Global method for time–frequency analysis of harmonic distortion in power systems using the wavelet packet transform

The paper proposes a method based on the use of the wavelet packet transform for the time–frequency analysis of harmonic distortion in power systems. The magnitude of harmonic and interharmonic groups, as defined in Standard IEC 61000-4-7, the magnitude of the subharmonic group, defined as an extension of the standard method, and the time evolution of odd harmonics in voltage and current waveforms can be simultaneously computed using different levels of the same wavelet decomposition tree applied to the samples of the input signal. The paper shows the performance of the method proposed in different measurement conditions and the comparison of the results with those obtained applying the standard method.