Surface charge accumulation on the insulator of direct current gas-insulated transmission lines (DC-GILs) under thermal-electric multiphysics fields is investigated using the finite element method (FEM). To obtain the accurate temperature and charge distributions in the horizontally installed gas-insulated transmission lines (GILs) with a basin-type insulator, a three-dimensional (3-D) geometric model is constructed. First, the equations and parameters are optimized to improve the computing efficiency. The thermal gradient (TG) negligibly affects the surface electrical conductivity. The recombination and diffusion terms in the ion transport equation can also be removed. After omitting these terms, the calculation efficiency is improved by approximately 70% without affecting the calculation accuracy. The surface charge density increases under TG but varies slightly in different radial directions along the insulator surface. In contrast, the electric field distribution obviously depends on the radial direction. The calculations confirm that the improved method properly analyzes the surface charge characteristics under thermal-electric fields and can thus evaluate the insulation performance of DC-GILs.

中文翻译：

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多物理场下 DC-GIL 绝缘体的表面电荷特性：3-D 建模

使用有限元法 (FEM) 研究了热电多物理场下直流气体绝缘传输线 (DC-GIL) 绝缘体上的表面电荷积累。为了获得具有盆式绝缘子的水平安装气体绝缘输电线路 (GIL) 中的准确温度和电荷分布，构建了三维 (3-D) 几何模型。首先，优化方程和参数，提高计算效率。热梯度 (TG) 对表面电导率的影响可以忽略不计。离子传输方程中的复合和扩散项也可以去掉。省略这些项后，在不影响计算精度的情况下，计算效率提高了约 70%。表面电荷密度在 TG 下增加，但沿绝缘体表面的不同径向方向略有变化。相反，电场分布明显取决于径向。计算证实，改进的方法可以正确分析热电场下的表面电荷特性，从而可以评估 DC-GIL 的绝缘性能。