N.L. Hydro hatches 4-year, $28M fix to 'galloping' problem on Muskrat Falls transmission line
Work will be done by outside contractor in remote areas of province
Newfoundland and Labrador's hydroelectric giant is expecting to spend $28 million to add and replace components to a transmission line carrying power from Muskrat Falls in Labrador.
N.L. Hydro released the results of four investigations on Friday into failures on the Labrador-Island Link during the winter of 2022-23. In the most substantial investigation, the utility found a process called "galloping" had caused turnbuckles on the transmission poles to snap.
It's the latest in a long line of unexpected expenses for the megaproject but one that Hydro president Jennifer Williams says is not out of the ordinary.
"The results of the investigations today show that what we have found is normal for very early in the operation of an asset of this size," Williams said. "We're very confident in the reliability of the LIL this winter."
The $28 million, to be spent over four years, will cover the cost of equipment and labour for an outside contractor to complete the work in some of the most remote parts of the province.
Galloping occurs when a number of factors such as wind and ice align to cause wires to bounce up and down. The turnbuckles that hold the wires were designed to withstand ice and snow, but not galloping.
Hydro officials told reporters Friday that no system is designed to withstand galloping, because it would be too expensive to build an entire system that way. Instead, transmission lines are monitored to identify areas more prone to galloping, and those areas are adjusted after construction.
Hydro says three turnbuckles snapped last winter with lines falling to the ground. No customers experienced outages.
One of the turnbuckle breaks was more than 60 kilometres off the highway, and it took two weeks to plow snow to reach it.
None of the 1,308 turnbuckles can be reused. They'll be replaced with pieces of equipment called extension links, which serve the same function but are more flexible.
Williams said they'll be "more robust" and that engineers have confidence it will fix the problem.
In areas more prone to galloping, they'll also be installing pieces called air flow spoilers — coils that go over the wires and disrupt air flow, preventing conditions that cause galloping.
Hydro will bear the entire cost of the repairs, since the failures don't fall on the manufacturer. Williams also refused to call it a design flaw or an underestimation of winter conditions in remote areas.
"To predict the exact climatic conditions for every kilometre of line wouldn't be possible in the original design," she said. "So we certainly did not underestimate the original design and we are now refining in a specific, narrow focus."
The first year of the four-year plan is nearly complete, Williams said, with some of the most remote sections tackled first.
Next big test delayed
The Labrador-Island Link is currently approved for 700 megawatts, having cleared tests in April to allow it to operate at those levels. The line was designed, however, for 900 megawatts.
N.L. Hydro had intended to perform tests at max capacity this fall, but Williams said those plans have been pushed back to April 2024.
She said they have to do "a few cleanup items" with a new version of the software underlying the operation, and they don't feel a need to rush.
Even the plan for April is subject to change based on a number of factors, Williams said.
"We want to do this 900-megawatt test. We will do this 900-megawatt test. But it's important to know that the exact timing of it does often have some flexibility, as it does this year."
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