500 kV输电线路绝缘地线雷电流分布

Lightning Current Distribution of Insulated Ground Wire in 500 kV Transmission Line

对于重覆冰区域的输电线路来说,地线覆冰会严重威胁到线路的安全运行。采用绝缘地线直流融冰的方式是解决架空地线覆冰问题的方法之一。当输电线路发生雷击事故时,直流融冰采用的绝缘地线与杆塔之间的雷电流分布情况决定了杆塔的塔顶电位,影响着杆塔的耐雷水平与线路防雷接地的保护。利用电磁暂态软件EMTP,对杆塔和绝缘地线中的雷电流分布进行了计算分析。计算结果表明,在500 kV输电线路中,雷电流主要通过杆塔流人大地,雷电流的幅值、杆塔档距、接地电阻的大小、地线结构、直径以及地线接地方式等对绝缘地线和杆塔分流情况有重要的影响。计算结果可为绝缘地线分流系数和杆塔分流系数的研究提供重要的参考价值,并有利于指导输电线路的优化设计。

Ground wire icing severely affects the safeoperation of overhead transmission line in medium and heavyicing area.Direct Current(DC)melting ice is one of the effectivemeasures to solve overhead transmission line icing.When lightning stroke failure of the transmission line occurs,the lightning current distribution between insulated ground wire and towers decide the top potential of tower,which has impacts on lightning protection level and the grounding of transmission line.This paper uses the electromagnetic transient analysis program EMTP to calculate and analyze the lightning current distribution.The results show that the majority of lightning current pass through the towers in 500 kV transmission line,and lightning current amplitude,horizontal span of tower and grounding resistance have a greater impact on shunt coefficient of insulated ground wire and tower.This research has a significant theoretically value to tower shunt coefficient,potential's increase tower and economical design of power system.