Québec - New England

When Hitachi Energy was awarded the contract for the Québec - New England Phase II HVDC project in 1986 by Hydro Québec and National Grid USA (formerly New England Electric Systems), it was the first large multiterminal HVDC system ever contracted. In 2013, Hitachi Energy received an order to upgrade the control and protection systems in the three stations of the link.

Power is generated at the La Grande II hydropower station in the James Bay area, converted into DC at the Radisson Converter Station, and transmitted over the multiterminal system to load centers in Montreal and Boston.

Phase I of the bipolar HVDC transmission consisted of two converter stations, each rated 690 MW. One terminal, Des Cantons, is near Sherbrooke, Quebec, and the other, Comerford, near Monroe, New Hampshire. The Phase I converter terminals were operational in October 1986.

The contract for Phase II included three additional converter terminals and modifications to the existing ones. The line was extended 1,100 km north from Des Cantons to the 2,250 MW Radisson terminal, located within the La Grande hydroelectric generating complex. The line was also extended over a distance of 214 km south from Comerford to a new 1,800 MW converter terminal at Sandy Pond, Massachusetts, and went into full commercial operation in 1990.

In 1992, another terminal rated at 2,138 MW was made operational in this multiterminal HVDC system, located at Nicolet in the Montreal area.

The Comerford and Des Cantons converter stations were originally have been integrated into the multiterminal scheme to enable even more operating flexibility, allowing five stations to operate simultaneously. After reassessing the benefits of this additional flexibility, the owners, however, elected to suspend the commercial multiterminal integration of Des Cantons and Comerford.

Hydro-Quebec's multiterminal DC installations have performed well, providing operational flexibility for internal and external power transfers. Since 2000, the volatile hourly energy market has increased line use significantly, without affecting the system's overall benefits.