Analysis of power quality disturbances using M-band wavelet packet transform

The increased use of non-linear loads, power electronic switches and changing regulations in today's power distribution system has made power quality (PQ) a major concern. Poor PQ may lead to partial or complete failure of equipment, loss of important data etc. The mitigation strategy can also be planned only if these PQ disturbances are correctly monitored. Conventional way of identifying PQ disturbances using Fourier Transform produces unrealistic results in case of non-stationary PQ disturbances. So, in order to measure it accurately, Wavelet packet transform is explored with its capability. In this paper, an attempt has been made to analyse PQ disturbances using M-band Wavelet packet transform. For Power quality disturbances such as voltage sag, voltage swell, momentary interruptions, voltage sag plus harmonics, voltage swell plus harmonics and flicker a statistical parameter RMS is computed for each WPT coefficient. Analysis is done for different magnitudes and time durations of PQ disturbances which are simulated as per their IEEE 1159-2009 standards definition.