110 kV覆雪绝缘子串电场有限元仿真分析

近年来,我国内陆重污区输电线路在冬季频发短时积污雪而引起的快速污雪闪。快速污雪闪相比于传统污闪具有以下显著特点:一是地域性,快速污雪闪多发生在内陆重工业污染地区久旱之后的降雨雪过程;二是短时性,绝缘子在短时间内快速受潮且积污严重湿润,其污秽条件与受潮条件几乎是同时具备。为了研究覆污雪对输电线路外绝缘电气性能的影响,对覆雪110 kV绝缘子串进行了三维建模与电场仿真研究。结果表明,覆雪会畸变绝缘子串电位分布,导致导线侧与杆塔侧绝缘子分担电压显著提升;当绝缘子表面严重积雪并形成雪柱时,绝缘子串有效爬电距离被短接,污雪柱之间空气间隙电场畸变严重,电场增强约27.5倍,易形成"污雪柱-空气间隙-污雪柱"放电通道,从而引起绝缘子串闪络。

Finite Element Simulation of Electric Field of 110 kV Snow-covered Insulators String

Recently,more and more attention has been drawn in fast dirty snow flashover occurred in power system.The differences between dirty snow flashover and pollution flashover are in two aspects:①fast-dirty-snow flashover mostly occurred in the heavily polluted region.②the pollution accumulation process and wetting process of fast-dirtysnow flashover are occurred at the same time.In order to analyze the influence of snow on the electric insulation performance of insulator string,the snow-covered 110 kV insulator strings are modeled and analyzed by finite element method.The analysis results indicate that snow covered on insulator surface could change the total electric potential distribution of insulator string.The electric potential withstand by wire side insulator and tower side insulator are increased significantly.When insulator surface is covered by heavy snow and dirty snow pillar is formed,the total electric field distribution along the string axis direction will be distorted significantly.The electric field strength of the air gap between the neighboring dirty snow pillars will be distorted and which is 27.5 times than that of the normal value.The creepage distance probably be reduced and the flashover channel between dirty snow pillar and air gap may be formed.