Hydro outage brings down Canada’s Yukon grid

Yukon Energy Corp. reports a generator failure at its 30-MW Aishihik hydro station caused a cascading failure in the power grid, knocking out power throughout much of Canada’s southern Yukon Territory.

The Ashihik failure overloaded a second generator at the station and the 40-MW Whitehorse Rapids hydro station. The event occurred about 1:30 p.m. Jan. 29, causing an outage throughout the Whitehorse-Aishihik-Faro power grid.

Many customers were without electricity for several hours while Yukon Energy restored power from other hydropower sources and from seven back-up diesel generators. Both Aishihik generators were back in operation two days after the event.

Yukon Energy blamed the outage on a short in a cable leading from the generators at the Aishihik facility to a transformer. It is investigating the cause of the short.

Yukon Energy: Catastrophic outage “a rare occurrence”

“This is what’s known as a catastrophic outage,” Yukon Energy spokesman Janet Patterson said. “It began when one of our Aishihik generators went down. That put too much of a strain on the other operating generators, causing a cascade effect as one by one, they shut down as well. We were left with no hydro generation at all. This is a rare occurrence that tends to happen every 10 to 15 years.”

Yukon Energy operates three hydro plants — Aishihik, Whitehorse Rapids, and 5-MW Mayo. Aishihik, built to serve the growing demand of Whitehorse and of a large lead-zinc mine, began operating in 1975. The utility’s back-up diesel generators total 39 MW. Yukon Energy also operates two small wind turbines.

Yukon Energy directly serves about 1,700 of the territory’s 15,000 consumers, most in and around Dawson City, Mayo, and Faro. Indirectly, it provides power to many other Yukon communities, including Whitehorse, Carcross, Carmacks, Haines Junction, Ross River, and Teslin, through Yukon Electrical Co. Ltd. Yukon Electrical buys wholesale power from Yukon Energy and sells it to retail customers.