基于MMC拓扑的构网型变流器动态均压策略研究OA

When the grid-forming modular multilevel converter(MMC)is applied in the high-voltage and large-capacity scenarios,there occurs an imbalance in voltage among a large number of bridge arm sub-modules.Voltage equalization strategies relying on sorting algorithms will give rise to problems such as excessive computational burdens and delayed responses.This paper first reveals the action mechanism and internal connection of each functional link within voltage balancing strategies,and comparatively analyzes the sorting mechanisms and sorting efficiencies of different sorting algorithms.Secondly,based on the characteristics of the actual operating voltage data of sub-modules,the optimization principles of the sorting algorithm are established from three aspects:time complexity,space complexity and stability;a dynamic switching strategy based on the historical information of the voltage data of sub-modules and the constraints of physical storage space is proposed.According to the voltage distribution characteristics of sub-modules and the real-time physical memory,sorting algorithm of the controller is adaptively allocated,with the time and space complexity of the equalization process optimized.Finally,an MMC simulation verification model is built based on PSCAD/EMTDC.The results show that when the computing resources are sufficient,the sorting mechanism of the sorting algorithm has no impact on the equalization voltage effect,and that the proposed equalization strategy can both significantly reduce the computational load take the physical memory into account,with the system running speed improved.