Leveraging extra high voltage grid supplies for the dynamic performance analysis of large power transformer in short-circuit scenario

Abstract The current study introduces a novel approach to evaluating the short-circuit (SC) withstand capability of 3-phase, 400/220/33 kV, 500 MVA power transformer through dynamic short-circuit (DSC) tests conducted under actual grid conditions. Departing from conventional lab-based methods, it utilizes a 765 kV grid supply for high-voltage to medium-voltage (HV-MV) windings (i.e., 400kV–220kV) and a 400 kV grid supply for medium-voltage to low-voltage (MV-LV) windings (i.e., 220kV–33kV), replicating operational conditions with greater accuracy. The actual-grid energization technique highlights the feasibility of performing high-fidelity DSC testing without the need for specialized test facilities. The research establishes a detailed correlation between transformer design parameters and short-circuit performance, providing essential insights into mechanical and thermal robustness during fault events. Additionally, it identifies the equipment and setup required for field-based DSC tests across different supply configurations, presenting a viable testing framework for utilities and manufacturers. The results confirm the transformer’s ability to withstand SC stresses across varying dynamic conditions, including those involving auxiliary LV supplies. This grid-based testing methodology enhances the reliability assessment process and sets a new benchmark for realistic, cost-effective validation of transformer short-circuit performance in high-capacity transmission systems.