Power Quality Improvement by using DVR

Abstract

A power system having three main subsystems such as generation, transmission and distribution. While transmitting the power from generation to end user’s utility has to face power quality issues such as voltage sag, voltage swell, harmonics, transmission losses, transients, voltage fluctuation/ flickering and many more, there are various devices and protecting system exist to improve power quality of the system such as DVR, FACT Devices (STATCOM, UPQU, UPFC, SSSC, TCSC). Problem like voltage sag and voltage swell generally affect to the end user’s equipment’s probably sensitive equipment’s like computer, electronic devices, medical devices (Patient monitors, lights, ultrasounds, electrosurgical units, anesthesia machines). To control voltage sag and voltage swell problem at one time DVR is most efficient and accurate device, by using DVR we can mitigate both the problems through one device. During voltage sag condition additional have to feed to the system and at voltage swell condition increased voltage have to eject from the system to make the system voltage at constant magnitude. To feed the voltage into the system at sag condition DVR provides the voltage of decreased magnitude with same phase angle and to eject increased voltage of system at voltage swell condition DVR provides the voltage of increased magnitude but in opposite phase angle to the system voltage. This research helps to improve voltage quality at load side specifically at end user’s side.