Equivalent Circuit Model and Experimental Validation of Transformer Windings Considering Long-Distance Conductor Effects and Frequency-Dependent Parameters

The impulse frequency response method is often combined with the transformer winding equivalent circuit to jointly analyze the frequency response mechanism of the transformer and the winding state while winding modeling is the necessary fundamental work. Therefore, this paper proposes a new approach to transformer winding modeling. Firstly, based on the design parameters of the transformer, a finite element model constructed using ANSYS Maxwell simulation software is used to calculate the capacitance, inductance, and resistance parameters of the transformer winding. Secondly, the model not only considers the capacitance effect between distant conductors and the mutual inductance between distant coils, but also takes into account the frequency variation effect of parameters. Subsequently, an equivalent circuit model is formulated with the acquired parameters to analyze the frequency response characteristics of the winding. Finally, the equivalent winding model was subjected to various mechanical fault simulations across different operating conditions to investigate the alterations in the frequency spectrum curve under fault conditions. The results show that the simulated IFRA curve closely aligns with the measured IFRA curve, providing indirect evidence of the effective correspondence between the circuit model, which takes into account various influencing factors, and the actual physical model.