Simulation Analysis of Dry-Type Transformer Thermal Network Model Considering Fluid Dynamics

In order to analyze the axial temperature distribution and hot spot temperature of the windings of dry-type transformers under typical overload conditions, this paper proposes a thermal network model that considers fluid dynamics. First of all, considering the influence of temperature on material loss characteristics, a dry-type transformer three-dimensional magnetic-heat-fluid coupling simulation model was established. Accordingly, the forced heat dissipation process of dry-type transformers was accurately simulated, the temperature rise of transformer windings was calculated and the hot spot temperature under different load factors was predicted. The errors between the simulation and the factory temperature rise test data of the hottest temperature of the high-voltage winding and the low-voltage winding were 4.1% and 9.0%. According to the fluid field simulation results of the finite element model, the convective heat transfer resistance in the thermal network model was corrected. It is shown that after the thermal network model is corrected for the convective heat transfer resistance, the errors between the hottest temperature simulation results of the high-voltage winding and low-voltage winding and the factory temperature rise test data are 2.9% and 10.7%, respectively, and the axial temperature distribution has a good agreement. The proposed thermal network model of dry-type transformers considering fluid dynamics overcomes the shortcomings of low calculation accuracy of traditional thermal circuit models and long calculation time of finite element models, which has good guidance for dry-type transformer design and operation evaluation effect. © 2022 Chinese Machine Press. All rights reserved.