中文摘要：

为解决传统牵引供电系统中所存在着电能质量和过分相问题，首先介绍了一种基于MMC—MTDC的新型牵引供电系统。新型牵引供电系统中需要单相变流器向牵引网提供稳定的电压和频率，据此对单相H桥型模块化多电平换流器MMC（modularmultilevelconverter）进行了研究。介绍了该变流器的拓扑特性，建立了相应的数学模型。将牵引网络认为成无源网络，设计一种基于虚拟同步坐标系下外环定交流电压、内环电流的单相H桥MMC型逆变器向单相无源网络供电的双闭环控制策略：为了抑制桥臂电流所含的二次分量，使用准比例谐振器设计了环流抑制器。最后，在PSCAD／EMTDC中搭建仿真模型。仿真结果验证了系统控制策略的可行性和环流抑制器的有效性，变流器能够向牵引网络提供稳定的电压和频率。

英文摘要：

To solve the problems of power quality and split section that existing in the traditional traction power supply system （TPSS）, a novel TPSS based modular multilevel converter multi terminal high voltage direct current （MMC-MTDC） was presented in this paper. The novel TPSS requires single-phase converter provides the voltage and frequency stability to traction network. Accordingly, a single-phase H bridge modular multilevel converter （SPH-MMC） was studied in this paper, its topological characteristics is describes and its mathematical model is established. Considering traction system as passive network, a double closed loops control strategy is proposed for SPH-MMC inverter supply to single-phase passive network, which constant ac voltage outer and current inner loops. To suppress the secondary component contained in arm current, circulating current suppressing controller is developed with quaisproportion resonant controller （QPR）. Finally, a simulation model was constructed in PSCAD/EMTDC. The simulation results verifies that the proposed control strategy of system is feasible, the suppressing controller of circulating current is effective, and the converter can provides stable voltage and frequency to traction network.