Thoughts on power system flexibility quantification for the short-term horizon

This paper reviews the notion of flexibility and applies it to the problem of power system adequacy of supply and reserve computations in the face of a class of input uncertainties. It first presents some definitions given to flexibility and flexibility indices in the power systems and process control industries. This is by no means a comprehensive review, but it does highlight some of the main ideas in the field. The notion of flexibility is applied to assess the quality of a solution strategy, based on some initial criterion for a given scenario, for example reliability, and then on its success in satisfying a set of scenarios. The paper then illustrates the use of a flexibility index borrowed from the process control literature to evaluate a solution strategy that provides balancing reserves to mitigate wind generation uncertainties. The paper concludes that flexibility can only be obtained at a cost and that it could prove itself to be a useful tool for the operator in an emerging technological environment.