Chelan County PUD
To make sure the regional electric grid remains highly reliable, Chelan County PUD commissioners on Monday authorized a three-year survey of all District transmission lines by helicopter and development of computerized models to look for potential problems with line clearance above the ground or trees.
All utilities nationwide are being asked to check their transmission lines – the larger lines that carry higher voltage power from one area to another. Chelan PUD has about 250 miles of transmission line that needs to be surveyed in order to meet a recent requirement issued by the North American Electric Reliability Corporation (NERC). The review must be finished by the end of 2013, and any clearance problems found during the review must be corrected within one year of finding the problem.
NERC is concerned that lines built decades ago may no longer have the clearances that were required at the time they were built. Clearance is important, explained PUD Director of Transmission and Compliance Chad Bowman, because lines sag when temperatures get hot and when large amounts of electricity are being carried. If a line touches a tree or the ground, it can cause an outage or be a safety hazard.
HDR Engineering, Inc., Billings, Mont., was authorized by board action Monday to spend up to $850,000 doing the survey and modeling work over three years. The PUD has divided the lines into high, medium and lower priority, and the survey work will be done in that order.
To do the survey, a helicopter flies at about 850 feet elevation and uses lasers in a technique called LIDAR (Light Detection and Ranging) to create a computerized profile of the transmission line that can then be evaluated with a computerized model. A staff analysis concluded this approach would be most effective in meeting the NERC requirement.
Bowman said a survey this comprehensive is good for system reliability. "This will get good information on our system into the computer model," he said. "It should be helpful in maintaining a reliable system that helps protect customers throughout the region against large outages."
In other items:
The next regular commission meeting is at 1 p.m. on Monday, May 23, in the PUD boardroom at 327 N. Wenatchee Ave. Commissioners have canceled the May 30 meeting due to the Memorial Day Holiday.
Most PUD commission meetings are recorded, and a link to the audio is available on the PUD’s home page at www.chelanpud.org.
509-661-4639, direct line