Research Of Photovoltaic /Storage Integrated Home Energy System With Grid-connected/islanded Seamless Transfer Function

With the development of energy harvesting and power electronics technology,distributed energy generation systems including wind and solar energy are increasingly being developed.As a complement to centralized power generation,distributed generation(DG)have made it possible to plan new horizons for conventional power systems for its cleanliness and efficient utilization of energy.In this paper,a photovoltaic/storage integrated energy system is built based on DC microgrid.And the grid-connected/islanded seamless transfer,bidirectional DCDC converter and the system energy management strategy are illustrated about the energy system.Firstly,this paper introduces the significance of photovoltaic power generation,the research status of microgrid energy system and its key technical problems.The control model and output impedance calculation model of the inverter are given in this paper and a voltage-source-based grid-supporting inverter model is constructed to address the dual mode operation and seamless transfer problem.And the availability of the proposed method has been proved by experimental results.Then this paper introduces an analysis tool called first harmonic approximation(FHA)to analyse the directional full bridge LLC resonant converter.FHA is used to obtain the linear sinusoidal circuit.And the voltage-transfer function,operating waveforms and soft-switching realization are derived from the linear sinusoidal circuit.Then the main topology of bidirectional LLC resonant converter is given in this paper.And the operating status,soft-switching realization and voltage and current stress are analyzed as well.Finally,based on the practical requirements,the parameters of the converter are designed and simulations with Saber are built.The simulation results prove the theoretical research.Then this paper illustrates the fundamental principles for DC microgrid and introduces the different operating modes of the energy system depend on these principles.Finally,the swiching conditions for different modes in the energy system are given and the transition diagram is illustrated.