A COMPARATIVE ANALYSIS OF THE PERFORMANCE OF DYNAMIC VOLTAGE RESTORER BASED ON INVERTER TOPOLOGY AND CONTROL TECHNIQUE

Abstract

Dynamic Voltage Restorer (DVR) is one of the custom power devices employed in distribution systems to mitigate power quality problems such as voltage sag and swell affecting critical loads. In the event of a voltage disturbance, the DVR injects a voltage in series with the line to maintain the voltage quality at the load terminals. Conventional DVRs are designed based on voltage source inverters and classical control theory. They lack fast dynamic response and require a large rating energy source to mitigate deep voltage sags of longer duration. To overcome this limitation, the design and development of a DVR based on a quasi impedance (Z) source inverter and associated control is being proposed. A Quasi Z source inverter ensures a constant dc link voltage during the voltage compensation in a DVR with reduced energy storage. A sliding mode controller implemented here does not depend on accurate system model and is capable of compensating any variations in the source voltage with good dynamic response. The efficacy of the proposed system is established against the conventional DVR system through simulation studies and validated with an experimental model.