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Study: Wind Energy Needs Controls to Minimize Risk of Instability on the Grid

Christina Nunez's picture
, National Geographic
  • Member since 2018
  • 38 items added with 22,728 views
  • Jan 4, 2014
  • 1249 views

Wind Energy Stability

The location of a wind farm can play a key role in the potential for wind energy to add or detract from stability on the electric grid, according to researchers at North Carolina State University and Johns Hopkins University. The paper, released this month, notes that some wind farms, because of their location and the fact that wind generators differ from conventional generator systems, might actually worsen instability when there are disturbances on the grid, increasing the risk of power outages; others, in turn, could bolster the grid if sited in favorable locations. (See related quiz: “What You Don’t Know About Wind Energy.”)

The paper’s authors detail a technique employing controllers to moderate the flow of wind power coming onto the grid by matching control efforts between wind farms and energy storage facilities. “By matching the behavior of the two controllers, we can produce the desired damping effect on the power flow and restore stable grid behavior,” said senior author Aranya Chakrabortty in a release about the paper. (See related story: “New ‘Flexible’ Power Plants Sway to Keep Up With Renewables.”)

The researchers point out that their system can be put to use regardless of where the turbines and batteries are located, making it applicable in decentralized systems over large geographical areas.

Though wind energy accounts for just a small percentage of U.S. electricity generation as a whole (3.4 percent in 2012), it is growing by leaps and bounds: the added electricity generation capacity for wind in 2012 was larger than for any other source, and is expected to grow by nearly 50 percent between 2015 and 2040, according to the Energy Information Administration.

Meanwhile, creative minds around the world are exploring ways to store surplus wind energy when the breeze generates more than the grid can handle. Ideas for storage vessels range from rock reservoirs to frozen fish. (See related stories: “Too Much Wind Energy? Save It in Underground Volcanic Rock Reservoirs” and “Frozen Fish Help Reel In Germany’s Wind Power.”)

Note: This post has been modified to reflect that wind farm location and equipment, not wind variability, were the key factors in the destabilizing effect researchers sought to correct.

 

Photo Credit: Wind Energy Stability/shutterstock

Discussions
Michael Goggin's picture
Michael Goggin on Jan 4, 2014

Christina, you should take this article down or significantly revise it immediately, as NC State has taken down their press release to correct the errors in how it presented the study’s findings. In personal correspondence with the study author yesterday, he acknowledged that wind energy’s variability had nothing to do with the study’s results, which is the central claim you make in your article. Wind energy variability is simply too small and slow to have that type of impact. I’d be happy to forward those emails to you if you’d like. NC State is working to correct their press release, which when corrected I expect will highlight what were actually the study’s positive findings about how wind energy can further contribute to reliability by mitigating grid disturbances.

Thanks,

Michael Goggin

American Wind Energy Association

Bob Meinetz's picture
Bob Meinetz on Jan 7, 2014

Michael, this from the conclusion of the paper:

“This paper demonstrates how closed-loop control of wind power generation and BES power consumption can be used for damping selected sets of oscillation modes of a power system. We design coordinated controllers for the wind farm and the BES, and show how their controller parameters can be optimized to guarantee nearly perfect matching of the grid spectral response to a desired response.”

The paper describes using battery electric storage to damp oscillations in the output of a windfarm which are out of phase with grid alternating current, increasing efficiency. The oscillations are a product of the AC output of the turbines’ generators, are in the >1Hz range, and (as you correctly note) have nothing to do with wind variability.

Christina Nunez's picture
Thank Christina for the Post!
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