The conventional half-bridge submodule (HBSM)-based multilevel modular converter (MMC) cannot block DC faults. To solve this problem, a novel flexible overhead-line high-voltage direct current (HVDC) transmission converter station topology is proposed in this study, which provides DC fault blocking capability. By adding blocking submodules (SMs) onto the positive and negative DC buses of a conventional HBSM converter station, a rapid fault current blocking can be achieved in the case of a DC bus short circuit. The DC fault blocking principle of the proposed topology and the rapid fault blocking capability of the blocking SM are analyzed. The quantity of required major components is also calculated. In addition, the IGBT, the system loss and the control complexity quantities are comprehensively compared with those of existing topologies. The validity of the proposed topology is demonstrated based on simulation and experimental studies.

中文翻译：

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具有直流故障阻断能力的新型柔性高压直流输电换流站拓扑结构

传统的基于半桥子模块 (HBSM) 的多电平模块化转换器 (MMC) 无法阻止直流故障。为了解决这个问题，本研究提出了一种新型灵活的架空线高压直流 (HVDC) 输电换流站拓扑结构，它提供了直流故障阻断能力。通过在传统HBSM换流站的正负极直流母线上添加闭锁子模块（SM），可以在直流母线短路的情况下实现快速故障电流闭锁。分析了所提出拓扑的直流故障闭锁原理和闭锁 SM 的快速故障闭锁能力。还计算所需的主要成分的数量。此外，将IGBT、系统损耗和控制复杂度与现有拓扑进行了综合比较。