Today, with attention to increase in sensitive electrical equipments application in distribution networks and their susceptibility to the power quality deficiencies, the protection necessity of sensitive loads against undesirable effects of these disturbances are in focus. So, in this paper voltage sag deficiency and Dynamic Voltage Restorer (DVR) would be introduced as the most prevalent power quality problems and most effective voltage sag’s compensators, respectively. Continuously, different parts of DVR structure would be discussed in which control system would be taken into account as the most important part. In this part, after different compensation strategies analysis and with attention to great importance of compensator response in sensitive load protection against the duration of voltage sag, various voltage estimation algorithms would be introduced. Afterwards a novel estimation algorithm would be proposed which has the desirable accuracy and less delay among the mentioned ones. Then a proposed control system based on the proposed algorithm in the fault detection system and pre-fault based symmetrical component strategy would be introduced. Finally the effects of the novel system on asymmetrical voltage sag and swell of the distribution system improvement would be simulated in Matlab/Simulink.