Development of a Transformer Model Using Optimization Method for Parameter Estimation

The precise modeling of a transformer, including the estimation of its equivalent model parameters, is fundamental for power system analysis. Accurate determination of these parameters is required for both steady-state and transient studies, with particular attention to low-frequency transients such as transformer energisation. These phenomena are governed by the nonlinear characteristic of the transformer’s iron core, with the nonlinear saturation curve playing a key role in their behaviour and representing a major challenge in transformer modeling. This paper proposes an algorithm for the transformer’s nonlinear saturation characteristic estimation, based on measured inrush current waveforms. The method employs the Nelder–Mead optimization technique to minimize a defined objective function, ensuring minimal deviation between simulated and measured inrush currents with zero remanent flux. The validity of the proposed approach is demonstrated through a comparative analysis of measured and simulated inrush current waveforms.