Technology of fault line selection for single-phase-to-earth fault in small current grounding system

摘要

To perfect the existing fault line selection methods and enhance the accuracy in small current grounding system, the fault line selection technology combined the multicriterion with fuzzy theory was proposed. Firstly, the mechanism of single-phase-to-earth fault in small current grounding system was further discussed. For the common neutral nongrounding system and neutral grounding system via arc-suppression coil, the current mathematical models on single-phase-to-earth fault were analyzed respectively. Then the basic principles on three different fault line selection methods were described that were the zero-sequence current frequency analysis, the addition of the integral of multiplying the zero-sequence current and others, and the current injection. Afterwards, the multicriterion fault line selection approach integrated fuzzy decision was advanced, and the efficiency was proved successfully. By using of DSP and PC, the system models were implemented. Through system simulation and a great deal of experiments, the results also have proven the reliability of this novel technology of fault line selection in small current grounding system.