Introduction: This paper uses a dynamic voltage restorer (DVR) to improve the voltage quality from voltage sags. It is difficult to satisfy various of compensation quality and time of the voltage sag by using single compensation method. Furthermore

high-power consumption of the phase jump compensation increases the size and cost of a dynamic voltage restorer (DVR). Methods Results: In order to improve the compensating efficiency of DVR

an optimized compensation strategy is proposed for voltage sag of micro-grid caused by interconnection and sensitive loads. The proposed compensation strategy increases the supporting time for long voltage sags. Discussion: Firstly

the power flow and the maximum compensation time of DVR are analyzed using three basic compensation strategies. Then

the phase jump is corrected by pre-sag compensation. And a quadratic transition curve

which involves the injected voltage phases of pre-sag strategy and minimum energy strategy

is used to transform pre-sag compensation to minimum energy compensation of DVR. Conclusions: The transition utilizes the storage system to reduce the rate of discharge. As a result

the proposed strategy increases the supporting time for long voltage sags. The analytical study shows that the presented method significantly increases compensation time of DVR. The simulation results performed by MATLAB/SIMULINK also confirm the effectiveness of the proposed method.