Integrated Design of Filter and Controller Parameters for Low-Switching-Frequency Grid-Connected Inverter Based on Harmonic State-Space Model

In high-power grid-connected inverter for new energy power generation system, low switching frequency makes the control loop, LCL-filter resonant peak, and sideband harmonics generated by modulation coupled so that the parameter design of filter and controller affects each other. This increases the difficulty of design of filter parameters and controller parameters. To solve this problem, the accurate current harmonic calculation method based on the harmonic state-space model and considering switching frequency and control delay is proposed in this article first. Second, based on the above model, the parameter optimization process considering current harmonic distortion rate, filter cost, and so on is constructed. The integrated optimization design of filter and controller parameters of low-switching-frequency LCL grid-connected inverter is completed through intelligent algorithm. Thus, the filter cost is minimized on the premise that inverter performances meet the specific requirements. In addition, considering the nonideal characteristic of grid, a scheme of integrated parameter design that can adapt to the large-scale change of grid strength is proposed. Finally, the effectiveness of the proposed method and scheme is verified by simulation and experiment.