Study of dynamic voltage restorer under the abnormal voltage conditions

This paper presents a single-phase and three-phase dynamic voltage restorer (DVR) to protect the sensitive loads against the voltage disturbances due to short-term abnormal voltage conditions. The reduced switch-count inverter is adopted in the single-phase system to compensate voltage disturbance for low power applications. The front-end ac/dc converter is used to maintain constant dc-link voltage and provide the necessary active power for DVR under the voltage sag condition. Under the voltage swell condition, the ac/dc converter is operated as an inverter mode to deliver the active power back to the utility system. Three-phase DVR system with three single-phase full-bridge inverters is also presented to against the abnormal utility voltage conditions such as voltage sag, swell, flicker, harmonic and unbalance voltage. The adopted topology and control strategy are evaluated through several simulation studies.