Simulation And Research On Photovoltaic Grid-connected System And Its Control

Along with the increasingly serious energy crisis and environmental pollution,energy issues which become an important integral part of the human environment, hasincreasingly gained attention. Solar photovoltaic technology is clean energy generationtechnology based on high-tech, in recent years, governments all over the world havetaken important initiatives to promote and support the development of solar, PV powergeneration has been a rapid development in the international community’s attention．Thesolar energy is transformed to electric energy，and the electric energy is fed to the grid bythe grid-connected photovoltaic system．This is the mostly form of the exploitation ofsolar energy system．Expensive as the price of photovoltaic cells and efficiency iscurrently low, the control method of the grid-connected photovoltaic power generationsystem is absolutely necessary in order to reduce system costs and improve efficiency.The grid-corrected photovoltaic system and its control are deeply researched．Thispaper studied the characteristics of the photovoltaic array and carried out simulation andanalysis, Equivalent circuit of the photovoltaic cells on the basis of the establishment ofphotovoltaic power generation system simulation model, and check the accuracy of themodel based on mathematical models and the two MATLAB digital simulation model,the two models can better reflect the power output of photovoltaic cells and the externalfactors relations, can accurately reflect its physical properties and has high simulationaccuracy. On the basis of the analysis and comparison of classical MPPT controlalgorithm, this paper built a simulation model of the MPPT control and gave a newMPPT algorithm-fixed voltage method combined with adaptive duty cycle perturbationmethod, through the establishment of digital simulation models, compared to thealgorithms of the simulation results verify the superiority of the algorithm.The Topology and working principle for grid-connected inverter was described; the inverter control method, simulation and design of the system were given. Themethod of current PI regulator control, the establishments of a grid-controlled digitalsimulation model, simulation analysis were described to verify the correctness of thecontrol strategy. By analyzing and comparing several traditional islanding detectionmethods, a new islanding detection method of intermittently active frequency drift withpositive feedback was described, and the superiority of the method was verified byMATLAB simulation. The simulation results show that the control strategies and designmethods used in this paper is feasible and effective.