Analysis and Handling of One Stator Ground Fault of Generator Unit

The present work was aimed at a malfunction of the stator ground fault protection during the trial operation of 600 MW power generation unit in a power plant.According to the spectra and data of the recorded fault wave and the analysis on the characteristics of the generator voltage variation when the stator were grounded,and also through the generator start-up test,the malfunction was found to be caused by an underlying water pipe leakage in the phase A of exciter side which led to the phase A stator grounded by high impedance.According to the handling and analysis of the whole accident,some experiences and advices were proposed for handling similar faults.