The Research On MPPT Algorithms And Controller Of Photovoltaic Power Generation System

As the development of economic, the limited fossil fuels such as coal, oil, naturalgas will not be able to meet the needs of human development. In order to avoid theenergy crisis, we must develop renewable energy. Solar energy is clean, inexhaustible.Photovoltaic power generation has become one of research focuses.The maximum power output of photovoltaic cells is affected by the externalenvironment conditions, such as light and temperature. But a unique maximum powerpoint exists. To make full use of the battery, maximum power point tracking must beused in the photovoltaic system.This paper presents the design of hardware and software of the controller, anddiscusses the algorithms of maximum power point tracking seriously. The theory ofphotovoltaic power generation is first be analyzed, the simulation model ofphotovoltaic cells is established using Matlab/Simulink software. And characteristiccurve of battery output is drawn and analyzed. Algorithms of maximum power pointtracking which are in common uses will be analyzed, comparing their advantages anddisadvantages. Then a new method is proposed. Variable tracking step size andVariable cycle have a relationship with the slopes of P-U curve, the step size andslope of P-U curve have exponential relationship, and tracking cycle is inverselyproportional to step changes. To make the algorithm more responsive to the rapidlychanging environment, three tracking points method is put forwarded, which candetermine whether the environment is changing, avoid false justice, and reduce theoscillation of output voltage in changing environment.To test the algorithms, analysis is made using Matlab programming languagewith simulation models. Simulation results show that new method is effective. Afteranalyzing the circuit of solar controller and hardware design, photovoltaic powergeneration system of150W is build. Results of experiments show that new method notonly improves the speed of maximum power point tracking system, but also improve sthe stability of the system output. Results of simulation and experiment show that newmethod is possible and practical.