CPT-based Active Power Filter with Repetitive Controller and Capacitor Voltage Feedforward under Non-Ideal Grid

This paper proposes the design of a repetitive controller along with capacitor voltage feedforward applied to an LCL filter active power filter (APF). The repetitive controller can operate in systems with disturbances exhibiting high harmonic content and the feedforward action can reshape the output impedance of the APF. The conservative power theory (CPT) is proposed to obtain reference signals for the purpose of total mitigation of unwanted currents. The proposed technique ensures that only the active current flows through the electrical grid, while maintaining the stability of the APF-grid system through passivity theory. Finally, the proposed control strategy is validated using the Matlab/Simulink® software under several conditions of grid imbalances and harmonic distortions.