A Top-Oil Thermal Model for Power Transformers That Considers Weather Factors

The aim of this work is to develop a top-oil thermal model based on the thermal-electrical analogy and heat transfer principles that captures influence prevailing winds solar radiation which can be generally applied large power transformers. key improvements proposed are calculating coefficient radiator air side using Nusselt number combined forced natural convection, including as an addition source. validated with operational measurements 3 transformers comprised 120/240-MVA unit two 90/180-MVA units. results also compared predictions IEEE-Annex G model. more accurate over windy summer periods expected.