Research On MPPT Control For PV System Based On Model Predictive Control

In order to alleviate the pressure of energy crisis and environmental protection,research and development of renewable energy has attracted widespread attention,Solar energy has become the focus of application research because of its characteristics of access and use.The conversion efficiency of photovoltaic array is one of the key problems that need to be solved in the process of solar energy application,MPPT(Maximum Power Point Tracking,MPPT)technology as an effective means to this problem has become a hot issue in this research field,At present,MPPT algorithm mainly has constant voltage tracking method,perturbation and observation method,incremental conductance method and the dynamic impedance matching method,etc.,these control methods share the common characteristics: the optimal value gradually is found by observing changes in the PV array output characteristics,to complete the largest power point tracking.However,The above method exists the conflicting issues between the system tracking speed and steady state performance.In this paper,the MPPT method based on model predictive control(MPC)is proposed for the research of this problem.Firstly,this paper introduces the basic composition and classification of the photovoltaic systems,focuses on analysing the photovoltaic cell circuit,simplifies the mathematic expression of the PV array,as well as establishes a model of PV array in MATLAB / Simulink,and simulates the photovoltaic array system under different light and temperature conditions,sets up the foundation for the subsequent research model predictive control and maximum power point tracking.Secondly,this paper introduces the MPPT algorithm and the principle of the Boost circuit,and its mathematical expression is obtained by the equivalent circuit of the Boost circuit.And then it establishes the mathematical model of the Boost circuit,analyses the four common used MPPT algorithm,such as Constant Voltage Tracking(CVT),Perturbation and Observation Method(P&O),and etc..Considering one of the most important MPPT control method,MPC has a detailed introduction from the aspects of principle,the present situation,and etc..In order to improve the online computation speed of system and reduce the amount of online calculation,this paper proposes the MPC control algorithm based on conditional trigger strategy and analyzes its stability.Finally,this paper builds the model of photovoltaic power generation system in the Matlab/Simulink.The simulation of MPPT methods including P&O,IC,DIM respectively based on the traditional MPC control method and the trigger condition MPC control method were established.Then on the basis of comparisons of series of control method,The simulation results approve the MPC control method based on trigger conditions feasibility and effectiveness in MPPT control method.