Fault Section Location Based on Transient Zero-Sequence Current Waveform Dissimilarity for Single-Phase Grounding Faults in Distribution Networks

A fault-section location method based on waveform-difference analysis of transient zero-sequence currents is proposed for distribution networks with small-current grounding systems. The method addresses weak single-phase-to-ground fault-current amplitudes, indistinct fault features, and limited adaptability of steady-state-quantity-based location criteria under arc-suppression-coil compensation. Steady-state and transient characteristics of single-phase-to-ground faults were analyzed in neutral-point ungrounded systems and arc-suppression-coil-grounded systems. Transient zero-sequence currents exhibited more pronounced amplitude, polarity, and waveform differences than steady-state zero-sequence currents, with lower sensitivity to compensation effects. These characteristics provide effective features for fault-section discrimination. The discrete Fréchet distance was used to quantify the overall waveform difference between transient zero-sequence currents at both ends of each line section. The coefficient of variation was introduced to characterize the dispersion of waveform differences among different sections. A fault-section location criterion was then constructed. The location performance was verified through PSCAD/EMTDC–MATLAB co-simulation under different neutral-point grounding modes, transition resistances, and fault inception angles. The results show that the proposed method accurately identifies fault sections and maintains good adaptability under both distinct and weak fault-feature conditions. Compared with the correlation-coefficient method, grey relational analysis, and empirical mode decomposition, the proposed method more comprehensively characterizes waveform differences in transient zero-sequence currents at both ends of a line section. It shows good section-discrimination capability under the representative fault conditions considered in this study.