AUTHOR=Qian Jianhang , Liu Zhijie , Li Ke-Jun , Li Liangzi , Guo ZhongLin 

TITLE=Reducing Submodule Capacitance for Modular Multilevel Converter-Based Medium-Voltage Wind Power Converter

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2022.883004

DOI=10.3389/fenrg.2022.883004

ISSN=2296-598X

ABSTRACT=This paper presents a strategy to reduce the capaci-tance of the submodule (SM) capacitor of modular multilevel converter-based medium-voltage wind power converter. Since the design of SM capacitor of modular multilevel converter (MMC) should consider the actual operating conditions, especially the influence of wind speed, because wind speed will affect the voltage ripple and voltage amplitude of SM capacitor. In the traditional method, the capacitance design of SM capacitor will be based on relatively high wind speed and leave a certain safety margin. However, in most cases, the system operates at the highest frequency wind speed (HFWS). For the MMC based wind energy conversion system, a constant capacitor voltage ripple (CCVR) control method is proposed. Through this method, the SM capacitor voltage ripple can be significantly reduced by injecting the second harmonic component of circulating current. In this way, the SM capacitor with smaller capacitance can be used. Finally, the effectiveness of the proposed method is validated in RT-Lab Platform.