PSO-Based LQR Design for Grid-Connected LCL Filter with THD Constraints

Linear quadratic regulator is an effective control technique that can provide active damping to grid-connected inverter with LCL filter. To meet the design requirements, the designer can alter the response and control expenditure by choosing the cost matrices of the state and control signals. The selection of these matrices relies on experience and is usually done empirically. In this paper, swarm intelligence is utilized to design a non-diagonal state cost matrix that outperforms an empirically tuned one. Furthermore, diagonal cost matrices are designed such that the total harmonic distortion requirements are met at multiple loading conditions.