PROJECT TITLE :

On the Redundancy Strategies of Modular Multilevel Converters - 2017

ABSTRACT:

The modular multilevel converters (MMCs) became an enticing topology in recent years. The MMC has been utilized in many applications as HVdc, energy storage, renewable energy, electrical drives, and static synchronous compensators (STATCOMs). One advantage of MMC-primarily based topologies is that the inherited fault-tolerant operation associated with the high variety of submodules (SMs). This work proposes the study of four redundancy strategies, which will be employed in modular multilevel converters: commonplace redundancy, redundancy strategy primarily based on further submodules (RAS), redundancy strategy based on extra submodules optimized (RASO), and redundancy strategy based mostly on spare submodules. These strategies are compared through a case study of a fifteen MVA MMC STATCOM. A replacement approach for the SM capacitance design is proposed, together with the impact of the negative sequence current within the converter storage energy variations. The comparisons of the redundancy ways are accomplished based on dynamic behavior, capacitor voltage balancing, control complexity, and power losses. Finally, the benefits and disadvantages of each redundancy strategy are presented.