Applications of Selective Stator Ground Fault Protection on Expanded Unit Connection

The principles of Nari-relays RCS-985/S-type generator stator ground fault protection are analyzed in this paper. The zero sequence current on generator terminal, secondary current of grounding transformer, and generator zero sequence voltage tectonic zero sequence directional components are applied in Nari-relays RCS-985/S-type protection. Based on zero-sequence fundamental voltage, the single phase earth fault in and outside the generator area could be judged, showing the applicability of the protection in Changzhou Key Water Control Project. Furthermore, the range of application of the protection in Changzhou Key Water Control Project is introduced, providing references for selecting the stator ground fault protection of Nari-relays RCS-985/S-type protection.