Research On Coordinated Control Strategy Of Photovoltaic/energy Storage Microgrid Cluster

Facing the problem of fossil energy consumption and environmental pollution,seeking and utilizing alternative clean energy has become a hot research direction.Microgrid can effectively use clean distributed power sources,However,when a single microgrid is not supported by distribution network,it will face the problems of difficult power regulation and low power supply reliability.Several microgrids are connected to the same feeder adjacent to each other to form a microgrid cluster system,which can effectively improve the stability of each microgrid through mutual power supply.The microgrid system composed of photovoltaic power generation and hybrid energy storage can not only overcome the intermittent and fluctuating problems of photovoltaic output power,but also solve the shortcomings and limitations of a single energy storage battery.Therefore,based on the photovoltaic and hybrid energy storage microgrid,this paper analyzes and studies the coordinated control strategy of the photovoltaic/energy storage microgrid group.First,the basic working principle of the photovoltaic system is studied,and its output characteristics are analyzed by mathematical model and modeling simulation.Then,the basic principle,model and connection topology of lead-acid battery and supercapacitor are analyzed and studied,and a photovoltaic m icrogrid system with hybrid energy storage is built.Then,the architecture and coordination control strategy of microgrid cluster system are studied.A hybrid control method combining hierarchical control with master-slave control is proposed,and the microgrid cluster is divided into three layers:unit layer,microgrid layer,and microgrid cluster layer.The microgrid cluster layer takes the microgrid as the control unit,and the cluster controller adapts master-slave control to divide each sub-microgrid into a master-slave microgrid.Each microgrid system includes unit layer and microgrid layer control strategies.The improved variable step disturbance observation method is used to achieve maximum power point tracking in the unit layer photovoltaic system;A second-order low-pass filtering method is proposed to allocate the power borne by the hybrid energy storage.Combined with the state of charge limit management strategy,the hybrid energy storage working state is reasonably divided,and the photovoltaic converter is controlled to operate in MPPT or constant voltage drop power mode.Then,the control strategy of bidirectional DC / AC converter in microgrid layer is studied to make microgrid operate stably in grid-connected or off-grid state.Finally,according to the proposed power management and coordinated control strategy,a simulation system was first built on the Matlab/Simulink platform to verify the feasibility and effectiveness of the photovoltaic and energy storage microgrid control strategy.At the same time,the advantages and necessity of the hybrid energy storage system can be seen.Then,based on the microgrid,a simulation model of photovoltaic/energy storage microgrid cluster system is built.Through the simulation of different operating conditions,the feasibility and effectiveness of the coordinated control strategy of the photovoltaic/energy storage microgrid cluster proposed in this paper is verified.