Expansion of Appalaches substation

Project description Expanding a strategic substation in the transmission system

The transmission system needs to be upgraded to meet current and future needs, in particular those related to the development of wind potential in eastern Québec, and to improve grid reliability and resilience. It is within this context that Hydro‑Québec is developing the project to upgrade the main transmission system in the Appalaches⁠–⁠Bas‑Saint‑Laurent area.

The work planned for Appalaches substation is part of this project. The work involves adapting existing infrastructure by adding new equipment, which requires an expansion of the substation. With the expansion, it will be possible to integrate a new 315‑kV transformer section and maintain proper functioning of the transmission system.

The expansion will be primarily carried out on land that already belongs to Hydro‑Québec, on either side of the current substation. The selected scenario will help maximize the use of existing space and reduce the impacts on local land use, particularly on nearby tapped sugar bushes.

Throughout the project, Hydro‑Québec will pay particular attention to integrating facilities into the environment, reconciling the various ways the territory is used and taking into account the concerns expressed during the consultation steps.

A new 315‑kV transformer section

The work involves the addition of a new 315‑kV section located southwest of Appalaches substation. This new section will include two transformers, making it possible to lower the voltage from 735 kV to 315 kV, as well as two 315‑kV feeder bays. To accommodate the new section, the site needs to be expanded by approximately 200 metres by 600 metres. Once completed, the entire substation will cover a total area of about 600 metres by 600 metres.