In MMC-HVDC (modular multilevel converter-based high-voltage direct current) applications, conventional control methods have defects such as complicated control and difficulty in controlling the internal energy of the converter. To ensure the safe and stable operation of an MMC-HVDC system, the problem of uneven internal energy distribution and increased fluctuations in the modular multilevel converter under asymmetrical network voltage conditions must be addressed. This paper has designed, a novel model predictive control (MPC) for MMC-HVDC applications. Through the proposed strategy, the switching states of all the MMC units can be optimized, which eliminates the circulating currents and achieves a voltage balance of the capacitor by redundant switching states. Moreover, an energy control circuit is established to adjust the DC bus power distribution in the MMC three-phase bridge arm. Thus, the symmetrical ac-side current can be realized, and the MMC internal energy imbalance caused by the transient process of the system can be avoided. Finally, the proposed novel predictive control strategy is tested via a case study. The obtained simulation and experimental results verify the effectiveness of the proposed control strategy.

在MMC-HVDC（基于模块化多电平转换器的高压直流电）应用中，传统的控制方法具有诸如控制复杂和难以控制转换器内部能量的缺陷。为了确保MMC-HVDC系统的安全稳定运行，必须解决内部能量分布不均匀以及模块化多电平转换器在不对称网络电压条件下波动增加的问题。本文设计了一种适用于MMC-HVDC应用的新型模型预测控制（MPC）。通过提出的策略，可以优化所有MMC单元的开关状态，从而消除了循环电流，并通过冗余开关状态实现了电容器的电压平衡。而且，建立能量控制电路以调节MMC三相桥臂中的DC总线功率分配。因此，可以实现对称的交流侧电流，并且可以避免由系统的瞬态过程引起的MMC内部能量失衡。最后，通过案例研究对提出的新型预测控制策略进行了测试。所获得的仿真和实验结果验证了所提出的控制策略的有效性。