UF and Florida utilities assess impact of wind on power lines

GAINESVILLE, Fla. – Aug. 21, 2008 – With Tropical Storm Fay still impacting Florida, thousands of residents are faced with power outages. To find ways to cost-effectively reduce the number of blackouts that historically accompany tropical storm or hurricane landfalls, University of Florida (UF) researchers are engaged in a major collaboration with Florida’s utility companies.

The Hurricane Hardening Project is examining how hurricane winds affect both underground and overhead power lines. Researchers hope to eventually minimize tree-related outages and other potential threats in an effort to speed power restoration in the aftermath of storms.

Researchers and utilities are studying the impact of moving lines underground and also examining the possibility of strengthening existing overhead systems as a cheaper alternative, says Mark Jamison, director of UF’s Public Utility Research Center. The research has resulted in an experimental computer model to assess the costs and benefits of burying power lines.

“People need to know the costs and benefits to decide whether it’s worth moving lines underground,” Jamison says. “Once we have this information, customers, policymakers and utility companies can make sound choices.”

Researchers have also examined four cases in Florida where utilities have converted overhead lines to underground. Their main conclusion: Moving existing overhead lines underground is costly and usually not justified solely by the economic benefits, but rather by other benefits that are difficult to quantify such as aesthetics. That said, burying utility lines in some communities may have advantages, especially in the case of new construction, when underground lines can be included in the development’s planning process.

People often view underground power lines as a solution to storm-caused outages. But they are not the cure-all they appear to be, according to Jamison. Underground facilities are more prone to damage from flooding, storm surge and erosion, which can lead to increased costs and repair times, he said.

To obtain detailed information, project partners installed 50 wind observation stations on existing or specialized utility poles along the coast of Florida. Instruments on each station collect wind speed, wind direction, barometric pressure and other data.

Kurt Gurley, an associate professor of civil and coastal engineering, has tested the wind stations using the UF hurricane simulator to ensure their electronics can withstand hurricane force winds and driving rain. He will also help interpret the data supplied by each station. The National Oceanic and Atmospheric Administration and utility companies will receive this data from the stations in real-time, and NOAA will use the data to create wind field maps.

Once a hurricane passes, utilities will mobilize teams of first-responders to assess where and how the electric system failed. Using the NOAA wind maps, they will match wind speeds with damages on the ground. This “forensic data” will then be analyzed to determine which hardening strategies work best.

“If the power distribution system failed, we will be better able to analyze the damage and determine why the damage occurred,” Gurley said.

As part of the Hurricane Hardening Project, utility companies are also studying ways to improve their vegetation management programs. They maintain a regular schedule of trimming to keep lines clear and routinely monitor critical distribution facilities.

© 2008 FLORIDA ASSOCIATION OF REALTORS®

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