The Research And Implementation Of Optimization Method In Photovoltaic Grid-connected System

With the social development, energy and environmental issues are increasingly becoming a hot topic and people has begun to focus on a new energy. The industry of solar power has broad prospects for development, because solar energy is non-polluting and inexhaustible. Because the high cost and the relatively low conversion efficiency of solar cells, in order to reduce system cost and efficient use of solar energy, the role of maximum power point tracking technology is very important as a core part of the photovoltaic system.In this paper, single-phase two-stage photovoltaic grid system was selected for the study, and research and experiments in terms of circuit design, parameter selection, MPPT control methods were done and made. The main content is as follows:Firstly, the principles of photovoltaic power generation, the mathematical model and the output characteristics were described; several typical photovoltaic maximum power point tracking control methods were focused on, besides the advantages and disadvantages of each method were analyzed and compared, and the corresponding control flow figure was given.Then, for the shortcomings of conventional variable step climbing method, a new and improved method for controlling variable step climbing was proposed. The method combined a constant voltage tracking method to improve the starting characteristics and corresponding control algorithms was added to prevent the phenomenon of false judge.Thirdly, the design of the main circuit and peripheral control circuit of PV systems were completed; the Boost circuit was adopted in main circuit through the analysis of the DC/DC converter circuit topology; in addition to the driver circuit, power supply circuit and the voltage detection circuit of direct current were studied and a detailed study of the design was given. Another the effect of Boost circuit on the output voltage of the PV array and the effect of inverter circuit after the class on the DC bus voltage level were analyzed and studied.Lastly, simulation and hardware test platform were built. Firstly the reasonableness of the design for the main circuit and the peripheral circuit and parameter selection was verified. Simulation and comparative experiments of the fixed-step climbing method, variable step climbing method and the proposed improvements variable step hill climbing were given. The advantages of proposed method,such as having a good starting characteristic, and tracking speed and having good stability when the light mutation were shown by comparative results.