基于小波能量矩的高阻接地故障检测方法

High-impedance grounding fault detection based on wavelet energy moment

中性点不接地中压配电网时常发生高阻接地故障,普通的零序电流保护难以对其检测。通过对仿真和实验得到的高阻接地故障电流信号进行频谱分析,发现其高频分量分布显著区别于系统其他扰动暂态信号。由此,引入小波能量矩算法,通过对高频段能量矩进行归一化、求和及取对数处理,提出了一种高阻接地故障的检测方法,该方法只需要利用故障后第1个工频周期内的电流信号,通过小波能量矩分析得到诊断判据,即可实现高阻接地故障的有效识别。大量的仿真和实测数据表明,该方法适应性强,且不受线路非高阻接地故障暂态信号的影响。

HIGF（High-Impedance Grounding Fault） often occurs in the mid-voltage distribution network with ungrounded neutral point,which is hardly detected by normal zero-sequence current protection. The frequency spectrum of HIGF current obtained by simulation or experiment is analyzed,which shows that the distribution of its high-frequency components is obviously different from that of other disturbed transient signals. The wavelet energy moment algorithm is introduced,the energy moments of high-frequency components are normalized,summed and processed in logarithm,and a method for detecting HIGF is then proposed,which only carries out the wavelet energy moment analysis for the current signals of the first postfault fundamental frequency cycle to get the detection criterion. Massive simulative and measured data show that,the proposed method has strong adaptability and is not affected by the non-HIGF transient signals of lines.