Defining the possibility of resonant modes onset in power supply systems (PSS) is a relevant task in selection and validation of VAR compensators (VC). At the current resonance negative consequences take place: supplemental heating of conducting parts, overload with the consequent outage of static capacitor batteries (SCB), excessive heat of transformer windings and a core. Existing practices to determine the boundaries of non-sinusoidal modes acceptance are developed for stationary modes and they use effective values of currents and voltages defined by the Fourier transform (FT). The methods of mathematic modeling allowed the frequency decomposition of the signal to be performed using the mathematical apparatus of the wavelet packet transform. This decomposition into the frequency components allowed the time intervals of HH in PSS to be determined. This paper presents the modification of existing algorithms and techniques based on packet wavelet transform. The validity of the presented technique was confirmed by a numerical experiment.

A correct definition of mode parameters is of great importance for examination of power quality indices under non-sinusoidal modes, these parameters being effective values of current, voltage, active and reactive power. A wavelet transform is a later method of digital signal processing. This method enables information about signal to be saved both in amplitude-frequency and time space. The technique of defining effective current values of non-sinusoidal transient mode is presented. This technique assumes the preliminary frequency decomposition of the examining signal using the packet wavelet transform. Modernization of existing mathematical models of instantaneous, active and reactive power calculation as well as distortion power under non-sinusoidal modes based on the packet wavelet transform is carried out. The comparison of simulation modeling results shows qualitative coincidence with analytical mode calculation.