基于SFB和相关分析法的小电流接地故障选线方法

Selection of faulty line based on SFB and correlation analysis for small-current neutral grounding system

提出了利用B-样条小波包选择出故障暂态特征最明显的有效频带(SFB),并融合相关分析法对单相接地后各条馈线间的故障暂态波形进行综合相关度分析的方法。利用B-样条小波在阶数增加时具有最优时频窗口的特点,与一般小波分解相比能够更好地提取暂态零序电流信号故障特征,运用相关分析法对各条线路的特征进行分析,正常线路的相关系数较大,故障线路较小。通过求取相关系数平均值,避免数据采集不同步引起的计算误差,得到按照发生线路故障可能性大小排列的故障选线序列。EMTP仿真结果表明该方法不受故障条件的影响,能准确、可靠地解决小电流接地系统单相接地故障选线的问题。

The B-spline wavelet packet is used to select the SFB（Selected Frequency Bands） with most obvious fault transient characteristics and the integrated correlation between the transient waveforms of feeders during single-phase grounding fault are analyzed. As the B-spline wavelets have the optimal time -frequency window when order increases,it extracts the fault characteristics of transient zero sequence current much better than the general wavelet decomposition does. The characteristics of each line are analyzed with the correlation analysis and the correlation coefficient of faulty line is smaller than those of healthy lines. The average correlation coefficient is calculated to remove the errors caused by asynchronous sampling and the faulty line selection list is sorted according to the fault probability of line. Simulation with EMTP shows the proposed method selects the faulty line correctly and reliably under different fault conditions.