Linear active disturbance rejection control for a dual unified power quality conditioner

Abstract

In this paper, a linear active disturbance rejection control (LADRC) method is presented for a dual unified power quality conditioner (iUPQC). Compared with the traditional PI controller that requires double closed-loop control and decoupling design, the presented LADRC control method with Quasi-resonant (QR) feedforward has the benefits to simplify controller structure, and improve system steady-state, dynamic and anti-interference performance under the conditions with system uncertainty and external disturbances. By considering the unfavorable factors as control disturbances, the LADRC control method is able to obtain ideal performance through utilizing linear error state feedback (LESF) and dynamic disturbances compensation. In addition, in order to reduce DC link voltage fluctuation and eliminate double frequency ripple, a super capacitor is connected to DC link through a bidirectional DC/DC converter. By controlling the PWM signal of converter, the DC link capacitor can be charged or discharged to keep its voltage stable. Finally, the feasibility and effectiveness of this method are verified by MATLAB/SIMULINK simulation on a three-phase power distribution system.