基金项目:国家自然科学基金(51667007)；中国南方电网有限责任公司重点科技项目(GZKJQQ00000417)。Project Supported by National Natural Science Fund (51667007); The key science and technology projects of China Southern Power Grid Co., Ltd. (GZKJQQ00000417). 相较于交流配电网,直流配电网在很多领域取得了技术和经济优势,具有巨大的发展前景[1-3]。在直流配电领域,目前多以低压直流配电为主,对中压直流配电网的研究还较少。在低压直流配电网中,换流器多采用电压源换流器(Voltage Source Converter,VSC), 其控制方式已相当成熟。自德国学者Marquardt R.及其合作者提出了模块化多电平换流器(Modular Multilevel Converter,MMC)的拓扑结构后,有关MMC的研究就已成为输配电领域的热点。
Modular multi-level converter has been extensively studied in the field of HVDC transmission and many engineering applications have been made so far. This article describes the topology and working principle of a modular multilevel converter and its submodules. A two-terminal modular multi-level converter simulation system based on PSCAD / EMTDC is built, which realizes the comparison of the two most commonly used modulation strategies. The output voltage, output current, A-phase bridge current and capacitor voltage fluctuation of each bridge arm sub-module 1 are compared under different modulation modes. It is of certain reference value to the engineering application of the modular multi-level converter in medium voltage DC distribution network.