A New Phase-Coordinate Transformer Model for y Bus Analysis

A new method of modeling three-phase transformers has been developed. The method can represent transformers with two or more windings and can incorporate the effects of interphase coupling, particularly the lowered impedance of three-phase units to zero-sequence magnetizing currents. For two-winding transformers, the model requires only four data items per transformer and can still be used even in the absence of some of them, in which case it simplifies to existing well-established modeling techniques.