WEN Ya,ZHUO Fang,ZHANG Xiao,et al.Decentralized online expansion strategy for islanded microgrid based on short-term harmonic injection[J].Electric Power Automation Equipment,2026,46(03):69-76.
To achieve islanded microgrid online expansion,traditional solutions usually rely on communication lines for the synchronization among converters,which cannot realize the function of plug-and-play,and the cost is relatively high. Therefore,the entire process and critical technologies of online expansion are systematically analyzed,a decentralized online expansion strategy based on short-term harmonic injection is proposed to achieve synchronous and coordinated control between newly joined converters and existing units. The proposed strategy mainly consists of two parts,one is to realize the system reset and synchronization among converters by short-term small-signal harmonic injection,and the other is to realize the multi-machine synchronous frequency adjustment based on an event-triggered mechanism. As the core technology,namely small-signal harmonic injection,is carefully designed with the parameters of duration,frequency and amplitude to ensure no power quality issues introduced. The proposed strategy enables communication-free online expansion of islanded microgrid and ensures state synchronization among multiple converters. The feasibility and effectiveness of the control strategy are verified under an experiment platform composed of three converters.
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