This paper describes the problem of voltage sags and swells and its severe impact on non linear loads or

sensitive loads. The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the

protection of sensitive loads voltage sags and swells. The control of the compensation voltages in

DVR based on dqo algorithm is discussed. It first analyzes the power circuit of a DVR system in order to

come up with appropriate control limitations and control targets for the compensation voltage control. The

proposed control scheme is simple to design. Simulation results carried out by Matlab/Simulink verify the

performance of the proposed method.-This paper describes the problem of voltage sags and swells and its severe impact on non linear loads or

sensitive loads. The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the

protection of sensitive loads　voltage sags and swells. The control of the compensation voltages in

DVR based on dqo algorithm is discussed. It first analyzes the power circuit of a DVR system in order to

come up with appropriate control limitations and control targets for the compensation voltage control. The

proposed control scheme is simple to design. Simulation results carried out by Matlab/Simulink verify the

performance of the proposed method.