Time-frequency analysis of non-stationary phenomena in electrical engineering

This paper serves the idea of applying joint time-frequency representations in electrical engineering. Main directions of researches are concentrated around Cohen’s class of transformation which gives some possibilities of adaptation for analysed signal by choosing appropriate kernel function. Additionally, novel approach delivered by S-transform is also introduced. In order to investigate the methods several experiments were performed using simulated phenomena of switching on the capacitor banks in distribution system. Firstly some aspect of S-transform application were present. Then the influence of different kernel functions were investigated when Wigner-Ville, Choi-Williams and Zhao-Atlas-Marks distributions were applied. Obtained results were supplemented by comparison to classical spectrogram. Proposed methods allowed to track instantaneous frequency as well as energy with better time-frequency precision than classical spectrogram. It leads to applications in diagnosis and power quality area