Control Strategy for Fault-Tolerant Cascaded Multilevel Converter based STATCOM

Cascaded multilevel converters have been widely used in STATCOM application. Attentions were drawn to the issue of reliability because of the high number of power devices. In this paper, the concept of redundancy is applied to improve the reliability of CMC, a protection scheme to achieve HBBB redundancy in CMC-based STATCOM is proposed. The operating principle and control strategy are introduced and discussed. A 7-level CMC-based STATCOM simulation platform is set up. Controller for the system is designed. Proposed protection scheme is implemented. Simulation results verify the proposed HBBB redundancy protection scheme.