Distortions in three-phase transformer magnetizing currents with nonsinusoidal conditions considering magnetic hysteresis and leg-flux coupling effects

This paper investigates the magnetizing behavior of three-phase three-leg transformers under nonsinusoidal operating conditions. The electromagnetic steady-state and transient behavior of three-phase transformers significantly differs from single-phase transformer operation mainly because of the unique flux coupling interactions in multi-leg and asymmetric core structures. With the aid of newly developed three-leg nonlinear transformer core model, this paper studies the influence of magnetic hysteresis, flux couplings in the core-structure and nonsinusoidal operation in three-phase transformers. Simulations results demonstrating the magnetizing current behavior based on the model are presented and discussed.