Multi Busbar Sub-module Modular Multilevel STATCOM with Partially Rated Energy Storage Configured in Sub-stacks

This paper presents a modular multilevel STATCOM with partially rated energy storage configured in sub-stacks based on full bridge multi busbar Sub-module (SM). The soft-paralleling mechanism and doubled paths increase the current limit. The lower level controller of the proposed topology is detailed introduced and the performances are compared with a conventional single-busbar full bridge STATCOM controlled by classic SM sorting based low level controller. When providing reactive power compensation, power losses is reduced by 14.9%, and the maximum SM voltage deviation is reduced by 35.2%, while active power capability is further improved from power factor = 0.5 to power factor = 0.7 with the proposed control framework of the MBSM STATCOM.