Wavelet-based diagnostics and protection of power transformers

This paper introduces a novel current diagnosis and protection technique, which is based on a wavelet packet transform (WPT). The WPT algorithm is implemented and the output of the second level details are able to provide the needed signatures to diagnose the type of the current flowing through the transformer. The proposed technique is implemented using Daubechies mother wavelet with two levels of resolution. An experimental setup is developed and the proposed WPT technique is tested on-line on a three-phase laboratory power transformer. The WPT technique performed successfully by identifying different currents including magnetizing inrush, normal current (through-fault) and different internal faults currents.