Research on three-phase PV grid-connected inverter based on LCL filter

Based on the harmonic suppression of grid-connected inverter, it is suggested to use LCL filter instead of traditional L filter. First, it establishes a mathematic model based on LCL filter of PV grid-connected inverter, Then it analyses the function of LCL filter and the advantage of LCL filter based on the response characteristic of LCL filter and L filter. Second, This paper proposes detailed methods for selecting the parameters of LCL filter based on analysis the effect factor of LCL filter so that an optimized performance can be achieved, Third, This paper probes into the influence of sample current´s position on system stability, In addition, this paper proposed an improved passive damping which make the system have a smaller losses and more stable. It concludes that by adopting double-loop control which sample inverter-side current as inner loop, sample dc-voltage as outer loop to ensure the stability of system and suppress harmonic efficient. Finally, This paper certifies the feasibility and validity.