Research On High Power Photovoltaic Simulator

With the continuous progress in photovoltaic (PV) technology, PV inverter power level ranges from small scale to the high power level. MPPT performance of PV inverter is directly related to the power generation and investment pay back of PV power plants. If real PV arrays are used for testing, the cost is high, and the research and development cycle is long due to the limited environmental conditions. Therefore, it is necessary to develop a way to simulate the output characteristics of PV array. This thesis describes a PV simulator based on PWM rectifier, studies its control strategies, and verifies the correctness of control strategies and the feasibility of PV simulator through simulation and experiments.Firstly, in order to get the data of the PV array, the output characteristics of PV cells are analyzed. Based on the existing mathematical model of PV cells, unified piecewise polynomial fitting model that is suitable for PV simulator is improved, and the human-machine interface is established through Matlab/GUI. Considering the output characteristics of PV array under partial shading, multi-peak characteristics fitting algorithm is researched.Secondly, the research about PV simulator control strategies is carried on. The principle of PWM rectifier is introduced, and the mathematical models are established. Analysis and comparison of the three control methods based on grid voltage oriented of PV simulator are made, including virtual line-flux-linkage oriented control strategies. Matlab simulations of PV simulator based on the two directional modes are made for the analysis and research.After that, DC voltage control strategies of PV simulator based on PWM rectifier are studied. Based on analysis of the SVPWM overmodulation algorithm, the control strategy of virtual flux-weakening is researched. The correctness of the algorithm is verified through simulation and experiments.Finally, MPPT between PV simulator and grid inverter is simulated, including the multi-peak characteristics of PV simulator based on Matlab. As the validations of the theory and simulation, PV simulator experimental platform is built, on which experiments are conducted. The effectiveness and feasibility of PV simulator control strategies are verified through MPPT experiment, etc. It provides the engineering foundation for test equipments of high power PV inverter in the future.