Hydro-Québec's Electricity Transmission System

Hydro-Québec's electricity transmission system is an expansive, international power transmission system located in Quebec, Canada with extensions into the Northeastern United States. Major expansion of the network began with the commissioning of the alternating current 735 kV power line in November 1965, as there was a need for electricity transmission over vast distances from hydroelectric power stations in northwestern Quebec and Labrador to southern Quebec.

The transmission system, containing over 32,000 kilometres (20,000 mi) of power lines, is managed by Hydro-Québec TransÉnergie, a division of the crown corporation Hydro-Québec. One unique feature of the power system is its alternating current (AC) 735 / 765 kV power lines that stretch from the population centers of Montreal and Quebec City to the distant hydroelectric dams and power stations of the James Bay Project and Churchill Falls. The 735 kV power lines serve as the main backbone of the entire transmission system, and thus much of Quebec's population is powered by a handful of 735 kV power lines. This contributed to the severity of the blackout that ensued after the Ice Storm of 1998. The extent and duration of this blackout has generated criticism of the transmission system, and there is controversy concerning the use of hydroelectric dams.

Hydro-Québec's electric system is part of the Northeast Power Coordinating Council, even though it technically is its own interconnection, and its own system is minimally connected with other NPCC member utilities.