Unexpected Consequences: Global Blackout Experiences and Preventive Solutions

Power system blackouts result in complete interruption of the electricity supply to all consumers in a large area. Systems need to be planned and engineered in a way that minimizes exposure to and prevents cascading blackouts. Blackouts are caused by a sequence of cascading outages caused by a combination of multiple low-probability events (e.g., a transmission line sagging into a tree, hidden failures in equipment protection, the loss of multiple generation units because of a weather event, and aging equipment failure) occurring in an unanticipated or unintended sequence. The likelihood for power system disturbances to escalate into a large-scale cascading outage increases when the grid is already under stress. This stress can be caused by lower operational margins, overloaded equipment, and other factors, which are discussed in detail in this article.