Cascading Failure in Widespread Blackouts

Blackouts of electric power grids generally become widespread large blackouts by a series of cascading events in which successive failures progressively weaken the system. The largest blackouts can affect millions of people. These cascades of failures are very complicated, but the overall propagation of the cascade can be summarized by statistical models such as branching processes. Large blackouts are rarer than small blackouts, but they are expected to occur occasionally because of the power law or "heavy tail" distribution of their frequency. (They are not "perfect storms".) I will briefly discuss how the power transmission grid can be thought of as an evolving complex system that self-organizes to produce the heavy tails. Strong engineering, economic, and social forces may gradually shape the electric power grid to have particular patterns of reliability, including occasional large blackouts.