The Application Of Wavelet Transforms To Transformer's Computerized Protections

The basic characteristics and physical meaning of transformation are discussed in detail, and the application of wavelet analysis principal in digital filter for protection is illustrated clearly. The filter based on wavelet analysis is much better than the traditional filter based on Fourier analysis. It is more suitable for computer real time processing.It is very important to identify magnetizing inrush and internal fault conditions in large transformer differential relays. The thesis presents a method that can discriminate magnetizing inrush from internal fault conditions based on Wavelet Transform. It is shown that the features extracted by the wavelet transform have a more distinctive property than those extracted by the fast Fourier transform due to the good time and frequency localization characteristics of the wavelet transform. The extensive simulation studies have verified this methods is an effective way.