The Sequence Components based Identification of Internal Fault in Power Transformer

Abstract

This paper presents a novel method to distinguish internal fault from magnetizing inrush of a power transformer. In this method, the fundamental frequency positive and negative sequence components have been utilized to calculate internal fault detection (IFD) ratio that effectively classify the internal (LG, LL, and turn-to-turn) faults from magnetizing inrushes such as residual and sympathetic inrush. Moreover, this method remains stable against over-excitation and CT saturation during external fault events. Evaluation of the proposed scheme has been carried by simulating various types of power transformer operating conditions on a small part of Indian power system network that is precisely modeled in PSCAD/EMTDC. At the end, a comparative evaluation with recently developed method reveals superiority of the proposed method.