Research On Grid - Connected Photovoltaic Characteristics And Its Impact On Power Grid

With the grid-connected photovoltaic(pv) power generation capacity increasing, it has gradually become the main development direction of photovoltaic power generation. Because the number of photovoltaic(pv) grid connected is bigger and bigger, the problem followed is also growing, so people have to devote more attention to it. In this paper, the thorough analysis and the research is made based on the generation principle,output characteristics of solar cells, the maximum power tracking as well as the working principle of inverter then the MATLAB software is used to establish grid PV models.Based on the theoretical model and engineering mathematical model of the solar cell, a simulation model is established according to the changes of environmental temperature and irradiance,and then run the simulation model, to get the output characteristic curves of solar cell.By analyzing the traditional perturbation and observation method, which is a kind of maximum power point tracking control method, an improved perturbation and observation method which improves the efficiency and stability of the system is put forward, and, simulation model is established. The simulation results prove that this improved perturbation and observation method is more efficient, in the process of MPPT.Based on the research on topological structure of photovoltaic grid connected inverter and its mathematical model, the simulink simulation model which is based on the voltage oriented vector control strategy is built.And the solar battery simulation model and improved perturbation and observation method simulation model which are already established are used to set up the grid system simulation model. Simulation shows that the inverter model built in this paper has good output voltage and current characteristics, which can realize interconnection function.Finally, this paper presents further research and analysis of the two features of grid pv system, namely the Islanding Effect and Low Voltage Ride Through.Take Yunnan Normal University 120 kw photovoltaic curtain wall project as an example to analyse the effect of pv grid and off-grid on grid power quality. By comparing and analysing the real system and simulation system, it turns out the simulation model is correct, and it’s used for an in-depth analysis of the simulation grid pv system,which presents the effect to the quality of grid connected photovoltaic power station caused by irradiance change in the case of real system.