应用于智能配电网的子模块混联MMC-HVDC系统配置及启动策略

摘要

To provide a better scheme with DC fault-crossing capability for the voltage source converter based high voltage direct current(VSC-HVDC)transmission system,a novel configuration method and its matched start-up strategy are proposed for a sub-module hybrid modular multilevel converter-high voltage direct current(MMC-HVDC)system based on various sub-module hybrid MMC systems. The configuration method mainly includes two parts: one is the configuration method for the number of sub-modules,and the other is for the internal parameters of sub-modules.The first configuration method can save economic cost and reduce system loss while making the converter have the DC fault-crossing capability and improving the system capacity; the second can limit the voltage variation of the full-bridge sub-module during the crossing process and guarantee the normal operation of fault-crossing. Since different sub-modules adopt different capacitors,the start-up strategy for the traditional MMC-HVDC system is not applicable, thus a novel start-up strategy is proposed to match the configuration method. Finally, a simulation model of a two-terminal MMC-HVDC transmission system is constructed in Matlab/Simulink, and simulation results show that the novel configuration method and the corresponding start-up strategy are feasible and effective.%为了提供更优的具备直流故障穿越能力的柔性直流输电系统方案,在多种子模块混联的模块化多电平换流器系统基础上,提出了一种新型子模块混联MMC-HVDC系统配置方法及与其匹配的启动策略.该系统配置方法主要包括系统子模块数目配置方法及子模块内部参数配置方法两部分.子模块数目配置方法能使换流器在具备直流故障穿越能力、提升系统容量等优势的同时,尽量节约经济成本及减小系统损耗;而子模块内部参数配置方法则主要为了限制穿越过程中全桥子模块电压变化量,保证故障穿越能够正常进行.由于不同子模块选用了不同电容,传统MMC-HVDC系统的启动策略不再适用,因此提出了与配置方法相匹配的启动策略.最后基于Matlab/Simulink搭建了MMC-HVDC双端系统仿真模型,验证了所提出的新型系统配置方法及其启动策略的可行性和有效性.