Application of lifting based wavelet transforms to characterize power quality events

This paper discusses the analysis of voltage disturbances in the time scale domain using Lifting Based Wavelet Transforms (LBWT) to quantify Power Quality (PQ) events. Characteristics of the investigated signals are generated on a time-frequency plane. Converter operation, load interruption/reenergizing, nonlinear loading and two types of capacitor switching, representing five common power quality events at the distribution level, are presented. These examples provide the basis for further characterization of other power quality events. Magnitudes of transient PQ events are located in the width of the signal. Furthermore, meaningful time and frequency components of transients are analyzed. The whole method is implemented and tested over a sample representing disturbances. Simulation results for five types of PQ events show that the proposed method is more efficient and faster in tracking signal dynamics than classical Wavelet Transforms (WT).