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.

对南瑞继保RCS 985/S型发电机定子接地保护原理进行了分析。南瑞继保RCS985/S型发电机定子接地保护采用发电机机端零序电流、接地变压器二次侧电流以及发电机零序电压构造零序方向元件，以基波零序电压作为动作判据，能够准确判断发电机区内、区外单相接地故障，分析了该保护在长洲水利枢纽工程应用中的可行性。介绍了该保护在长洲水利枢纽工程中的应用并提出了使用范围，为南瑞继保RCS985/S型发电机定子接地保护选型提供了依据。