摘要
模块组合多电平变换器是应用于高压大功率电能变换领域的优秀拓扑之一,具有高度模块化、输出波形谐波含量少、无需工频变压器等优点。然而环流的存在使得模块组合多电平变换器的桥臂电流发生畸变,提高了器件的额定电流容量,进一步增加了系统成本。本文提出了模块组合多电平变换器的环流模型,将环流的作用等效为两个电流控制的电压源(CCVS),推导了环流和直流母线电流的定量关系,并结合实际系统特点对该关系式进行了修正。最后本文分析了环流中存在低频分量的原因,分析结果同时表明了模块组合多电平变换器适用于需要实现三相负序平衡的场合。
Modular multilevel converter（MMC） is one of the excellent selections for high voltage and high power conversion applications without transformers.It provides the advantages such as high modularity,availability,low generation of harmonics,etc.However,the circulating current distorts the leg currents and increases the rated current of power devices,which further increases system cost.By controlling the circulating current as CCVS（current controlled voltage sources）,this paper derived the circulating current model of MMC.Then the quantitative relationship between the circulating currents and dc-bus current is derived and modified considering the actual characteristics of the circulation system.Further,this paper also reveals the existence of low-frequency components in the circulating currents.It means that MMC is suitable for the need to achieve negative sequence balancing applications.
出处
《电工技术学报》
EI
CSCD
北大核心
2011年第5期21-27,共7页
Transactions of China Electrotechnical Society
基金
北京交通大学优秀博士生科技创新基金资助项目(141091522)
关键词
模块组合多电平变换器
环流
桥臂电流
电流控制电压源
负序
Modular multilevel converter
circulating current
leg current
current controlled voltage source
negative sequence
