Research On The Maximum Power Point Tracking Characteristic Based On Distributed Photovoltaic Power System

Solar photovoltaic power generation is one of the major new and high technologyindustries of the world’s energy conservation and green electricity. Developingphotovoltaic industry has become one of the best ways for the world’s countries tosolve the energy and the contradiction between economic development andenvironmental protection. Solar photovoltaic power generation is a way of generatingelectricity by using the solar cell converts light into electrical, is one of the mostpromising power generation technology. However, there have been two majorbottlenecks of photovoltaic power generation systems, one is the cost is higher, theother is the photoelectric conversion efficiency of solar cell is too low. In order to solvethese problems, on the one hand, low cost and high energy conversion efficiency ofphotoelectric material need to developed, on the other hand, we need to achievemaximum power output of solar cells. Therefore, the research of the maximum powerpoint tracking (MPPT) technology for photovoltaic system become an importanttopic. In this paper, for the purpose of optimizing the efficiency of photovoltaic powergeneration system, based on the research line on the control technology of MPPT, athorough theoretical and experimental research are launched.First of all, the working principle and mathematical model of photovoltaic cellswere analyzed, according to its mathematical model, a model of photovoltaic cells isestablished by using the software MATLAB/SIMULINK, under different temperatureand solar irradiance, the simulation research on output characteristics of photovoltaiccells are carried out, I studied the influence of different temperature and solarirradiance on the maximum power output of photovoltaic cells. Then the research onworking principle and voltage transformation relations of the Buck and Boostconversion circuit was carried out, based on the advantages and disadvantages of twokinds of conversion circuit, we choose the Boost conversion circuit to achievemaximum power point tracking in this paper.Secondly, several kinds of commonly used maximum power point tracking algorithms were analyzed, such as constant voltage method, perturbation andobservation method and incremental conductance method. On the basis of theshortcomings of the traditional perturbation and observation method, an improvedMPPT algorithm is proposed, and the theoretical analysis and research of the improvedalgorithm has carried out.What’s more, in this paper, the design of the hardware circuit and software of thephotovoltaic maximum power point tracking is carried out, hardware circuit mainlyincludes the design of the parameters for Boost circuit to achieve maximum powerpoint tracking, the voltage and current sampling circuit of photovoltaic panels and thedesign of maximum power point tracking control unit. In software, the voltage andcurrent data acquisition programs of PV panels, the maximum power point trackingprograms and display program are designed.Finally, based on software MATLAB/SIMULINK, the simulation models of theconstant voltage method, the traditional perturbation and observation method and theimproved MPPT algorithm are established, and the simulation researches of the threekinds of maximum power point tracking algorithm are carried out. To further verifythe improved MPPT algorithm’s feasibility and correctness of the theoretical andsimulation calculation, the experimental platform of maximum power point trackingsystem is set up, some experiments of the improved MPPT algorithm performancetesting are implemented, I compares and analyzes the performance of the two MPPTmethods in this paper, the results show that the output power of the improvedalgorithm is higher than the traditional perturbation and observation method. Theexperimental results are in conformity with the simulation results.