Synthetic Zero-Sequence Signal-Based Intelligent Location Method for Single-Phase Ground Fault in Distribution Networks

Distribution system structures are intricate and variable, with single-phase ground (SPG) fault occurring frequently. Existing section location methods for SPG faults are often influenced by manually set thresholds, resulting in low accuracy. This article analyzes the relationship between the zero-sequence voltage (ZSV) and zero-sequence current (ZSC) synthesized from three-phase voltage and current under the condition of no zero-sequence transformer installed on the line and proposes an SPG fault section threshold-free location method based on Swin-Transformer (S-T). First, Fourier transform-based data processing methods correct phase errors caused by current transformers (CTs) and eliminate the dc bias in synthesized ZSCs. Second, the synthesized ZSC waveform and the derivative of ZSC (DZSV) waveform are overlaid on the same image, with the enclosed areas shaded to highlight the relationship between the two electrical quantities. Finally, the transformer model is used to classify the differentiated images between the SPG fault section and sound section to achieve threshold-free fault location. The proposed method has been tested and validated on an industrial prototype in a 10-kV full-scale test system and deployed in the actual distribution network. Experimental results demonstrate that the method can accurately locate fault sections even under conditions of noise interference and inaccurate trigger timing.