Global Thermal Network Model for Oil-immersed Transformers
LU Fei1,SU Xiang2,LI Hua2,LIN Fuchang2,LU Yangze1
1. Electric Power Research Institute, State Grid Hubei Electric Power Corporation Limited, Wuhan, Hubei 430077, China
2. School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
Abstract：The hot spot temperature is an important index to measure the insulation performance and safety margin of the transformer. It is of great significance to calculate it quickly and accurately. We analyzes the heat generation and heat transfer mechanism inside the oil-immersed transformer, the relationship between the velocity and temperature distribution and the fluid Prandt number Pr in the natural convection boundary layer are obtained. Considering the axial variation of local natural convection heat transfer coefficient and the difference of heat transfer characteristics in different regions, the oil-immersed transformer is divided and layered. Based on the thermoelectric analogy method, multiple types of thermal resistances are defined, and the global thermal network model of the oil-immersed transformer is constructed. The calculation results of the thermal network model are compared by finite element simulation. The temperature change trend of the windings obtained by the two is the same. The difference of the hot spot temperature is about 1.9%, and the difference of the hot spot position is about 7.7%. Compared with finite element simulation, the thermal network model has more advantages in solving time and efficiency. It can realize online monitoring, real-time analysis and dynamic evaluation of the operating status of oil-immersed transformers.
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2024, Vol. 45 
