Unbalance Voltage Sag Fault-Type Characterization Algorithm for Recorded Waveform

This paper presents a new algorithm, namely, a three-phase-angle algorithm, for accurate characterization of three-phase unbalanced voltage sags, associated with line-to-line and single-line-to-ground faults, from recorded voltage waveforms. This new algorithm uses the relation between the angles of three-phase voltages and the angle of characteristic voltage. The performance of the proposed algorithm is evaluated by considering numerical examples and recorded voltage waveforms available with the IEEE database. A thorough comparison of the results, obtained using the proposed algorithm and other existing algorithms, is made to demonstrate its efficiency. The results suggest that the proposed algorithm is advantageous in accurate characterization of voltage sags in two ways. First, it is proficient under large/small phase-angle jump as well as for solidly and resistance-grounded systems. Second, it is capable of extracting the information about faults, associated with voltage sags.