The SOUFVM and SUFEM Hybrid Computational Method for Flow-Heat Coupling Analysis of Oil-Immersed Power Transformer Windings
Xin Jiwei1, Li Lin1, Liu Gang2
1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China; 2. Hebei Provincial Key Laboratory of Power Transmission Equipment Security Defense North China Electric Power University Baoding 071003 China
Abstract：With the continuous development of power systems, oil-immersed power transformers, as key power equipment, are experiencing rising winding temperatures, which has become a core factor affecting their safe and stable operation. Studies show that excessively high hotspot temperatures in windings can directly cause transformer failures. Therefore, accurately calculating the windings' temperature distribution and hotspot temperatures is crucial. Traditional temperature-rise calculation methods often struggle to balance numerical accuracy, stability, and computational complexity when dealing with the coupled, complex flow and temperature fields inside transformers. Combined with the second-order upwind finite volume method (SOUFVM) and the streamline upwind finite element method (SUFEM), this paper proposes a coupled flow-heat calculation method to eliminate the non-physical oscillations arising from the classical Galerkin finite element method when solving convection- diffusion equations. To avoid additional interpolation operations in staggered grids, the second-order upwind finite-volume method on structured collocated grids is used to solve the flow-field control equations, thereby obtaining the oil flow velocity distribution. The streamline upwind finite element method is employed to solve the unified temperature field equation for oil flow and winding heat transfer, thereby obtaining the temperature rise distribution. The proposed coupling calculation method is applied to a two-dimensional single-region winding simulation model of an oil-immersed power transformer, with a rated capacity of 321.1 MV·A and a rated voltage of 530/$\sqrt{3}$ kV. The distributions of oil flow and temperature rise are calculated. The results indicate that the proposed method achieves higher numerical accuracy than the Galerkin finite element method. Compared with fluent software, the absolute errors (relative errors) for the peak oil flow velocity and the hotspot temperature are 0.000 8 m/s (1.38%) and 2.06 K (0.6%), respectively. Overall, the relative error of this method remains within 2%. In summary, the coupled flow-heat calculation method proposed in this paper integrates the advantages of finite volume and finite element methods, overcoming the shortcomings of existing numerical methods in handling complex geometries and flow-structure coupling problems. This method effectively solves the problem of calculating temperature rise in transformer windings and also provides strong technical support for other complex multiphysics coupling problems. With the continuous advancement of computer technology, this method has broad application prospects in the multiphysics simulation software for power equipment. It is expected to play an essential role in promoting the intelligent and accurate development of high-voltage power equipment simulation software.
辛纪威, 李琳, 刘刚. SOUFVM和SUFEM混合计算方法与油浸式电力变压器绕组流热耦合分析[J]. 电工技术学报, 2026, 41(6): 1844-1859.
Xin Jiwei, Li Lin, Liu Gang. The SOUFVM and SUFEM Hybrid Computational Method for Flow-Heat Coupling Analysis of Oil-Immersed Power Transformer Windings. Transactions of China Electrotechnical Society, 2026, 41(6): 1844-1859.
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