Estudo e análise da falta interna espira-terra em um transformador de potência monofásico

Abstract

This work presents a study and analysis of internal turn-ground fault in a singlephase power transformer. It was initially presented a theoretical review about the subject matter including the ideal and real model of a power transformer utilized in the literature. From the real model, it was presented a mathematical formulation for the calculation of the power transformers’ parameters when there is a turn-ground fault in one of the windings. The calculations of the parameters can be done in two ways, the linear and the non-linear calculations, by splitting one winding to apply the turn-ground short-circuit on a power transformer. After presenting the theorical foundation, the circuits were modeled in the PS SIMUL software by using real data of a high voltage single-phase power transformer. To simplify the analysis, it was used a power transformer with a 1:1 transformation relation. For each batches of tests, it was analyzed the current and voltage outside the power transformer and at the fault point. The first simulations were done to compare the faults of each circuit for when they were operating empty and at full load, and the faults were applied in both sides of the power transformer. After analyzing these parameters, the faults were compared to each other by using the linear and non-linear mathematical developments. Lastly, it was discussed the results. In general, the results showed a divergent from the expected, because the linear mathematical model presented a non-linear behavior. The reason of this result was not clear until the conclusion of this work and, as a suggestion, can be topic of study for future works. The results from the non-linear calculations also showed results different from the expected but, however, this model is a property of the software’s manufacturer, and it can also be a possible study case for future works.