For a gas‐solid insulation system with direct current (DC) voltage, the surface charge accumulation and decay phenomenon are directly related to the capacitive‐resistive electric field transition process. The accumulated charges will affect the electrical insulation performance of a gas‐solid insulation system, which is a challenge for the development of DC gas‐insulated metal‐enclosed transmission line (GIL) equipment. In this paper, a study of the surface charge accumulation characteristics for a DC GIL insulator in the electric field transition process is presented. The charge accumulation model for the gas‐solid insulation system was established with consideration of the bulk charge conductivity in the solid dielectrics, the ion conductivity in the weakly ionized gas, and the charge conductivity at the interface. A surface potential measurement system was then built. The charge accumulation model was verified by measurements of the surface potential on a cylindrical insulator sample, and the charge accumulation characteristics on the surface of the GIL insulator were investigated. The simulation results indicate that the accumulated homopolar charges led to the decrease of the electric field strength near the conductor by 9.4% and the increase of the electric field strength near the GIL shell by 23.5%. The concave surface of the insulator mostly accumulated heteropolar charges, which led to an increase in the electric field intensity by 5.5%. The transition of the charge accumulation mechanism with the variation of the bulk conductivity was also analyzed. The convex surface of the insulator accumulated homopolar charges, and the concave surface mostly accumulated heteropolar charges when the bulk conductivity was between 10⁻¹⁴ and 10⁻¹⁷ S/m. However, with the further reduction of the bulk conductivity, the mechanism of the charge accumulation gradually became dominated by ion conductivity in the SF₆ gas. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

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高压直流输电GIL绝缘子的表面电荷积累和电容-电阻电场转变特性

对于具有直流（DC）电压的气固绝缘系统，表面电荷的积累和衰减现象与电容-电阻电场的过渡过程直接相关。累积的电荷将影响气固绝缘系统的电绝缘性能，这对于开发DC气体绝缘金属封闭的传输线（GIL）设备是一个挑战。本文提出了一种DC GIL绝缘子在电场过渡过程中表面电荷累积特性的研究。建立了气固绝缘系统的电荷累积模型，其中考虑了固体电介质中的整体电荷电导率，弱电离气体中的离子电导率以及界面处的电荷电导率。然后建立了表面电势测量系统。通过测量圆柱形绝缘子样品上的表面电势来验证电荷积累模型，并研究GIL绝缘子表面上的电荷积累特性。仿真结果表明，累积的同极性电荷导致导体附近的电场强度降低了9.4％，GIL壳附近的电场强度提高了23.5％。绝缘子的凹面大部分积累了异极性电荷，这导致电场强度增加了5.5％。还分析了电荷积累机制随体电导率变化的转变。绝缘子的凸面累积了同极性电荷，^-14和10 ^-17 S / m。但是，随着整体电导率的进一步降低，SF ₆气体中的电荷积累机理逐渐由离子电导率所主导。©2020日本电气工程师学会。由Wiley Periodicals LLC发布。