Surface charge accumulation subjected to direct current (DC) voltages poses hazardous effects on the surface insulation performance of the involved insulators. It is of great significance to investigate surface charge regulation methods applicable to industrialized spacers. In this study, we propose a graded conductivity coating method, with excellent adhesion strength consisting of TiO₂/epoxy composites with different TiO₂ contents, realizing a gradually decreased conductivity distribution on the spacer surface from high voltage (HV) to grounded (GND) electrodes. Surface charging behavior and flashover performance under DC voltages on this kind of spacer is obtained. A simulation model for surface charge computation is constructed for the sake of better understanding the surface charging mechanism on spacers with graded conductivity coating. The results indicate that the randomly distributed surface charges are obviously suppressed by this coating manner and the ring-shaped homo-charges adjacent to HV and GND electrode dominate surface charge patterns. The main cause lies in the fact that surface charge dominant mechanism changes from the bulk conductivity model to the surface conductivity model, where surface leakage current becomes the primary sources of surface charges, with the increase in coating conductivity. DC flashover performance is enhanced as well due to the improvement of surface charge accumulation and electric field distribution. This study supplies an important reference for designing DC gas insulated transmission line spacers of high reliability as well as inspires novel ideas in surface charge regulation.

承受直流 (DC) 电压的表面电荷积累会对相关绝缘体的表面绝缘性能产生有害影响。研究适用于工业化隔离物的表面电荷调控方法具有重要意义。在这项研究中，我们提出了一种由TiO ₂ /环氧树脂复合材料与不同TiO ₂组成的具有优异附着力的梯度导电涂层方法。内容，实现从高压（HV）到接地（GND）电极的间隔表面上的电导率分布逐渐降低。获得了这种隔板在直流电压下的表面充电行为和闪络性能。为了更好地理解具有梯度导电涂层的隔板的表面充电机制，构建了表面电荷计算的模拟模型。结果表明，这种涂覆方式明显抑制了随机分布的表面电荷，并且与 HV 和 GND 电极相邻的环形同电荷在表面电荷模式中占主导地位。主要原因在于表面电荷主导机制从体电导模型转变为表面电导模型，随着涂层电导率的增加，表面漏电流成为表面电荷的主要来源。由于表面电荷积累和电场分布的改善，直流闪络性能也得到了增强。该研究为设计高可靠性直流气体绝缘输电线路间隔器提供了重要参考，并激发了表面电荷调节的新思路。