North American power transmission grid

Last updated
The two major and three minor North American Electric Reliability Corporation (NERC) interconnections, and the nine NERC Regional Reliability Councils. NERC-map-en.svg
The two major and three minor North American Electric Reliability Corporation (NERC) interconnections, and the nine NERC Regional Reliability Councils.
The electric power transmission grid of the contiguous United States consists of 120,000 miles (190,000 km) of lines operated by 500 companies. UnitedStatesPowerGrid.jpg
The electric power transmission grid of the contiguous United States consists of 120,000 miles (190,000 km) of lines operated by 500 companies.

The electrical power grid that powers Northern America is not a single grid, but is instead divided into multiple wide area synchronous grids. [1] 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 60 Hz 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 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]

Contents

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. [1]

The Energy 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  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.[ citation needed ]

In 2009 there were four RTOs in the U.S.:[ citation needed ]

There are also three ISOs:

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:

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.

North American Electric Reliability Corporation

The North American Electric Reliability Corporation (NERC) is a nonprofit corporation based in Atlanta, 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-scale blackout in November of 1965. The original NERC was formed on June 1, 1968, by the electric utility industry to promote the reliability and adequacy of bulk power transmission in the electric utility systems of North 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 the interconnected power systems of the contiguous United States, Canada and a portion of Baja California in Mexico.

NERC's major responsibilities include working with all stakeholders to develop standards for power system operation, monitoring and enforcing compliance with those standards, assessing resource 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.

Interconnections

Eastern Interconnection

The Eastern Interconnection is one of the two major alternating-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 from Saskatchewan eastward to the Atlantic coast (excluding Quebec), south to Florida, and back west to the foot of the Rockies (excluding most of Texas). The USA part has 700 GW of generating capacity. [2]

Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties), or with variable-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, the Tres Amigas SuperStation was planned to connect the Eastern, Western and Texas Interconnections via three 5 GW superconductor links. [10] As of 2021 it has not started construction.

Western Interconnection

The Western Interconnection is the other major alternating 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 Western Canada south to Baja California in Mexico, reaching eastward over the Rockies to the Great Plains. The USA part has 250 GW of generating capacity. [2]

Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties) as well as containing internal DC connections such as the north-south Pacific DC Intertie, or with variable-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.

Texas Interconnection

The Texas Interconnection is one of the three minor alternating 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 of Texas.

Interconnections can be tied to each other via high-voltage direct current power transmission lines (DC ties), or with variable-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 in Mexico. There is one AC tie switch in Dayton, Texas that has been used only one time in its history (after Hurricane Ike).

Quebec Interconnection

The Quebec Interconnection is one of the three minor alternating-current (AC) electrical grids in North America.

The Quebec Interconnection covers all of the Province of Quebec 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 four high-voltage direct current power transmission lines (DC ties), and with one variable-frequency transformers (VFTs) line, which isolate the unsynchronized AC frequencies of each side.

Alaska Interconnection

The Alaska Interconnection is one of the three minor alternating-current (AC) electrical grids in North America.

It is composed of two grids isolated from each other as well as from the rest of North American grids, so there is not actually, physically, an Alaska Interconnection.

Proposed improvements

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 storage tax credit. In California, the state Senate had a bill that would "create a new energy storage rebate program". [13]

In August 2018, Advanced Energy Economy (AEE) and Citizens for Responsible Energy Solutions Forum (CRES Forum) published a policy 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 and energy 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 by National 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]

See also

Related Research Articles

<span class="mw-page-title-main">Electric power transmission</span> Bulk movement of electrical energy

Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the electrical grid.

<span class="mw-page-title-main">North American Electric Reliability Corporation</span> Non profit Electric Reliability Organization

The North American Electric Reliability Corporation (NERC) is a nonprofit corporation based in Atlanta, Georgia, and formed on March 28, 2006, as the successor to the North American Electric Reliability Council. The original NERC was formed on June 1, 1968, by the electric utility industry to promote the reliability and adequacy of bulk power transmission in the electric utility systems of North America. NERC's mission states that it "is to assure the effective and efficient reduction of risks to the reliability and security of the grid".

<span class="mw-page-title-main">Electric power industry</span> Industry that provides the production and delivery of electric energy

The electric power industry covers the generation, transmission, distribution and sale of electric power to the general public and industry. The commercial distribution of electric power started in 1882 when electricity was produced for electric lighting. In the 1880s and 1890s, growing economic and safety concerns lead to the regulation of the industry. What was once an expensive novelty limited to the most densely populated areas, reliable and economical electric power has become an essential aspect for normal operation of all elements of developed economies.

<span class="mw-page-title-main">Utility frequency</span> Frequency used on standard electricity grid in a given area

The utility frequency, (power) line frequency or mains frequency is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains electricity by country.

<span class="mw-page-title-main">Regional transmission organization (North America)</span> Electric power coordinator

A regional transmission organization (RTO) in the United States is an electric power transmission system operator (TSO) that coordinates, controls, and monitors a multi-state electric grid. The transfer of electricity between states is considered interstate commerce, and electric grids spanning multiple states are therefore regulated by the Federal Energy Regulatory Commission (FERC). The voluntary creation of RTOs was initiated by FERC Order No. 2000, issued on December 20, 1999. The purpose of the RTO is to promote economic efficiency, reliability, and non-discriminatory practices while reducing government oversight.

