具备阻断直流侧故障电流模块化的多电平换流器应用研究

摘要

In view of sub-modules (SMs) in larger quantities and the incapability of blocking DC fault current of the modular multilevel converter (MMC) for high voltage direct current (HVDC) transmission projects in current operation,a new modular multilevel topology based on traditional MMC topology was presented with its bridge arm consisting of two serial SMs groups constituted by half bridge sub-module (HBSM) and clamp double sub-module(CDSM) in series,incorporating features of low conduction loss and reduce additional components.Its basic parameters design and the coordination switching processes of SMs in two groups were elaborated.The corresponding model predictive control (MPC) strategy was adopted for the new MMC topology.The results show that the new MMC topology not only has the ability to block DC fault current,but also increases output level number at the same number of SMs requirements.The AC voltage output waveform is closer to a sine wave.%针对当前已投入运行的高压直流(HVDC)输电工程中模块化多电平换流器(MMC)存在子模块数量较多、不具备阻断直流侧故障电流等问题,提出一种基于传统MMC拓扑结构的新型模块化多电平拓扑,其桥臂由2个子模块组串联构成,2个子模块组分别由半桥子模块和箝位双子模块串联组成,降低稳态运行损耗和元器件使用数量;阐述该新型拓扑的基本参数选取原则及上、下2组子模块的协调投切过程;针对新型MMC拓扑,采用相应的模型预测控制策略.最后,通过实验进行验证.研究结果表明:新型拓扑不仅具备阻断直流侧故障电流能力,而且在子模块数量相同时,输出电平数增多,交流电压输出波形更接近正弦波.