A Differential Protection Scheme for a Typical Three Phase Power Transformer
Authors: Oyedoh MO, Agbonaye O, Obasohan O
This research presents a model and simulation of differential protection scheme for a three phase two-winding transformer using MATLAB/Simulink software. It is modelled to guide against false tripping during inrush magnetizing current. It also presents a fast response and fault clearing time of the protection scheme using the Simulink work tool. A 150 MVA, 330/132 kV transformer was used as case study. The digital differential protection scheme was incorporated using related Simulink block components. Data relevant to the study were collected from Transmission Company of Nigeria (TCN), Benin sub-region, and inputted into the blocks. These data include; transformer ratings, current transformer (CT) ratings, source voltage and receiving end voltage. From the simulated results, it was observed that the differential protection scheme gave a good response by discriminating between through faults and inrush magnetizing current. During the inrush magnetizing current there was no tripping of the relay. When fault was induced within the transformer, the relay gave a fast switching response of 0.52 msec after the fault had occurred.
Affiliations: Department of Electrical and Electronic Engineering, Faculty of Engineering, University of Benin, PMB 1154, Benin City, Nigeria
Keywords: Inrush Current, Circuit Breaker, Differential Protection, MATLAB, Transformer
Published date: 2019/06/30