Compensation of Voltage Sag and Swell by using Dynamic Voltage Restores

The electrical energy is one of the easily used and available forms of energy. For electrical engineering, power quality is a noteworthy topic. At present day, the problem of power quality has become one of the major problems which have to be taken into account for the maintenance of power supply quality. Today’s equipment like electric motors, computers, machines, etc. cannot be used without electricity. The voltage sag and swell is one of the severe problems for an industrial customer which has to be dealt with urgent attention for its compensation. There are many methods which can compensate the problems of voltage sag and swell. Today the most popular methods of sag and swell mollification is Dynamic Voltage Restorer (DVR), which can used in low voltage as well as medium voltage applications. Dynamic Voltage Restorer is a cascaded connected device; which is based on the principles of power electronics which can immediately mitigate the voltage sag in the system and will be restoring the load voltage to the pre-fault system value. It is a voltage source converter which is connected to the circuit in cascade with supply through the help of injection transformer where voltage swell or voltage sag takes place. For the compensation of voltage sag and voltage swell in the distribution system, DVR is the most technically advanced, convenient and economical device. Dynamic voltage restorer stores energy that is responsible for the supply of active power needed during the voltage sag & gain at swell. This paper gives the idea of usage of the error signal that can be controlled by using DVR.