Theelectrical power grid that powersNorthern America is not a single grid, but is instead divided into multiplewide area synchronous grids.[1] TheEastern Interconnection and theWestern Interconnection are the largest. Three other regions include theTexas Interconnection, theQuebec Interconnection, and theAlaska Interconnection. Each region delivers power at a nominal60Hz frequency.[2]
The regions are not usually directly connected or synchronized to each other, but there exist someHVDCinterconnectors. The Eastern and Western grids are connected via seven links that allow 1.32 GW to flow between them. A study by the National Renewable Energy Laboratory found that increasing these interconnections would save energy costs.[2]
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 thePublic Utility Holding Company Act, electric utilities were recognized aspublic 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. 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, becauseDC ties were found to work more reliably.[1]
TheEnergy Policy Act of 1992 required transmission line owners to allow electric generation companies open access to their network[3][4] 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.[5]: 21 TheEnergy Policy Act of 2005 allowed incentives and loan guarantees for alternative energy production and to advance innovative technologies that avoidedgreenhouse emissions.
There are two majorwide area synchronous grids in North America: theEastern Interconnection and theWestern Interconnection. There are three minor power grids in North America: theAlaska Interconnection, theTexas Interconnection, and theQuebec Interconnection. The Eastern, Western and Texas Interconnections are tied together at various points withDC interconnects allowing electrical power to be transmitted throughout the contiguous U.S., Canada and parts of Mexico.
The transmission grids are operated bytransmission 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) andRegional Transmission Organizations (RTOs). ISOs operate within a single state. RTOs cover wider areas, crossing state borders.[citation needed]
In 2009 there were four RTOs in the U.S.:[citation needed]
There are three ISOs:
RTOs are similar but not identical to the nine Regional Reliability Councils associated in theNorth 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:
The FERC distinguishes between 10 power markets in the U.S., including the seven for which RTOs have been established, as well as:
ISOs and RTOs were established in the 1990s, when states and regions established wholesale competition for electricity.
The North American Electric Reliability Corporation (NERC) is anonprofit corporation based inAtlanta, Georgia, and formed on March 28, 2006, as the successor to the National Electric Reliability Council (also known as NERC), which formed in the wake of the first large-scaleblackout in November of 1965. The original NERC was formed on June 1, 1968, by the electric utility industry to promote the reliability and adequacy ofbulk power transmission in the electric utility systems ofNorth America. NERC's mission is to "ensure the reliability of the North American bulk power system."[7]
NERC oversees eight regional reliability entities and encompasses all of theinterconnected power systems of the contiguousUnited States,Canada and a portion ofBaja California inMexico.
NERC's major responsibilities include working with all stakeholders to develop standards for power system operation, monitoring andenforcing compliance with those standards, assessingresource adequacy, and providing educational and training resources as part of an accreditation program to ensure power system operators remain qualified and proficient. NERC also investigates and analyzes the causes of significant power system disturbances in order to help prevent future events.
The Eastern Interconnection is one of the two majoralternating-current (AC)electrical grids in North America.
All of the electric utilities in the Eastern Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency operating at an average of 60 Hz. The Eastern Interconnection reaches fromSaskatchewan eastward to the Atlantic coast, excludingQuebec, south toFlorida, and back west to the foot of theRockies, excluding most ofTexas. The USA part has 700 GW of generating capacity.[2]
Interconnections can be tied to each other viahigh-voltage direct currentpower transmission lines (DC ties), or withvariable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Eastern Interconnection is tied to the Western Interconnection with seven DC ties (ca. 200 MW each) in the US[8][9] and one in Canada, to the Texas Interconnection with two DC ties, and to the Quebec Interconnection with four DC ties and a VFT.
In 2009, theTres Amigas SuperStation was planned to connect the Eastern, Western and Texas Interconnections via three 5 GWsuperconductor links.[10] As of 2021[update] no progress has occurred.
