具备直流短路故障阻断能力的子模块桥臂复用型模块化多电平固态变压器  

Modular Multilevel Solid State Transformer of Arm Integrated Submodule With DC Short Circuit Fault Blocking Capability

作　　者：鄢寅宇 孙毅超 郭宛鑫 侯凯 YAN Yinyu;SUN Yichao;GUO Wanxin;HOU Kai(State Key Laboratory of Smart Grid Protection and Control(NARI Group Corporation),Nanjing 211106,Jiangsu Province,China;NARI School of Electrical and Automation Engineering,Nanjing Normal University,Nanjing 210023,Jiangsu Province,China)

机构地区：[1]智能电网保护和运行控制国家重点实验室(南瑞集团(国网电力科学研究院)有限公司),江苏省南京市211106 [2]南京师范大学南瑞电气与自动化学院,江苏省南京市210023

出　　处：《电网技术》2024年第3期1224-1234,共11页Power System Technology

基　　金：国家自然科学基金项目(52277188);智能电网保护和运行控制国家重点实验室项目(SGNR0000KJJS2200303);江苏省高校自然科学基金面上项目(22KJB470005)。

摘　　要：模块化多电平换流器的固态变压器(modular multilevel converter based solid state transformer,MMC-SST)由于具备多电压等级、多电压形态的端口,在交直流混合配电网中得到广泛关注。传统的输入串联输出并联(inputseriesoutput parallel,ISOP)型MMC-SST具有较高的功率密度,但是在中压直流(medium voltage DC,MVDC)端口短路故障情况下无法持续向低压侧供电;双向有源全桥变换器(dualactive bridge,DAB)型MMC-SST则存在功率密度低、成本高等问题,并且传统的半桥结构的DAB型MMC-SST在MVDC端口短路故障情况下同样无法持续向低压侧供电。文章提出了一种子模块桥臂复用(arm integrated submodule,AISM)型MMC-SST拓扑,在不改变MMC-SST端口电气特性的情况下,在有效减少开关器件数量的同时,还使得SST具备中压直流端口短路故障下的不间断运行能力,进而提升SST的功率密度和供电可靠性。针对文中提出的AISM型MMCSST拓扑,该文还提出了一种针对输入级MMC的混频调制方法,基于共模、差模解耦原理,实现输入级MMC桥臂电压的高频分量和低频分量的解耦。通过理论分析与仿真模拟,验证了所提拓扑及控制方法的可行性。The solid state transformer based on the modular multilevel converter(MMC-SST)has attracted an extensive attention in the AC/DC hybrid distribution network due to its multi-voltage levels and multi-voltage configuration ports.The traditional input series output parallel(ISOP)typed MMC-SST has a high power density,but it cannot supply power to the low voltage side continuously under the condition of a medium voltage DC(MVDC)port short circuit fault.The dual active bridge(DAB)typed MMC-SST has the problems of low power density and high cost.The traditional DAB typed MMC-SST with a half bridge structure cannot continuously supply power to the low-voltage side either in the case of an MVDC port short circuit fault.This paper proposes an arm integrated submodule(AISM)based MMC-SST topology(AISM type MMC-SST).Without changing the electrical characteristics of the MMC-SST ports,the number of switching devices is effectively reduced,and the SST has got the ability of uninterrupted operation under the condition of a short circuit on the MVDC port,thus improving the power density and power supply reliability of the SST.Meanwhile,for the proposed AISM typed MMC-SST,a hybrid frequency modulation for the MMC is proposed in the paper.Based on the common mode and differential mode decoupling principles,the decoupling of the high and low frequency modulation signals in the MMC-SST is realized.The feasibility of the proposed topology and control method is verified by theoretical analysis and simulation.

关 键 词：模块化多电平固态变压器 子模块桥臂复用 中压直流短路故障不间断运行 混频调制 

分 类 号：TM721[电气工程—电力系统及自动化]