NEW APPROACH FOR CLASSIFYING TRANSIENT PHENOMENA IN POWER TRANSFORMER USING DISCRETE WAVELET TRANSFORMS (DWT) AND FUZZY LOGIC

Abstract

The role of a power transformer relay is operate and restraints in the cases of differenttransient phenomena. This paper presents a new approach for classifYing transient phenomena inpower transformer. The discrimination among internal faults, external faults, inrush currents andover-excitation is achieved by the combination of discrete wavelet transforms (DWT) and fuzzylogic analysis.First, the analyzed data are obtained from simulations abnormal operating cases such asexternal faults, internal short circuit, magnetizing inrush by using ATP - EMTP. Next, thesignals are analyzed by discrete wavelet transforms (DWT) and using detection methods basedon direct recognition of the wave shape distortion of DWT detail (high frequency). Finally, theresults are brought in fuzzy logic system for the recognition of the transient phenomena in powertransformer. All codes are programmed by Matlab 6.5 compiler. The paper shows, the waveshape distortion is difference in different cases that is favorable condition for recognizing of the,iransient phenomena in power transformer.