A comparative investigation on three-phase transformers modeling with and without magnetic coupling between phases

Three-phase transformer models in EMTP-like programs have been usually carry out through an association of three single-phase transformers, without taking into consideration the magnetic coupling between phases produced by the yokes of the transformer ferromagnetic core. It has been found, however, that this magnetic coupling is essential when power system unbalanced phenomena are to be studied. In this paper it is shown the simulation results of a comparative investigation between two three-phase transformer models: one represented by a bank of three single-phase transformers (no magnetic coupling) and one that considers the magnetic coupling between phases. Various situations of system imbalance are simulated and discussed.