A generalized power system reliability and security index

This paper develops a risk-based general index reflecting power system reliability and security both directly and indirectly. Direct characteristics express the risk to not fully supply load. Indirect characteristics that address circuit overloads, voltage problems, low stability margins, etc., signal a reduced security/reliability margin. The index combines these contributing factors using a fuzzy logic like approach. The existing indices such as expected unserved energy, system minutes, expected stability margins etc., can be linked to or derived from the general index. Numerical examples deal with a large multi-area power system model derived from but not identical to the real US Southern System. It contains more than 4400 busses and 6400 branches.