FEA and CFD Based Multi-Physics Modeling, Simulation, and Validation of Oil-Immersed Power Transformers

Power transformers serve as indispensable elements in nearly every electrical power system. Ensuring the continuous operation of power transformers is pivotal in maintaining the reliability and safety of the power network. Hotspot temperature (HST) in windings is a key factor that indicates the health condition of a power transformer. To determine the temperature of the transformer windings, it is essential to obtain the temperature distribution inside the transformer. This paper introduces a high-fidelity multi-physics modeling and simulation framework focused on predicting the reliability of large power transformers. The methodology relies on the application of three-dimensional (3D) finite element analysis (FEA) and computational fluid dynamics (CFD). In particular, electromagnetic modeling and simulation using FEA are conducted to calculate transformer losses. Subsequently, a thermal-hydraulic model is established to determine the temperature distribution. More importantly, this is to identify the HST in the transformer windings, which is further utilized to determine the transformer lifetime. Additionally, a sensitivity analysis is carried out to evaluate how the properties of the cooling oil affect both temperature distribution and HST. Finally, experimental results are provided to confirm the multi-physics modeling and simulation results.