电工技术学报2025，Vol.40Issue(15)：4740-4754,15.DOI:10.19595/j.cnki.1000-6753.tces.241474
具有宽运行范围的混合复用型模块化多电平拓扑及其能量均衡控制策略
A Hybrid Multiplexing MMC Topology with Wide Operating Range and Energy Balance Control Strategy
摘要
Abstract
The modular multilevel converter(MMC)faces challenges due to the excessive number of submodules,which causes disadvantages such as a large area,heavyweight,and high cost of the converter station.A hybrid multiplexing modular multilevel converter(HM-MMC)is proposed to address this issue.On the AC side,HM-MMC achieves full-cycle multiplexing of the bridge arms through the alternating conduction of switch groups.Thus,the number of submodules in HM-MMC is reduced.An energy exchange circuit is established between the bridge arm and the DC side on the DC side,which balances energy in the bridge arms and facilitates wide-range voltage regulation. Firstly,by applying the coordination of switch groups,two MMCs'bridge arms at each phase are changed into a single multiplexed bridge arm in HM-MMC,reducing submodules and capacitors for lightweight construction.The topology features positive and negative guided operation modes that alternate every half cycle,allowing the multiplexing of bridge arms.These arms are designed to output a sinusoidal half-wave under two guided operation modes.With the help of switch groups,the HM-MMC achieves half-wave inversion,thereby generating a full sinusoidal wave on the AC side.Furthermore,a controlled energy exchange circuit is constructed using the DC side unit in each cycle,with the bridge arm directly connected to the DC side capacitor.This circuit allows surplus or missing energy from the bridge arms to charge or discharge the capacitor on the DC side,ensuring the voltage stability of submodules.Due to the structure and control strategy of HM-MMC,a slight increase in the number of submodules extends the energy exchange time,thereby removing limitations on the modulation ratio. Through simulation and experimental results,the following conclusions can be drawn: (1)Through the cooperation of the switch groups,the full-cycle multiplexing of the bridge arm submodules is realized.The number of submodules is reduced by about 72%compared to conventional MMC.Besides,the operating frequency of the multiplexing switch groups is the power frequency or triple power frequency.There are no high-frequency switching actions during the operation of HM-MMC,which reduces the requirements for dynamic voltage balancing and switching consistency of the series insulated gate bipolar transistors(IGBTs). (2)HM-MMC establishes an energy exchange circuit for the bridge arms by multiplexing DC side units.Accordingly,the submodules in arms can carry out controlled charge or discharge to maintain capacitor voltage stability,and the modulation range of HM-MMC is extended to[0,4/π].In addition,due to the coordination of the DC unit and the switch groups,when more submodules are required at a low modulation ratio,the exchange time of the bridge arm is extended.The average number of submodules per phase of HM-MMC is 0.567N. (3)The proposed energy balance,current control,hybrid multiplexing operation modes,and time-sharing modulation strategy form a comprehensive control strategy of HM-MMC.This strategy achieves a controllable energy balance based on lightweight MMC and avoids the influence on the output AC voltage of the phase unit.关键词
高压直流/模块化多电平换流器/桥臂复用/能量均衡策略Key words
High voltage direct current/modular multilevel converter/bridge arm multiplexing/energy balance strategy分类
信息技术与安全科学引用本文复制引用
王锐,王毅,杨晗菲,高玉华,苏子萌,马骏超..具有宽运行范围的混合复用型模块化多电平拓扑及其能量均衡控制策略[J].电工技术学报,2025,40(15):4740-4754,15.基金项目
国家自然科学基金项目(52077079)和国网浙江省电力有限公司科技项目(5211DS24000D)资助. （52077079）
