Research And Design Of LCL Single-phase Photovoltaic Grid-connected Inverter

With the rapid growth of renewable energy market,more and more attention has been paid to the development and utilization of new energy,especially the use of distributed solar power.However,these renewable energy sources cannot be directly integrated into the grid or provided to the users in need.Therefore,a complete energy transfer system is needed to convert the new energy direct current into alternating current for the users to use.The output waveform of photovoltaic grid-connected inverter needs to be filtered to meet the relevant technical standards.The conventional filter circuit structure is mainly composed of L filter,LC filter and LCL filter,the characteristics of the L filter and the LC filter are the same basically,to achieve good filtering effect,the value of the inductance value or the filter capacitance can be increased,but the cost and the volume are increased.LCL filter not only has smaller volume in the same effect,but also has more outstanding attenuation ability in high frequency than L filter and LC filter.However,the LCL filter is a third-order system with a phase of-180 °jump at the resonant frequency.If the damping of the system cannot be effectively increased to suppress the resonant spike and phase mutation,the continuous oscillation of the photovoltaic power generation system will be caused.Make the whole system very fragile and unstable,affecting the quality of grid-connected current.In view of the resonance characteristics of LCL filter structure,the proportional feedback active damping of capacitive current can suppress the resonance spike of the system.In this paper,the singlephase LCL photovoltaic grid-connected inverter is taken as the research object,and the related research and analysis are carried out based on capacitive current active damping control and grid-connected current regulator technology.The active damping feedback of capacitive current and the grid-connected current regulator are considered,and the calculation scheme of the parameters of the active damping and current regulator is given.Based on the analysis theory,a specific simulation model is built by using the simulation software matlab/simulink,and the control strategy based on capacitive active damping and gridconnected current is simulated and verified.At the same time,the experimental platform is built with the digital processing chip DSP2812 of TI company as the core technology.The simulation and experimental results verify the validity and correctness of the designed filter,controller and active damping parameters...