A WAVELET TRANSFORM APPROACH TO DISCRIMINATE INTER-TURN FAULTS FROM MAGNETIZING INRUSH CURRENTS IN TRANSFORMERS

Abstract

The transformer protection is critical issue in power system as issue lies in the accurate and rapid discrimination of magnetizing inrush current from different internal faults. This paper describes a new method to discriminate the magnetizing inrush current and inter-turn fault using the wavelet transform. Method is independent of setting any threshold for discrimination amongst these. Practical results over the custom built transformer are presented with detailed description of proposed criterion. A discriminating function and feature extraction is defined in terms of difference of two-peak amplitude of wavelet coefficients in a specific band. This discrimination will aid in development of an automatic detection method shall give information to predict the failure ahead of time so that the necessary corrective actions are taken to prevent outages and reduce down time.