中文摘要：

针对现行换相式和同相牵引供电系统的特点，分析一种采用直接三相-单相交直交变换型贯通同相供电系统方案。该方案既能解决牵引供电系统电能质量问题，又能取消掉牵引网上的薄弱环节“电分相”，有利于高速、重载机车实现全线贯通运行。针对贯通供电变电所控制方式，提出采用直接功率控制策略。该方法以瞬时无功理论为基础，控制三相侧和单相侧功率交换。仿真结果表明，在有功和无功指令突变的情况下，变流器能够进行快速跟踪指令，有良好的控制效果。

英文摘要：

To slove the problems with the current phase-change and cophase traction power supply systems , the continuous cophase traction power supply system with direct three phases to single phase AC-DC-AC conver-sion was proposed . The new power supply scheme was able to supply power without quality problems , remove neutral sections , the weak link of the traction network ,and provide favourable conditions to realize continuous traffic of high-speed heavy-load trains over the w hole journey . In view of the substation control mode , the di-rect power control strategy was suggested .On the basis of the instantaneous reactive power theory ,active and reactive power conversion between the three-phase and single-phase sides was controlled . Simulation results show that in the case that active and reactive power instructions change suddenly , the current converter can fast trace the instructions , thus producing good control effect .