Power quality (PQ) survey reporting: discrete disturbance limits

Discrete or event type power quality (PQ) disturbances mainly include voltage sags, swells, and the transients. An extensive literature survey suggests that there is no generally accepted method for characterization of these disturbances and suitable limits are not yet found in any international standard. One of the reasons for the lack of characterization methods is the difficulty of defining suitable site indices for each discrete disturbance type. In this paper existing characterization methods are reviewed and discussed. A new generalized approach is then given to show a better way of characterizing voltage sags, swells and transients. This is followed by a proposed new method of defining MV/LV distribution discrete disturbance limits for general utility networks and their suitability is shown by an examination of some Australian sites.