Abstract A hybrid HVDC transmission system based on a line-commutated converter (LCC) and an alternate arm converter (AAC) is developed in this article. The basic operation principles and control methods of the proposed LCC-AAC hybrid HVDC system are demonstrated following with appropriate system design and parameter selection. In addition, this paper proposes a set of control schemes for riding through ac faults and handling dc fault. The operation and performance of both converters in such a hybrid HVDC configuration are verified through a detailed set of results based on a 3000 MVA LCC-AAC hybrid HVDC system including steady state operation, ac-grid harmonics & dc-side ripple analysis, reference tracking (active power change at LCC station, reactive power change at AAC station) and system performance under ac-grid faults without blocking converter at both terminals of the HVDC system. Also, the response of the hybrid system under dc fault presents potential dc fault handling capability compared with the hybrid system based on LCC and modular multilevel converter (MMC) with half-bridge submodules (HBSMs). The hybrid LCC-AAC HVDC transmission system lays preliminary steps for research on complex mixed converter multiterminal dc configurations in future dc super grids.

中文翻译：

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混合LCC-AAC高压直流输电系统

摘要 本文开发了一种基于线换相换流器（LCC）和交变臂换流器（AAC）的混合高压直流输电系统。所提出的 LCC-AAC 混合 HVDC 系统的基本操作原理和控制方法将在下面通过适当的系统设计和参数选择进行演示。此外，本文提出了一套克服交流故障和处理直流故障的控制方案。通过基于 3000 MVA LCC-AAC 混合 HVDC 系统的详细结果集，包括稳态运行、交流电网谐波和直流侧纹波分析、参考跟踪，验证了这种混合 HVDC 配置中两个转换器的运行和性能（LCC 站的有功功率变化，AAC 站的无功功率变化）和交流电网故障下的系统性能，而不会在 HVDC 系统的两端阻塞变流器。此外，与基于 LCC 和具有半桥子模块 (HBSM) 的模块化多电平转换器 (MMC) 的混合系统相比，混合系统在直流故障下的响应表现出潜在的直流故障处理能力。混合 LCC-AAC 高压直流输电系统为研究未来直流超级电网中复杂的混合换流器多端直流配置奠定了基础。