Model Predictive Control with Circulation Suppression for MMC

Model predictive control (MPC) is increasingly employed in modular multilevel converters (MMC) control due to its flexible management and rapid response capabilities. It is still challenging to minimize the computational load due to its large-scale sub-modules. To address this issue, this paper introduces an improved model prediction algorithm based on sub-control sets. The proposed control strategy is derived from the discrete model of the MMC. It also considers the inhibitory effects on bridge arm circulation. The objective function for finite control set model predictive control (FCS-MPC) is formulated to effectively tackle multi-objective control challenges. The algorithm not only reduces computational demands but also demonstrates strong control performance with respect to the AC side current and circulating current. The proposed method improves the current harmonic distortion (THD) suppression rate by 1.6 % compared to traditional method, thereby validating the effectiveness of the introduced control strategy.