Improved thermal hydraulic network modelling and error analysis in disc‐type transformer windings

Abstract Temperature distribution in transformer windings is a crucial factor that influences the safe operation, and lifespan of an insulating system in an oil‐immersed power transformer. Thermal hydraulic network modelling (THNM) has been the subject of numerous studies because of its lower computation cost as compared to a computational fluid dynamics (CFD) simulation. This study proposes improvements to THNM, with primary focus on non‐uniformity of temperatures in the entry and exit vertical oil ducts, and the feasibility of using a piecewise fitting formula for Nusselt number (Nu) of convection heat transfer coefficient in transformer windings. The deviation of hot spot temperature was 0.3°C, and the location of hot spot for CFD and THNM was 34th disc and 35th disc, respectively. The calculation time of CFD and THNM was about 34 h and 35 s under the same computer hardware situations. This provides an acceptable THNM method for the rapid prediction of transformer hot spot temperature and location at low costs for digital twin.