Purpose/Aim
In order to promote the application and development of DC GIL transmission lines, there is an urgent need to clarify the mechanism of charge accumulation on the surface of DC GIL. The current experimental studies are mostly based on the resultant experimental phenomena to infer the properties of surface charge accumulation, but it is difficult to analyze the underlying process evolution mechanism in depth. At the same time, most of the related simulation studies are conducted using a two-dimensional axisymmetric geometric model, and the simulation results with missing geometric dimensions are difficult to provide a deeper mechanistic explanation of the corresponding experimental phenomena.
Experimental/Modeling methods
In this paper, a three-dimensional time-varying model of charge accumulation on the surface of DC GIL basin insulator is constructed to calculate the charge accumulation model for different solid intrinsic conductivities (6×10^-17S/m, 6×10^-15S/m and 8×10^-14S/m, respectively); in addition, the distance between the upper and lower surface ground of the basin insulator in the charge accumulation model is changed and calculated separately.
Results/discussion
The surface charge accumulation processes of gas-side dominant and solid-side dominant are completely restored by the simulation calculation results in three-dimensional view, and the evolution characteristics of surface charge accumulation in two dominant accumulation modes under ideal conditions are summarized and analyzed separately. In addition, the coupling relationship between electric field-surface charge during charge accumulation was investigated by comparing and summarizing the charge accumulation characteristics of insulators with different thicknesses on both sides
Conclusions
In the charge accumulation process dominated by the gas side, the increase of insulator thickness decreases the effective rate of surface charge accumulation and the surface charge density at the stable moment is smaller due to the influence of space charge field distortion effect in the whole insulator surface charge accumulation process.
 

Surface charge, charge accumulation, numerical simulation, charge behavior, insulator