Research And Implementation Of Grid-connected Photovoltaic Inverter System

With the depletion of the fossil energy and environmental pollution, developing and using ofwind energy, solar energy and other renewable energy become more and more severity. With theadvantages of clean and huge reserves, solar energy become one of the most potential kind ofenergy for development. The dissertation chooses grid-connected photovoltaic power generationsystem as the object of study, and deeply researches the topology of system, the parameter of themain circuit components and control strategy. The main contents are as follows：The paper analysis the characteristics of the different topology of photovoltaic grid-connectedinverter, detailed study of the work process of the non-isolated transformerless photovoltaic gridinverters, gives the control strategy of output voltage control and voltage current double closed loopcontrol.A mathematical model of the photovoltaic cell is established. MATLAB/Simulink is used tostudy the relationship of between the output characteristics of photovoltaic cells and light intensityand ambient temperature.The components parameters of main circuit of Boost and full-bridge inverter are theoreticallycalculated, and the experimental circuit is producted. The control panel is designed using DSP asthe core. They and the main circuit of converter together form a single-phase5Kw photosvoltaicgrid-connected inverter experimental prototype.The control strategy of voltage and current double closed loop is studied detailedly. Theparameters of the PID regulator is setted, in accordance with the typical type II and the typical typeI system.Under a certain condition, the initial grid experiments is hold by using the experimentalprototype.The results of the experiment show that the system can work stabilitily under unity powerfactor.