Determination of OD cooling system parameters based on thermal modeling of power transformer winding

Power transformers are the main and one of the most expensive parts of electrical networks. Optimum design of power transformers and their cooling system requires the precise calculation of losses, hot spot temperature and position. In this paper, thermal behavior of winding in power transformers and its insulation system have been modeled and parameters affecting the transformer cooling have been determined. This study is based on the thermal modeling of disk winding. Using software programs, several cooling schemes have been simulated and the results show the effect of different geometrical parameters on cooling of the transformer winding. The exact position of hot spot and the heat loss of a model transformer has been obtained and compared with the results provided by the manufacturer. It is shown that inclusion of eddy current losses improves the prediction of the hot spot position, while ignoring this loss could lead to inaccurate prediction of the hot spot position and temperature.