Converting the Îles‑de‑la‑Madeleine transmission system to 34.5 kV

In order to ensure the sustainability of its transmission system in Îles‑de‑la‑Madeleine, Hydro‑Québec is planning to convert the voltage of the current system from 69 kV to 34.5 kV. This conversion will involve replacing the overhead transmission line connecting Cap‑aux‑Meules and Grosse‑Île substations. The line was commissioned in the early 1980s and has reached the end of its service life. A new switchyard will also be built for the Îles‑de‑la‑Madeleine generating station in Cap‑aux‑Meules.

The conversion will secure the archipelago’s supply of electricity, particularly since a section of the line will be rebuilt underground, in accordance with current standards, taking into account conditions specific to the region.

Given the harsh climate and salt air, which have led to service quality issues over the years, the section of the transmission line between Havre‑aux‑Maisons and Grosse‑Île substations will be buried over roughly 45 kilometres. The existing overhead section of the line, supported by wooden poles, will be dismantled.

Work will also be required on the archipelago’s substations. Havre‑aux‑Maison, Grosse‑Île and Havre‑Aubert substations will be converted to 34.5‑kV/12.5‑kV distribution substations. The new equipment will be installed within the boundaries of the existing substations.