Harmonic indices assessment by Wavelet Transform

In this paper, Total Harmonic Distortion (THD) and K-Factor based on Discrete Wavelet Transform (DWT) are inspected. A flexible THD based on DWT is proposed and the way of using Wavelet Transform, sampling frequency, suitable wavelet functions, and time interval to assess the signal are investigated. In addition, the effects of harmonics order, phase degrees, and transient on the indices are shown. The DWT-based indices are used to study some real waveforms and their advantages over Fast Fourier Transform (FFT) based indices are presented.As a case study, some of the system indices are utilized to compare the values of DWT with FFT indices in a typical distribution network in Tehran. In addition to the common system indices for this purpose, some new system indices based on K-Factor are proposed. At the end, the diversity of the DWT and FFT indices values are depicted.

► We inspect DWT based indices and compare them with FFT ones (THD and K-Factor).
► We propose a more flexible definition of THDW.
► We propose some new system indices based on K-Factor.
► We assess some real waveforms to verify the advantages of the DWT indices.
► We assess a real distribution network to compare the values of different indices.