Inserted Window Recognition Based Capacitor Condition Monitoring Method for MMC Sub-Module with Nearest Level Modulation

Wenqi Lin and Jianyu Pan ()
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Wenqi Lin: State Key Laboratory of Power Transmission Equipment Technology, School of Electrical Engineering, Chongqing University, Chongqing 400044, China
Jianyu Pan: State Key Laboratory of Power Transmission Equipment Technology, School of Electrical Engineering, Chongqing University, Chongqing 400044, China

Energies, 2025, vol. 18, issue 5, 1-19

Abstract: The sub-module capacitor is the most vulnerable component in a modular multilevel converter (MMC), and its aging poses a significant challenge to system stability. To accurately monitor capacitor aging, this article utilizes capacitor voltage fluctuations to recognize the inserted window for capacitance calculation using nearest-level modulation. Additionally, a time-slicing method is developed to improve accuracy. The proposed method, which combines the inserted window recognition method with the time-slicing algorithm, offers a simple, easy-implementation approach. Simulations and experimental results validate that the method achieves high accuracy (less than 0.5%). Moreover, it does not require additional sensors, precise extraction of switching signals, or interruption to the system’s normal operation, making it highly suitable for MMC systems with a large number of sub-modules. Furthermore, the proposed method also demonstrates strong robustness in dynamic conditions and can be extended to all sub-modules.

Keywords: modular multilevel converter; capacitance monitoring; nearest level modulation; high precision (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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