Operating Characteristic of HVDC Wall Bushings Used in CSG

As a connecting device between DC field and valve hall of converter station, the DC wall bushing is in the“throat” position in HVDC project. Since the first 500kV DC wall bushing was put into operation in 1999, more than 88 DC wall bushings have been operated in CSG system. Long-term operating experience has shown that the main problems in the operation of DC wall bushings concentrated on mechanical failure, current-carrying structure and external insulation. In this paper, the structure and material of Resin Impregnated Paper bushing was described in detail first, and then the typical weakness during the electrical and mechanical design, such as internal discharge, overheating, mechanical damage and aging of silicone rubber, were analyzed respectively. More importantly, specific solutions for these damage were also put forward. The purpose of this paper is to sort out the design and structure of the DC wall bushing in operation of CSG, summarize and analyze the problems in the operation of the wall bushing, and then propose guidance and suggestions for the design, manufacture, operation and maintenance of the DC wall bushing.