Study on Charge Accumulation Characteristics of Tri-post Insulators Under Temperature Gradient Field

The insulator of DC gas-insulated transmission line (DC-GIL) will accumulate surface charge under the action of thermal-electric coupling field, which will cause local electric field distortion and make insulator flashover along the surface. In this paper, the actual GIL model is used for simulation. Based on the 3D horizontally mounted GIL model, the surface charge accumulation characteristics of transient DC GIL tri-post insulators under the action of thermal-electric coupling field are studied by COMSOL finite element simulation software. The results show that the surface charge density and the electric field intensity increase by 168 and 19.37% when the temperature gradient is considered at the same position on the belly of the tri-post insulator. Therefore, the distribution of surface charge and electric field under the action of temperature gradient field should be considered when designing and optimizing GIL tri-post insulators.