Research On PV Grid-connected Generation System Based On Fibonacci Numbers

Facing the worse and worse problems of environmental pollution and exhaustion of energy sources, the distributed generation power using renewable energy has been attracted extensive attentive. Solar energy is accepted commonly for its advantages such as economic and cleanness. The PV grid-connected system will be the main utilization of solar energy. Furthermore, with the development of high-performance Digital Single Processor (DSP) chip, it is easier to use some advanced control strategies in the PV grid-connected inverter.Under this background, the dissertation focuses on single-phase PV grid-connected system. The system design and validate is based on the research of solar array maximum power point tracking (MPPT) and photovoltaic grid-connected inverter control which are the cores of PV grid-connected system. The main contents are as follow:(1)The significance and good foreground of the solar power using is narrated. The main content of this subject is simply introduced. Then introduces the operational principle and performance characteristic of PV cells, and describes the equivalent circuit and mathematical model dentally. This paper introduces several traditional Maximum Power Point Tracking (MPPT) control algorithms. By comprising these control algorithms, the respective advantages and disadvantages have been found. Based on the analysis results, the Fibonacci numbers is adopted to track the MPP of the solar arrays. This method guarantees the veracity, stability and rapidity of tracking process, and the experiments proved the method had a good performance of tracking.(2)The principle and characteristics of the main circuit topology of grid-connected PV system is analyzed in detail. Comparing with several control strategies of single-phase grid-connected system, the improved fixed switching frequency control method adopted in this paper can avoid the changing switching frequency problems and reduce the noise and switching losses.(3)For the current of PV grid-connected system must be the same phase and the same frequency as the grid voltage. The structure, operating principle, designing the sampling circuit and soft PLL were researched in detail. The experiment results testified that the output current of the inverter has the same phase with the gird.(4)Islanding effect should be well solved in grid-connected Photovoltaic system. This Paper presents the meanings and the criterion of the islanding effect. The causations, potential harm and detection principle are discussed and the main problems of the common detection methods are concluded. Finally, adopted a simple active anti-islanding method and the influence of this method to the original system is discussed. The results of simulation and experiment indicated this method is feasible and effective.