Hot Spot Temperature Prediction of Transformer Windings Naturally Cooled by Internal Oil Based on Thermoelectric Analogy Principle

Aiming at the problem that the hot spot temperature of oil-immersed power transformer with natural oil cooling is affected by oil temperature and oil time constant, a prediction model of hot spot temperature of transformer winding based on thermoelectric analogy principle is proposed in this paper. Firstly, based on the principle of thermoelectric analogy, considering the change of time constant of top oil affected by oil temperature, the Susa thermal model is improved, and the thermal model of power transformer with natural cooling of internal oil is established. Secondly, based on the top oil temperature, the fourth-order Runge–Kutta method is used to calculate the winding hot spot temperature. Then, the research group used the model SFSZ7-31500/110 transformer for temperature rise test. Finally, the proposed algorithm is verified by simulation experiment and compared with Susa’s temperature rise algorithm. The results show that the proposed algorithm has less error, which verifies the effectiveness of the proposed method.