| In the photovoltaic grid-connected system,the grid-connected inverter is the key component that connects the photovoltaic array module and the grid,and its topology and control method are the focus of current research.Aiming at the problem of the single-stage three-phase photovoltaic inverter grid-connected system,the anti-interference ability is not ideal and the traditional control strategy is difficult to ensure the fast and accurate tracking of the sine wave current output by the grid-connected inverter,a dual loop based on sliding mode control is proposed.Integral control strategy and MPPT control strategy are designed to improve the robust anti-disturbance ability of the system,so as to realize safe and stable grid-connected operation.The main research contents are as follows:The basic theory of sliding mode control is analyzed.Firstly,the basic principle,advantages and disadvantages of traditional control methods,the development status,mathematical model and design process of inverter are summarized.And the sliding mode control technology of the inverter is deeply studied and analyzed,and the traditional sliding mode control is improved.Aiming at the problems of the control system,an improved double closed-loop integral sliding mode control strategy method is proposed,which has a better control effect.The research of MPPT control strategy.The principle and characteristics of several common grid-connected control strategies are analyzed,and the dual closed-loop PI control strategy and the parameter design of the PI controller are analyzed and studied.Aiming at the problems of tracking speed and steady-state accuracy in common MPPT control methods,a MPPT algorithm based on improved sliding mode control is proposed.The MPPT algorithm of the traditional method and the improved sliding mode control is simulated in Matlab/Simulink.The simulation results verify the feasibility of the proposed method.Research on control strategy of grid connected inverter.The principle and characteristics of several common grid-connected control strategies are analyzed,and the dual closed-loop PI control strategy and the parameter design of the PI controller are analyzed and studied.A double closed-loop sliding mode control strategy based on sliding mode control is proposed to achieve the desired inverter performance.This paper makes a detailed theoretical analysis of the above two methods and establishes a mathematical model;The controller design and Simulation of control algorithm are carried out.Using Matlab/Simulink simulation platform,the anti-interference ability,dynamic response characteristics and grid current harmonic content of photovoltaic grid connected system are studied,and the feasibility and superiority of the proposed control strategy are verified. |
