A fast detection algorithm suitable for mitigation of numerous power quality disturbances

In this paper, a fast detection method for voltage disturbances is explored. The proposed method provides reliable and fast detection for single-phase and poly-phase voltage disturbances such as voltage sags, voltage swells, flicker and frequency change in the utility voltage. The algorithm is based on the theory that allows a set of three-phase voltages be represented as DC voltages in a d-q synchronous rotating frame. In this case, the utility input voltages are sensed and then converted to DC quantities in the d-q reference frame. Thus, any disturbance at the utility input voltages will be reflected as disturbances in the d-q values. Further processing of the signals minimized the point-on-wave effect and yields an output signal indicating if the disturbance is a voltage sag or a voltage swell. Analysis, simulation and experimental results are presented for a variety of disturbances on a three-phase system. The proposed algorithm is implemented on a DSP based system to provide ride-through for critical loads.