Study On The Solar Photovoltaic Power Generation Systems Of Maximum Power Point Tracking (MPPT) Technology

With the rapid development of modern society,people's demand for energy is increasing day by day.At the same time,because of the Continuous use of fossil fuels,environmental pollution is becoming more and more serious.The development and utilization of renewable energy is a necessary way to solve the energy demand,reduce environmental pollution and improve people's quality of life.Solar photovoltaic power generation technology is one of the major renewable energy technologies,however,affected by the light intensity and temperature,the utilization of solar energy is low by the Photovoltaic power generation technology.So it is very important to make the power up to the maximum by tracking the maximum power point(MPPT)of photovoltaic power generation system.Although solar energy is inexhaustible clean energy,but the high manufacturing cost,and the low energy conversion efficiency of the solar power generation system greatly limits the widespread use of solar power generation system.Therefore,how to improve the conversion efficiency of photovoltaic cells has become a hot research topic.According to the U-P output characteristic curve of photovoltaic cells that the output power of photovoltaic cells affected greatly by ambient temperature and solar irradiance,and the maximum power output changes with the temperature and irradiance.But at a certain time,when the temperature and the solar radiation intensity is certain,Photovoltaic cells have the only maximum power output point;and the variation of temperature and radiation intensity will lead to the maximum power output of photovoltaic cells changes.MPPT technology improve the conversion efficiency of photovoltaic battery,by making it works at the maximum power point with the maximum power controller.At present,the more mature application of MPPT algorithm are the fixed voltage method,the disturbance observation method,the condu ctance increment method,the mountain climbing method,the fuzzy control law and the improved algorithm based on these algorithms.The fixed voltage control method is simple,has the high reliability,good stability,fast tracking speed,and the system is not easy to appear oscillation.but this method ignores the effect of temperature on the power output of the solar cell,the control precision is poor,it is difficult to realize automatic tracking;disturbance observation method has the advantages of sim ple structure,easy to implement,but it is difficult to satisfy the tracking speed and stability,and easy to produce false positives;The maximum power and the tracking performance of incremental conductance is better,but the choice of step size is more difficult and the stability of the system is poor;fuzzy control method have good steady-state performance.However,its dynamic performance is poor when the external environment changes.Therefore,in view of the traditional single MPPT algorithm cannot take into account the dynamic performance and steady-state performance of the problem,people began to look at the combination of algorithm research.In this paper,Matlab/Simulink is used to establish the mod el of solar photovoltaic cells,and the relationship between the operating voltage and current,voltage and power of PV cells is obtained by using the environmental temperature and the intensity of solar radiation as input parameters.According to the output characteristics of photovoltaic cell model curve,that when the surface temperature and light intensity are certain,solar photovoltaic battery output power is first decreases and then increases as a nonlinear relationship and has a maximum power output point only,while the output voltage increases.Therefore,by adjusting the output voltage of photovoltaic cells,and keeping the system load at the maximum p ower point all the time,that the conversion efficiency of photovoltaic cells can be greatly improved.Finally,this paper introduces the technology of maximum power tracking of common solar photovoltaic power generation system,and studies the disturbance observation method,incremental conductance method,the output characteristics of the fuzzy control method of maximum power tracki ng of photovoltaic power generation system respectively and Comparatively,through MATLAB /Simulink simulation.The results showed that compared with the perturbation and observation method,the combination algorithm is stable,the control accuracy is high;compared with the incremental conductance method,the combination algorithm is of fast response speed;compared with the fuzzy control method,the combination algorithm has high tracking efficiency,fast response time.In summary,the combination method has the advantages of fast response,high control precision,good stability and so on,compared with the traditional MPPT control method.