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.