A diode-clamped multi-level inverter for the StatCom/BESS

Flexible AC transmission systems (FACTS) are potentially becoming more flexible and more economical local controllers in the power system. The integration of traditional FACTS devices with energy storage system (ESS) will increase FACTS device functionality. The voltage-sourced inverter is an important part of many FACTS devices, such as the StatCom and SSSC. Considerable research has been done on 2-level inverter usage in FACTS. Multilevel inverters, however, can improve the voltage quality and reduce the voltage stress on the power electronic devices. This paper uses a diode-clamped multilevel inverter in the StatCom/BESS. The multilevel inverter switching strategy and output voltage model are proposed. The voltage balancing issue is addressed and a circuit solution is proposed. Finally, StatCom/BESS using a diode-clamped multilevel inverter is simulated in the power system.