High-Frequency Model of the Power Transformer Based on Frequency-Response Measurements

In this paper, a new high-frequency black-box model of the power transformer is presented for the calculation of transferred lightning overvoltages. The model is based on frequency-response analysis measurements and the application of four-terminal network theory. The computational verification of the presented model was successfully performed on a white-box transformer model in Electromagnetic Transients Program-Restructured Version software. The experimental verification was carried out on 130-kVA and 36-MVA three-phase power transformers. The presented calculation and measurement results confirm the validity of the proposed model for full and chopped lightning impulse voltages.