A New Principle Based On Fault Component Of Phase Current For Fault Line Detection In Small Current Neutral Grounding System

To detect fault line exactly and reliably is of great importance when the single phase to ground fault occurs in the small current neutral grounding system. Based on theoretical analysis of the fault component of phase current after the single phase to ground fault occurs, a new principle for fault line detection is proposed in this paper combining amplitude criterion with phase criterion in the case of distribution network of feeders of various length. The simulation demonstrates this method could well satisfy the distribution network of feeders of various length that makes the detection of fault line difficult, be suitable for different kinds of neutral grounding mode and fault state, and have high sensitivity and reliability. This method's biggest advantage is making judgment by merely using electrical quantities of the feeder itself and easily combined with feeder protection. This paper also includes research on different phase two point to ground fault in neutral non-grounded system and digital simulation of ferroresonance.