About voltage sags and swells analysis

Time at level analysis of discrete events is proposed to characterize voltage sags and swells instead of the simple magnitude vs. duration characteristics presently used. Although requiring a little more computer memory and digital processing, the proposed methodology constitutes a significant improvement for the characterization of unpredictable temporary voltage disturbances through simple numerical index. Some potential applications of the new method are: full conformity verification to existent or future standards; direct comparison with load sensitivity curves; implicit data compression for transmission and storage; automatic event classification; events ranking and propagation analysis. An IEEE database of voltage sags and swells was used to test the proposed methodology.