Author(s): T. Madhu, V.K.R. Mohan Rao, Y.Rambabu

With the increase in use of electronic equipments there has been rise in problems related to power quality. Power quality deals with utilization of electric energy from the distribution system successfully without interference or interruption. The various power quality disturbances are transients, interruptions, voltage sag, voltage swell, voltage collapse, harmonics etc. These power quality related problems can be solved with the help of various custom power devices. Dynamic voltage restorer (DVR) is a custom power device used for the compensation of voltage sag and swell. It can provide the most commercial solution to mitigation voltage sag by injecting voltage as well as power into the system. In this paper an overview of DVR, its components, functions, compensating techniques and control methods are reviewed in detail and the compensating techniques are compared.