I. Introduction
In 2009 the U.S. became the world leader in total wind plant capacity with over 25 000 MW installed, 8 500 MW of which were installed in 2008 alone [1]. Though the energy converted by these wind plants is approximately one percent of the total electrical energy demand in the U.S., operational concerns are growing as system operators must integrate the power from these inherently uncertain and variable resources [2], [3]. For example, in February of 2008 a weather system swept through Texas causing a significant down ramp of wind power which, along with other non-wind related factors, led to the use of an emergency electric curtailment plan [4]. In July of 2008, the Bonneville Power Administration balancing authority in the Pacific Northwest of the U.S. had an unmanageable surfeit of wind power that caused curtailment of the wind plants [5]. Similar challenges have arisen in other parts of world, for example the 2001 blackout in Crete [6].