基于多判据协调的配电网单相接地故障选线方法

Single-Phase-to-Ground Fault Line Selection for Distribution Networks Based on Multiple Coordinated Criteria

中文关键词:小波包分解  傅里叶变换  基频信号  相关系数  自由振荡分量  关联距离

keywords:wavelet packet decomposition  Fourier transform  fundamental frequency signal  correlation coefficient  free oscillation component  correlation distance

中文摘要:为充分利用单相接地故障时刻暂态分量与稳态分量的特征信息，提升不同故障场景下的选线精度，提出一种基于多判据协调的自适应故障选线方法。该方法在故障发生后，记录2周期内的暂态零序电流；针对低阻接地故障，通过小波包分解提取各线路能量最大的频带，以此判定故障线路；针对高阻接地故障，采用离散傅里叶变换计算各线路基频信号的相位差—若存在两线路相位差大于等于60°，引入基频相关性选线方法，选取综合相关系数倒数最大的线路为故障线路，若相位差大于60°，则提取自由振荡分量并根据其首半波极值进行有序重排，通过计算各线路综合关联距离，选取关联距离最大的线路作为故障线路。理论分析与仿真实验结果表明，所提方法具有良好的可靠性与鲁棒性，可有效提升低阻、高阻等不同故障场景下的故障选线准确率。

Abstract:To fully exploit the characteristic information of transient and steady-state components during single-phase-to-ground faults in distribution networks and improve the faulty feeder detection accuracy under different fault scenarios，this paper proposes an adaptive faulty feeder detection method based on multi-criterion coordination. First，after fault occurrence，the transient zero-sequence current of two power frequency cycles is recorded. Second，for low-resistance grounding faults，wavelet packet decomposition is adopted to extract the frequency band with the maximum energy of each feeder to judge the faulty line. Third，for high-resistance grounding faults，discrete Fourier transform is used to calculate the phase difference of fundamental frequency signals of each feeder. If the phase difference between two feeders is no more than 60°，the fundamental frequency correlation line selection method is introduced，and the feeder with the maximum reciprocal of comprehensive correlation coefficient is selected as the faulty line. If the phase difference is greater than 60°，the free oscillation components are extracted and sorted orderly according to the extreme value of the first half-wave. By calculating the comprehensive correlation distance of each feeder，the feeder with the largest correlation distance is selected as the faulty feeder. Theoretical analysis and simulation results show that the proposed method has good reliability and robustness，and can effectively improve the accuracy of fault line selection under different fault scenarios such as low-resistance and high-resistance faults.