Wavelet-based directional stator ground fault protection for generator

This paper introduces a wavelet-based stator ground fault protection scheme with selectivity for generator. It is found that the WT results of the measured zero sequence current at the terminals, zero sequence voltages at the neutral and the terminals of a fault generator, especially the modulus maxima, contain important information. It can be used to discriminate the generator stator ground fault. By applying the zero sequence current, the proposed scheme can detect if the fault is in the internal generator or out of the generator. The effectiveness of the proposed scheme was verified both in the experiment and in the field. Investigation results show that the scheme can detect the ground fault with high sensitivity and selectivity during all operating conditions.