Research On The Parameters Optimization Of LCL Filter In Photovoltaic Grid-connected Inverter

With the lack of fossil energy reserves and the growing of environmental problems caused by the massive fossil consumption, people have realized the importance of developing renewable energy. Because of its large reserves and many outstanding advantages, solar energy is gained comprehensive attention. In photovoltaic power system, LCL filter, as a core part, has been a research hotspot. This paper has taken LCL filter of three-phase photovoltaic grid-connected inverter as research object and studied in depth for parameter optimization of LCL filter.(1) Establishment of three-phase photovoltaic grid-connected inverter mathematical model. First, this paper used voltage source inverter. Then, L-type, LC-type and LCL-type output filter of grid-connected inverter were compared and analyzed to select LCL filter as the main research object, considering filtering effect, cost and other factors. Finally the three-phase photovoltaic grid-connected inverte based on LCL filter mathematical model was built in rotary two-phase coordinate.(2) Analysis of LCL filter in three-phase grid-connected inverter. First, the design principles and resonant suppression method of LCL filter were analyzed. Then, for the problems of complex design process, huge computation and difficult to meet constraint conditions, quantum-behaved particle swarm optimization algorithm(QPSO) was proposed to optimize the parameters of LCL filter.(3) Simulation results demonstration. First, the simulation model of three-phase photovoltaic grid-connected inverter system based on LCL filter was set up by the software of MATLAB. Then, parameters of LCL filter were optimized by QPSO and particle swarm optimization algorithm(PSO) respectively. The optimized LCL filter was used in three-phase grid-connected inverter,to further illustrate the efficiency of QPSO,make the traditional design method of LCL filter parameters are obtained as a comparison,The results were compared and analyzed to verify the feasibility and efficiency of QPSO superior to PSO and the traditional design method from harmonic suppression effect, filtering convergence and so on.