Series Connected IGCT based High Power Three-Level Neutral Point Clamped Voltage Source Inverter Pole for FACTS Applications

This paper reports requirements, issues and design considerations for high power three-level neutral point clamped (NPC) inverter pole. Dynamic voltage sharing issues, viability and advantages of series connected 4.5 kV, 4 kA IGCT for high power 12 MVA three-level NPC inverter pole are investigated. IGCT turn-off tests at high DC voltage and rated current are used for snubber design and inverter pole clamp design, and to verify simulation results. Experimental results are presented for a two 12 MVA three-level NPC inverter poles operated as H-bridge with three series connected 4.5 kV, 4 kA IGCT per switch