Fast repetitive controller based low-voltage dynamic voltage restorer for voltage-quality issues in distribution system

Dynamic voltage restorer (DVR) has been demonstrated to be a very effective mechanism to deal with key voltage-quality disturbances. Although the dynamic response requirement for voltage sag could be satisfied with a feedforward control strategy, the steady-state requirement and zero-error tracking need an advanced feedback control strategy. This paper proposes a fast repetitive controller based feedback control strategy for DVR system. In the control system, the feedforward control loop could meet the dynamic requirement; the repetitive controller based feedback control loop could realize zero steady-state error tracking for fundamental voltage and harmonic components. The fast repetitive controller: 1) could eliminate all odd signals (including fundamental component); 2) could be simply implemented in digital signal processors just with a time delay loop; 3) has fast dynamic response when compared with traditional repetitive controller as its delay time is reduced to half of traditional´s. This paper also chooses the small gain theorem for control system analysis and parameters design. The simulation on MATLAB/simulink also demonstrates the validity and superiority of proposed control strategy.