A New Wideband Modeling Method of Converter Transformer

In order to effectively calculate the electromagnetic transient characteristics of converter transformer to avoid resonance and overvoltage faults, it is essential to master the impedance variation and resonance properties of converter transformers. This paper proposes a new segmented wideband modeling method for converter transformers from low frequency to high frequency. Firstly, the resistance parameters considering the skin effect of resistance in high frequency of transformers are calculated. The leakage inductance parameters of transformers are obtained by calculating inductance matrix through finite element method. The capacitance between windings and the distributed capacitance to earth are measured by energy method. Then, the segmented wideband model of converter transformer is obtained by considering the dispersion characteristics of stray capacitors at high frequencies. Lastly, by comparing the simulation data with the measured data, the results show that the segmented wideband modeling method of converter transformer can effectively reflect the actual impedance variation and harmonic vibration characteristics of transformer in the fundamental frequency to megahertz band, and provide theoretical basis for the optimization design of converter transformer.