Based On The Fuzzy Recognition Of Comprehensive Criterion Of Generator Stator Single-phase Grounding Protection Research

Generator stator winding single-phase ground fault is one of the most common faults.when the fault current exceeds the allowable value,it will burn stator core, and thus damage the stator winding insulation, causing short circuit between phases or between turns, and expand the accident. If the single-phase ground fault is in the generator outside, the capacitor current is greater than a certain value, fault point arc is also unable to extinguish, often accompanied by intermittent arc, so that causing a non-fault phase overvoltage and resulting in insulation damage.Therefore, installation of large generator stator Single-phase grounding protection is necessary.Currently in china most generators install on 100% stator ground fault protection by base wave zero sequence voltage protection and third harmonic voltage protection composition, whose advantage is simple in principle, the wiring is concise and economical to implement. In power plants, when the main transformer in high voltage side or high factory transformer in low voltage side causes earthing fault, zero sequence voltage will be passed to the generator side cause base wave zero sequence voltage grounding protection malfunction, moreover the third harmonic voltage in operation is unstable, three times harmonic grounding protection easy also malfunction.This paper puts forward fuzzy recognition comprehensive criteria of generator stator ground fault protection, whether application more quantities comprehensive judge generator is occurring earth-fault or not, overcome traditional protection of malfunction faults.Using genetic algorithm this paper reasonably determine the comprehensive criterion of weight coefficient;With multi-loop simulation model was verified protection sensitivity.