摘要
九边形模块化多电平换流器(modular multilevel converter,MMC)是一个三端口AC/AC/AC变换器,可替代两个独立AC/AC变换器以减少器件数量,可实现两个低频系统与工频系统互联。拓扑输入、输出端口电流在桥臂上的叠加,导致全桥单元电容电压低频波动,需要容值更大的直流电容抑制电容电压波动。此外,9个桥臂间环流包含较大直流分量与交流分量,造成桥臂电流应力提升。文中基于九边形MMC拓扑结构,推导电容电压波动表达式,分析环流产生机理,并设计一种环流注入和环流抑制混合控制,实现桥臂间电容电压均衡,降低电容电压纹波率和桥臂电流幅值。最后,在RT-lab仿真平台上验证环流控制有效性。
Nonagonal modular multilevel converter(NMMC)is a three-port AC/AC/AC converter.It can decrease the number of power switches and achieve the interconnection of AC grid and two low frequency systems.The input and output currents of converter coupled on the branch,cause large low-frequency fluctuation in DC voltage,and larger capacitors are required to suppress DC voltage fluctuation.Moreover,the circulating current comprises large DC component and AC components,which also increases the current stress.Based on NMMC topology,DC voltage fluctuation and generating mechanism of circulating current are analyzed in this paper,and the combination of circulating current injection control(CCJC)and circulating current suppression control(CCSC)is proposed to achieve DC voltage balance among the branches and suppress DC voltage fluctuation and current stress.Eventually,the proposed control is verified at RT-lab simulation platform.
作者
黄文慧
刘飞
庄一展
黄艳辉
刁晓光
查晓明
HUANG Wenhui;LIU Fei;ZHUANG Yizhan;HUANG Yanhui;DIAO Xiaoguang;ZHA Xiaoming(School of Electrical Engineering and Automation,Wuhan University,Wuhan 430072,Hubei Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2023年第22期8850-8861,共12页
Proceedings of the CSEE
关键词
九边形MMC
低频波动
电容电压波动
环流注入
环流抑制
nonagonal MMC
low frequency fluctuation
DC voltage fluctuation
circulating current injection control(CCJC)
circulating current suppression control(CCSC)
