Wind Concurrent Cooling Could Increase Power Transmission Potential by as Much as 40%

May 18, 2015

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Researchers at the U.S. Department of Energy’s (DOE’s) Idaho National Laboratory (INL) are working with industry to model wind’s cooling effects on power transmission lines to dynamically couple transmission systems with concurrent cooling processes. In areas where wind farms are being developed, there is potential to take advantage of concurrent cooling—in which wind enables wind farms to produce power while cooling nearby transmission lines. Concurrent cooling helps power companies transmit greater amounts of electricity along power lines, increasing transmission capacity limits and reducing costs for power companies and wind facilities.

An illustration with a row of houses on the lower left and illustrated gusts of wind, and a wind farm on the upper right.
INL and the Idaho Power Company are gathering data from more than 40 weather stations positioned along 450 miles of transmission lines in windy southern Idaho. The data gathering targets two 230-kilovolt (kV) and two 138-kV lines, plus 345-kV and 500-kV lines within the 2,400-square-mile testing area. Using computational fluid dynamics (CFD) software, INL researchers are analyzing airflow and environmental data at these locations to measure how temperature and other weather conditions affect power lines.

The researchers first used the Institute of Electrical and Electronics Engineers’ 738 Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors, and a commercially available CFD program called WindSim, in their analysis. They then developed a new tool called General Line Ampacity State Solver (GLASS), which aggregates real-time data, system models, CFD model results, and physics-based calculations to estimate how wind flow impacts concurrent cooling of power lines. GLASS’s reliable data will help transmission owners and operators better understand the benefits of concurrent cooling and the potential for increasing electrical transmission.

“Concurrent cooling depends on a complex relationship between the transmission system configuration and wind speed, wind angle of incidence, solar radiation, and ambient air temperature, but can create conditions that permit 10% to 40% additional usable transmission capacity,” said Jake Gentle, an INL power systems research engineer. “Power companies typically use a conservative static rating system to decide how much power to transmit on their lines. Concurrent cooling, also known as dynamic line rating, enables utilities to operate their existing transmission systems more efficiently, reduce transmission congestion, and support wind integration.”

“Manipulating transmission systems based on changing environmental conditions has proven to be advantageous for operations,” said Mike West, another INL wind power researcher. “The unique approach that INL is developing links live weather conditions with CFD to safely transmit power above the static rating.”

While continuing to validate their approach, Gentle and his colleagues are refining their CFD models and a dynamic line rating methodology that uses detailed weather, line loading, and conductor temperature information to speed up the models and data analytics and improve forecast accuracy in complex terrain environments. They are also working with power companies to train their personnel in generating transmission capacities and operating limits to move toward coupling transmission systems dynamically with concurrent cooling processes.

“This type of technology is a win-win for the industry because we are able to make better use of existing transmission infrastructure at the times we need it the most, when the wind is blowing the hardest,” said Charlton Clark, DOE’s program manager for grid integration in the Office of Energy Efficiency and Renewable Energy Wind and Water Power Technologies Office.

America’s electrical grid has more than 160,000 miles of high-voltage power lines, which requires modernization and expansion to service the demand for electricity in the 21st century.