Research On Operation And Control Of AC/DC Microgrids

AC/DC hybrid microgrid is one of the main forms of microgrid at present,which can realize high-efficiency access to different types of distributed generations and highreliability power supply for various types of loads.The capacity constraints,control and protection difficulties and power supply stability of a single microgrid are attracting more and more attention.Interconnection and operation of multiple microgrids is the effective solutions to such problems and is one of the research focus of this paper.In addition,multi-converter parallel operation control is one of the key technologies to improve the reliability and security of microgrid power supply.It has important academic value and practical guiding significance,which is another research focus in this paper.For AC/DC microgrids based on isolated bidirectional DC-DC converter interconnection,a unified control strategy is proposed,and the design method of the control strategy is analyzed.Simulation research and experimental verification show that the proposed control strategy can realize flexible interconnection and control between multiple microgrids.Aiming at the parallel operation of multiple DC-AC converters in island mode of AC/DC microgrid,the parallel operation control technology without interconnection line based on droop control is studied,and a power decoupling method based on virtual impedance is proposed.Numerical simulation and physical experiments verify the effectiveness of the proposed control method.Small signal modeling is carried out for parallel operation of multiple DC-AC converters.The influence of key parameters on stability is analyzed by eigenvalue method,and simulation and experimental verification are carried out.