Power transformer protection using wavelets and pattern recognition — part I: Theoretical verification

This paper introduces a modified algorithm for the three-winding power transformer protection based on wavelet transform and pattern recognition in order to differentiate between internal faults and inrush current. Using ATP® software, a simulation for 100 MVA, 150/70/16 KV three winding transformer is done to verify the accuracy and speed of the suggested technique. Results indicate that the proposed technique is stable, reliable, and fast during the discrimination between internal and external faults, magnetizing inrush currents, and switching on internal faults. The results are validated in the laboratory using a 5 kVA, 380/190 V transformer "part 2".