具有直流故障穿越能力的模块化多电平换流拓扑推演与对比

直流故障具有影响范围广、故障电流大的特征，已成为制约直流系统发展的重要因素之一。模块化多电平换流器可通过配置双极性子模块实现直流故障穿越，但相比于基于半桥子模块的拓扑，其建造成本与运行损耗均大幅增加。为寻求兼顾硬件成本、运行效率与直流故障穿越能力的模块化多电平换流拓扑，首先通过拓扑抽象定义与模块配置约束，遍历并推导出4大类共13种模块化多电平换流拓扑；进而优选出T型桥臂交替多电平换流器，并提出桥臂移相导通调制，实现其高效功率变换与直流故障穿越的兼顾；最后，计及硬件成本、运行损耗、可靠性与可实现性等维度，对各类具有直流故障穿越能力的拓扑进行了系统性对比，为具有故障穿越能力需求的交直流变换场景提供模块化多电平换流拓扑的选择依据。

Derivation and Comparison of Modular Multilevel Converter Topologies with DC Fault Ride-through Capability

The DC fault has become one of the most serious obstacles for the development of DC system because of its wide impact range and large fault current. The modular multilevel converter (MMC) can realize the DC fault ride-through by deploying bipolar submodules, which however sacrifices the characteristics of both low construction cost and high efficiency under normal operation. In order to find out a MMC topology with consideration of hardware cost, operating efficiency and DC fault ride-through capability, four categories including thirteen kinds of modular topologies are derived by abstracting the general structure of DC-AC converter and allocating the basic modules for each arm. A T-type alternate arm multilevel converter is proposed with the arm phase-shift modulation that promises both high efficiency and DC fault ride-through. Various modular topologies with DC fault ride-through capability are compared in terms of construction costs, operating losses, reliability and applicability, which can provide a direction for DC-AC conversion applications.