NL Hydro is trying to find answers after the High Power Mosquito transmission test failed

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Utility experts in Newfoundland and Labrador are scrambling for answers after a high-power test of the Muskrat Falls transmission line ended in failure, with future tests on hold.

About 58,000 customers lost power for up to 25 minutes Thursday morning after Newfoundland and Labrador Hydro cranked power on the troubled Labrador-Island Link — known as LIL — to 700 megawatts.

It was the largest test yet for the 1,100-kilometre high-voltage line from Muskrat Falls to Newfoundland’s Avalon Peninsula, with previous tests of about 500 megawatts.

The high-power test began at 10 a.m. and initially went well, with power flowing over the two lines to Soldiers Pond on the Avalon Peninsula and over the Maritime Link to Nova Scotia.

LIL is designed so that if one of the two lines stops sending power, the other line can carry the entire load, up to 900 megawatts.

But after one of the lines was intentionally tripped to test the system’s overload capability, something went wrong and the connection lost power.

The sudden loss of 700 megawatts meant large blocks of customers lost power temporarily while backup systems turned on and stabilized the grid.

In a call Thursday afternoon with reporters, Hydro vice president Rob Collett said the incident is being investigated.

“This could have been a sensor, equipment or software problem. Our experts are reviewing the sequence of events,” Collett said.

Future testing on teams

The test is one of the final steps in the commissioning process for the link, which has been plagued by computer software glitches and synchronous condenser vibration problems at Soldiers Pond.

The plan was to test the overload capacity on one line this week, and the other line next week. But Collett said those plans are now on hold and future tests will depend on the outcome of the investigation.

“It may be simple and testing may resume in the next few weeks. If this turns out to be a more significant problem … it may take some time to resolve. It could go either way,” he said.

The Muskrat Falls hydroelectric plant, with a capacity of 824 megawatts, was commissioned a year ago. But GE has struggled to complete the power line that brings Muskrat’s zero-emissions electricity to Newfoundland and Nova Scotia.

The link has been operating at around 300 megawatts, helping to displace expensive and polluting oil-fired electricity at Holyrood generating station.

Collett described Thursday’s setback as “significant” and that the power outage was regrettable. But he said the test is necessary to ensure the link’s future reliability.

“We’re crawling our way out of the trench,” he said. “We are closer to the finish line than we have ever been.”

Read more from CBC Newfoundland and Labrador

NL Hydro is trying to find answers after the High Power Mosquito transmission test failed

Written by

Utility experts in Newfoundland and Labrador are scrambling for answers after a high-power test of the Muskrat Falls transmission line ended in failure, with future tests on hold.

About 58,000 customers lost power for up to 25 minutes Thursday morning after Newfoundland and Labrador Hydro cranked power on the troubled Labrador-Island Link — known as LIL — to 700 megawatts.

It was the largest test yet for the 1,100-kilometre high-voltage line from Muskrat Falls to Newfoundland’s Avalon Peninsula, with previous tests of about 500 megawatts.

The high-power test began at 10 a.m. and initially went well, with power flowing over the two lines to Soldiers Pond on the Avalon Peninsula and over the Maritime Link to Nova Scotia.

LIL is designed so that if one of the two lines stops sending power, the other line can carry the entire load, up to 900 megawatts.

But after one of the lines was intentionally tripped to test the system’s overload capability, something went wrong and the connection lost power.

The sudden loss of 700 megawatts meant large blocks of customers lost power temporarily while backup systems turned on and stabilized the grid.

In a call Thursday afternoon with reporters, Hydro vice president Rob Collett said the incident is being investigated.

“This could have been a sensor, equipment or software problem. Our experts are reviewing the sequence of events,” Collett said.

Future testing on teams

The test is one of the final steps in the commissioning process for the link, which has been plagued by computer software glitches and synchronous condenser vibration problems at Soldiers Pond.

The plan was to test the overload capacity on one line this week, and the other line next week. But Collett said those plans are now on hold and future tests will depend on the outcome of the investigation.

“It may be simple and testing may resume in the next few weeks. If this turns out to be a more significant problem … it may take some time to resolve. It could go either way,” he said.

The Muskrat Falls hydroelectric plant, with a capacity of 824 megawatts, was commissioned a year ago. But GE has struggled to complete the power line that brings Muskrat’s zero-emissions electricity to Newfoundland and Nova Scotia.

The link has been operating at around 300 megawatts, helping to displace expensive and polluting oil-fired electricity at Holyrood generating station.

Collett described Thursday’s setback as “significant” and that the power outage was regrettable. But he said the test is necessary to ensure the link’s future reliability.

“We’re crawling our way out of the trench,” he said. “We are closer to the finish line than we have ever been.”

Read more from CBC Newfoundland and Labrador

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