Protection testing of a 100% stator ground fault using a phase domain synchronous machine model in real time

This paper utilizes a significantly improved phase domain synchronous machine model to test a multi-function relay model created for a real time digital simulator. One of the features of the machine model is its capability of simulating stator internal faults. Third harmonic voltage on the neutral and terminals of the machine and its variation with load and stator-ground faults is accurately represented. This feature makes the machine model a good candidate for testing a "100% stator-ground fault protection scheme" based on the third harmonic voltage. The performance of the relay model for "stator differential protection", "100% stator-ground protection" and the "loss of field excitation protection" schemes is verified and the results are presented in this paper.