混合型MMC单站带电投入运行的充电策略

Charging Strategy of Hybrid MMC for Single-Station Live Operation

混合型模块化多电平换流器(modular multilevel converter,MMC)结合了半桥子模块和全桥子模块的优势,具有较好的应用前景。相比于半桥型MMC,混合型MMC由于全桥子模块的加入,其充电过程已发生较大变化。本文首先研究分析了带线路和不带线路两种情况下子模块的充电特性,发现在不控充电期间存在半桥子模块欠压和全桥子模块过压等问题,然后提出了预防上述问题的相关策略。在PSCAD/EMTDC内建立了真实仿真模型,进行了不同子模块比例下的仿真研究,仿真结果验证了理论分析的正确性和充电策略的可行性。

Hybrid modular multilevel converter(MMC)combines the advantages of half-bridge sub-module and full-bridge sub-module,and has a good application prospect.Compared with the half-bridge MMC,the charging process of hybrid MMC has changed a lot due to the addition of full-bridge sub-modules.Firstly,this paper studies and analyzes the charging characteristics of sub-modules in the case with and without transmission lines.It is found that there are some problems such as under-voltage of half-bridge sub-modules and over-voltage of full-bridge sub-modules during the uncontrolled charging period.Then,a corresponding charging strategy is proposed to prevent the above problems.A real simulation model is established in PSCAD/EMTDC.Through the simulation research in different sub-module proportion,the results verify the correctness of theoretical analysis and the feasiblity of the charging strategy.