Analysis and Rapid Calculation of Magnetic Thermal Coupling Characteristics of Large Power Transformers

Abstract

Conventional single-phase nuclear main transformers are susceptible to certain risks such as an increase in high local temperature in the windings, high leakage fields, and high short-circuit forces. Moreover, these transformers are too costly to use. In this paper, simulation and test studies are carried out for a 500 kV single-phase two-core column nuclear power main transformer. First, using the principle of fluid-thermal coupling simulation, a three-dimensional simulation of a single-phase two-core column nuclear power main transformer is performed to obtain its temperature field distribution, and the accuracy of the established 3D model is validated through experimental tests. Second, because the 3D simulation calculation time is long, the computer occupies a large amount of memory, but the 3D winding temperature distribution in the allowable error range in line with the axisymmetric distribution can be replaced by the 2D axisymmetric model. Therefore, a two-dimensional axisymmetric simulation is conducted for a single-phase two-core column nuclear power main transformer. Simultaneously, the h-type adaptive mesh refinement method is used to optimise the two-dimensional mesh distribution based on the coupled fluid-thermal field. The optimised simulation results are compared with those from the three-dimensional model and experimental tests, confirming the accuracy of the two-dimensional approach. Finally, the winding temperature distribution under various loading conditions is computed via a two-dimensional optimised simulation and validated against the three-dimensional temperature profile, thereby verifying the precision of the two-dimensional method. The temperature data obtained under different operational loads can serve as a critical dataset to construct a digital twin model of the transformer.