Investigation on the 30MVA IGCT-based voltage source converter

The high power AC-DC-AC converters are widely used in various industrial fields. The integrated gate commutated thyristor (IGCT) is applied in medium and high voltage converter on a large scale due to its excellent characteristics. In this paper the investigation on the 30MVA IGCT-based high power voltage source converter is presented. The 30MVA converter is composed of two 15MVA IGCT-based five-level converters and the outputs of the two converters are in parallel connection. Each phase of the 15MVA five-level converter is composed of two IGCT-based three-level neutral point clamped (NPC) legs in an H-bridge form. The detailed topology design of the 30MVA large power converter is introduced in this paper. The modularization design is adopted in the converter to reduce its size and improve its power density. The power module of IGCT-based three-level NPC leg has been developed. The switching characteristics of IGCT are investigated and the influences of snubber circuit are simulated. The experiment of turn off process of IGCT is carried out. One type of carrier-based modified in-phase disposition (IPD) modulation scheme is researched and simulated.