Research On Photovoltaic Generation System And Grid-Connected Control

At present, with the green and renewable energy's developing and applying on a large scale, solar energy is accepted commonly attention because of its particular advantages. Solar energy is one of the most clean, practical and large scale regeneration energy resources. The PV grid-connected system will be the main utilization of solar energy, so it will be developed rapidly. Under this background, the dissertation deeply researches the Maximum Power Point Tracking(MPPT) control, control strategy of gird-connected system and Islanding detection. It has significance to research on the PV grid-connected system.Solar array maximum power point tracking control algorithms and photovoltaic grid-connected inverter control are the two core part of PV grid connected system.Firstly, this paper introduces the operational principle and performance characteristic of PV cells, and describes the equivalent circuit and mathematical model detailedly.Secondly, this paper introduces several traditional maximum power point tracking control algorithms. By comparing these control algorithms, the respective advantages and disadvantages have been found.Thirdly, this paper introduces the mathematical analysis on the gid-connected inverter and establishes the mathematical model. According to the mathematical model, the paper proposes and realizes grid-connected current control method of virtual value outer loop and instantaneous value inner loop. It establishes a system of simulation model with matlab and simulink tool, and analysis the feasibility of the control strategy, and then achives better results.Finally, Islanding detection is the very important issue in the application of the grid-connected photovoltaic system. The paper analyzes and studies some kinds of islanding detection method being in common presently, including passive and active techniques, and the conception of the nondetection zones is discussed in this paper. And then, the new method of detection based the drift of the power is put in this paper, which can not only detect the Iislanding timely and accurately, but also can reduce the influence on the grid-connected current.