Heat Transfer Characteristics of Novel Resin Impregnated Paper Converter Transformer Valve‐Side Bushing With Two‐Phase Closed Thermosyphon

ABSTRACT Resin impregnated paper (RIP) converter transformer valve‐side bushings are the key equipment in converter stations. Local overheating of the RIP core not only reduces the transmission efficiency but also causes insulation failure of converter transformers. In this paper, a new heat dissipation structure is proposed to improve the temperature distribution homogeneity of the bushing using two‐phase closed thermosyphon (TPCT). A test model is developed to determine the optimal working fluid inventory. Then, the temperature distribution of a ± 400‐kV RIP converter transformer valve‐side bushing with an optimised heat dissipation structure is obtained using the coupled three‐dimensional electromagnetic‐fluid‐thermal numerical simulation method considering multiphase flow and phase change processes. The influence of the new structure on the electric field is analysed. The simulation result is verified by the temperature rise test. The results show that two‐phase closed thermosyphon can reduce the maximum temperature of the RIP valve‐side bushings and significantly improve the temperature distribution homogeneity.