To promote the application of HVDC system and FACTS devices with voltage sourced converters, it is essential to attain performance improvement and cost reduction simultaneously through the rationalization of converter design. This kind of design coordination first requires comprehensive evaluation of the relation between converter performance and design parameters. This paper discusses the effect of various design parameters on VSC performance-such as loss, harmonics and maximum overcurrent at the system fault. The design parameters particularly include semiconductor device characteristics as well as PWM pulse number and converter control speed. Performance of a 300 MW IGBT converter when applied to an HVDC system has been evaluated through numerical analyses. The results obtained make it possible to elaborate a rational converter design with satisfactory performance requirements for the HVDC application.