Numerical and Experimental Investigation of Temperature Distribution for Oil-Immersed Transformer Winding Based on Dimensionless Least-Squares and Upwind Finite Element Method

To accurately analyze the temperature rising and locate the hot-spot of oil-immersed transformer windings, a hybrid method based on the dimensionless least-squares finite element method (DLSFEM) and upwind finite element method (UFEM) is proposed in this paper. To solve the fluid-thermal coupling problem, the sequential iteration method was utilized. After that, the two-side equilibration method and the Jacobi preconditioned conjugate gradient method were used to solve the equations. Moreover, a product-level experimental platform for oil-immersed transformer windings was built. The influence of the turn-to-turn insulation and gravity on the temperature was discussed, and the results show that the influence is significant. To verify the effectiveness of the proposed method, a comparison between the simulation results of the proposed method and experimental results were made, which shows a good agreement. Aiming at verifying the efficiency of the proposed method, the convergence of the proposed method was compared with that of the commercial computational fluid dynamic (CFD) software Fluent. The results indicate that the convergence speed of the proposed method is much faster than that of Fluent, which means a better performance of the new method.