Over-Voltage Protection Strategy for Sub-Module of Modular Multilevel Converter with Reduced Sensors
Luo Derong1, He Ruizhi1, Huang Shoudao1, Zhang Zhigang2, Hou Weiyang1
1. College of Electrical and Information Engineering Hunan UniversityChangsha 410082 China; 2. College of Electronic Information and Electrical Engineering Changsha University Changsha 410003 China
Abstract：For the over-voltage problem in sub-module of modular multilevel converter (MMC) with reduced sensors, this paper proposes a sub-module over-voltage protection strategy. First of all, it is pointed out that the sub-module voltage not being directly measured in real-time is the cause of over-voltage. Then, the necessity of pre-detection of sub-module voltage before load access operation is studied. The sub-module over-voltage detection and prevention strategy during load access operation are proposed. Finally, case studies are performed on a 31-level single-phase MMC in Matlab/Simulink. Meanwhile, a 9-level single-phase MMC laboratory prototype is built to verify the effectiveness of this strategy. The simulation and experimental results show that the over-voltage protection strategy proposed in this paper can achieve good overvoltage protection effect when the capacitance parameters are consistent and deviated, and has strong parameter adaptability.
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2019, Vol. 34 
