Abstract
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.
Highlights
As one of the most critical equipment in the power system, the power transformer plays a significant role in the process of power transmission and transformation
Due to the high cost of the transformer, its lifespan is one of the most concerned indices and it is affected by many factors, The associate editor coordinating the review of this article and approving it for publication was Mengmeng Li
EFFECTS OF TURN-TO-TURN INSULATION ON TEMPERATURE As shown in Fig. 4, the insulation paper was so thin that finer meshing of the fluid-solid interface and coil-paper interface was needed to ensure the accuracy of calculation, which leads to a dramatic increase in the number of elements and nodes
Summary
As one of the most critical equipment in the power system, the power transformer plays a significant role in the process of power transmission and transformation. Due to the high cost of the transformer, its lifespan is one of the most concerned indices and it is affected by many factors, The associate editor coordinating the review of this article and approving it for publication was Mengmeng Li. among which the main one is the insulation aging. Once the insulation paper begins to age and to a certain extent, its maintenance is so demanding that it should be replaced as soon as possible. The lifespan of insulation paper often determines the service life of the transformer. Excessive winding temperature will accelerate the aging of insulation paper, which will greatly shorten the expected life of the transformer [4], [5]
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