Contingency ranking based on severity indices in dynamic security analysis

Fast contingency screening is expected to be an integral part of any practi cal on-line dynamic security analysis (DSA). Ranking of contingencies requi res the use of severity indices, and for DSA such an index must be a measur e of stability. From experience in static security analysis, it is well kno wn that some indices work better than others for particular power systems a nd that combinations of indices usually work better than a single index. Fo r DSA, which is still in its infancy, severity indices are more complex and very few have been tested for screening. In this paper, several indices ar e proposed for contingency screening in online DSA. These indices are based on the concepts of coherency, transient energy conversion between kinetic energy and potential energy, and three dot products of system variables. Te st results on realistic power systems show the promise of these indices in contingency screening.