GTO thyristor applications for HVDC transmission systems

Conceptual designs for convertor substation equipment for a HVDC (high-voltage direct current) transmission system using current- as well as voltage-source-type GTO (gate turn-off thyristors) power convertors (referred to as VSTGC and CSTGC) are presented. A study indicates that the VSTGC is preferable to the CSTGC. Also presented is a preliminary economic comparison between two HVDC-system alternatives for applying power to a weak AC system, one using a self-commutated GTO power convertor and the other combining a line-commutated convertor and a synchronous condenser. The result indicates that the two HVDC convertor substation alternatives cost about the same.<>