In order to solve the problem of single-phase grounding fault judgment in non-solid-earthed distribution network, the power flow in non-solid-earthed distribution is analyzed. A single-phase grounding fault judgment method based on mutation current logic matrix is proposed. The minimum fault judgment area model is constructed by the parent and child nodes. The feeder mutation current matrix is generated by the feeder real-time current matrix and the feeder history current matrix. The feeder mutation current matrix is transformed into the feeder mutation current logic matrix by the capacitance current threshold, and the non-zero elements of the feeder mutation current logic matrix are extracted into the mutation current logic sequence list. Then the single-phase grounding fault can be determined in the minimum fault judgment area of the last element of the mutation current logic sequence list as the parent node. The detailed calculation formulas are given. This method is also applicable to the non-solid-earthed distribution network containing distributed generation. The simulation results show that the method proposed in this paper has a good adaptability to the permanent grounding fault and it is worth popularizing.
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