Active Voltage-Drop Arc Suppression and Property Identification Methods for Generator Stator Ground Fault

Single-phase stator winding ground fault is one of the most frequent faults in the marine nuclear power platform. The internal space of the platform is compact and contains the nuclear reactor loads, so it is sensitive to the arcing process and needs reliable arc suppression. Therefore, the active voltage-drop arc suppression and fault property identification methods are presented in this paper. For the fault point location method constructed by the fundamental potentials, multiple solutions may be calculated under certain fault conditions. Thus, a low frequency injection-based checking criterion is proposed to determine the unique location result. On this basis, the arc suppression compensation currents containing the fundamental and third harmonic components can be calculated and injected into the generator neutral point. Since the neutral point voltage is controlled to be equal to the amplitude of the fault potential and the phase is opposite, the fault point voltage is suppressed to zero, and effective arc suppression is realized. The fault property identification is realized by using the value difference of the grounding transition resistance. Thus, transient and permanent fault conditions are distinguished. Simulation and dynamic experiment results verify the effectiveness of the proposed method.