A novel approach to investigate the hot-spot temperature rise in power transformers

For large power transformers, the hot-spot temperature rise in their structural parts is an essential issue to address. Computation of the hot-spot temperature rise is, however, a complicated engineering problem because of the uneven loss distribution and effect of internal oil flow upon the convective heat transfer coefficients on the body surfaces of transformers. This paper presents a novel approach to compute and analyze the hot-spot temperature rise of the structural parts for an ODFS-334 MVA/500 kV single-phase auto-transformer. The surface convection heat transfer coefficients, which are computed based on computational fluid dynamics, are used as the boundary conditions of the magnetic-thermal coupling analysis using finite-element method. To validate the feasibility and applicability of the proposed method, the numerical results obtained from the proposed method are compared with those of experimental ones.