摘要
针对光伏直流升压汇集并网系统,基于半桥全桥混合型模块化多电平换流器(MMC),分析了系统预充电启动过程及停机过程。启动过程中,不控充电阶段半桥子模块及全桥子模块电压不能同步上升,且直流母线电压过低,分析了其原因并且给出了软启动方案。停机过程中,采用MMC系统的传统分组放电策略,放电初始时刻及放电组别切换时刻会产生较大的冲击电流。提出了停机过程中加入能量分配阶段,可大幅度降低直流母线电压值,从而可降低放电电阻值和耐压等级。放电阶段采用了均衡放电策略,配合能量分配阶段,有效抑制了上述冲击电流。最后,通过MATLAB/Simulink搭建了基于混合型MMC的光伏直流升压汇集系统,验证了系统启停控制策略的有效性。
Based on a half-bridge and full-bridge hybrid modular multilevel converter(MMC),the pre-charging start-stop process of the PV DC boost converging system is analyzed.During the start process,the voltage of the half-bridge and the full-bridge sub-module in the uncontrolled charging stage can not rise synchronously,and the DC bus voltage is excessively low.This reason is analyzed and the soft start scheme is given.During the stop process with the packet discharge strategy used in the traditional MMC system,the larger impulse current will be generated at the beginning of the discharge and the switching time of the discharge group.Moreover,an energy allocation stage is proposed to reduce the DC bus voltage value during the stop process and reduce the discharge resistance and withstand voltage level.In the discharge stage,the balanced discharge strategy and the energy allocation stage are adopted to effectively suppress the above impulse current.Finally,a photovoltaic high DC collection system optimized by hybrid MMC is built in MATLAB/Simulink,which verifies the effectiveness of the proposed control strategy.
作者
田艳军
魏石磊
王毅
陈波
TIAN Yanjun;WEI Shilei;WANG Yi;CHEN Bo(Key Laboratory of Distributed Energy Storage and Microgrid of Hebei Province,North China Electric Power University,Baoding 071003,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2020年第1期178-186,共9页
High Voltage Engineering
基金
国家重点研发计划(2016YFB0900203)
中央高校基本科研业务费专项资金(2017MS097).
关键词
光伏
直流汇集
混合型MMC
优化
软启动
软停机
photovoltaic
DC collection
hybrid MMC
optimization
soft start
soft stop
