Research On Droop Control Of Interlinking Converter In Microgrid Based On Data Driven

Under the dual pressures of increasing energy demand and serious environmental pollution,the installed capacity of renewable energy power generation such as photovoltaics and wind energy has gradually expanded,making the new energy distributed power generation technology widely used.At the same time,due to the unpredictability of the natural environment,resulting in technical applications distributed generation is limited,so microgrid technology came into being.As a new type of power distribution,the AC/DC hybrid microgrid supplies power to both AC and DC loads,thereby reducing the use of power conversion devices,making the microgrid simple in structure,convenient to control,and safe to operate.As a connected converter in AC/DC hybrid microgrid,the three-phase voltage source inverter is used to connect the AC microgrid and the DC microgrid.It is the core device to ensure the reliable operation of the entire hybrid microgrid.Therefore,the research of interlinking converter has become crucial.In this thesis,the interlinking converter in AC/DC hybrid microgrid is taken as the research object.A data-driven model-free adaptive control strategy and improved droop control strategy are proposed to ensure the stability of the DC bus voltage and the power balance inside the hybrid microgrid.The main work of the thesis is as follows:Firstly,on the basis of studying the structural characteristics and control methods of AC/DC hybrid microgrid,the importance and key problems of interlinking converter control in hybrid microgrid are pointed out.According to the working mode of hybrid microgrid,the power balance relationship between grid-connected mode and island mode is studied.The internal structure and working principle of the interlinking converter are analyzed in detail,and the Kirchhoff voltage current theorem is used to establish the mathematical model of the interlinking converter in the natural coordinate system.It lays a foundation for the research of the subsequent interlinking converter control strategy.Secondly,aiming at the problems of high nonlinearity and difficult modeling of interlinking converters,a data-driven model-free adaptive control strategy and improved droop control strategy are proposed to ensure stable operation of DC bus voltage and proportional power of hybrid microgrid.The dynamic linearization model of the interlinking converter is obtained by introducing the dynamic linearization method of partial format.Based on this model,a datadriven model-free adaptive voltage controller is designed.The control method only utilizes the input and output data of the system,and does not need to know the model,structure and unmodeled dynamics of the controlled system,and can realize fast robust voltage tracking control.An improved droop control is designed to further realize the stable operation and precise power distribution of the hybrid microgrid.The simulation analysis of the AC/DC hybrid microgrid under different operating conditions is carried out to verify the effectiveness and feasibility of the proposed control method.Finally,for the loop phenomenon caused by the difference of the voltage amplitude,phase and line impedance of the parallel interlinking converter output,based on the control of a single interlinking converter,the data driven full format with loop suppression compensation is proposed.The model adaptive inner loop voltage control strategy provides good voltage support for the DC microgrid.Based on the stable operation of the inner ring,considering the capacity and load type of AC and DC microgrid,a double droop control strategy based on DC voltage and AC frequency is designed.When the power fluctuates,two microgrids are realized.Excellent power balance.The simulation analysis is carried out in the AC/DC hybrid microgrid grid-connected mode and island mode to verify the effectiveness and feasibility of the proposed control method.