Research On Maximum Power Point Tracking Techniques And Photovoltaic Grid-connected System

With the energy shortage and environmental pollution increase of the world, looking for renewable energy has the important meaning. Because of Photovoltaic (PV) power of no poll-ution and can be found everywhere, more and more pattions are paied to it. In this paper, A3kW single Phase two-stage transformerless Photovoltaic grid-connected inverter is designed, focusing on maximum power point tracking (MPPT) and the control technology of the grid-connected inverter.Firstly, the paper summarizes the background significance and development prospects of photovoltaic power generation at home and abroad, then introduces the work principle and the topology structure of povoltaic power system. A non-transformer and two-level topology is proposed, in which the principles of Boost circuit and full-bridge circuit are described. Then the thesis analyzes the working mechanism of photovoltaic array and its output characteristics. The methods to calculate the solar cell’s parameters are given in detail, different simulation models of solar cells under Matlab have been builted. The improved engineering PV arrays mathematical model can simulate the shadowing and uneven light condition under which the power generation efficiency of PV arrays would sharply decline and present multi-peak power output. Secondly, the paper illustrates the principle of maximum power point tracking (MPPT), and gives a system introduction of general MPPT methods. Perturb and observe and INC are detailly discussed, include the reason of the failure estimate on, optimized design method and arithmetic is introduced, due to common MPPT can get confused and track in wrong direction during PSC. a improved PSC-MPPT method has been proposed, and simulation analysis are presented to verify the correctness.Thirdly, the photovoltaic inverter principle and common control strategy is researched. The hybrid control strategy with mixing repetitive control and PI control is studied because of the drawback of traditional PI control.A3kW single Phase Photovoltaic grid-connected inverter based on DSP28335and ARM2132is builded. Designing system software and hardware, some experiments are carried out to validate the above theory design.