Where is the edge for cascading failure?: challenges and opportunities for quantifying blackout risk

In this paper, we review some emerging approaches to the challenging problem of cascading blackout risk. International data suggests an increased (but still rare) frequency of large blackouts that makes the risk of large blackouts substantial. We argue that the problem of avoiding blackouts should be posed as jointly mitigating the risk of blackouts of all sizes. There is evidence of a change in cascading blackout risk at a critical loading or stress that provides a reference point for power system design and operation with respect to cascading failure. There are a range of power system simulations and high-level models of cascading failure that could be used to develop risk analysis methods appropriate to cascading failure. One of the high-level models is a branching process that models cascading failure probabilistically as initial failures followed by propagation of these failures. The amount of propagation lambda can be quantified from data and is under investigation as a metric for cascading failure that can help predict overall blackout risk.