Adaptive 100% stator ground fault protection based on subharmonic injection method

The paper presents a novel adaptive 100% stator ground protection scheme for high-impedance grounded synchronous generators. The scheme is based on the subharmonic injection method and Kalman adaptive filtering. Using data from a 618 MVA generator, simulation studies show that the new adaptive scheme is capable of real-time monitoring of stator windings insulation condition and can detect high-resistance ground faults independent of the total capacitance to ground of the generator stator windings, iso-phase bus work and delta-connected windings of the step-up transformer.