The Modeling And Real-time Simulation Technology Of Photovoltaic Grid-connected System Based On FPGA

Due to the large consumption of traditional fossil fuels causing energy shortages and environmental pollution,new clean energy needs to be developed.The photovoltaic grid-connected system is a power electronic system that converts solar energy into electrical energy.The application of power electronic hardware-in-the-loop real-time simulation technology can help reduce the development cycle and cost of power electronic equipment.The dissertation studies the modeling and real-time simulation algorithms based on the the photovoltaic grid-connected system,and conducts experimental verification.The main research contents of the full thesis include:1)Summarize the background and purpose of the research of this subject,the development status of photovoltaic grid-connected system and real-time simulation technology.Taking single-phase two-stage photovoltaic grid-connected system as the object,the circuit principle of each module in the main circuit are analyzed.Mathematical models,such as photovoltaic,inverter,etc.2)According to the switching circuit modeling method,the binary L/C switch equivalent method,the discrete iterative model of the photovoltaic grid-connected system is established,and the parameter value formula of the switch equivalent method is given.Aiming at the switch transient error in the binary L/C model,this dissertation optimizes the switch model parameter G_s.The offline simulation of Matlab/Simulink shows that the mathematical model of the main circuit of the photovoltaic grid-connected system established in this dissertation is correct,and the optimized parameters can reduce the transient error of the L/C model.3)Based on FPGA and System Generator,a real-time simulation algorithm of power electronic system is designed.The traditional real-time simulation algorithm based on node analysis method has limitations.For example,it can only solve the node voltage state quantity in the circuit.The dissertation optimizes this method:the improved node method is used to solve the branch current information quantity in real-time simulation.And by simplifying the intermediate calculation process of model iteration within a single step,the efficiency of real-time simulation is improved.4)A real-time simulator platform based on FPGA was built,and the photovoltaic grid-connected system experiment was carried out on this platform.By comparing with the results of offline simulation,the real-time simulator accurately simulates the operating conditions of the photovoltaic grid-connected system,and verifies the correctness of the real-time simulation modeling and algorithm in this dissertation.