Long tails from the distribution of 23 years of electrical disturbance data

A public access database lists major disturbances in the power network of the USA over the last 23 years. Initial analysis of this data set raised several questions that were subsequently debated but not fully resolved. These questions relate to the seasonal pattern of disturbances, the possibility of an upward trend in the number and severity of disturbances, and the exact form of the distribution of statistics from these data. The latter question relates to the current view, held by some researchers, of the power network as a complex system, and its implications for a deeper understanding of disturbances, especially the catastrophic variety. The work reported here takes advantage of new data that has extended this dataset to cover 23 years of disturbances. We present the first analysis based on this more complete dataset, and using time series breakpoint and statistical analysis, show evidence of seasonal and upwards trends in the statistics of disturbances. While questioning previous assertions about the form of the tails of the distributions for measures of severity, we support the view that the electricity network can be analyzed and understood from a complex systems viewpoint.