绝缘子不均匀积污成因及其对交流闪络特性的影响

在单一风向的作用下，线路运行绝缘子会呈现背风侧污秽积聚较多的现象，降低其绝缘性能。通过建立三维电场-流场耦合模型，仿真模拟污秽颗粒运动过程，揭示了绝缘子背风侧回流和涡流是造成污秽积聚的主要原因。采用人工涂污法模拟绝缘子表面迎/背风侧不均匀积污，并开展交流闪络试验，研究平均盐密(SDD)、迎风侧与背风侧盐密比(J)和背风侧面积占比(R)对平均闪络电压(U_f)的影响。结果表明，U_f随SDD的增大而降低，随J和R的增大而升高，且J在SDD较低和R较小时对U_f影响更大，R在SDD较低和J较小时对U_f影响更大。通过观测绝缘子闪络过程发现，均匀染污时放电电弧随机发展，而在不均匀染污时电弧总出现在背风侧，且升压过程中泄漏电流幅值较大。

Causes of uneven pollution accumulation on the insulator and its influence on AC flashover characteristics

Under the action of a single wind direction, more contamination accumulates on the leeward side of the insulator in service, which reduces its insulation performance. The movement of charged pollution particle was simulated by establishing a three-dimensional coupling model, revealing that the backflow and eddy flow on the leeward side of the insulator are the main reasons for pollution accretion. The manual coating method was used to simulate non-uniform pollution on the windward/leeward side, and AC flashover tests were conducted to investigate the effects of average salt density (SDD), salt density ratio (J) between the windward and leeward sides, and leeward area ratio (R) on the average flashover voltage (Uf). The results show that Uf decreases with the increase of SDD, and increases with increasing J and R. Moreover, J has a stronger impact on Uf under the small values of SDD and R. While R imposes a greater effect on Uf when SDD and J are low. By observing the flashover process of polluted insulator, it was found that the arc develops randomly when uniformly polluted, while the arc always propagates along the leeward side under non-uniform pollution, and the amplitude of the leakage current is larger during the voltage increment.