The Development Of Off-grid Photovoltaic System Based On MPPT Control

Power generation making use of solar energy has aroused more and more attention gradually in many countries because of its advantages of sustainability and cleanliness. Therein, photovoltaic system has more practice value in this area because of its technical improvement and decreasing cost. In order to reduce more cost, research of optimum usage and control strategy of photovoltaic system has been a hotspot in the area of photovoltaic application. Under this background, off-grid photovoltaic system has been studied in depth in this article. Under the premise of without adjusting the light angle of photovoltaic panels, in order to make use of solar energy in maximum and elevate the performance of the storage battery, TMS320LF2407A from TI is introduced into the system. Based on above, theory and experiment study of off-grid photovoltaic system based on MPPT has been performed during this research. Most technical essentials are indicated as below:Firstly, on the base of analyzing the system, the whole design of off-grid photovoltaic system is carried out in this paper; in addition, the technical guideline is also listed by investigating the system. In this article, design principles of all parts of the main circuits in the system are introduced respectively, and the parameters of the main circuits are given out definitely, and also the work process is described in detail.Secondly, the model of solar energy battery and its output characteristics are studied. Comparing some usual MPPT methods, the realization process aiming at off-grid photovoltaic system studied in this paper is brought forward. Simulation about MPPT is also carried out and its results explain that the control strategy designed for the former BOOST circuits of this system can track the max power point effectively.Thirdly, the work principles and usual control strategies of the storage battery are also studied. For the system in this paper, we advance the control strategy of two-level charge and invariable voltage discharge. In order to validate the validity of the control strategy, stimulation on the charge and discharge circuits of the storage battery is carried out, and the results show that the control strategy and parameters design are very effective.Finally, based on above, according to the whole design, assistant circuits and software of the control system are provided. Besides, selection scenario of the experiment equipments about the main circuits is also given out. During the research, a 1kVA off-grid photovoltaic system with the function of MPPT is developed. According to the experiment study, it shows that this system can achieve the functions required in the control project simply and effectively.