基于动态小波变换的小电流接地系统故障选线研究

Research on Earth Fault Line Selection Based on Dynamic Wavelet Transform in Small Current Neutral Grounding System

小电流接地系统发生单相接地故障时,由于故障电流小及接地点电弧不稳定等原因,其零序故障电流准确获取和定值整定困难,使其故障线路的检出仍是难题。提出一种基于动态小波变换的故障选线方法,利用所有健全线路暂态能量与故障线路暂态能量之差为最小值作为判据。该方法充分利用了动态小波变换分析故障信号的优势,克服常规小波变换在这方面的不足。仿真结果表明,该判据不受接地条件和接地方式影响,能够准确可靠地选出故障线路。

Due to small grounding current and unstable electric are at fault position, it is difficult to obtain the zero-current of fault line and to tune the parameters of equipments in a small current grounding system. Hence the fault line selection in this system has always been a complex and difficult problem. A fault line selection method was proposed based on dynamic wavelet transform as the principle that the difference of transient energy of normal line between that of fault line is minimal. The proposed method took the advantages in use of dynamic wavelet transform in failure signal analysis in power system, and then overcame the shortage of failure analysis by using wavelet transform. Simulation expatiates that the fault line can be selected based on the criterion more reliably on condition of various earth faults.