Research on Thermal Characteristics and Overload Capacity of Offshore Converter Transformers

As a core component of offshore flexible DC power transmission systems, the thermal characteristics and overload capacity of converter transformers have garnered significant attention.This study employs a field-circuit coupled calculation method that combines steady-state simulation and thermal circuit modeling to precisely evaluate these properties.Using Fluent, the temperature and flow fields of a 2D model are solved, examining the temperature-dependent variations in transformer oil's density, specific heat capacity, and thermal conductivity.These findings enhance the accuracy of thermal field simulations.Detailed descriptions of solid domain material properties and heat source configurations, including silicon steel, copper, and cellulose, are provided, along with heat flux density calculations for each low and high-voltage winding segment.Results indicate that the transformer's hot spot is at the low-voltage winding top, with the high-voltage winding's maximum temperature in the top segment, and the highest internal oil flow velocity at the internal baffle.The field-circuit coupled model, considering real-time requirements, demonstrates higher computational accuracy than standard methods through hotspot temperature calculations.These outcomes are highly valuable for improving the performance, reliability, and costeffectiveness of offshore wind power transmission systems and advancing the sustainable growth of the offshore wind energy sector.