Independent Photovoltaic Power Generation System With Energy Storage Device

As an important way of the efficient utilization of solar energy,solar power generation has developed rapidly in the world in recent years.The stand-alone photovoltaic system can convert solar energy into stable electrical energy and store it in the battery.During night,cloudy or the time of need,the battery will provide electricity to the load in the form of discharge.The independent photovoltaic power generation system is widely used in the area without public grid,in order to improve the efficiency and reliability of independent photovoltaic power generation system,the independent photovoltaic power generation system as the research object to design a storage device of independent photovoltaic power generation system,and analyzed the MPPT algorithm simulation,prototype development,and experimental results.First of all,the working principle of photovoltaic cells is analyzed,and the simulation model of photovoltaic cells are established,and the change of its output characteristics in different environment is studied.The advantages and disadvantages of a variety of commonly used maximum power point tracking control methods are analyzed,and a variable step size perturbation observation method is proposed.In the MATLAB software,the MPPT model is built and the simulation and contrast study is carried out.The results show that the control effect of the variable step size perturbation observation method is better than the perturbation observation method.Then,the hardware and software parts of the independent photovoltaic power generation system are designed,in which the hardware part is composed of the charging module and the inverter module.The main circuit of charging module is composed of BUCK circuit.STM32F103RCT6 is used as main control chip to realize current and voltage detection,maximum power point tracking,PWM wave generation and communication with host computer.The inverter module is composed of two parts: the front stage boost and the rear stage inverter.The main circuit of the front stage boost part is a push-pull boost circuitand a TL494 control chip.The main circuit of the back stage inverter is full bridge inverter circuit and KA7500 B control chip.The inverter module realizes the two functions of boost and inverter,and converts the DC power from the battery to the 220 V power frequency quasi sinusoidal alternating current for the use of the load.The upper computer information acquisition system is designed to communicate with the charging module,and real-time collection and display of charging voltage,current and duty cycle experimental data.Finally,a prototype is developed and experimentation is carried out to verify the validity of the maximum power point tracking algorithm and the stability of the system output.The experimental results show that the maximum power tracking effect of the system charging module is good,and the output waveform of the inverter module is smooth and the voltage is stable.The prototype realized the two processes of charging and power supply,and the performance reached the design goal.