I. Introduction
Basic factors of the mathematical methods for wavelet transformation have been introduced by Y. Mayer, I. Daubechies, and S.A. Mallat. For the first time the thesis about applicability of the wavelet transformation method when analyzing modes of power systems operation have been introduced by D. Robertson and P. Ribeiro in 1994. These works introduced main ideas of the wavelet theory, as well as possible spheres of applications of the mathematical methods for wavelet transformation when studying current and voltage signals. Later, S. Santoso suggested applying wavelets for determining and localization of distortions in power quality parameters – voltage fluctuations, deviations, and voltage non-sinusoidal.