Heat dissipation performance analysis and structural parameter optimization of oil-immersed transformer based on flow-thermal coupling finite element method

Abstract

In this paper, a coupled flow-thermal field simulation model is established based on the parameters of the transformer. Then the distribution of the flow and thermal fields are obtained. The results show that oil backflow occurs to varying degrees at the top and bottom of the transformer. In addition, with the formation of backflow, the hot spot temperature of the transformer increases. Through the combination of orthogonal experiments and finite element method, the geometric structure of winding oil passage is selected as the optimization variable. The law between the winding structure and the maximum temperature is acquired by means of range and variance analysis, and the optimal parameters are obtained. The hot spot temperature is reduced by 34.27 K compared to the pre-optimization period, which is a guideline for the design of transformers.

Review of Modeling Approaches for Conjugate Heat Transfer Processes in Oil-Immersed Transformers

“…In addition, the analysis of condition is complicated by the fact that the transformer load is not constant during the day and throughout the year. Mathematical models for transformer thermal simulation can be broadly classified into two categories: those based on circuit theory [39][40][41][42], and those that solve field problems using numerical methods [116][117][118][119][120][121][122][123]. The first group has the advantage of allowing for real-time calculations, as they do not require significant computational resources.…”

“…In [117,118], a coupled thermal and hydrodynamic calculation based on Boussinesq's approximation is used to determine the thermal conditions of the transformer, aiming to identify weaknesses in the structure and optimize it further. Numerical simulation of the temperature field of general parts of an oil-immersed power transformer, including conjugate heat transfer, requires significant computational resources and high-quality engineering.…”

Full-Scale Modeling and FBGs Experimental Measurements for Thermal Analysis of Converter Transformer

“…During normal operation, the maximum temperature in the windings can exceed 80 • C [7], with temperature rises surpassing 40 • C, and a bidirectional coupling relationship exists between electromagnetic losses and temperature [8]. Transformer oil facilitates cooling through continuous circulation, with the cooling effectiveness significantly influenced by the oil flow rate [9], as well as the size and structure of the oil channels [10], which directly relate to the hotspot temperature and its distribution within the transformer. Moreover, the operational environment and the loading ratio [11] of the transformer also exert substantial impacts on the hotspot temperature.…”