Investigation Of Grid-Connected Photovoltaic System Based On DSP

Along with the improvement of the people's standard of living, energy sources are needed increasingly for people. As a novel green and renewable energy, the solar energy is abundant, economic and non-pollution. So its application attracts lots of attentions and the solar photovoltaic energy technology has been the focus that people attend to. In the soon future, one of the main utilization of solar energy will be the photovoltaic grid-connected system. With the appearance of high-performance Digital Signal Processor (DSP) chip, it is possible that some most advanced control strategies can be used to the PV grid-connected system.Generally, a fundamental photovoltaic grid-connected system consists of the solar cell, solar controller and converter. In particular, the solar controller and converter are the hard core of the system. Aims at how to increase the efficiency of conversion for the photovoltaic energy system, this paper researches the PV grid-connected system with maximum power point tracking (MPP'I) from the simulation. The first part is an introduction to China's present application of the solar photovoltaic and summarizing the composing of the photovoltaic energy system. The second part is a demonstration of a dynamic model of the grid-connected PV system with simulation, which is developed by using the POWER SYSTEM BLOCKSETS tool of the MATLAB. The model will help a lot in designing the real machine in the future. Third, according to a comparison of the working principles, a proposal is raised to use the push-pull DC/DC convertor to transform the voltage, instead of using other DC/DC convertor in common use. By analysing the datas, a simulation model is made. MPPT is the most common problem of the grid-connected PV system; this part gives a detailed analysis of some old solutions and proposes some new solutions as well. A control unit based on DSP (TMS320F240) rnicrochip for grid-connected PV system has been developed. The authors have established a control model adopting the feed forward of grid voltage and current tracking technology. The sine grid-connected current and unity power factor are achieved. Last, a detailed analysis will be given on the produce theory of the SPWM, a design pattern and a software flow chart with a combination of reality will be given as well.