Research on adaptive tripping for single phase earth fault in neutral point non-effectively grounded system

摘要

Running with single-phase earth fault improves reliability of power supply in neutral point non-effectively grounded system, but arc-grounding and intermittent fault caused over-voltage is most likely to damage insulating security. In view of developing line-selection techniques, the increasingly success ratio of that has met the requirement on site, a new method is proposed for adaptive earth fault protection in neutral non-effectively grounded system, to be specific, the reliability of online monitoring fault line selection, the condition of over-voltage and insulation of line, severity of fault, line types and power supply reliability demand to the loads, adaptive fault line-selecting whether or when to trip, all above factors are taken comprehensively into consideration. The adaptive protection technology has been applied with well effect in enterprise grid of Shandong province of China.