Survey of the Research on the Complexity of Power Grids and Reliability Analysis of Blackouts

A comprehensive account of a complex systems approach to large blackouts caused by cascading failure is given from the viewpoint of the statistics, dynamics and risk of series of blackouts with approximate global model. According to the analysis of a 15-year record of power outages occurred on the North American power grid provided by NERC, it suggests that the frequency of large blackouts is governed by a power law, and a more reasonable clustering property is also revealed. This result stimulates many theoretical models to come forth which are used to explain the mechanism of cascading of the blackouts in power gird. Moreover, inspired by concepts from self-organized criticality, we suggest that power grid operating margins evolve slowly to near criticality and the critical loads at which blackout risk sharply increase is an vital element to the risk of power system. To mitigate and prevent the blackouts, a new synthetical evaluation framework of power system risk must be established and we should try our best to find the force to reduce the risk of power system.