Harmonic Detection in Power Signals Based on Fast Modified S-Transform

Abstract

In this paper, a new approach for harmonic detection in power signals based on fast modified S-transform (FMST) is proposed, which combines the advantages of the incomplete S-transform and the modified S-transform. Initially, the Fast Fourier Transform was performed and dynamic measurement values were obtained from the envelope of power spectrum, then the valid harmonic frequency points were detected by selecting the dynamic measurement values which were larger than the set thresholds. Further, the FMST was specifically performed on these major frequency points and a complex matrix was generated. The row vectors of the matrix reflected the phase and the time location information of harmonic disturbances, while the column vectors reflected the amplitude-frequency characteristics. And the feature vectors extracted from the complex matrix were used to detect the harmonic amplitude, phase and transient information. Simulation results validate the high accuracy, strong noise immunity and rapidity of the proposed approach.