In this article, the surface charge characteristics of the direct current gas-insulated transmission lines (DC-GIL) insulator under thermal–electric coupled fields are investigated. A horizontally installed GIL with a basin-type insulator is employed. The 3-D charge distribution under different ambient temperatures, load currents, and gas pressures is obtained based on the finite-element method. It is found that the charge density increases with increasing ambient temperature since the bulk conduction is promoted due to the increasing insulator temperature. At lower ambient temperature, the surface charge distribution shows a more obvious difference in different radial directions along the insulator due to the increasing difference in electric conductivity in different directions. With increasing load current, the charge density increases, and the difference in charge density in different radial directions becomes more obvious. The charge density increases with increasing gas pressure although the temperature decreases, which is attributed to the domination of decreasing ion mobility over decreasing bulk conduction. It can be concluded that attention should be paid to these conditions when dealing with the insulation property of DC-GIL considering the effect of thermal gradient on the charge accumulation. Besides, simulation based on a 3-D model is necessary, especially for horizontal GILs.

中文翻译：

---

多物理场耦合场下 DC-GIL 绝缘体的表面电荷特性：环境温度、负载电流和气体压力的影响

本文研究了热电耦合场下直流气体绝缘传输线 (DC-GIL) 绝缘体的表面电荷特性。采用带有盆式绝缘子的水平安装 GIL。基于有限元法获得了不同环境温度、负载电流和气压下的3-D电荷分布。发现电荷密度随着环境温度的增加而增加，因为绝缘体温度的增加促进了体传导。在较低的环境温度下，由于不同方向的电导率差异增加，沿绝缘体的不同径向方向的表面电荷分布表现出更明显的差异。随着负载电流的增加，电荷密度增加，并且不同径向的电荷密度差异更加明显。尽管温度降低，但电荷密度随着气体压力的增加而增加，这归因于降低离子迁移率对降低体导电率的支配。可以得出结论，考虑到热梯度对电荷积累的影响，在处理 DC-GIL 的绝缘特性时应注意这些条件。此外，基于 3-D 模型的仿真是必要的，特别是对于水平 GIL。可以得出结论，考虑到热梯度对电荷积累的影响，在处理 DC-GIL 的绝缘特性时应注意这些条件。此外，基于 3-D 模型的仿真是必要的，特别是对于水平 GIL。可以得出结论，考虑到热梯度对电荷积累的影响，在处理 DC-GIL 的绝缘特性时应注意这些条件。此外，基于 3-D 模型的仿真是必要的，特别是对于水平 GIL。