标题：A novel comprehensive control scheme of low frequency of the modular multilevel converter
作者：Li, Feng ;Wang, Guangzhu
作者机构：[Li, Feng ;Wang, Guangzhu ] School of Electrical Engineering, Shandong University, Jinan, China
会议名称：2014 International Power Electronics and Application Conference and Exposition, IEEE PEAC 2014
会议日期：5 November 2014 through 8 November 2014
来源：Proceedings - 2014 International Power Electronics and Application Conference and Exposition, IEEE PEAC 2014
摘要：This paper analyzes the active power in modular multilevel converters (MMCs), and presents a novel comprehensive control scheme of low frequency operation for the arm capacitor voltages and high frequency circulating current. The inner loop of this scheme employs the arm current direct control which can control the AC side currents, dc-link current and circulating currents simultaneously; an improved feed forward current control scheme is presented, reducing the capacitor voltage dynamic fluctuations as well as avoiding feed-forward currents into the AC and dc sides. The outer-loop capacitor voltage control of each arm is almost independent of each other and can be easily implemented by distributed control, which introduces Proportional and Resonant (PR) regulator to suppress different frequency capacitor voltages. Meanwhile, the capacitor voltages balancing control between upper- and lower-arms of three phase are added to the outer loop to achieve circulation constraints control. Lastly the effectiveness of the scheme is verified under low frequency operation of three-phase load and an AC machine via the OPAL-Rtlab real-time simulation system. © 2014 IEEE.