An Improved Thermal Model for Power Transformers with Dynamic Loading

This paper proposed an improved thermal-circuit model for power transformer hot-spot temperature prediction with dynamic loading. The influences of solar radiation and the environmental temperature on the heat dissipation were also considered. When calculating the heat dissipation from the transformer tank to surroundings, the average oil temperature was selected as the node value in the thermal circuit. The new thermal models will be validated with the delivery experimental data of a 220kV-300MVA unit and a 220kV-75MVA unit.