Application of High Power Thyristors in HVDC and FACTS Systems

Both HVDC and FACTS systems use power electronic converters for the power conversion and power quality control. High power thyristors have been serving as the key component in HVDC and FACTS converters for several decades now and are still being further developed for higher power rating nowadays. This paper describes the thyristor technology and its development in application in HVDC and FACTS. The fundamental features and characteristics of high power thyristors is discussed with particular reference to its application in high voltage and high current area. Many thyristors connected in series together with specially designed auxiliary mechanical and electronic systems build so called thyristor valves, which form the HVDC and FACTS converters. An overview of thyristor valve design is provided. Furthermore, the latest development in the thyristor and thyristor valve technology and its application in the ultra high voltage DC application (800 kV) is introduced. A summary of technical key parameters and design features of 6” thyristor valves are provided including the valve design date for the first UHVDC application.