Modular multilevel converter based ship medium voltage DC grid capacitorless design, control and fault protection
Yang Rongfeng1, Yu Yannan2, Wang Guoling1, Wu Defeng1, Yu Wanneng1
1. School of Marine Engineering, Jimei University, Xiamen, Fujian 361021; 2. College of Mechanical and Control Engineering, Guilin Unversity of Technology, Guilin, Guangxi 541006
Abstract There exist a large number of capacitors in conventional ship DC grid, which not only enlarges the system size, but also generates great current under fault condition, and this deteriorate fault protection. This paper proposed one capacitorless structure for ship medium voltage DC grid (MVDC), and this design avoids the capacitor discharge process during DC grid short circuit fault. Different from conventional DC grid, the DC voltage exists great fluctuations without the capacitor filter, thus the modular multilevel converter (MMC) is employed as interface converter to extenuate this influence, realizing DC/DC, DC/AC conversion. The MMC application problems caused by the abnormal grid voltage are also analyzed, and two control strategies are proposed to resolve this problem. Furthermore, this type DC grid fault features are also discussed, and the protection strategy based on AC side is provided. The proposed DC grid performance is validated by PLECS simulation and experimental results.
Yang Rongfeng,Yu Yannan,Wang Guoling等. Modular multilevel converter based ship medium voltage DC grid capacitorless design, control and fault protection[J]. Electrical Engineering, 2020, 21(10): 41-49.
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2020, Vol. 21 
