STUDY ON ADAPTIVELY CHOOSING FAULT LINE UNDER SINGLE-PHASE TO GROUND FAULT BASED ON ANALYSIS OF MULTI-FREQUENCY BANDS
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Applying the good property of frequency division of wavelet packets, each lines transient zero sequence current, which appears in the distribution networks occurring a single phase to ground fault, is decomposed to obtain the outputs of different frequency bands in this paper. The characteristic frequency band of each line, in which the transient capacity current is most concentrated, is chosen according to the view of maximum energy. Based on the principle that the transient capacity currents polarity of the fault line is contrary to the ones of normal lines in its characteristic band, the fault line choosing can be adaptively carried out by contrasting the polarities of the wavelet packets decomposition coefficients of the transient capacity currents of all lines in each characteristic frequency band. The results of theoretical analysis and ATP simulations show that the proposed method can choose out the fault line in distribution networks exactly and reliably.