架空配电线路雷电感应过电压计算研究

Calculation of Lightning Induced Overvoltage on Overhead Distribution Lines

为了研究雷电感应过电压特性,指导架空配电线路雷电防护,分析了现有雷电感应过电压计算方法的不足,提出一种改进计算方法。该计算方法分为雷电电磁脉冲计算和雷电电磁脉冲激励下的多导体瞬态响应计算2个步骤,考虑了大地损耗对雷电电磁脉冲和多导体传输线瞬态过程的影响以及线路带有分支和集中参数元件的实际情况。通过与火箭引雷感应过电压实测波形的对比验证了计算方法的有效性。利用该文的计算方法对雷电感应过电压进行了计算分析,其基本特征表现为:雷电感应过电压为短尾波,在导线上距离落雷点最近处最大,并延导线逐渐衰减;大地损耗越大,最大雷电感应过电压值越大,但沿线衰减越快;雷电感应过电压的最大幅值受雷电回击速度的影响较小,受线路分支影响明显,同时与线路高度、线路与落雷点间距离为非线性关系。

In order to study the characteristics of the lightning induced overvoltage, the deficiencies of available lightning induced overvoltage algorithms were analyzed and an improved algorithm was proposed. In the improved algorithm, lightning induced overvolatge calculation was performed in two steps： lightning electromagnetic pulse calculation and transient response of multi-conductor transmission lines excited by lightning electromagnetic pulse calculation. The improved algorithm considered the impacts of earth loss on lightning electromagnetic pulse and transient processes on multi-conductors, and also considered the line has branches and lumped parameter elements. As a validation, simulation of rocket triggered lightning induced overvoltage experiment was conducted and showed good correspondence with simulation results. In addition, the lightning induced overvoltage characteristics were analyzed. The results show that： the lightning induced overvoltage is short-tail impulse; the maximum value appears on the line where closest to lightning striking point, and attenuate gradually along the line, the larger earth loss, the larger maximum value, but in faster attenuation. The maximum amplitude of lightning induced overvoltage is affected obviously by branches, but affected hardly by return stroke velocity. There are non-linear relationships between the maximum amplitude of lightning induced overvoltage and line height, as well as the distance line to striking point.