Injected current regulation based stator ground fault arc suppression method for large hydro-generators

Abstract

Generator stator ground faults are common, and a reliable ground fault arc suppression method is required to ensure generator safety and avoid unnecessary impact on the power system. A fault arc suppression method is proposed in this paper by regulating the neutral injected current and controlling the fault point voltage to a low level. Considering the required injected current is different for different fault positions on the stator winding, a fault location method and a fault winding potential calculation method are proposed. In addition, a fault type discrimination method based on the neutral fundamental voltage variation is proposed to distinguish temporary and permanent faults. In this paper, the grounding transformer impedance and irregular distribution of the stator grounding capacitance are considered. The PSCAD/EMTDC simulation results verify that the proposed method can effectively realize arc suppression at different fault scenes and the ground fault type can be distinguished effectively.