A fast single-phase voltage sag detection for voltage sag compensation system

This paper proposes a fast single-phase voltage sag detection for voltage sag compensation system. The operation of proposed method is based on synchronously rotating reference frame which provides fast and accurate voltage sag detection. a proposed fast single-phase voltage sag detection uses the differentiator as a (-90)-degree phase shifter to produce an orthogonal AC voltage (Vβ) from existing grid voltage (Vα) and convert these voltages to the DC voltages (Vd, Vq) by using of αβ-dq transformation (Park transformation). Finally the sag signal can be generated by these DC voltages (Vd, Vq). The voltage sag can be recognized by the proposed method in a very short time in every condition of voltage sags. When it is integrated to the voltage sag compensation system, the voltage sag can be compensated in a very short time due to fast detection and the load voltage is slightly affected from the voltage sag event.