ETO light multilevel inverter for STATCOM

This paper presents a 10 MVA multilevel inverter for the application of static synchronous compensator (STATCOM). Emitter Turn-Off (ETO) thyristors are used as active switching devices in the inverter. The cascade multilevel inverter is based on ETO light H-Bridge Building Block (HBBB). The technology innovations of ETO simplify the HBBB construction. Air-cooled heat pipes also decrease the cost and increase the reliability. Large turn-off SOA and self-power of ETO, modular design and multi-layer protection fatherly enhance the reliability. The optimal combination modulation strategy is used to optimize the tradeoff between switching frequencies and harmonic constraints. Finally, the paper presents the complete control strategy, including the new control for balancing individual dc capacitor voltages, and multi-layer protection as well. Experimental results are given to verify the performance.