Optimal locations for protection system enhancement: A simulation of cascading outages

Recent studies have shown that hidden failures in the protective devices ha ve a great impact on the power system reliability. In this paper, we provid e the definitions of vulnerability and reliability of protection system to numerically characterize this impact. A random search algorithm based on po wer system heuristics is given for fast rare-event simulation of consecutiv e relaying malfunctions in bulk power systems. We also propose an economica l system upgrading strategy that can best enhance the protection system rel iability under limited budget. Finally, we present the result of a case stu dy on New York Power Pool (NYPP) 3000-bus system.