Statistical modelling of dependence between net demands and deficits in two area power systems

Power system resource adequacy risks is dominated by the extremes of the relevant distributions or processes: the upper tail of demand and the lower tail of available generation. Because of this, relevant data in the historic record are sparse. Moreover, for interconnected systems, the degree of statistical dependence in these extremes between systems can also have a sizeable impact on the level of risk in each system. This paper uses results from statistical extreme value theory (EVT) to fit smoothed joint distributions for the values of (demand minus available renewables) and of surplus/deficit dependence in a two-area system, using data from the Irish and Great Britain power system for examples.