Research on Inversion Model of Winding Hot Spot Temperature of 10-kV Oil-Immersed Three-Dimensional Coiled Core Transformer

Realizing online monitoring of the hot spot temperature of grid mounted transformer windings is a challenge for the power industry. The heat exchange process between the internal heat source area and the external field area of the transformer is the direct cause of the temperature increase of the transformer shell. In this paper, based on the numerical coupling calculation of temperature - fluid field of 10kV oil immersed solid coiled iron core transformer, the typical heat flow streamline is extracted, and the measurable temperature characteristic points strongly correlated to the winding hot spot temperature are selected in the heat dissipation area of the shell, and the inversion model of the transformer winding hot spot temperature is established. This article verifies the effectiveness of the simulation results and the accuracy of the inversion model through the multi condition temperature rise test of transformer. The maximum error between the calculated steady-state temperature rise of each temperature measurement point in the simulation model and the test value is no more than 3°C, the simulation calculation results are in good agreement with the test results, and the average absolute error of the inversion model winding hot spot temperature inversion is 2.67 %, the maximum temperature difference is less than 3°C. This research provides an effective method for online monitoring of the hot spot temperature of the winding of a 10kV oil-immersed three-dimensional coil iron core transformer, and provides a reference for the state detection of grid mounted transformers.