The variability of interconnected wind plants

This paper could help make a case for siting wind at different locations on the base. May be a section of our report

The variability of interconnected wind plants
Warren Katzensteinn
, Emily Fertig, Jay Apt

a b s t r a c t
We present the first frequency-dependent analyses of the geographic smoothing of wind power’s
variability, analyzing the interconnected measured output of 20 wind plants in Texas. Reductions in
variability occur at frequencies corresponding to times shorter than 24 h and are quantified by
measuring the departure from a Kolmogorov spectrum. At a frequency of 2.8 10
4
Hz (corresponding
to 1 h), an 87% reduction of the variability of a single wind plant is obtained by interconnecting 4 wind
plants. Interconnecting the remaining 16 wind plants produces only an additional 8% reduction. We use
step change analyses and correlation coefficients to compare our results with previous studies, finding
that wind power ramps up faster than it ramps down for each of the step change intervals analyzed and
that correlation between the power output of wind plants 200 km away is half that of co-located wind
plants. To examine variability at very low frequencies, we estimate yearly wind energy production in
the Great Plains region of the United States from automated wind observations at airports covering
36 years. The estimated wind power has significant inter-annual variability and the severity of wind
drought years is estimated to be about half that observed nationally for hydroelectric power.
& 2010 Elsevier Ltd. All rights reserved