基于零序电压小波包能量比的配网单相高阻接地故障辨识分析

配网高阻故障大多是架空线接触高阻抗物体引起的单相高阻接地故障,难以通过稳态特征进行识别。基于等值网络分析故障产生高频分量的原因并考虑正常状态对辨识的影响,提出一种基于零序电压小波包能量比的配网单相高阻接地故障辨识方法。利用小波包频段分解对零序电压进行能量特征提取,提取低频段能量与高频段能量的比值作为高阻故障的识别特征量。基于某10 kV配电网对方法进行测试,通过BP神经网络的辨识对比结果,证实了方法的有效性;通过中性点接地方式、拓扑结构及故障条件变化等多种因素的分析及仿真,验证了方法的适用性。

Identification Analysis of Single-phase High Resistance Earth Fault in Distribution Network Based on Wavelet Packet Energy Ratio of Zero Sequence Voltage

Most of high resistance faults in distribution network are single-phase earth faults caused by overhead line contacting high impedance objects. These faults are difficult to identify by steady-state features. In this paper, the high frequency components of faults are analyzed based on equivalent network and the influence of normal state on identification are considered. An identification method of single-phase high resistance earth fault in distribution network based on wavelet packet energy ratio of zero sequence voltage is then proposed. Wavelet packet decomposition is used to extract energy features of zero sequence voltage. The ratio of energy in low-frequency band to energy in high-frequency band is used as the identification feature of high resistance faults. Based on a typical radial 10 kV distribution network, the performance of the proposed identification feature is evaluated. The validity of the method is evaluated by the identification and comparison results of BP neural network. The applicability of the method is verified by the analysis and simulation of different neutral grounding modes, different topologies and the change of fault conditions.