DIAGNOSTIC METHOD FOR FERROMAGNETIC RESONANCE IN 10 KV NEUTRAL UNGROUNDED SYSTEM

摘要

A diagnostic method for ferromagnetic resonance in a 10 kV neutral ungrounded system, the method comprising: when a voltage at two triangular ends of a PT opening exceeds a preset limit value, capturing a voltage A relative to ground, a voltage B relative to ground, a voltage C relative to ground, a neutral point voltage, and a neutral point frequency; according to the three-phase voltage A-B-C, first classifying a fault as a fractional frequency resonance/high frequency resonance fault type or a fundamental resonance/single-phase-to-ground fault type; classifying the fault as a fractional frequency resonance or a high frequency resonance according to the frequency thereof, and respectively processing the fundamental resonance/single-phase-to-ground fault type according to an energy method and a loop ground current method; firstly obtaining a result via the energy method, and then verifying the same via the circuit ground current method, and if the two methods produce the same result, it indicates that the determination is correct, thereby distinguishing the fault as a fundamental resonance fault or a single-phase-to-ground fault; transmitting the classified faults or a result indicating a non-ferromagnetic resonance single-phase-to-ground fault to a terminal for display, so as to assist maintenance personnel in processing a corresponding fault in a timely manner.