Multi-Physical Field Coupled Method for Temperature Rise of Winding in Oil-immersed Power Transformer

Abstract

Power transformer failures often result from elevated hot spot temperatures, which disrupt the regular operation of power systems. To precisely determine the hot spot temperature of transformer windings, this paper employs a 110kV oil-immersed power transformer as a case to develop a three-dimensional electromagnetic-temperature-fluid multi-physics coupling simulation model for the transformer. The core and winding loss density distribution is obtained through magnetic field calculations. On this basis, the loss density serves as the heat source, and temperature and flow field simulations for the transformer are conducted using thermal-fluid coupling. In addressing the issue of temperature discontinuity at the interface of fluid and solid coupled heat transfer, an adaptive grid refinement method is adopted to enhance grid resolution at the interface while employing a coarser grid in flatter regions, thus enhancing the precision of numerical simulations. Finally, the simulation results are compared with hot spot temperature calculations obtained through empirical formulas, confirming the method's feasibility.