Hybrid wavelet-Fourier spectrum analysis

This paper deals with the problem of estimation of voltage and current spectrum, especially harmonics, in the field of electrical power engineering. After description of hitherto used methods, a method of the combined wavelet-Fourier spectrum analysis has been proposed. The method consists in applying the wavelet transform for samples of the original signal, then using digital Fourier transform to the results for spectrum extraction. As a result, the significantly decreased number of needed multiplications is observed. A comparison of the method and fast Fourier transform, as well as the recently introduced wavelet packet decomposition, has been carried out. Finally, the results of experimental research have been shown and commented on. During research, various kinds of wavelet "mothers" and varying filter length have been taken into consideration.