Studies in the Assessment System of Voltage SAGs

On the basis of a general five-step framework proposed by IEEE project group P1564 for obtaining system indices for voltage sag performance, this paper analyzes and organizes parts of indices studied by some international organizations like IEEE and IEC, recommends some indices to be adopted from aspects of single event¿single site and system respectively by summarizing their merits and shortcomings. This paper also compares three methods of identifying types of sag event, that is——S-C and S-P method proposed by Bollen, and another algorithm named TP-TA which is based on three-phase voltage magnitudes and their phase angles. At last, a set of specific and integrated assessment system combined with a variety of indices and feature extraction methods has been proposed.