Identification of internal faults in power transformer using symmetrical components and Park´s plots

A new scheme to discriminate between internal fault current and inrush current of power transformer is presented in this paper. In the proposed method, space vector analysis of the differential signal and their time characteristic shapes in park´s plane is used as a core classifier to discriminate between magnetizing inrush and internal fault of a power transformer. Conventionally, second harmonic component is commonly used for blocking differential relay in power transformer differential protection. A comparison of performance between the proposed method and the conventional harmonic restraint method is also discussed in this paper. Extensive simulation studies have been performed to demonstrate the efficiency of the proposed scheme using PSCAD/EMTDC and MATLAB.