Robust Control Strategy for Grid-connected Inverters with LCL Filter

To solve the difficulty in designing the controller of the grid-connected inverters due to the high order mathematical model of LCL filter and its natural resonant point,we established a mathematical model of the grid-connected inverter with an LCL filter in synchronous rotating frame,and proposed a robust control strategy by the established model.The proposed strategy by the state space model,of which the robust controller is easy to obtain analytically,can reduce the complex of the control design for the grid-connected inverter with LCL filters.Furthermore,it can meet the demands of removing the pulsations of grid-connected power or eliminating the harmonic components of grid-connected current in the non-ideal voltage condition of utility grid.Finally,the correctness and effectiveness of the proposed control strategy are confirmed using simulations with power system computer-aided design/electromagnetic transients with DC analysis(PSCAD/EMTDC).