Research On Grid-connected Photovoltaic System With Improved MPPT

With the increasing exhaustion of traditional energy,the development of new green energy is imminent.Solar energy is undoubtedly one of the most ideal alternative energy because of huge reserves and polution-free.Therefore, the photovoltaic systems have become a research focus in the field of global new energy.This paper mainly studied the MPPT control technology.The main principle and mathematical model of PV cell has been analyzed,some commonly-used MPPT algorithm has also been introduced.On this basis, the paper proposed a novel MPPT algorithm which based on introducing a complex function for photovoltaic systems,the principle and realization way of Function method has been analyzed in detail.Then the Function method is compared with Incremental conductance method in Matlab/Simulink,which turned out that Function method is verified on the tracking effect especially when external conditions change drastically.Secondly,the double closed-loop control strategy of three-phase photovoltaic systems is studied.The article established the mathematical model in the dq frame.On the basis, the feedforward decoupling control strategy and the design method of voltage and current control loops are reserched in detail,and the performances has been simulated.Finally, the entire photovoltaic systems are simulated.A simulation model is built in the MATLAB/Simulink,in which the Function method MPPT control system and the double closed-loop control system are included.The simulation results show that the output current of photovoltaic grid-connected inverter system can well realize the network voltage of tracking,and the tracking effect of MPPT controller based on function method is also excellent.