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6 ~ 35kV low voltage distribution network and most of the non-effectively grounded neutral point operation mode , known as the small current grounding system . Small current grounding system of the single- phase ground fault is a common form of the failure , more than 80% of the failure of the whole networking . Faulted phase voltage is zero when a fault occurs , the non - faulted phase voltage is increased to three times , but still symmetrical three - phase line voltage system running with fault two hours , to improve the reliability of the system . But must find fault phase as soon as possible in order to avoid the spreading of the accident and the damage to the equipment and troubleshooting . The grounding line selection is a very difficult problem , especially Neutral Point arc suppression coil grounding system , due to the weak fault current arc instability and other reasons , not ideal single phase grounding line selection method is effective based on steady-state information . Therefore, the study of single phase grounding line selection in small current grounding system is necessary and meaningful . This article describes the development of the single-phase ground fault line selection in small current grounding system , success and failure , and in -depth analysis of fault characteristics , research and development of a small current grounding system single-phase ground fault line selection mode the integrated intelligent diagnosis system, the formation of a full integration of a variety of criterion criterion and effective use of domain technology , the continuous judgments technology , resulting in the true sense of the intelligent accurate fault diagnosis system . Accurate fault diagnosis system newly developed by the laboratory , the substation simulation test , correct rate reached 100% , installed in Puyang, Henan Zhongyuan station operational since May 2009 , and accurately determine the grid 10kV system single- phase ground fault occurs . System work so far achieved satisfactory results , to achieve the desired objectives .
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