Power Quality Analysis Using S-Transform

This paper presents a new approach for power quality analysis using a modified wavelet transform known as S-transform. The local spectral information of the wavelet transform can, with slight modification, be used to perform local cross spectral analysis with very good time resolution. The ´phase correction´ absolutely references the phase of the wavelet transform to the zero time point, thus assuring that the amplitude peaks are regions of stationary phase. The excellent time-frequency resolution characteristic of the S-transform makes it an attractive candidate for analysis of power system disturbance signals. Several power quality problems are analysed using both the S-transform and discrete wavelet transform, showing clearly the advantage of the S-transform in detecting, localizing and classifying the power quality problems.