基于零序电流比相的零序方向元件新原理

New Principle Used in Zero-sequence Directional Relay Based on Current Phase-comparison

通过对线路单相接地故障时零序电流电压分布特点、零序功率方向元件动作的分析,提出了微机继电保护采用两零序电流比相判断零序功率方向的方法,零序方向元件不受电压元件断线、系统振荡及负荷的影响,从原理上确保了动作的可靠性。

The set which takes the pre-phase voltage to replace the zero-sequence voltage can not perform correctly whenever the system surges or is overloaded. A new method is proposed to be used in microcomputer-controlled power system protection device. It adopts the phase-comparison of two zero-sequence currents to estimate the power direction which can overcome the disvantages caused by open circuit in potential element, system surge and variational load.