对谐振接地系统单相接地故障特征的分析表明，单相接地初始阶段故障线路与健全线路间的零序电流波形相似度低于各健全线路间的零序电流波形相似度，且故障初始时刻故障线路与健全线路的零序电流极性相反，高阻接地时该结论仍成立。仿射不变矩恰能反映各零序电流波形的整体形状特征和极性关系，且不受波形平移、旋转和缩放等仿射变换的影响，抗干扰能力强。对从各故障暂态零序电流波形图中提取的仿射不变矩特征量进行谱系聚类分析，并计算聚类有效性指标，选取聚类有效性最高的聚类树实现故障选线。各种故障工况的大量仿真表明，该选线方法适应性好，可靠性高。%The analysis of the characteristic of neutral point resonant earthed system with single⁃phase⁃to⁃ground fault is made. The result shows that the similarities of zero sequence current waveforms between the fault line and each healthy line are below those between healthy lines, and zero sequence current of the fault line is in opposite polarity as those of healthy lines in initial stage of single⁃phase⁃to⁃ground fault. This situation remains during high resistance grounded fault. Affine moment invariants can just reflect the overall shape and polarity of each zero se⁃quence current without influence from affine transformation (such as rotation, translation and scale), and has a strong anti⁃jamming capability. The fault line is detected according to the pedigree clustering analysis of affine mo⁃ment invariants which is extracted from transient zero⁃sequence current waveforms of each line. Substantial simula⁃tions are conducted among various kinds of fault conditions. The results in various fault conditions show that the method is flexible and reliable.
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