Investigation of a cascade multilevel inverter as an STATCOM

A 7-level cascaded H-bridge inverter was chosen as candidate design for a multilevel STATCOM (M-STATCOM). The investigation studied the operation of the M-STATCOM in areas such as: steady state performance, dynamic behavior of the M-STATCOM and control and balancing of the capacitor voltages. There are two switching methods used in this study, the first one is the fundamental frequency switching (FFS) method with pulse rotation and the second method is pulse width modulation (PWM) switching techniques. The system is digitally modelled to obtain the study results.