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SOMBA K'E/YELLOWKNIFE
After more than one month of reliable power, the city went dark for about an hour and a half on Friday.

"It was a pretty lengthy power failure," said Cindy Dolynny, owner of the Yellowknife Shoppers Drug Mart. "Obviously, it's quite inconvenient for our customers and the pharmacy in general to have to wait it out like that. It kind of puts business at a halt and it puts their purchasing at a halt."

Brendan Bell, chair of the NWT Power Corporation, said Friday's outage is a reminder of the work that needs to be done to get the power system up to par.

"The fact that we haven't had any outages in the last month or so is because we're through the lightning season," said Bell, alluding to the fact that roughly 40 per cent of the power outages in Yellowknife since Sept. 1, 2011 were caused by lightning.

Friday's power outage was system-wide, meaning all of Yellowknife was without power, as well as Ndilo, Dettah and Behchoko. The outage was caused by a fault in a power substation at the Con-Miramar site, said Bell. At press deadline, it was unclear what had caused the damage to the substation and investigations into the incident continue.

Regardless of the cause, the faulty substation caused the entire power grid to go offline at about 2:15 p.m. on Friday. The outage lasted about one hour and 20 minutes on average and the last few Yellowknife customers had their power restored within one hour and 40 minutes, said Bell.

This is too long of a time for the system to be down, he said.

"We should be able to deal with a substation failure," said Bell. "It shouldn't be able to shut down our entire system."

Normally, an outage of this scale will trigger the backup diesel generators at Jackfish Lake to come online and restore power. However, on Friday this didn't happen. The diesel backup attempted to turn on, but an imbalance in the system caused the generators to oscillate, making them unable to co-ordinate with each other - in short, they could not turn on.

In order to restore power, the power corporation had to test individual sections of the network to find where the problem was coming from. Once the corporation isolated the Con-Miramar power station, it was able to turn off that section of the system, making it possible to restore power.

"That shouldn't happen. We should be able to bring up diesel backup fairly quickly and in this case, we were unable to do that," said Bell. "I think that points to the difficulties that we're facing and the failings in the system that we're currently working to address."

After a significant public outcry late in the summer over the number of power outages, the power corporation vowed in mid-September to decrease the number of outages in the city by 70 per cent by 2015.

To accomplish this goal, the corporation is implementing an 18-point plan. To date, more bird deterrents have been put along power lines to the Bluefish power plant, a foot and air patrol of the line to Bluefish was conducted, infrared and corona scans looked for damaged lines and weaknesses along the lines for the entire system, a brush removal project along the Bluefish line is scheduled to be completed this week, and an engineering firm is working on a plan to upgrade the entire system's lightning protection devices, said Bell. None of the tests or patrols have turned up damage within the system to date.

The main weakness in the power system is difficulties with load balancing and co-ordination between different generators, said Bell. There will always be birds or lightning or shorts that shut down part of the system, but the system should be resilient enough to rebalance the load and stay turned on.

"Even when a bird takes down one part of the line, it shouldn't send Yellowknife into darkness," said Bell.

To address this problem, a co-ordination study is underway. This report should be completed within three or four months, said Bell.

"There's some urgency. We know we need to get this addressed before the serious winter weather here," he said.

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