October 2009

Early warning on the wires

A new technology will help distribution systems fix problems before they lead to outages.

On a small screen, a horizontal line spikes up, then down.

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John Bowers, Pickwick Electric Co-op operations manager, shows the Distribution Fault Anticipator that is helping his company and other distributors discover problems before they affect system reliability.

Monitoring a piece of equipment called the Distribution Fault Anticipator, or DFA, John Bowers John Bowers, operations manager at Pickwick Electric Cooperative in West Tennessee, sees several spikes in a matter of seconds.

After several years observing patterns on his DFA and comparing notes with systems operators at 11 other utilities around the country, Bowers can be fairly sure in making a diagnosis: In a certain area of Pickwick’s system, a tree limb is blowing against a line and, if not corrected, will probably cause an outage.

“It can be a massive effort to track down a problem in a large service area when you don’t know where to start looking,” says Bowers. “The DFA enables us to locate and respond to problems before they affect system reliability.”

Pickwick and the 11 other utilities are participating in a project — sponsored by the Electric Power Research Institute, or EPRI, and in partnership with TVA’s Science & Technology group — to test, gather data and refine the DFA technology, first developed at Texas A&M University.

“Working with EPRI, we’re able to leverage a lot of research,” says Greg Stewart, program manager in the Science & Technology group. “A tree limb blowing in the wind and up against a line creates a signature in the sine wave. The utilities in the program studied the patterns of the sine waves on the DFA screens over many instances of these things happening. The research helps us recognize that it’s a tree limb.”

Different DFA readings can point to different problems, Stewart says. “For example, it’s a fact of distribution-system life that equipment often deteriorates slowly over time. As it does, it produces measurable electrical changes. Similarly, damage caused by wildlife also can create a signature signal. Recognizing these signals means that utilities can anticipate faults and thereby avoid some full-blown outages.”

Since 2001, TVA has invested about $135,000 in the DFA Smart Grid Technology. Texas A&M is getting ready to install the pre-commercial version of the DFA for demonstration. If the demonstration is successful, the DFA could soon be available to utilities everywhere.