A study on the circulation suppression method of modular multilevel converters (mmc) in flexible dc transmission systems
柔性直流输电系统中模块化多电平换流器（MMC）的环流抑制方法

摘要

模块化多电平换流器（MMC）在柔性直流输电系统中广泛应用，但其内部环流问题严重影响系统稳定与效率。针对此，深入研究 MMC 环流特性，剖析其产生机理与影响因素。基于数学模型，提出优化控制策略与拓扑改进方案，有效抑制环流。通过理论分析与仿真验证，所提方法能显著降低环流幅值，提升系统运行性能与可靠性，为柔性直流输电系统的优化设计与稳定运行提供重要参考，对推动相关技术发展具有积极意义。

Abstract

Modular multilevel converters (MMC) are widely used in flexible DC transmission systems, but their internal circulation issues significantly impact system stability and efficiency. To address this, the study delves into the circulation characteristics of MMC, analyzing the mechanisms and influencing factors behind these issues. Based on mathematical models, the study proposes optimization control strategies and topological improvements to effectively suppress circulation. Theoretical analysis and simulation validation show that the proposed methods can significantly reduce the amplitude of circulation, enhancing system performance and reliability. This provides important references for the optimization design and stable operation of flexible DC transmission systems and has positive implications for advancing related technologies.