Dynamic Voltage Restorer as a sag mitigator and harmonic restorer

This paper presents a generalized control algorithm for voltage disturbance extraction and mitigation. The proposed mitigating device is the dynamic voltage restorer (DVR). A DVR is commonly used to mitigate the voltage sags. In this paper the proposed DVR can compensate the voltage unbalance and mitigate harmonics in the time of normal operation as well as performs its basic function during the fault condition. The suggested control algorithm employs the synchronous stationary frame (SSF) for sag detection and instantaneous p-q theory (IPQT) technique for harmonic extraction to effectively track and extract the most common voltage disturbances. Digital simulation results are obtained using PSCAD/EMTDC to verify the effectiveness of the proposed control algorithm. Experimental results are demonstrated to prove the practicality of the mitigating device.