President Obama in this year's State of the Union address talked about the future of energy and mentioned "self-healing power grids" -- a grid that is able to keep itself stable during normal conditions and also to self-recover in the event of a disturbance caused, for example, by severe weather.
But as the national power-grid network becomes larger and more complex achieving reliability across the network is increasingly difficult. Now Northwestern University scientists have identified conditions and properties that power companies can consider using to keep power generators in the desired synchronized state and help make a self-healing power grid a reality.
The Northwestern team's design for a better power grid could help reduce both the frequency of blackouts and the cost of electricity as well as offer an improved plan for handling the intermittent power sources of renewable energy, such as solar and wind power, which can destabilize the network.
"We will be looking at a completely different power grid in the future," said Adilson E. Motter, who led the research. "The use of renewable energy is growing. More people will be driving electric cars, and the power grid will be delivering this energy, not gas stations. We need a power grid that is more capable and more reliable. This requires a better understanding of the current power grid as well as new ways to stabilize it."
Motter is the Harold H. and Virginia Anderson Professor of Physics and Astronomy at Northwestern's Weinberg College of Arts and Sciences.
The crux of the challenge is that for the U.S. power grid to function the power generators in each of its three interconnections (Eastern, Western and Texas) must be synchronized, all operating at the frequency of 60 hertz. Out-of-synch power generators can lead to blackouts that affect millions of people and cost billions of dollars -- losses similar to those of the Northeast blackout of 2003.
Having a network that can synchronize spontaneously and recover from failures in real time -- in other words, a self-healing power grid -- could prevent such blackouts. To help achieve this, power companies could apply the Northwestern guidelines as they add power generators to the network or tweak existing generators.
A paper describing the researchers' mathematical model, titled "Spontaneous synchrony in power-grid networks," is published in the March 2013 issue of the journal Nature Physics.
When a problem develops in the power-grid network, control devices are used to return power generators to a synchronized state. Motter likens this to using medicine to treat someone who is ill. He and his colleagues are suggesting conditions to keep synchronicity in good shape so interventions are kept to a minimum.
"Our approach is preventive care -- preventing failures instead of mitigating them," said Motter, an author of the paper and an executive committee member of the Northwestern Institute on Complex Systems (NICO). "The guidelines we offer could be very useful as the power grid expands."
The researchers derived a condition under which the desired synchronous state of a power grid is stable. They then used this condition to identify tunable parameters of the power generators that result in spontaneous synchronization. This synchronization can be autonomous, not guided by control devices.
"The blackout at this year's Super Bowl was caused by a device that was installed specifically to prevent blackouts," said Takashi Nishikawa, an author of the paper and a research associate professor of physics and astronomy at Northwestern. "A large fraction of blackouts have human and equipment errors among the causes.
"Reduced dependence on conventional control devices can improve the reliability of the grid," he said. "Our analysis also suggests ways to design control strategies that potentially can improve the existing ones."
Power generators are very different from each other; some are large and others small. Motter and his colleagues identified a "body mass index" for power generators, which they suggest should be kept approximately the same (making, in essence, all generators look the same to the network) in order to strengthen spontaneous synchronicity in the system. If the body mass indices change, they should be changed in a coordinated way.
The researchers demonstrated their model using real power grids of hundreds of power generators, similar to the size of the Texas portion of the U.S. power grid.
In addition to Motter and Nishikawa, other authors of the paper are Seth A. Myers of Stanford University and Marian Anghel of Los Alamos National Laboratory.
The Nature Physics article is available at http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2535.html
Megan Fellman | Source: EurekAlert!
Further information: www.northwestern.edu
More articles from Power and Electrical Engineering:
Iowa State Engineers Design, Test Taller, High-Strength Concrete Towers for Wind Turbines
16.05.2013 | Iowa State University
New report identifies strategies to achieve net-zero energy homes
16.05.2013 | National Institute of Standards and Technology (NIST)
Researchers have shown that, by using global positioning systems (GPS) to measure ground deformation caused by a large underwater earthquake, they can provide accurate warning of the resulting tsunami in just a few minutes after the earthquake onset.
For the devastating Japan 2011 event, the team reveals that the analysis of the GPS data and issue of a detailed tsunami alert would have taken no more than three minutes. The results are published on 17 May in Natural Hazards and Earth System Sciences, an open access journal of ...
A new study of glaciers worldwide using observations from two NASA satellites has helped resolve differences in estimates of how fast glaciers are disappearing and contributing to sea level rise.
The new research found glaciers outside of the Greenland and Antarctic ice sheets, repositories of 1 percent of all land ice, lost an average of 571 trillion pounds (259 trillion kilograms) of mass every year during the six-year study period, making the oceans rise 0.03 inches (0.7 mm) per year. ...
About 99% of the world’s land ice is stored in the huge ice sheets of Antarctica and Greenland, while only 1% is contained in glaciers.
However, the meltwater of glaciers contributed almost as much to the rise in sea level in the period 2003 to 2009 as the two ice sheets: about one third. This is one of the results of an international study with the involvement of geographers from the University of Zurich.
Second sound is a quantum mechanical phenomenon, which has been observed only in superfluid helium.
Physicists from the University of Innsbruck, Austria, in collaboration with colleagues from the University of Trento, Italy, have now proven the propagation of such a temperature wave in a quantum gas. The scientists have published their historic findings in the journal Nature.
Below a critical temperature, certain fluids become superfluid ...
Researchers use synthetic silicate to stimulate stem cells into bone cells
In new research published online May 13, 2013 in Advanced Materials, researchers from Brigham and Women's Hospital (BWH) are the first to report that synthetic silicate nanoplatelets (also known as layered clay) can induce stem cells to become bone cells without the need of additional bone-inducing factors.
Synthetic silicates are made ...
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News