Transformer Terminal-Duality Model for Windings Tum-to-Tum Faults Simulation

Turn-to-turn fault (TTF) inception on a transformer can be very destructive and damaging. In order to check the performance of TTF protection algorithms, it is necessary to model the transformer in the presence of TTFs. Under minor TTF inception, the rise in the terminal currents of the transformer is just in the order of its no-load current. Therefore, in this study, a suitable transformer model should be employed to address the role of core and windings under the occurrence of minor TTF, accurately. This paper presents a new equivalent reluctance circuit for three-phase transformers in the presence of TTFs. This equivalent model employs the parameters determined by the finite element method. This model contains the admittance matrix and it is well-known as the terminal-duality model. For verification of the model, a real three-phase custom-built transformer is employed and modeled in this paper. The results obtained from the developed model are validated against the experimental results of TTF tests carried out on this transformer.