Verification of a Synchronous Machine Model for Stator Ground Fault Simulation Through Measurements in a Large Generator

This paper presents a synchronous machine model designed to simulate internal ground faults along the stator windings. The purpose of this model is to help to set the 100 % stator ground fault protection based on the measurement of the third harmonic in the grounding resistor. The setting of the above protection is not easy, as the third harmonic in the generator depends on the operation point and the saturation of the machine. The main contribution of this paper is that the model has been validated through the measurements on a 106 MVA hydro-generator under no-faulty condition obtaining good results. The model has been also tested under faulty conditions obtaining coherent results.