Research Of The Islanding Effect And The Smooth Switching Of The PV

With the rapid development of the new energy,the proportion of the photovoltaic is getting bigger and bigger in the power system.The grid-connected PV system is the main method of the using of the photovoltaic.The PV system connects to the grid will necessarily bring island effect problem,this requires that(1)the PV system can detect the islanding effect and(2)the PV system can work normally when the system switch from the grid-connected mode to islanding mode.To grid-connected PV system with multiple inverters,there are a variety of inverters with many islanding detection method.So it’s very important to analysis the coexistence of multiple island detection methods to the multiple inverters system.When the islanding effect happened in the PV system,to make the PV system work normally on the islanding mode instead of cutting it off simply to supply the local load’s power has became a possible choice.So the research of the smooth switching of the grid-connected mode and the islanding mode is necessary.The research of the smooth switching of the grid-connected mode and the islanding mode is to smooth and quickly switch the control mode from the constant power strategy of the grid-connected mode to the control Strategy for CVCF of the islanding mode.Firstly,based on the research of the various islanding detection methods used in PV systems,this thesis proposes the research of the affection of the islanding detection method used in muti-inverters PV system.This thesis makes the theory and simulation research of the affection to the detect effect of the using of the different islanding detection method in muti-inverters PV system.This thesis uses the MATLAB/Simulink to build the muti-inverters PV system model and make the simulation comparison of different islanding detection method used in muti-inverters PV system.Secondly,on the basis of theoretical research on the auto disturbance rejection technology,this thesis proposes the research of the smooth switching of the PV system control mode in PV system based on ADRC.This thesis makes the theory and simulation research of the switching of the grid-connected and the islanding mode of the PV system based on the ADRC.This thesis uses the MATLAB/Simulink to make the simulation comparison of the smooth switching of the PV system control mode in PV system based on ADRC and the switching in PV system control mode based on the traditional PID control.