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 (V-beta) from existing grid voltage (V-alpha) and convert these voltages to the DC voltages (V-d, V-q) by using of alpha beta-dq-transformation (Park transformation). Finally the sag signal can be generated by these DC voltages (V-d, V-q). 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.