This paper deals with a new quasi Z-source Dynamic Voltage Restorer(DVR). The proposed system based on single-phase quasi Z-source AC-AC converter which has features such as the input voltage and output voltage are sharing ground, and the input current operates in continuous current mode. Also the proposed system is able to compensate voltages sags and swells. For the detection of voltage sag-swell, the fast detection of an instantaneous value detection algorithm is applied. The operating principles of the proposed quasi Z-source AC-AC converter are described and PSIM simulation is presented to verify the proposed concept and theoretical analysis.