An Improved Voltage Control Scheme Based on Deadbeat-Repetitive Techniques of a Single Distributed Generation Unit In Island Mode

This paper proposes a voltage control of a single distributed generation (DG) unit powered local load. The DG system utilizes three phase four wire voltage source inverter VSI with split DC link as the medium interface and LC filter. A dual loop scheme is employed. Hysteresis current controller is used in the inner loop. In the outer loop, a compound control method based on deadbeat and repetitive controllers is proposed in this paper. Using repetitive controller the unwanted harmonics from the output voltage caused by nonlinear loads can be eliminated. The deadbeat regulator is adopted to increase dynamic response of the system to disturbance due to load transit. The proposed controller provides a set balanced three phase voltage despite unbalanced current load, low THD in worse case (uncontrolled rectified load) for a local load, guarantees a fast dynamic response to disturbance. Effectiveness of the proposed control strategy is evaluated based on time domain simulation studies in Matlab/Simulink (TM) environment and is verified by results obtained on laboratory benchmark.