摘要
分析了模块化多电平换流器(MMC)的电路结构和运行特性,指出了MMC每相上、下2个桥臂交流输出端是等电位点。将三相等电位点虚拟短接后,每相上、下2个桥臂换流电抗可以并联成一个电抗,与交流系统相连,其结构与传统电压源换流器(VSC)类似。文中据此得到了MMC的简化等效电路理论模型。根据该等效电路理论模型,MMC的控制可以直接使用传统VSC的控制策略。将传统VSC常用的矢量控制策略应用于MMC型直流输电系统。时域仿真结果表明,MMC每相上、下2个桥臂交流输出端的电位非常接近,验证了所提出的MMC等效电路理论模型的正确性。仿真结果也表明所设计的MMC型直流输电系统的矢量控制策略控制性能良好。
Modular multilevel converters （MMCs） belong to a new cascaded multilevel voltage source converter （VSC） suitable for HVDC transmission purpose. The analysis of circuit configuration and operation mechanism of MMC indicates that the potentials of the two AC terminals in one phase are approximately equal,such that these two AC terminals can be short circuited. By doing so,the upper and lower converter reactors in one phase are connected in parallel and hence can be merged into one. Accordingly,the theoretical equivalent circuit model of a MMC can be derived. The derived model has three terminals at the AC side,each one of them is connected to the three-phase power system through a converter reactor. The equivalent circuit model has the same structure as a conventional VSC. In this way,the conventional VSC control strategies can be directly used for MMC. The vector control strategy which is widely used in conventional VSCs is used for a MMC based HVDC transmission system. The time-domain simulation results show that the potentials of the two AC terminals in one phase are nearly equal,and the derived equivalent circuit model of the MMC is valid. Moreover,the vector control strategy is effective for controlling of the MMC based HVDC transmission systems.
出处
《电力系统自动化》
EI
CSCD
北大核心
2010年第19期64-68,共5页
Automation of Electric Power Systems
基金
"十一五"国家科技支撑计划重大项目(2006BAA02A21)~~
关键词
电压源换流器
电压源换流器型直流输电
模块化多电平换流器
换流电抗
等效电路
矢量控制
voltage source converter （VSC）
voltage source converter based high voltage direct current （VSC-HVDC）
modular multilevel converter （MMC）
converter reactor
equivalent circuit
vector control
