Research On Grid-connected Inverter Based On Gain Scheduling Adaptive

With the development of renewable energy power generation technology,as a connector for connecting new energy power generation device and the grid or load,grid-connected inverter becoming more and more important.Microgrid is different from traditional power grid who's impedance is infinitely small.As a weak grid,the impedance of Microgrid can't be ignored.If the grid impedance varies too far,the behavior of the grid-connected inverter with fixed parameter regulator may be deteriorated or even instable.In this paper,a gain scheduling adaptive control strategy is used to design the controller of grid-connected inverter,who can overcome the effects of grid impedance variations on the system stability.Firstly,the control technology and topology of grid-connected inverter are compared in this paper.Mathematical modeling of grid-connected inverter system,with full-bridge inverter as the main circuit topology,LCL output filter,double closed-loop control of current and capacitance current and SPWM control strategy,is established.Secondly,the open loop transfer function and output impedance of single-phase grid-connected inverter are given.This paper presented the small signal modeling of grid connected inverter and Microgrid interconnected system,and given the stable operation condition of the system.And analyzed the effects of Microgrid impedance and controller parameters on the stability of the system.Thirdly,divided the impedance interval based on the phase margin.The simulation model is used to verify the correctness of the impedance interval partition and the feasibility of gain scheduling adaptive control.And finally,a prototype of single-phase grid-connected inverter is designed,and the feasibility of gain scheduling adaptive control strategy is verified by experiments.