A power electronic converter based series compensator that can protect critical loads from all supply side disturbances is called a Dynamic Voltage Restorer. It is used for protecting a load from sag/swell in the supply voltage. In three-phase systems, sag/swell may involve one or more phases. If only some phases are affected, the resulting fault becomes more complicated to analyse due to the simplifying assumption of equal current magnitude in all phases being no longer applicable. This paper proposes a strategy of separating positive and negative sequence components of the supply voltage to control separately. Two controllers are realized for each sequence based on vector control. The validity of proposed strategies is demonstrated through MATLAB Simulink simulation on 415 V DVR, when the grid is subjected to unbalanced voltage dips.
L. Devadas, Vanitha, V., and Resmi, R., “Modified Double Vector Control Theory Based Dynamic Voltage Restorer”, International Journal of Applied Engineering Research, vol. 10, no. 20, 2015.