Design of a voltage sag generator based on impedance switching

This paper describes an experimental setup of a voltage sag generator (VSG) based on impedance switching. Bidirectional switches with IGBTs, snubber and clamping circuits are adopted to obtain fast turn on, turn-off while avoiding undesirable voltages and currents stresses. In addition, with the proposed VSG it is possible to adjust the depth and duration of balanced and unbalanced voltage dips making it possible to observe the behavior of wind turbines (WT) under, for instance, voltage dips indicated in the IEC 61400-21.