Translated Abstract
The transformer is an important equipment in power system, which plays an extremely important role in the transmission and transformation of electric energy. The calculation of temperature rise of the transformer is very important for the design, life and running of the transformer. This paper takes the oil-immersed transformer as the research object, to study the temperature distribution inside the transformer by calculating the temperature of the transformer under different conditions.
First of all, a brief summary of mainformulas for the core and winding and transformer oil temperature rise and the basic principles of numerical heat transfer coupling finite volume method are presened through the analysis of transformer internal heat generation and transfer process. Based on the Ansoft software, the two-dimensional magnetic fields of a 10000kVA, 35kV/10kV three-phase power transformer under no-load and short-circuit conditons are calculated by finite-element analysis. The loss of the core and high-voltage winding and low-voltage are also caculated.
A two dimensional physical model of temperature field and the calculation domain of mesh for the transformer are built by Gambit software. The steady-state temperature distribution of each part in the transformer under different oil temperature and different oil speed are computed by Fluent. The results show that the transformer temperature could be reduced by increasing the oil speed, the transformer temperature rise will not be affected by changing the entrance oil temperature.
Then, a three dimensional physical model of temperature field is built, and the steady-state temperature distribution of each part in the transformer under different oil temperature and different oil speed are computed by Fluent, in which the assumptions and calculation process conditions are the same with the two-dimensional model. The three dimensional solution results in the same simulation conditions are consistent with the two-dimensional model. The more detalied temperature distribution of the three-dimensional results and the position of the hottest temperature in the transformer are also obtained.
Finally, the simulated results of the transformer temperature field are validated with the experimental measurements, the calculation results in some parts of the transformer and the measured results were compared to verify the correctness of this analysis method. Some of the results and conclusions of this thesis has certain guiding significance for us to understand the specific location of the hottest temperature in the transformer and strengthen the hottest spot temperature monitoring and transformer protection in the practical work.
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