Abstract:

To address the issues of weak fault characteristics and low accuracy of fault line selection in distribution networks, a fault line selection method based on the combination of wavelet transform and Hilbert-Huang transform (HHT) is proposed. Firstly, the modulus maxima of the transient high-frequency components of the zero-sequence current of each feeder are extracted using wavelet transform to construct the initial criterion. Secondly, the zero-sequence current signal is decomposed into multiple intrinsic mode functions by empirical mode decomposition, and the instantaneous energy of each component is calculated through Hilbert transform (HT) to construct the energy comprehensive criterion of HHT. Finally, the dual criteria are fused to achieve accurate identification of the faulty feeder. The method is verified in a 10 kV distribution network simulation model under different fault conditions. The results show that the accuracy of fault line selection reaches 97. 1%, with strong anti-interference ability and good adaptability to transition resistance and initial fault phase angles.

Key words: distribution network, single-phase grounding, wavelet transform, Hilbert-Huang transform (HHT), fault line selection