Phase Transitions in the Probability of Cascading Failures

Abstract

A cascading failure can be thought of as an alternating sequence of equipment-outages and thresholdcrossings. This paper studies the probability of such failures in two simple models of electric power networks. The experimental results display phase transitions--large and abrupt changes in the probability of a cascading failure with only small changes in network stress. We conjecture that such phase transitions also occur in actual power networks. If this conjecture is true, on-line techniques for assessing the risk of cascading failures could be based on searching the neighborhood of the current operating point for the nearest phase transition.