基于相差统计的小电流单相接地选线新判据

A New Criterion for Earth Fault Line Selection Based on Phase Comparison Statistical Method

小电流接地系统发生单相接地故障时,故障线路与健全线路在特征频段内零序电流的相位差别是接地选线判据的重要依据之一。文中在详细分析小电流单相接地故障暂态过程的基础上,提出了一种新的基于相差统计的小电流接地系统单相接地选线新判据。这种方法直接利用复小波提取各条线路零序电流各子频段信号的相位,借鉴统计学的方法计算出特征频段内线路间整体的相位差,通过对相位的直接比较选择出故障线路,充分利用了特征频段内的所有信息,计算方法简单可靠,抗干扰能力强,且判据不受系统接地方式、过渡电阻、合闸角的影响。仿真结果表明,这种方法能够可靠地选择出故障线路。

The phase comparison between fault feeder and healthy feeder is one of important criteria in fault line selection for neutral non-effective grounding systems. A new criterion for earth fault line selection with phase comparison statistical method is presented based on the detailed analysis for transient process of non-solidly earthed network. The complex wavelet transform is directly adopted to extract each zero-sequence current＇s phase of sub-band signals that can accurately select earth fault line after the statistical comparison of every line＇s phase. All information of special frequency band is sufficiently utilized and the algorithm proposed is simple. The detecting process with the new criterion is not sensitive for disturbance and immune to earth mode, path resistance and inception angles. Numerical simulation results have shown the validity and reliability of the algorithm proposed.