Mitigation of Voltage Sag using DVR and PI Controller

This paper represents the modelling and simulation of dynamic voltage restorer (DVR) ,which is one of the most commonly known custom power device which is used for protection of sensitive loads against voltage sag. As the technological developments have been at its peak power quality improvement have become a important aspect of power system. The main function of power system is to provide their consumers a continuous power supply all the time, but in general practice it is the main concern of power system engineers. However there are some of the loads like sensitive loads (e.g. medical labs devices), in which voltage sag/swell in the supply system are not desirable. For the improvement of power quality custom power devices like dynamic voltage restorer (DVR) is simulated in power system. The main purpose of the DVR is the injection of voltage to power line and uphold the pre-sag voltage condition in the sensitive load side, it is the most efficient and effective modern custom power device used in power distribution networks. The controlling of the system is done using PI controller. The proposed DVR is modelled and simulated using MATLAB software.