A Reversible Model For Single-Phase Three-Wire Transformers

In this paper, a reversible model for single-phase three-wire transformers for electromagnetic transient studies is proposed. Building on a recent reversible model for single-phase two-wire three-winding transformers, the proposed approach can be constructed solely from generally available parameters: the leakage inductance between the primary and secondary windings and the air-core inductances of the windings. Unknown subwinding parameters are estimated under practical assumptions, and the coupled magnetic-reluctance matrix is uniquely determined. The model was validated on a 500 VA test transformer. Short-circuit tests demonstrated close agreement in leakage inductance across multiple configurations, whereas energization tests showed accurate reproduction of inrush currents irrespective of the energized winding.