Some Techniques for the Analysis and Visualization of Time-varying Waveform Distortions

The time-varying nature of waveform distortions requires a precise analytical tool that is essential in power quality analysis. The time-frequency representation (TFR) provides a powerful method for identification of the time-varying nature of the waveform distortions. The paper presents a comparative study on four techniques for analysis and visualization of waveform distortions with time-varying amplitudes. The techniques include the traditional fast Fourier transform (FFT) and three TFR techniques, which are the short time fourier transform (STFT), the discrete wavelet transform (DWT), and the S-transform.