Five level diode clamped voltage source inverter and its application in reactive power compensation

This paper deals with multilevel diode clamped voltage source inverter applied as STATCOM. The authors use "offline" optimization of switching angles together with fundamental frequency modulation switching strategy (FFM). They show that reactive power compensation is achieved by controlling the exchange of active power between the DC side of the inverter and the AC system. Moreover, they show that it is not possible to achieve the proper compensation during unbalanced conditions of the system while an FFM switching strategy is used together with "offline" optimization of switching angles. Simulation and experimental results are presented.