The Western Interconnection is the other majoralternating current (AC)power grid in North America.
All of the electric utilities in the Western Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency of 60 Hz. The Western Interconnection stretches from WesternCanada south toBaja California inMexico, reaching eastward over theRockies to theGreat Plains. The USA part has 250 GW of generating capacity.[2]
Interconnections can be tied to each other viahigh-voltage direct currentpower transmission lines (DC ties) as well as containing internal DC connections such as the north-southPacific DC Intertie, or withvariable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. There are seven DC ties (ca. 200 MW each) to the Eastern Interconnection in the US[8][9] and one in Canada. There are proposals to add four additional HVDC ties.[11] It is not tied to the Alaska Interconnection.
The Texas Interconnection is one of the three minoralternating current (AC)power grids in North America.
All of the electric utilities in the Texas Interconnection are electrically tied together during normal system conditions, and they operate at a synchronized frequency operating at an average of 60 Hz. The Texas Interconnection covers most of the state ofTexas.
Interconnections can be tied to each other viahigh-voltage direct currentpower transmission lines (DC ties), or withvariable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Texas Interconnection is tied to the Eastern Interconnection with two DC ties, and has a DC tie and a VFT to non-NERC systems inMexico. There is one AC tie switch inDayton, Texas that has been used only one time in its history, afterHurricane Ike.
The Quebec Interconnection is one of the three minoralternating-current (AC)electrical grids in North America.
The Quebec Interconnection covers all of the Province ofQuebec and operates at an average system frequency of 60 Hz. It connects 18 systems in the US and Canada to one electric utility company:Hydro-Québec. It is operated as an independent AC grid for physical reasons.[12]
The Quebec Interconnection is tied to the Eastern Interconnection with fourhigh-voltage direct currentpower transmission lines (DC ties), and with onevariable-frequency transformers (VFTs) line, which isolate the unsynchronized AC frequencies of each side.
The Alaska Interconnection is one of the three minoralternating-current (AC)electrical grids in North America.
It is composed of two gridsisolated from each other as well as from the rest of North American grids, so there is not actually, physically, an Alaska Interconnection.
Thirty-seven states plus the District of Columbia took some action to modernize electric grids in the first quarter of 2017, according to the North Carolina Clean Energy Technology Center. The states did so to make electricity systems "more resilient and interactive". The most common actions that states took were "advanced metering infrastructure deployment" (19 states did this),smart grid deployment and "time-varying rates for residential customers".[13]
Legislatively, in the first quarter of the year 82 relevant bills were introduced in different parts of the United States. At the close of the quarter, most of the bills remained pending. For example, legislators in Hawaii introduced a bill that would create an energy storagetax credit. In California, thestate Senate had a bill that would "create a new energy storage rebate program".[13]
In August 2018, Advanced Energy Economy (AEE) andCitizens for Responsible Energy Solutions Forum (CRES Forum) published apolicy paper that gave five recommendations on ways to modernize the U.S. electric power grid. These recommendations are to streamline the federal permit process for advanced energy projects; encourage grid planners to consider alternatives to investment in transmission; allow energy storage andenergy efficiency to compete with additional energy generation; allow large customers to choose their own sources of electricity; and allow utilities and consumers to benefit from cloud computing software.[14]
In 2019,NREL calculated that new transmission between the grids could benefit consumers by a factor of 2.5 relative to the transmission investment.[15][2]
A 2022 study byNational Grid plc and Hitachi Energy indicates that installing charging infrastructure for fleet electrification will require location-specific upgrades to the US electrical grid.[16][17]
HVDC ties in: Miles City, MT; Rapid City, SD; Stegall, NE; Sidney, NE; Lamar, CO; Clovis, NM; Artesia, NM
Today, in NERC, there are four major interconnected areas: the Eastern Interconnection, the Western Interconnection, the Texas Interconnection, and the Québec Interconnection.
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