αβ-Transformatlon based algorithm for identifying the power quality events in electric distribution networks

αβ-Transformation is a de transformation used to transfer the three-phase ac system of voltage or current to a dc system. This paper presents the application of this transformation to identifying the power quality events, such as harmonics, voltage sages, flicker, swell and transients. The proposed transformation can be implemented for a single phase or three- phase system of voltage. The phasor voltage resulting from the combination of V_α and V_β has a magnitude proportional to the system operating voltage and rotates with a speed of the frequency of the system voltage. The estimated shape of the phasor voltage over the data window size gives the nature of the power quality event. The proposed technique can be implemented in off-line or on-line modes. Simulated results, for different types of events are presented in the text and the results show excellent identification using the proposed technique.