A fast WT‐based algorithm to distinguish between transformer internal faults and inrush currents

Abstract

SUMMARY This paper presents a novel algorithm for power transformer differential protection which differentiates internal faults from magnetizing inrush currents and saturation of current transformers using wavelet transform. The technique is based on pattern recognition of the instantaneous differential currents using the high-frequency components generated during the disturbance. These components are extracted using a wavelet-based processor stage. In this method, an appropriate criterion at a suitable frequency range is developed. Using the developed criterion for three phases, internal faults are correctly detected in about 1/8th cycle after occurrence of the disturbance. The proposed algorithm is evaluated using generated data from simulation of a model power system using Electromagnetic Transients Program software. The performance of the proposed algorithm is tested in many different cases and promising results are obtained. Copyright © 2011 John Wiley & Sons, Ltd.