Commissioning and Setting of Voltage-Injection Stator Ground Fault Protection for Largesized Generator

Generator capacity and stator winding capacity to ground per phase increasing cause large current circulating within the stator,which may result in severe damage to the stator insulation and earth faults in the stator.So higher requirements are needed for stator single-phase grounding protection of large generator.The paper introduces the basic principle of voltage-injection stator single-phase grounding protection and summarizes the field adjustment methods of the voltage injection scheme against the stator earth fault protection,and gives the experimental results of adopting impedance angle mutation and transition resistance.The actual operating status for inoperative generator and that with 30% rated voltage commissioning are analyzed,and the results have verified the accuracy of setting the grounding transition resistance and selecting the fault generator.