This paper aims to develop a combination method for the evaluation of power quality disturbances. First, we apply the Fast Fourier Transform, Wavelet Transform and Hilbert Huang Transform on a synthetic signal that represents typical behavior in a power system with high penetration of Renewable Energies. Then, we combine the methods to extract the best of each of these and achieve a better signal decomposition. The paper seeks to generate decision criteria on the method of analysis of signals to be used according to the application.