The converter transformer valve side bushing is an important equipment to realize the electrical connection between the converter transformer and the valve tower. The paper mainly discusses the design of the external insulation structure. The research content is divided into three parts

the actual operating environment and the characteristics of the voltage and current waveforms of converter transformer bushing are discussed. The design and analysis of the hollow composite insulator

corona ring and tail end of the bushing has been done. The three dimensional electric field simulation model has been set up to calcu

late and analyze the external insulation performance of the bushing.The results show that the main insulation of the bushing is fit to the capacitive structure

and the end of the bushing should be equipped with apple type corona ring. The insulation distance of the hollow composite insulator is designed as 7 490 mm. The insulation distance of the bushing tail is designed as 3110 mm. In the actual operating environment

the maximum field strength of the corona ring appears on the lower end surface

and the value is 2 386 V·mm

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. The results of the paper can provide the theoretical basis for the design of the external insulation of the converter transformer bushing used in the HVDC transmission project.