Research on the New Open-phase Protection Criterions for the Generator Circuit Breaker

Abstract

In 2012, Guangzhou Pumped Storage Power Station A (GPSPSA) once had an serious accident. The generator circuit breaker (GCB) had the open-phase fault when the generator ran with low load. The relevant protection failed to remove the fault and lead to expand the accident scope. Through the comparative analysis of the inverse time negative sequence current protection and the phase angle difference protection of the zero sequence fundamental voltages between GCB both sides, the compound protection based on the zero sequence voltage and the negative sequence current is put forward. Considering the phase and amplitude features of the zero sequence fundamental voltages between GCB both sides, new criterions of the GCB open-phase protection based on the zero sequence voltage amplitude ratio and phasor difference are given. GCB open-phase protection is further optimized by these new protection criterions and can be applied in the relevant power plants.