Research Of Control Strategy For Two Stage Three Phase Photovoltaic Grid Connected Generation System

The efficient use of energy is an important symbol of civilization and progress of human society,the traditional large-scale use of coal,oil and other non renewableenergy,not only has caused serious pollution to the environment,and the resultingenergy,nearly exhausted.Solar energy is inexhaustible,Everfount environmentalenergy.In order to alleviate the energy crisis,reduce environmental pollution,the use of solar energy efficient wide range is one of the effective measures.Therefore,all thecountries in the world have focused on the research of grid connected photovoltaicsystem.Firstly,the simulation model of photovoltaic cells is established,and the maximum power point tracking(MPPT)algorithm is simplified reasonably,expounds the principle of the traditional MPPT control method,and compares and analyzes the principle of various improved algorithms,and proposes a photovoltaic MPPT algorithm based on voltage self optimizing disturbance,the simulation results show that the improved algorithm has the advantages of fast tracking speed and high accuracy;Then,the mathematical model of the photovoltaic grid connected inverter is deduced,and then the mathematical model of the two stage three-phase topology is established based on the instantaneous power theory,the direct power control(V-DPC)strategy based on the grid side voltage sensor is applied to the three-phase photovoltaic grid connected system,The simulation model of MATLAB/SIMULINK is built,The simulation and experimental results show that the control scheme is feasible,and the waveform is good;Finally,the principle and classification of islanding detection methods are introduced,and the active phase shift(APS)islanding detection method based on fuzzy PID control is applied to the grid connected PV system,the simulation results show that the APS based islanding detection control strategy based on fuzzy PID can not only detect the islanding faster,but also can effectively reduce the THD.This article on how to improve the stability of grid connected photovoltaic system point of view,on two levels of control strategy of three-phase photovoltaic(pv)grid power system a series of studies,through the MATLAB/SIMULINK simulation environment,proved that the maximum power point of the photovoltaic grid connected system with high tracking accuracy in the simulation grid and waveform detection technology has reached the island of the national technical standards for safety.