Impacts of Operating Characteristics on Sensitivity of Power Grids to Cascading Failures

Sensitivity analysis of power grids to cascading failures by means of considering their critical dependence on their operating characteristics is an important step toward understanding and mitigating cascading failures. In this paper, a recently reported probabilistic cascading-failure model is further analyzed to provide key evidence that the reliability of power grids critically depends on operating characteristics of the power grid including the loading level, load-shedding constraints and the line-tripping threshold. The cascading-failure model is based on a Markov chain whose transition probabilities have a state-dependent functional form that is inspired by power-system simulations. It is argued through the asymptotic analysis of the Markov-chain model that certain changes in the operating characteristics make the power system prone to large-scale cascading failures, as evidenced by a power-law behavior in the tail of the probability distribution of the blackout size.