An Improved Method for Calculating the Radiative Cooling Heat Dissipation Power of an Oil‐Natural‐Air‐Natural Transformer

Abstract

ABSTRACT Radiative cooling holds potential for outdoor transformers in operation due to its zero‐energy consumption and high adaptability and has demonstrated effective heat dissipation in simulations of small distribution transformers. Accurate calculation of the transformer temperature rise and the radiative cooling effect is crucial for practical application. However, the existing method for evaluating the heat dissipation effect of radiative cooling technology on transformers approximates losses by using a constant heat source, neglecting the impact of temperature on losses, resulting in low accuracy in radiative cooling power. Consequently, this study introduces an electromagnetic‐thermal‐fluid‐radiation multiphysics coupling approach based on finite element analysis. This method accounts for the two‐way coupling of electromagnetic and thermal fields, along with the nonuniform distribution of losses. Firstly, based on the heat transfer process of an oil‐natural‐air‐natural (ONAN) transformer, a small test platform (tank dimensions of 30 cm × 20 cm × 30 cm, rated power of 250 W and similar to those of a 10 kVA–10 kV/220 V single‐phase ONAN transformer in dimensions and loss) is built to evaluate the proposed method's accuracy against the existing method. Comparative analysis shows that the proposed method yields maximum errors of −4.0% and −4.8% in temperature rise and radiative cooling heat dissipation effect calculations, respectively, demonstrating a significant accuracy improvement of 16.2% and 25.3% over the existing method. Finally, the radiative cooling heat dissipation characteristics of an 800 kVA–10 kV/3 kV three‐phase ONAN transformer (total losses amount to 8557.3 W) are simulated and analysed using the proposed method. This study serves as a guiding framework for the accurate estimation of radiative cooling power in outdoor power transformers.