复合绝缘子水珠模型的起晕和闪络电压影响因素及机理分析

Influencing Factors and Mechanism Analysis of Corona Onset and Flashover Voltage of Composite Insulator Water Droplet Model

复合绝缘子表面附着的水珠因畸变其电场而引发电晕放电并加速其老化。根据现场绝缘子的水珠分布情况和电场特性,建立了伞裙和芯棒试验和有限元仿真模型,并利用日盲紫外成像仪试验研究了水珠性质对模型起晕和闪络电压的影响;采用强电解质水溶液理论分析了不同NaCl添加量水珠的相对介电常数变化,并在静电场和电流场下研究了模型的电场特性、起晕和闪络电压;研究了水珠数量、体积和位置对模型电场特性的影响。研究结果表明:水珠电导率增大使模型起晕电压提高了14%,而使闪络电压降低了8.4%;水珠个数的增加使最大电场提高了2.5%~40%,随着水珠体积增加,模型起晕和闪络电压分别降低了23%和25%;芯棒和伞裙模型电晕分别起始于水珠边侧和顶部,且前者比后者低32.5%。为现场绝缘子水珠研究提供新的思路。

Water droplets on the composite insulator surface will distort the electric field on the surface so as to cause corona discharge and accelerate aging of the electric field.Based on the distribution of water droplet and characteristic of electric field on the insulator surface,we first built the model of sheath and shed and finite element simulation model.We employed the solar blind ultraviolet imager to study the influence of water droplet characteristic on corona and flashover voltage.Then we applied the theory of strong electrolyte aqueous solution to analyze the variation of the relative dielectric constant of water droplets with different NaCl addition.The electric field characteristics,corona onset and flashover voltage of the model were studied under the assumption of electrostatic and current fields.We finally studied the influence of water droplet number,volume and location on the electric field characteristic.The results show that,with the increasing conductivity,the corona onset voltage increases by 14%while the flashover voltage decreases by 8.4%.The maximum electric field increases by 2.5%~40%with the increase of the number of droplets.As the volume of droplet increases,the corona onset and flashover voltage of the model decrease by 23%and 25%,respectively.The corona of the shed and mandrel model starts at the sides and top of the water droplet,and the former is 32.5%lower than the latter.This paper provides new ideas for the research of insulator water droplets.