In this paper, a priority sorting approach based on simplified model predictive control (MPC) is proposed for modular multilevel converter (MMC). It aims at reducing the computational burden of conventional MPC method while maintaining the system performance, especially under high voltage levels. The proposed approach mainly consists of three parts, i.e., grid-side current control (GCC), circulating current control (CCC), and capacitor voltage balancing control (CVBC). The GCC and CCC are separately designed with simplified MPCs, avoiding the weight factor. Meanwhile, the redundant calculations are eliminated in GCC by considering the desired predicted output voltage of equivalent MMC model. To further minimize the optional combinations of the switching states, the CCC is constructed by utilizing the output of GCC and the arm current. Besides, a novel priority sorting approach is proposed for the CVBC to alleviate the sorting operation. The submodules are divided into three groups according to the detected capacitor voltages. Moreover, the groups are assigned with different priorities based on the arm current, and only one group needs the sorting process. Additionally, a reduced frequency approach is introduced to decrease the power loss in the steady state. The effectiveness of the proposed approach is validated by both simulation and experimental results.

中文翻译：

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基于简化模型预测控制的模块化多电平变流器优先级排序方法


本文针对模块化多电平转换器（MMC）提出了一种基于简化模型预测控制（MPC）的优先级排序方法。它的目的是减少传统MPC方法的计算负担，同时保持系统性能，特别是在高电压水平下。所提出的方法主要由三部分组成，即网侧电流控制（GCC）、环流控制（CCC）和电容器电压平衡控制（CVBC）。 GCC和CCC分别采用简化的MPC设计，避免了权重因素。同时，通过考虑等效MMC模型所需的预测输出电压，在GCC中消除了冗余计算。为了进一步最小化开关状态的可选组合，CCC是利用​​GCC的输出和臂电流构建的。此外，还为 CVBC 提出了一种新颖的优先级排序方法来减轻排序操作。根据检测到的电容器电压，子模块分为三组。而且，根据臂电流为各组分配不同的优先级，并且只有一组需要排序过程。此外，还引入了降低频率的方法来降低稳态下的功率损耗。仿真和实验结果验证了所提出方法的有效性。