Visualizing time-varying power system harmonics using a Morlet wavelet transform approach

In this paper, a Morlet wavelet transform approach for the study of time-va rying power system harmonics is proposed. By this method, because the time- frequency localization characteristics are embedded in wavelets, the time a nd frequency information of a waveform can be simultaneously presented as a visualized scheme. Different from the fast Fourier transform, the wavelet transform approach is more efficient in monitoring the signals of interest when time varies. The proposed method has been applied to visualize inrush current harmonics of transformers and to investigate arc-furnace-generated signals. From the test results. the merits of the proposed method have been demonstrated for applications. (C) 2001 Elsevier Science B.V. All rights r eserved.