基于多分辨率小波变换的配电网高阻接地故障检测方法

Detection Method of High Impedance Fault in Distribution Network Based on Multi-resolution Wavelet Transform

配电网中发生高阻接地故障时,故障特征电气量突变微弱,现有的故障检测方法难以有效识别高阻故障特征,且容易受到谐波、噪声等干扰。为实现高阻故障的可靠检测,提出一种基于多分辨率小波变换的高阻接地故障检测方法。该方法结合故障下零序电压的频域分布特征,先利用多分辨率小波分解对零序电压进行处理,然后对所得不同频段下细节系数进行信号重构,最后计算故障前、后一个工频周期内重构信号的绝对值之和,将前、后变化量与预设阈值对比实现高阻接地故障的有效检测。大量仿真结果表明,该方法能够准确识别高阻故障,对干扰具有较强的耐受能力,能够有效适应不同配电网场景下的高阻故障检测。

When a high impedance fault occurs in distribution network,the sudden change of electrical quantity of fault characteristics is weak.The existing fault detection methods are difficult to effectively identify the characteristics of high impedance fault,and are easy to be disturbed by interferences such as harmonic and noise.In order to realize the reliable detection of high impedance fault,a high impedance fault detection method based on multi-resolution wavelet transform is proposed.Combined with the frequency domain distribution characteristics of zero-sequence voltage under faults,the zero-sequence voltage is processed by multi-resolution wavelet decomposition,and then the detail coefficients are reconstructed under different frequency bands.Finally,the sum of the absolute values of the reconstructed signals within the power frequency cycle are calculated before and after the faults.And the changes before and after the fault with the preset threshold are compared to realize the effective detection of high impedance fault.A large number of simulations show that this method can be adopted to accurately distinguish faults and interferences,and has strong adaptability to high impedance fault detection in different distribution network scenarios.