基于改进变分模态分解和信息融合的故障选线

Fault Line Selection Based on ImprovedVariational Mode Decomposition and Information Fusion

小电流接地系统发生单相接地故障时,传统信号分解方法难以准确提取故障特征,而且单一选线判据不能适应所有工况,容易造成误判,导致选线准确率不高.针对上述问题,文中提出一种基于参数寻优的改进变分模态分解和信息融合技术的故障选线方法.利用参数寻优变分模态分解的优良信号分解性能,将暂态零序电流准确分解为衰减直流、工频交流和高频振荡3个分量.通过融合工频分量综合相关系数和所有分量的相对能量系数两种判据,构造可靠性更高的综合选线判据.针对母线故障时,仅凭综合相关系数阈值来区分母线故障和线路故障存在主观性的问题,在综合相关系数基础上提出了工频分量极性比较法的辅助选线方法.该方法结合了三种选线判据,有效改善了单一判据选线准确率不高的问题.采用Simulink搭建10 kV配电网故障选线模型,仿真结果表明该方法不受中性点接地方式、接地电阻、故障初始角、故障位置的影响,具有较高选线准确率.

When a single-phase grounding fault occurs in a small-current grounding system,the traditional signal decomposition method is difficult to extract the fault features accurately,and the single line selection criterion can’t adapt to all working conditions,which is easy to cause misjudgment and lead to low line selection accuracy.To solve these problems,a fault line selection method based on parameter optimization variational mode decomposition and information fusion technology is proposed in this paper.Based on the excellent signal decomposition performance of parameter optimization variational mode decomposition,the transient zero sequence current is accurately decomposed into three components:attenuated DC,power frequency AC and high frequency oscillation.By fusing the comprehensive correlation coefficient of power frequency components and the relative energy coefficient of all components,a more reliable comprehensive line selection criterion is constructed.In view of the subjectivity of distinguishing bus fault from line fault only by the threshold value of comprehensive correlation coefficient,an auxiliary line selection method based on the polarity comparison method of power frequency component is proposed.This method combines three kinds of line selection criteria and effectively improves the problem of low accuracy of the single line selection criterion.Simulink is used to build fault line selection model of 10 kV distribution network.The simulation results show that this method is not affected by neutral grounding mode,grounding resistance,fault initial angle and fault position,and has a high accuracy of line selection.