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

Newfoundland and Labrador Hydro is confirming that no power flowed from Muskrat Falls to Newfoundland for a seven-hour period this weekbut 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 multiday 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 megawatts 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.

• Newfoundland Power warns of 'elevated' supply risk given problems facing Hydro grid

"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.

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 regulatory legal counsel, wrote in a letter to the PUB on 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.

Unit 1 which went out of service 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 smallboiler tube leak was found on Unit 3 a week ago, knocking it down to less than half capacity. Hydro now says the 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 on Thursday stressed that current reserve forecasts "do not indicate any alert level will be triggered given current generation availability."

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