Improved Dynamic Thermal Model With Pre-Physical Modeling for Transformers in ONAN Cooling Mode

In order to dig out more potential of design parameters besides nameplate information, a set of pre-physical modeling methods was proposed and integrated into the dynamic thermal modeling procedure, aiming to optimize the key thermal parameters individually. In this method, a global oil momentum model was created considering the flow resistance, and for the problem of heat transfer between windings, oil flow, and radiator, a whole oil flow thermal model was established based on heat transfer principle and energy conservation. Then, the double logarithmic linear regression was applied to quantify the value of the exponents. According to the overload heat run tests, the temperature calculated by the existing models during multiple overloads is obviously different from the measured temperature, while the improved dynamic thermal modeling procedure with optimized thermal parameters attains estimates more accurately.