基于故障分量电流的单相接地保护新原理

Probe into New Principle of Single-phase Earth Protection Based on Fault Component Current

我国配电系统中,35 kV及以下电网主要采用中性点非有效接地方式。中性点非有效接地系统发生单相接地故障时,单相接地保护一般要进行故障选线,但实际中选线准确率较低。本文对单相接地故障时相电流故障分量进行理论分析,应用小波变换提出一种新的幅值和相位相结合的单相接地保护原理。EMTP仿真分析验证,该方法能够适应配电网复杂的拓扑结构和不同的故障状态,且只需根据本线路的电流故障分量的幅值和相位信息进行判断。

The neutral point non-effectively grounded manner is widely applied in the power distribution systems of 35kV and below in China. When single-phase-to-earth fault occurs in the neutral point non-effectively grounded system, faulty line selection is conducted by single-phase earth protection. This paper analyzes the fault component of phase current when the single-phase-to-earth fault occurs, and proposes a new principle of single-phase earth protection combining amplitude and phase based on wavelet transform. EMTP simulations show that the proposed method can adapt to the complex topology and different fault state of power distribution network, and the amplitude and phase of current fault component of the line is only need for judging the faulty line.