输电线路故障对附近电场分布的影响

Effects of Transmission Line Faults on Electric Field Distribution Nearby

为了研究输电线路故障对附近电场以及物体顶部附近电场分布的影响,基于Ansoft电磁仿真软件,建立具有弧垂的高压交流输电线路模型。对比分析了单相接地故障、两相接地短路故障、两相短路故障、三相短路故障等不同故障类型引起的高压交流输电线路附近电场的畸变。在此基础上构建了含有树木、建筑物的模型,分析各类故障发生后树木、建筑物附近电场强度的变化。结果表明:输电线路上不同的故障所产生的电场特征有着明显的差异,故障后线路附近的最大电场强度不会超过故障前的最大电场强度,且不同类型故障对线路周围的最大电场强度和电场幅值有不同程度的影响,有的故障类型甚至会出现“零点”,验证了利用电场变化诊断高压输电线路运行状态中故障类型的可行性。另外,故障发生后大幅提高了周围树木和建筑物顶部的电场强度,尤其是两相短路故障发生时,树木顶端的最大电场强度接近正常时的3.81倍,建筑物顶部附近的最大电场强度接近正常时的7.15倍,更容易造成电晕放电。研究结果可为今后输电线路的设计、故障诊断以及推进电网绿色发展提供参考。

Based on the electromagnetic simulation software Ansoft,a high-voltage AC transmission line model with sag is established to investigate the effects of transmission line faults on the nearby electric field and the electric field distribution near the top of objects.Through the changes of various faults,the distortions of electric field near the high-voltage AC transmission line caused by single-phase grounding fault,two-phase grounding short-circuit fault,two-phase short-circuit fault,and three-phase short-circuit fault are compared and analyzed.On this basis,a model containing trees and buildings is constructed to analyze the changes of electric field intensity around trees and buildings after various faults occur.The results show that the electric field characteristics generated by different faults on the transmission line are obviously different.The maximum electric field intensity near the line after the faults does not exceed the maximum electric field intensity before the faults;different faults have different degrees of influrnce on the maximum intensity and amplitude of electric field around the line,and some faults even have“zero points”.The feasibility of using the change of the electric field to diagnose operating state of the high-voltage transmission line is verified.In addition,after faults,the electric field intensity surrounding the tops of trees and buildings greatly increases,especially when a two-phase short-circuit fault occurs,the maximum intensity at the top of trees is close to 3.81 times of the normal value,and the maximum intensity near the top of the buildings is close to 7.15 times of the normal one,which is more likely to cause corona discharge.This study may provide reference for transmission line design,fault diagnosis,and green development of power grid in the future.