An IGCT-based Multi-functional MMC System with Commutation and Switching

This paper proposes an Integrated gate commutated thyristor (IGCT)-based modular multilevel converter (MMC) system with commutation and switching functions (IGCT-ICS-MMC) to implement its fast DC short-circuit fault recovery scheme. In the event of DC fault, the IGCTs are actively short-circuited to eliminate the rectifier mode of MMC itself. The DC voltage is clamped to zero to prevent the rapid increase of DC fault current, thus reducing the requirement of maximum current interruption capability of the DC switch, which makes the DC solid-state switch could be consisting of IGCT. Therefore, the proposed IGCT-ICS-MMC can be multi-functional, including commutation and switching functions. The IGCT-ICS-MMC showed advantages in fault recovery, economical cost, and power losses, verified by simulation result.