A novel optimisation method for the design of LCL filters for three-phase grid-tied inverters

Imprudent selection of passive LCL filter parameters may result in worse filtering and excessive power losses. Existing designs methods are only able to provide a range for LCL parameters to lie within and therefore are not able to guarantee performance before extensive trial and adjustments are carried out. To overcome this problem, a novel optimal filter design of LCL filters with passive damping is proposed in this paper. The method of this paper is based solving a multi-objective optimisation problem using genetic algorithm to obtain optimal parameters values for the LCL filter. The goal of the optimisation method is to achieve high harmonic attenuation performance, while at the same time achieve small switching frequency ripples. The design method is verified through simulation studies carried out on a three-phase grid-tied voltage source inverter (VSI) in a distributed generation (DG) system. The simulation results show that the new method can achieve ripple elimination and greater harmonic attenuation than existing methods.