110kV线路零序四段保护方向问题分析

Protection Direction Problem of Zero SequenceⅣSection of 110kV Line

输电线路经大过渡电阻接地短路时,会出现零序电压达不到方向元件门槛值的情况,造成保护拒动。为此,分析了不同网络接线取消110 kV零序电流保护Ⅳ段方向的电网风险,指出应选取对电网影响最小的方案,并针对整定计算提出了相应的改进方法。

It may occur failure of zero sequence voltage to reach threshold value of directional element when grounding short-circuit is happening to power transmission lines via big transition resistance which may result in protection refuse operation. Therefore,this paper analyzes power grid risk of cancelling Ⅳsection direction of 1 1 0 kV zero sequence current protection for different network connection. Meanwhile,the paper points out to select schemes which have minimum impacts on power grid. Aiming at setting calculation,it also proposes relevant improvement measures.