Evidence for self-organized criticality in electric power system blackouts

We analyze a 15-year time series of North American electric power system blackouts for evidence of self-organized criticality. Scaled window variance and R/S analysis of the time series shows moderate long time correlations. The probability distribution functions of various measures of blackout size have a power tail. Moreover, the same analysis applied to a time series from a sandpile model known to be self-organized critical gives results of the same form. Thus the blackout data is consistent with self-organized criticality. Self-organized criticality, if fully confirmed in power systems, would suggest new complex systems approaches to understanding and possibly controlling blackouts. 1.