Abstract: At present, in the actual operation of arc suppression coil grounding systems, the insufficient ability to collect transient quantities, zero-sequence quantities and other parameters of single-phase grounding faults leads to low efficiency of fault line selection. An algorithm for single-phase grounding fault line selection based only on the three-phase current data of each line is proposed in this paper. The principle of single-phase grounding fault is analyzed, and the variation characteristics of three-phase current during grounding fault are pointed out. According to the changes of the grounding phase current relative to the normal phase current before and after the fault, two line selection indicators, namely the ratio method and the difference method are proposed. The confidence levels of the two indicators are assigned based on the average current of the line, and then a function is constructed to assign weights to the current data sources at each moment for indicator calculation. Verification with actual fault cases shows that the proposed algorithm has a high accuracy of line selection in single-phase grounding faults, especially in single-phase metallic grounding faults. It can significantly improve the efficiency of dispatchers in accident handling, and reduce the cost of equipment transformation and power outage losses.

    Key words: arc suppression coil grounding system; single-phase grounding; fault line selection; phase current; ratio method; difference method