Short duration voltage disturbances like voltage sags are receiving much attention, since they are very common. Voltage sags are characterized by short duration; nevertheless they can result in the shut down of an industrial process or in the maloperation of the control system of devices like AC-DC converters. In this paper, a fast controller for a series connected VSC to mitigate voltage sags in distribution systems has been developed, which is also able to take into account the effect of the voltage sag phase-angle shift.