ABSTRACT
Large blackouts are infrequent but very costly to our society. e power system is sometimes subject to large initial disturbances from extreme weather, such as high winds or ice storms. Moreover, even a small initial power system disturbance can cascade into a complicated chain of dependent failures leading to a widespread blackout. On August 10, 1996, a blackout started in the Northwest United States and spread by cascading to disconnect power to about 7,500,000 customers (Kosterev et al., 1999). On August 14, 2003, a blackout started in Ohio and spread to disconnect power to about 50 million customers in Northeastern United States and Canada (U.S.-Canada Power System Outage Task Force, 2004). Although such extreme events are infrequent, the direct costs are estimated to be in the billions of dollars, disrupting commerce and vital infrastructure. Large blackouts also have a strong eŸect on shaping the way power systems are regulated and the reputation of the power industry.
