Novel heat pipe current-carrying tube of RIP valve-side bushing in converter transformer

Converter transformer reliability and efficiency is dependent on resin impregnated paper (RIP) valve-side bushings. High hot spot temperature (HST) and uneven electro-thermal coupling field drive the accident rate of RIP valve-side bushings above acceptable levels even with 50% reduced transmission power. This paper proposes a novel heat pipe current-carrying tube of RIP valve-side bushing in converter transformers. The main principle centers on the phase-change effect of the working fluid, which is optimized for enhanced thermal conductivity and uniform temperature distribution. A novel heat pipe current-carrying tube is designed for the +/- 800 kV RIP valve-side bushing; a multiphysics simulation model considering the electro-thermal-fluid coupling field is established accordingly. The electric field distribution and temperature distribution are obtained under different currents and ambient temperatures. The simulation results are validated by comparison against temperature rise test results. The result shows that the use of heat pipe current-carrying tube can significantly reduce the HST of the valve-side bushing, balance the electro-thermal coupling field, and increase the transmission power of converter transformer.