The 735-kV lines in Hydro-Québec’s transmission system have been commissioned gradually since the mid-1960s. These lines carry the electric power produced by generating facilities located primarily in the Baie-James and Côte-Nord regions to major load centres in southern Québec.
The five 735-kV lines that form the Manic-Québec corridor, the first in the system, were commissioned between 1965 and 1973.
Significant changes on the power transmission system
Since 2011, the power transmission system has undergone significant changes:
- Reduced consumption in the Côte-Nord area
- Decommissioning of the Tracy and La Citière thermal and Gentilly-2 nuclear generating station
These changes have brought about an increase to the power flow on the lines of the Manic-Québec corridor toward the major load centres and decreased the reliability of the transmission system. Hydro-Québec is thus required to take steps in order to restore adequate transmission capacity to the corridor and maintain system reliability.
After considering a number of scenarios, Hydro-Québec believes that the best solution is to build a new 735-kV line extending some 250 km between Micoua substation in the Côte-Nord region and Saguenay substation in Saguenay–Lac–Saint-Jean. The project also includes adding equipment to both substations and expanding Saguenay substation.
Commissioning of the new equipment is planned in 2022.
Advantages of the project
- Maintain transmission system reliability
- Reinforce the Manic-Québec corridor
- Reduce energy losses
- Increase the system’s operating flexibility