The ups-and-downs of wind power triggered by the shifts in speed pose a threat to generators in power grids, but an NCSU researcher and a colleague at Johns Hopkins say they have devised a mean to smooth out demands of equipment.
The changes in the wind cause what are described as “oscillations,” and these can cause generators to fail, triggering blackouts.
To the rescue – according to a paper published in IEEE Transactions on Power Systems – is linking controllers both on the wind turbines that generate the power and battery management systems supporting the grids.
“To counteract this problem, we have designed a technique that coordinates the activity of controllers inside the wind turbines and battery management systems to even out the flow of power from wind farms into the grid,” said Dr. Aranya Chakrabortty, an assistant professor of electrical engineering at NC State. He is the senior author of the paper describing the work. Dr. Dennice Gayme of Johns Hopkins is the co-author.
National Science Foundation grants were used to fund the research.
The two professors developed algorithms to match control efforts between the turbines and the 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,” Chakrabortty said.
Wind power is growing increasingly important as an energy source. N.C. State notes that wind power could contribute as much as 20 percent of U.S. power needs by 2020..
The abstract of the paper follows:
“Coordinating Wind Farms and Battery Management Systems for Inter-Area Oscillation Damping: A Frequency-Domain Approach”
Authors: Souvik Chandra and Aranya Chakrabortty, North Carolina State University; Dennice F. Gayme, Johns Hopkins University
Published: Online Oct. 17, 2013 in IEEE Transactions on Power Systems
DOI: 10.1109/TPWRS.2013.2282367
Abstract: This paper presents a set of linear control designs for shaping the inter-area oscillation spectrum of a large radial power system through coordinated control of a wind farm and a battery energy system (BES). We consider a continuum representation of the power system with the wind and battery power modeled as point-source forcings. A spectral analysis of the system demonstrates that its oscillation spectrum strongly depends on the locations of these power injections, implying that there are siting locations that produce more favorable spectral responses. However, the ability to site a wind farm or BES at a specific location may be limited by geographic, environmental, economic or other considerations. Our work provides a means to circumvent this problem by designing coordinated controllers for the power outputs of the wind farm and the BES by which one can shape the spectral response of the system to a desired response. The design is posed as a parametric optimization problem that minimizes the error between the two spectral responses over a finite range of frequencies. The approach is independent of the locations of the wind farm and the BES, and can be implemented in a decentralized fashion.
