Surface charge accumulation is the potential criminal for surface insulation failure on spacers under direct current (DC) voltages. The existence of thermal gradient posing the difficulty of surface charge regulation. This study proposes a temperature-dependent adaptive conductivity coating technique for surppressing surface charge accumulation under electro-thermal coupling field. A two-dimensional axis-symmetrical simulation model regrading surface charge computation is established. The effects of thermal gradients and coating conductivity on surface charge and electric field distribution are investigated. The results show that the thermal gradient increases the bulk conductive current, therefore aggravating surface charge accumulation. The effects of the coating condcutivity on surface charge and electric field contains three stages. The lower coating conductivity leads to aggravated homo-polarity charge accumulation. By increasing the coating conductivity, the surface charge and electric field are significantly suppressed at the obtained optimal conductivity, where the bulk and surface conductive current reach a balance stage. Continuously increasing the coating conductivity results in aggravated hetero-polarity charges. Besides, the increase of thermal gradient to an appropriate extent contributes to the further suppression of surface charge on coated spacers. It is hoped that this study could provide some references for designing highly reliable DC GIL under electro-thermal coupling field.

中文翻译：

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电热耦合场下表面电荷释放和电场控制的温度依赖性自适应导电涂层

表面电荷积累是直流 (DC) 电压下垫片表面绝缘失效的潜在罪魁祸首。热梯度的存在给表面电荷调节带来了困难。本研究提出了一种与温度相关的自适应电导率涂层技术，用于抑制电热耦合场下的表面电荷积累。建立了重新分级表面电荷计算的二维轴对称仿真模型。研究了热梯度和涂层电导率对表面电荷和电场分布的影响。结果表明，热梯度增加了体传导电流，从而加剧了表面电荷积累。涂层电导率对表面电荷和电场的影响包含三个阶段。较低的涂层电导率导致同极性电荷积累加剧。通过提高涂层电导率，表面电荷和电场在获得的最佳电导率下被显着抑制，其中体传导电流和表面传导电流达到平衡阶段。不断增加涂层电导率会导致异极性电荷加剧。此外，适当增加热梯度也有助于进一步抑制涂覆隔离物的表面电荷。希望本研究能够为电热耦合场下高可靠直流GIL的设计提供参考。