Research On Control Strategy Of Household AC/DC Hybrid Nanogrid

The traditional centralized grid is facing many unfavorable factors: environmental pollution,energy shortage,much power loss,difficult operation,and difficulty in meeting the increasing safety and reliability requirements of users.Therefore,power experts have begun to take a different approach to the development of the power system.In recent years,distributed generation,microgrid,and nanogrid have gradually become research hotspots of researchers.Although nanogrid are a relatively new research topic in the field of power systems,it has attracted extensive attention from many research institutions and researchers at home and abroad.In this paper,the power electronic converter control in the household AC/DC hybrid nanogrid and the energy management control strategy of the nanogrid are deeply analyzed and studied.This paper designs a household AC/DC hybrid nanogrid structure,which is mainly composed of AC/DC bus unit,renewable energy generation unit,energy storage unit,interconnected converter unit and load unit.The functions of each module in nanogrid are briefly described.The mathematical model and output characteristics of photovoltaic cells are analyzed.The energy storage devices and power electronic converters in nanogrid are optimized and selected.The large-signal models of Boost converter,bidirectional Buck/Boost converter and bidirectional DC/AC converter are established.Based on the steady-state mathematical model and error signal mathematical model of the converter,the Lyapunov controller of the above three converters is designed,and the effectiveness of the controller design is verified by simulation.Taking Boost converter as an example,the control effects of traditional voltage mode controller,current mode controller and new controller are compared.Two switching methods of battery charge and discharge control are given.In order to ensure the stable operation of the nanogrid,an energy management control strategy based on DC Bus Signaling(DBS)for AC/DC hybrid nanogrid is proposed,and six operation modes of the system are analyzed in detail.The operation control of each distributed generation and interconnected converter under the system energy management control strategy is analyzed.The effectiveness of the energy management control strategy of the nanogrid is verified by simulation.The experimental platform of PV converter,bidirectional energy storage converter and bidirectional interconnected converter in nanogrid is built.The validity of Lyapunov controller design is verified by experiments.