配电线路雷电感应过电压避雷线防护效果分析

Analysis on Protection Effect of Ground Wire Against Lightning Induced Overvoltage of Distribution Lines

雷电感应过电压是导致配电线路运行故障的主要因素之一,需要合理分析避雷线对线路感应过电压的防护效果。利用EMTP中的model模块编程计算配电线路雷电感应过电压,分析安装避雷线对感应过电压的抑制作用。讨论雷击点距线路距离、避雷线高度、避雷线数量和位置、多点接地间隔等因素对感应过电压抑制效果的影响。研究结果表明:配电线路安装避雷线能够明显抑制线路雷电感应过电压;随着雷击点距线路距离的增大,避雷线的抑制效果有所增加;避雷线高度越高,对感应过电压的抑制效果降低越明显;避雷线数量的增加能够增大对感应过电压的抑制效果,尤其是在接地电阻阻值较低的区域。避雷线对感应过电压的抑制效果随着避雷线接地间隔的缩短而增大,在线路绝缘子串闪络电压较低情况下可以通过缩短避雷线接地间隔来确保线路不发生两相闪络。

Lightning induced overvoltage is one of the major factors leading to operation faults of distribution lines.It is necessary to analyze application of ground wire against lightning induced overvoltage.Equivalent model of distribution line was establishedin EMTP as well as model to calculate lightninginduced voltage.Protection effect of ground wire was discussed.Influence of distance from lightning strike point to thedistribution line,height andnumber of the ground wire,multi-point grounding spacing were presented.Results show that:induced overvoltageof the distribution line could be inhibited significantly by installing ground wire.Suppression effect of the ground wire increases with the increasing of distance from lightning strike point to the line as well as the decreasing of height of the ground wire.Increasing the number of ground wires may result in an increase of inhibition effect,especially in areas with small grounding resistance.Inhibition effect are strongly influenced by multi-point grounding spacing of the ground wire,so it is practicable to shortengrounding spacing to prevent double phase flashover.