适用于架空线路的双极混合MMC-HVDC拓扑

Topology of Bipolar Hybrid MMC-HVDC for Overhead Line Transmission

为应对柔性直流输电在远距离大容量架空线输电领域应用问题,基于钳位双子模块和双晶闸管子模块拓扑构成的两种模块化多电平换流器,设计了串联双极混合直流输电系统,既提高了输电容量,又能缓解单种拓扑能耗较大或直流故障抑制时间较长问题。重点分析了双极混合拓扑在不同直流故障下等值电路和直流故障穿越机理及其抑制特性。最后,在PSCAD/EMTDC仿真环境下搭建双极混合直流输电模型,对系统稳态运行工况和直流故障穿越特性进行了对比研究。仿真结果表明,双极混合系统既体现出灵活多样的稳态运行特性,又具有直流故障穿越与快速恢复能力,较好地适用于远距离大容量架空线路输电应用领域。

To solve the problem of flexible application of high voltage direct current（HVDC）systems in long distance bulk power overhead line transmission,based on modular multilevel converter（MMC）with double clamp sub-module topology and dual thyristor sub-module topology,a bipolar hybrid MMC based HVDC（MMC-HVDC）transmission system is designed not only to tackle the level of DC voltage,output capacity and DC fault suppression capability,but also to solve the great energy consumption or long DC link fault enduring issues.The equivalent circuit and fault blocking mechanism is analyzed under different DC link faults,and the system restart process is also designed.Finally,the hybrid HVDC is built in PSCAD/EMTDC simulation environment,and a variety of operating conditions and fault ride-through characteristics of the system are studied.Simulation results show that the bipolar hybrid system has not only flexible and diverse steady-state operation characteristics,but also DC fault ride-through and rapid recovery capabilities better suited to large capacity long distance overhead line transmission applications.