Study On Single-phase Grid-connected Photovoltaic Inverter System And Its Stability

With the rapid development of society,human beings are increasingly dependent on traditional fossil energy,which is bound to cause severe energy crisis over time.Solar energy is a mainstream clean energy with abundant reserves and no pollution.Therefore,the development and utilization of solar energy has received extensive attention and research.In this paper,the single-phase grid-connected photovoltaic power generation system is taken as an example to study and analyze the key technologies of photovoltaic power generation.In this paper,the topological structure of single-phase inverter is firstly analyzed,and the two-stage non-isolated system structure is selected.The grid-connected inverter is taken as the center,and the photovoltaic power generation system is divided into dc and ac parts.For the ac side filter circuit,this paper mainly analyzes the topology of different filter circuits,and selects l-type filter as the research object.For the front DC circuit,the Boost circuit is selected as the front DC/DC Boost circuit,and the inverter is the single-phase full-bridge inverter.This paper carried out mathematical modeling of photovoltaic cells,and built a simulation model in Matlab/Simulink to simulate its output characteristics.Based on the simulation model of photovoltaic cells,this paper analyzed and studied the maximum power tracking technology and grid-connected inverter control technology.This paper analyzes several common MPPT technologies and their advantages and disadvantages,and proposes a variable step size perturbation observation method based on GM(1,1)model in combination with the grey system theory.For the inverter control technology,a grey PID double closed-loop control strategy based on GM(0,N)model is proposed by analyzing the shortcomings of the traditional double closed-loop control strategy.Through the establishment of the simulation model in Matlab/Simulink,the simulation experiments are carried out for the maximum power tracking technology and grid-connected inverter control technology respectively.Experiments show that the improved MPPT technology can effectively improve the system's optimization speed and tracking accuracy after stabilization,and can also respond quickly when the environment changes.Improved less grid inverter control technology can effectively in the grid current harmonic content,improve the quality of the grid current,at the same time,the improved control method can improve the dynamic performance of system,improve the stability of the dc bus voltage,reduce the volatility environment change brings to the system,effectively improve the efficiency and stability of photovoltaic(pv)grid power generation system.Through the above simulation experiments,the expected control effect is achieved,and the rationality and effectiveness of the proposed method are verified.