零序功率方向元件的探讨

分析了比幅与比相原理的零序功率方向元件接地短路故障远离保护安装处时零序方向元件灵敏度低，可能存在死区的问题。提出了微机线路零序方向电流保护采用线路零序电流与变压器中性点零序电流比相的判据，解决了电压回路故障及远离保护安装处接地故障零序方向元件灵敏度低的问题。通过仿真验证表明，所提出比相原理动作正确且简单。

Discussion on Zero-sequence Direction Power Element

This paper analyzes the possible dead zone in the low sensitivity or even the non-response of zero-sequence direction power element while the ground fault occurring far from the fixed point. The phase comparison criterion of zero-sequence current between transmission line and neuter point of transformer is brought up used in computer protection system. The phase comparison method is proved to be correct and simply via simulation experiment.