Hybrid transformer model for transient simulation - Part I: Development and parameters

A new topologically correct hybrid transformer model is developed for low and midfrequency transient simulations. Power transformers have a conceptually simple design, but behaviors can be very complex. The selection of the most suitable representation for a given behavior depends on the type of transformer to be simulated, the frequency range, and other factors, such as the internal design of the transformer and available parameters or design data. Here, a modular model suitable for frequencies up to 3-5 kHz is developed, utilizing a duality-based lumped-parameter saturable core, matrix descriptions of leakage and capacitive effects, and frequency-dependent coil resistance. Implementation and testing of this model was done for 15-kVA 208 Delta-120Y 3-legged and 150-kVA 12,470Y-208Y 5-legged transformers. The basis and development of the model is presented, along with a discussion of necessary parameters and the approaches for obtaining them.