高压直流复合绝缘子空间电荷积聚的仿真

Simulation of Accumulated Space Charge on HVDC Outdoor Composite Insulators

为了研究户外高压直流复合绝缘子空间电荷的积聚情况,笔者以实际运行中的绝缘子为研究对象,采用有限元分析软件COMSOL,对绝缘子空间电荷分布情况进行仿真研究。由于户外复合绝缘子易于受环境影响而导致表面电导率不均匀,文中引入了表面电流密度这一影响因素,从电磁场基本方程组出发,建立了计算模型。从仿真结果可知,在负极性电压作用下,复合绝缘子在伞裙护套交接处一定范围内电荷积聚量最大,且电荷极性与相邻电极极性一致;当阴极端第1个伞裙表面局部粘附污秽时,第1个伞裙上表层处空间电荷密度增大,下表层处空间电荷密度减小。

To understand the mechanism of space charge accumulation for high-voltage DC outdoor composite insulators, we take the composite insulator in operation as an object to simulate the surface charge distribution on the insulator by using the finite element analysis software COMSOL. Surface conductivity of an outdoor insulator is significantly influenced by local environment, so the surface current density, which is the most important influencing factor for outdoor polymeric insulator, is introduced, and a calculation model is established based on the basic electromagnetic field equation. Simulation results indicate that： the most charge accumulates on a certain area of the interface of umbrella and sheath of the composite insulator, and the charge polarity is the same with that of the adjacent electrode; the charge density on the upper surface of the first umbrella increases while the charge density on the lower surface decreases when the upper surface of the first umbrella at cathode end is partly polluted.