Research And Design On Maximum Power Point Tracking Control Of Photovoltaic Generation System

Photovoltaic power generation is the direct use of solar energy. As the solar battery is influenced by the external environment, how to use the energy generated by the solar effectively becomes the focus of study. So, in this paper, the focus of the study is maximum power point tracking control.First, the related concepts of photovoltaic power generation are introduced, including the classifications, components. Then after analyzing the characteristics of solar battery, the simulation model of PV battery is established.According to the contradictions between tracking speed and tracking precision of the traditional methods of MPPT, two improved methods are proposed in this paper:A method based on fuzzy control is designed by using the relationship among duty cycle, output voltage and output power of PV, this method uses variable step length in different area to improve the tracking speed. Another method based on EIM control according to the nonlinear of PV is designed as well. This method tracks the MPPT through solving the nonlinear characteristics of the PV resistance, reduces the adjustment process, and improves the tracking accuracy and tracking speed. Compared with the traditional methods, the simulation results show that the two proposed methods have better improvements in tracking accuracy and tracking speed.Finally, a "Double stage type photovoltaic grid-connected MPPT system" is designed. The simulation results show that:the designed system can track the maximum power point after connecting with the photovoltaic grid-connected inverter and the output current of inverter has the same frequency and phase with the power grid.