基于现场实录波形的小电流接地故障暂态选线研究

为解决小电流接地系统单相接地故障特征不明显的问题，借助小波理论提出了基于DS证据理论的融合判据。首先确定小波基及小波分解尺度，并构造小波能量矩阵以确定故障特征频带。进而，在此特征频带下提取出三种故障特征:小波能量比、小波重构系数方差及暂态功率方向，并分析对比了三种特征的灵敏性。考虑到各个故障选线特征的检测灵敏性不同，为了提高选线准确率，进一步提出了基于DS证据理论的选线融合判据。最后，对现场实录波形进行分析。分析结果表明，该融合判据能够有机融合三种选线特征，提升选线正确率，具有较好的工程应用价值。

Study on transient line selection of small current grounding fault based on field recorded waveform

In order to solve the problem of single-phase ground fault characteristics of small current grounding system, the fusion criterion based on DS evidence theory is proposed by wavelet theory. Firstly, the wavelet base and wavelet decomposition scale are determined, and the wavelet energy matrix is constructed to determine the fault characteristic frequency band. Further, three fault characteristics, including wavelet energy ratio, wavelet reconstruction coefficient variance and transient power direction, are extracted in this characteristic frequency band, and the sensitivity of them is analyzed. Considering the different detection sensitivity of each fault line selection feature, the line selection fusion criterion based on DS evidence theory is further proposed in order to improve the line selection accuracy. Finally, the on-site recorded waveform is analyzed. The analysis results show that the fusion criterion can organically integrate three line selection features, improve the line selection accuracy, and has better engineering application value. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. GY71-17-032).