Research On Three-Phase Grid-connected Inverter With LCL Filter

With the development of renewable-generating,three-phase grid-coonentedinverter has been become a hot research direction owing to its advanced featuresincluding sinusoidal output current and voltage,bi-directional power flow, highcontrol ability of grid-side active and reactive power,etc. The control technologyplays an important role of the interface between renewable energy and the grid.At present,with the increase of system power rating,LCL filter take L filter placeand are increasingly being used in grid-side converter, owing to its advancedfeatures of output’s THD and small size.This dissertation chose the Three-Phase Grid-connected Inverter with LCLFilter as the research object. Firstly,the topology of main circuit based on Three-Phase Grid-connected Inverter are introduced,Mathematical models of Three-Phase Grid-connected Inverter are established in three-phase static coordinateand tow-phase rotate coordinate.An LCL-filter design is proposed according toLCL-filter operation characteristic.Next the control strategy based on Three-Phase Grid-connected Inverter are introduced:The double closed-loop controlstratrgy based on the harmonic voltage of SVPWM,and the control system isdesigned.These stategis are simulated under MATLAB/SIMULINK,thesimulation results show the correctness of the control strategy and parameterdesign.Subsequently,a10kW engineering prototype inverter is built,the designingof the main and control circuit is given in detail,and the prototype system wastested comprehensively,verify the theoretical analysis and simulation.