Modeling, analysis and control of cascaded-multilevel converter-based STATCOM

Modeling techniques for cascaded-multilevel converter-based STATCOM in abc and dqo coordinates are proposed. The simplified models for a balanced three-phase three-wire system in dqo are used in feedback controller design for cascaded seven-level converter-based STATCOM system. The development and analysis of the models are presented. Feedback control schemes are proposed to achieve a fast dynamic response as well as DC capacitor voltage balance. Computer simulation is performed to verify the accuracy of the models and performance of the controller. The simulation results show the consistency of the proposed models. In addition, the fast step responses in the order of subline cycle can be achieved.