Time-Frequency Non-sinusoidal Current Decomposition Based on the Wavelet Packet Transform

Abstract

This paper introduces the decomposition of the distorted current into two components; active and residual components. The decomposition is performed in the time-frequency domain using the wavelet packet transform (WPT). The use of the WPT preserves both time and frequency information, provides uniform frequency bands, while give more accurate results than Fourier transform (FT) based approaches especially in case of inter-harmonics or time varying harmonics. The proposed approach can be useful for real-time monitoring of active and residual currents at each frequency, selective switching of harmonic, inter-harmonic elimination, instantaneous non-active power compensation and power quality evaluation.