Journal of Electrical Engineering and Automation

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.

Flexible DC transmission; Modular multilevel converter; Circulation suppression; Control strategy; Topological improvement