Third harmonic potential distribution based stator ground fault accurate location method for large generators

Abstract

The stator single-phase grounding fault location of large generator can provide guidance for rapid maintenance of faults. A third harmonic potential distribution based stator ground fault accurate location method is proposed. The current location methods mainly take coil as location unit and may have location error. However, accurate locate to the slot number is more meaningful for troubleshooting. In addition, the third harmonic potential induced by adjacent slots has larger phase difference, and has more distinct fault characteristics than the fundamental potential. In this paper, the fault location optimization model is constructed based on the analysis of the distribution characteristics of the third harmonic potential. The exhaustive solution of the location model is realized by artificially setting multiple reference points, and finally the reference point closest to the real fault point is obtained. The proposed method can accurately locate the fault slot number. PSCAD simulation verifies that the proposed method is robust against the transition resistance error and has higher accuracy than the existing methods.