Optimal Redundancy Configuration of Hybrid MMC Considering Maintenance Cost of Life Cycle

Modular multilevel converter (MMC) has been widely used in the field of HVDC transmission. In practical application, the hybrid MMC topology with half-bridge submodule(HBSM) and full-bridge submodule(FBSM) gradually shows its advantages. The configuration ratio of the two redundant sub-modules(SMs) in the hybrid MMC affects the reliability and economy of the system. Therefore, this paper proposes the hybrid MMC redundancy optimization strategy based on maintenance strategy. Firstly, the hybrid MMC topology is studied and the system reliability model is established; secondly, combined with the MMC maintenance and replacement strategy, a minimum cost model based on age replacement policy is established; finally, through the case, the minimum maintenance cost corresponding to the different proportion of redundant SMs and the sensitivity of the optimal maintenance cycle to the redundancy ratio parameters are obtained. The results show that under the premise of high reliability, the economic benefit of redundant configuration can be maximized by the above model under the optimal maintenance cycle.