Development of thermal model of an oil-filled transformer in Ansys environment

The paper deals with modelling of thermal modes of an underground substation using the Ansys software environment. The main attention is paid to the oil-filled transformer TRDN-63000/110, for which a simplified geometric model was created in the Design Modeler module. The thermal processes were modelled in Ansys Steady-State Thermal using a triangular mesh and adjusting material parameters such as thermal conductivity and cooling medium properties. The study analysed the transformer's operating modes: short circuit, no-load, and transient states. In the short-circuit mode, the modelling results showed that when using transformer oil, the maximum temperature of the active part is reduced to the range of 67–91 °C, which is significantly lower than in the case of air cooling, when the temperature exceeded the permissible values (225 °C). In the no-load mode, the maximum temperature of the transformer was only 35 °C, which indicates the effectiveness of oil cooling even at minimal power loads. Particular attention is paid to the study of the dependence of the maximum temperature of the transformer core on the density of heat fluxes in different operating modes. It is shown that the maximum temperature is directly proportional to the load and heat flux density, and the highest heat transfer intensity is observed near the windings. The obtained results allow us to assess the efficiency of heat dissipation of the transformer and its impact on the heat balance of the substation premises. The modelling data can be used to improve the design of transformers, optimise cooling systems and ensure reliable operation of power equipment in underground substations. This study emphasises the importance of using modern numerical methods to analyse the thermal characteristics of transformers and adapt them to difficult operating conditions.