A super grid is a wide area transmission network that makes it possible to trade high volumes of electricity across great distances. It is sometimes also referred to as a "mega grid".
The idea of creating long distance transmission lines in order to take advantage of renewable sources distantly located is not new. In the US in the 1950s, a proposal was made to ship hydroelectric power from dams being constructed in the Pacific Northwest to consumers in Southern California, but it was opposed and scrapped. In 1961, U.S. president John F. Kennedy authorized a large public works project using new HVDC technology from Sweden. The project was undertaken as a close collaboration between General Electric of the U.S. and ASEA of Sweden, and the system was commissioned in 1970. With several upgrades of the converter stations in the intervening decades, the system now has a capacity of 3100 MW and is known as the Pacific DC Intertie.
The concept of a "Super grid" dates back to the 1960s and was used to describe the emerging unification of the Great Britain grid.
In the code that governs the British Grid, the Grid Code, the Supergrid is currently defined - and has been since this code was first written, in 1990 - as referring to those parts of the British electricity transmission system that are connected at voltages in excess of 200 kV (200,000 volts). British power system planners and operational staff therefore invariably speak of the Supergrid in this context; in practice the definition used captures all of the equipment owned by the National Grid company in England and Wales, and no other equipment.
What has changed during the past 40 years is the scale of energy and distances that are imagined possible in a super grid. Europe began unifying its grids since the 1950s and its largest unified grid is the synchronous grid of Continental Europe serving 24 countries. Serious work is being conducted on unification of the European UCTE grid with the neighboring IPS/UPS grid. If completed, this massive grid would span 13 time zones stretching from the Atlantic to the Pacific.
While such grids cover great distances, the capacity to transmit large volumes of electricity remains limited due to congestion and control issues. The SuperSmart Grid (Europe) and the Unified Smart Grid (US) specify major technological upgrades that proponents claim are necessary to assure the practical operation and promised benefits of such transcontinental mega grids.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』