电网不对称条件下基于频数分布理论的谐振接地系统故障相辨识

不对称电网发生单相接地故障后，其故障相与非故障相电压数据分布的统计特征存在显著差异，据此提出了基于频数分布理论的故障选相方法。首先取故障后各相电压首个1/2工频周期的数据，采用扩展Prony算法提取各相电压的工频分量，确定组距范围。再应用频数分布理论对各相电压的采样数据进行处理，利用贝塞尔公式求取各相电压的频数分布值。最后，通过比较三相电压间频数分布值的大小选出故障相。Matlab仿真验证与适应性分析表明，所提出的选相方法准确率高，适应性强。

Grounding phase determination in resonant grounding systems based on frequency distribution theory in case of unsymmetrical voltage

After single phase-to-ground fault occurs in asymmetrical power network, statistical characteristics of the voltage data distribution between the fault phase and the non-fault phase are significantly different. So a novel method for fault phase selection based on frequency distribution theory is proposed. Firstly, it selects per phase voltage data in the first 1/2 power frequency cycle after the fault occurred, and the extended prony algorithm is used to extract the power frequency components of each phase voltage to get the range of class interval. Then, these sampling data are split up into several groups by means of the frequency distribution theory, and frequency distribution values of per phase voltage are obtained by Bessel formula. Finally, the fault phase can be detected directly by comparing the magnitude of it. Matlab simulation results and adaptability analysis verify that the proposed method has high accuracy and strong adaptability. This work is supported by Natural Science Foundation of Shandong Province (No. ZR2016EEM13).