The electrical power grid that powers Northern America is not a single grid, but is instead divided into multiple wide area synchronous grids. The Eastern Interconnection and the Western Interconnection are the largest. Three other regions include the Texas Interconnection, the Quebec Interconnection, and the Alaska Interconnection. Each region delivers power at a nominal frequency. The regions are not usually directly connected or synchronized to each other, but there exist some HVDC interconnectors. The Eastern and Western grids are connected with 1.32 GW.
History
In the United States in the 1920s, utilities formed joint operations to share peak load coverage and backup power. In 1934, with the passage of the Public Utility Holding Company Act, electric utilities were recognized as public goods of importance and were given outlined restrictions and regulatory oversight of their operations.
From 1967, the East and West interconnections were directly connected together. However, the AC ties did not have high capacity and were subject to oscillations, and so their connection proved unreliable. In 1975 the AC ties were disconnected, because DC ties were found to work more reliably.
The Energy Policy Act of 1992 required transmission line owners to allow electric generation companies open access to their network and led to a restructuring of how the electric industry operated in an effort to create competition in power generation. No longer were electric utilities built as vertical monopolies, where generation, transmission and distribution were handled by a single company. Now, the three stages could be split among various companies in an effort to provide fair accessibility to high voltage transmission. The Energy Policy Act of 2005 allowed incentives and loan guarantees for alternative energy production and to advance innovative technologies that avoided greenhouse emissions.
Description
There are two major wide area synchronous grids in North America: the Eastern Interconnection and the Western Interconnection. In addition, there are three minor power grids in North America: the Alaska Interconnection, the Texas Interconnection, and the Quebec Interconnection. The Eastern, Western and Texas Interconnections are tied together at various points with DC interconnects allowing electrical power to be transmitted throughout the contiguous U.S., Canada and parts of Mexico. The transmission grids are operated by transmission system operators (TSOs), not-for profit companies that are typically owned by the utilities in their respective service areas, where they coordinate, control and monitor the operation of the electrical power system. TSOs are obliged to provide nondiscriminatory transmission access to electricity generators and customers. TSOs can be of two types: Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs). The former operate within a single state, and the latter cover wider areas crossing state borders.
In 2009 there were four RTOs in the U.S.: ISO New England (ISO-NE, which is an RTO despite its name); Midcontinent Independent System Operator (MISO); PJM Interconnection in the Mid-Atlantic region; and Southwest Power Pool (SPP) covering Oklahoma, Kansas and parts of Arkansas, Missouri, Texas and New Mexico.
There are also three ISOs: California Independent System Operator (California ISO); New York Independent System Operator (NYISO); Electric Reliability Council of Texas (ERCOT, an ISO).
RTOs are similar but not identical to the nine Regional Reliability Councils associated in the North American Electric Reliability Corporation (NERC), a nonprofit entity that is in charge of improving the reliability and security of the bulk power system in the U.S., Canada and the northern part of Baja California in Mexico. The members of the Regional Reliability Councils include private, public and cooperative utilities, power marketers and final customers. The Regional Reliability Councils are: Eastern Interconnection Florida Reliability Coordinating Council (FRCC) Midwest Reliability Organization (MRO) Northeast Power Coordinating Council (NPCC) ReliabilityFirst Corporation (RFC) SERC Reliability Corporation (SERC) Southwest Power Pool (SPP) Western Interconnection Western Electricity Coordinating Council (WECC) Texas Interconnection Electric Reliability Council of Texas (ERCOT)
The FERC distinguishes between 10 power markets in the U.S., including the seven for which RTOs have been established, as well as: Northwest Southwest (covering Arizona, most of New Mexico and Colorado) Southeast
ISOs and RTOs were established in the 1990s, when states and regions established wholesale competition for electricity.