A novel parameter design for level grid-connected smart inverters

LCL filter is an important component in the grid-connected inverters. The parameters of LCL filter have a strong influence on the output current distortion of inverters. For three-level inverter system, a parameters design method is proposed in this paper based on genetic algorithm optimization of output current total harmonic distortion (THD). By deducing the transfer function of the filter, output current THD is calculated through double Fourier analysis. Then an adaptive immune genetic algorithm is designed to solve the objective parameters optimization issue under constraint condition. With harmonics attenuation in both fundamental band and carrier band taken into account, the filter parameters are optimized scientifically by the global search algorithm, which contains punishment mechanism, adaptive parameters and the mechanism of immune algorithm. The feasibility of the proposed method is verified by conducting simulation and experiment.