The Québec Interconnection is one of the three minor alternating current (AC)

Alternating current

In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

 power grids in North America. The other two minor interconnections

Wide area synchronous grid

A wide area synchronous grid, also called an "interconnection" in North America, is a power grid at a regional scale or greater that operates at a synchronized frequency and is electrically tied together during normal system conditions...

 are the Texas Interconnection

Texas Interconnection

The Texas Interconnection is one of the three minor alternating current power grids in North America. The other two minor interconnections are the Québec Interconnection and the Alaska Interconnection...

 and the Alaska Interconnection. The two major interconnections are the Eastern Interconnection

Eastern Interconnection

The Eastern Interconnection is one of the two major alternating current power grids in North America. The other major interconnection is the Western Interconnection...

 and the Western Interconnection

Western Interconnection

The Western Interconnection is one of the two major alternating current power grids in North America. The other major wide area synchronous grid is the Eastern Interconnection...

The Québec Interconnection covers all of the Province of Québec

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

 and operates at an average system frequency of 60 Hz. It is not technically an "interconnection" in the sense of having multiple synchronized systems, because it contains only one electric utility company: Hydro-Québec

Hydro-Québec

Hydro-Québec is a government-owned public utility established in 1944 by the Government of Quebec. Based in Montreal, the company is in charge of the generation, transmission and distribution of electricity across Quebec....

. Nonetheless it is operated as an independent AC grid for physical reasons. Because of its unique status, it is often functionally considered part of the Eastern Interconnection.

Interconnections can be tied to each other via high-voltage direct current

High-voltage direct current

A high-voltage, direct current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses...

 power transmission lines (DC ties), or with variable frequency transformer

Variable frequency transformer

A variable frequency transformer is used to transmit electricity between two alternating current domains. The VFT is a relatively recent development...

s (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Québec Interconnection is tied to the Eastern Interconnection with four DC ties and a VFT.

See also

• Hydro-Québec's electricity transmission system
  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...
  
  
• North American Electric Reliability Corporation (NERC)
• Northeast Power Coordinating Council (NPCC)
  Northeast Power Coordinating Council
  The Northeast Power Coordinating Council was formed January 19, 1966, as a successor to the Canada–United States Eastern Interconnection . NPCC is one of nine regional electric reliability councils under North American Electric Reliability Corporation authority. NERC and the regional...