Muskrat Falls link offline for 7 hours, N.L. Hydro downplays concerns

CBC
·4 min read
The Muskrat Falls dam on Labrador’s Churchill River is pictured in January. The project’s 1,100 kilometres of transmission lines still don’t work as designed. (Danny Arsenault/CBC - image credit)
The Muskrat Falls dam on Labrador’s Churchill River is pictured in January. The project’s 1,100 kilometres of transmission lines still don’t work as designed. (Danny Arsenault/CBC - image credit)
The Muskrat Falls dam on Labrador’s Churchill River is pictured in January. The project’s 1,100 kilometres of transmission lines still don’t work as designed.
The Muskrat Falls dam on Labrador’s Churchill River is pictured in January. The project’s 1,100 kilometres of transmission lines still don’t work as designed.

The Muskrat Falls dam on Labrador’s Churchill River is pictured in January. The project has 1,100 kilometres of transmission lines connecting to Newfoundland's power grid. (Danny Arsenault/CBC)

Newfoundland and Labrador Hydro is confirming that no power flowed from Muskrat Falls to Newfoundland for a seven-hour period this week, but is downplaying any concerns about the interruption.

According to Hydro, both poles of the Labrador-Island Link were brought back online around 7 p.m. on Wednesday.

Early Wednesday, Pole 1 tripped due to electromagnetic interference on a sensor. The sensor will be replaced.

Around noon, Pole 2 tripped, taking the LIL out completely, due to a damaged control component for a cable in the Strait of Belle Isle. That damaged component has also been replaced, and an investigation is ongoing.

"There were no customer impacts," Hydro spokesperson Jill Pitcher wrote in an emailed statement.

Pitcher noted that Hydro has not had any extended generation supply issues since 2014 — the year of a mutli-day outage known as DarkNL — and stressed there are sufficient available generating reserves at this time.

"We may have a piece of equipment come offline at any time, whether it's the LIL, or Holyrood or a station you don't hear about as often. This can happen at any time, and also during storm conditions," Pitcher wrote.

"We balance the system in response, while we assess, repair or correct, when needed. We plan for it, and we respond to changes on the system daily."

Hydro says it has plenty of reserve on the system over the coming days, anywhere from 650 to 720 MW at peak times — well above the total output of a fully-operating Holyrood plant.

The trips on the LIL come as Hydro is facing questions about winter readiness — including the reliability of the Labrador-Island Link.

"Equipment failures that have occurred on the LIL in the past two winter seasons are concerning to Newfoundland Power and highlight uncertainty regarding the LIL's ability to provide reliable service to customers for the upcoming winter," Dominic Foley, Newfoundland Power's legal counsel, wrote in a Dec. 6 letter to the Public Utilities Board.

In that letter, Newfoundland Power sounded the alarm about an "elevated" risk that electricity demand could surpass supply.

Powerlines linking the aging Holyrood Thermal Generating Station to the provincial electricity grid, last March.
Powerlines linking the aging Holyrood Thermal Generating Station to the provincial electricity grid, last March.

Power lines link the aging Holyrood thermal generating station to the provincial electricity grid. (Patrick Butler/Radio-Canada)

A group representing big industry in the province says it shared the PUB's concerns about this coming winter, and called the aging Holyrood assets a "particularly acute concern" for the years to come.

The Public Utilities Board wrote Hydro on Dec. 15 to say concerns about winter readiness have been "heightened," and to ask for more details about the reliability of the system.

1 Holyrood unit back in service, another to go offline

Hydro replied Thursday to that PUB request, and continued to stress it remains confident in its ability to provide reliable service to customers this winter.

"Hydro notes that current forecasts indicate sufficient reserves and Hydro will continue to update the board, as necessary," Shirley Walsh, Hydro's senior legal counsel (regulatory), wrote in a letter to the PUB Thursday.

And there was an update on the aging Holyrood generating facility.

As of last week, two of the three turbines at Holyrood were offline, with the third operating at less than half capacity.

There have since been some changes.

The smokestacks of the Holyrood Thermal Generating Station, last March. Newfoundland and Labrador Hydro is studying the possibility of building a new fossil-fuel-burning turbine to meet an expected spike in electricity demand.
The smokestacks of the Holyrood Thermal Generating Station, last March. Newfoundland and Labrador Hydro is studying the possibility of building a new fossil-fuel-burning turbine to meet an expected spike in electricity demand.

The smokestacks of the Holyrood thermal generating station are pictured in a file photo. Newfoundland and Labrador Hydro has provided an update to the Public Utilities Board on the status of the three turbines there. (Patrick Butler/Radio-Canada)

Unit 1 — which went out of service on Dec. 12 for repairs to the main steam control valves, which officials described as a safety concern — has now been fixed. It went back online Wednesday, earlier than expected.

Unit 2 remains out of service, and is expected to remain that way until March.

A small boiler tube leak was found on Unit 3 a week ago, knocking it down to less than half capacity. Hydro now says that unit is being monitored and is scheduled to come offline in early January for repairs — a fix estimated to take about two weeks.

Meanwhile, a turbine in Stephenville has been out of service since the summer.

The Holyrood and Stephenville generating assets are there to ensure Hydro can meet peak demand during the winter.

Hydro's reply to PUB Thursday stressed that current reserve forecasts "do not indicate any alert level will be triggered given current generation availability."

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