIL Insulators

Under DC voltage, charges accumulate on the surface of insulators inside gas-insulated switchgears (GIS) and gas-insulated transmission lines (GIL). Therefore, the influence of surface charge needs to be considered when evaluating the insulation characteristics and structural optimization. However, the traditional method of calculating surface charge by ion-flow model (IFM) occupies too much memory and takes a long calculation time, which limits the development of related study. Thus, this paper develops a fixed gas conductivity model (FGCM) based on the IFM. With the gas conductivity at 4×10⁻¹⁹ S/m and based on the basin-type insulator, the calculation results of the FGCM are compared with those of the IFM under various conditions. The results show that the calculation results of the FGCM are in good consistency with the IFM under various conditions such as changing the shape and conductivity of the insulator, changing the applied voltage, considering the temperature gradient and transient simulation. The memory usage of the FGCM is significantly lower than that of the IFM, and the calculation time is reduced by several orders of magnitude. This study can provide guidance for the design and optimization of DC-GIS/GIL insulators.