热备用子模块对MMC运行特性影响分析

摘要

Redundant conifguration is one of the main technical advantages for modular multilevel converter(MMC) in engineering application, greatly enhancing the reliability and availability of the system. The redundant Sub-Modules in MMC are mainly divided into cold standby state and active standby state, but the active redundant Sub-Module(SM) can participate in the work of MMC and affects the operating of MMC. Introducing the concept of redundancy rate and deifning the average switching function of the MMC with active redundant SMs, this paper deduces the analytical expressions for electrical quantities based on the average switching function, demonstrating the effects of active redundant SMs for such performance characteristics in MMC as the capacitor voltage, the circulating current and SM switching frequency and so on. Finally, the results of the analytical expressions coincide with the simulation results, which verify the effectiveness and feasibility of the proposed analysis.%冗余配置是模块化多电平换流器(MMC)在工程应用的一大技术优点,极大提高了系统的可靠性和可用率.冗余子模块在MMC运行中主要有冷备用和热备用两种状态,热备用子模块参与MMC的运行,会对MMC的运行特性产生影响.引入冗余度的概念,定义了配置有热备用子模块MMC的平均开关函数,基于开关函数法推导出配置有热备用子模块MMC的各电气量的解析表达式,主要研究分析了热备用子模块对于MMC子模块电容电压波动、桥臂环流、频率等稳态运行特性的影响,最后通过仿真进一步验证了理论分析的正确性和有效性.