Analysis And Control Of Flexible Multi-state Switch With Energy Storage System

With the transformation of energy structure and upgrading of distribution network structure,the problems of slow response and limited regulation ability of traditional distribution network regulation methods have become increasingly prominent,which seriously affect the safe and stable operation of distribution network.Flexible multi-state switch(FMS)can realize the flexible interconnection between different distribution networks,which makes it become one of the important solutions to the existing problems.Meanwhile,considering the increase of distributed energy penetration and short-term power fluctuation,energy storage system has become an effective method to enhance the distribution network power regulation ability.Combining the advantages of the above two schemes,this article proposes a flexible multi-state switch with energy storage system(FMS-ESS),and focuses on its topology,operation principle and key control technology.In order to solve the complex energy flow problem in the distribution network,this article proposes a modular multilevel converter with partial energy storage system(MMC-PESS)as the basic unit.The topology of FMS-ESS,its working principle and mathematical model are analyzed in detail,and the typical energy flow pattern in FMS-ESS is mainly studied.In terms of key control technology of FMS-ESS,the master-slave control scheme is adopted to realize the coordinated operation of the system.In terms of control technology of the basic structural unit MMC-PESS,in order to improve the dynamic performance of the system,the deadbeat current control strategy based on arm current tracking is studied.This strategy takes both AC current and circulating current into account,and simplifies the control system.As for energy storage control,the Buck/Boost power control strategy and state of charge(SOC)power correction and equalization control strategy are proposed.The theoretical analysis and key control technology of this article are verified by the simulation model.Finally,the FMS-ESS prototype is implemented to verify different operation conditions,such as energy storage local and cross-region compensation and power coordination among distribution networks.The experimental results show that FMS-ESS can not only realize the interconnection of different distribution networks,but also coordinate the energy storage units to solve the multiple energy fluctuations,which shows a broad prospect in the future distribution networks.