Classification of Transient Phenomena in Power Transformers Based on a Wavelet-ANN Approach

This paper presents an efficient wavelet and neural network (WNN) based approach for distinguishing magnetizing inrush currents from internal fault currents in three phase power transformers. The wavelet transform is applied first to decompose the current signals of the power transformer into a series of detailed wavelet components. The values of the detailed coefficients obtained can discriminate between an internal fault and magnetizing inrush currents in power transformers. The detailed coefficients are further used to train an Artificial Neural Network (ANN). The trained ANN clearly distinguishes an internal fault current from magnetizing inrush current. The simulation results obtained show that the proposed approach is more reliable and accurate. It provides a high operating sensitivity for internal faults and remains stable for inrush currents of the power transformers. KeywordsPower Transformer, Differential Protection, Wavelet Transform, Artificial Neural Network.