A variable-frequency transformer (VFT) is used to transmit electricity between two alternating current frequency domains. The VFT is a relatively recent development. Most asynchronous grid inter-ties use high-voltage direct current converters, while synchronous grid inter-ties are connected by lines and "ordinary" transformers, but without the ability to control power flow between the systems, or with phase-shifting transformer with some flow control.

<span class="mw-page-title-main">Texas Interconnection</span> Power grid providing power to most of Texas

The Texas Interconnection is an alternating current (AC) power grid – a wide area synchronous grid – that covers most of the state of Texas. The grid is managed by the Electric Reliability Council of Texas (ERCOT).

<span class="mw-page-title-main">Eastern Interconnection</span> Power grid in eastern North America

The Eastern Interconnection is one of the two major alternating-current (AC) electrical grids in the North American power transmission grid. The other major interconnection is the Western Interconnection. The three minor interconnections are the Quebec, Alaska, and Texas interconnections.

<span class="mw-page-title-main">Western Interconnection</span> Power grid in western North America

The Western Interconnection is a wide area synchronous grid and one of the two major alternating current (AC) power grids in the North American power transmission grid. The other major wide area synchronous grid is the Eastern Interconnection. The minor interconnections are the Québec Interconnection, the Texas Interconnection, and the Alaska Interconnections.

<span class="mw-page-title-main">Midwest Reliability Organization</span> Regional electric energy reliability organization

The Midwest Reliability Organization (MRO) began operations on January 1, 2005, as the successor to the Mid-continent Area Power Pool (MAPP), which was formed in 1965. MRO is one of six regional entities under North American Electric Reliability Corporation (NERC) authority. NERC and the regional reliability councils were formed following the Northeast Blackout of 1965. MRO's offices are located in St. Paul, Minnesota. MRO members include municipal utilities, cooperatives, investor-owned utilities, a federal power marketing agency, Canadian Crown Corporations, and independent power producers.

<span class="mw-page-title-main">Southwest Power Pool</span> American power-grid non-profit in the central Southern US

Southwest Power Pool (SPP) manages the electric grid and wholesale power market for the central United States. As a regional transmission organization, the nonprofit corporation is mandated by the Federal Energy Regulatory Commission to ensure reliable supplies of power, adequate transmission infrastructure and competitive wholesale electricity prices. Southwest Power Pool and its member companies coordinate the flow of electricity across approximately 60,000 miles of high-voltage transmission lines spanning 14 states. The company is headquartered in Little Rock, Arkansas.

<span class="mw-page-title-main">Midcontinent Independent System Operator</span> Transmission system operator in the United States and Canada

The Midcontinent Independent System Operator, Inc., formerly named Midwest Independent Transmission System Operator, Inc. (MISO) is an Independent System Operator (ISO) and Regional Transmission Organization (RTO) providing open-access transmission service and monitoring the high-voltage transmission system in the Midwest United States and Manitoba, Canada and a southern United States region which includes much of Arkansas, Mississippi, and Louisiana. MISO also operates one of the world's largest real-time energy markets. The 15 states covered by MISO are: Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, North Dakota, South Dakota, Texas, and Wisconsin.

<span class="mw-page-title-main">Hydro-Québec's electricity transmission system</span> International power transmission system centred in Quebec, Canada

Hydro-Québec's electricity transmission system is an international electric power transmission system centred in Quebec, Canada. The system pioneered the use of very high voltage 735-kilovolt (kV) alternating current (AC) power lines that link the population centres of Montreal and Quebec City to distant hydroelectric power stations like the Daniel-Johnson Dam and the James Bay Project in northwestern Quebec and the Churchill Falls Generating Station in Labrador.

<span class="mw-page-title-main">PJM Interconnection</span> Major electric grid coordinator in northeastern USA

PJM Interconnection LLC (PJM) is a regional transmission organization (RTO) in the United States. It is part of the Eastern Interconnection grid operating an electric transmission system serving all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and the District of Columbia.

<span class="mw-page-title-main">Electrical grid</span> Interconnected network for delivering electricity from suppliers to consumers

An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids consist of power stations, electrical substations to step voltage up or down, electric power transmission to carry power long distances, and lastly electric power distribution to individual customers, where voltage is stepped down again to the required service voltage(s). Electrical grids vary in size and can cover whole countries or continents. From small to large there are microgrids, wide area synchronous grids, and super grids.

<span class="mw-page-title-main">Wide area synchronous grid</span> Regional electrical grid

A wide area synchronous grid is a three-phase electric power grid that has regional scale or greater that operates at a synchronized utility frequency and is electrically tied together during normal system conditions. Also known as synchronous zones, the most powerful is the Northern Chinese State Grid with 1,700 gigawatts (GW) of generation capacity, while the widest region served is that of the IPS/UPS system serving most countries of the former Soviet Union. Synchronous grids with ample capacity facilitate electricity trading across wide areas. In the ENTSO-E in 2008, over 350,000 megawatt hours were sold per day on the European Energy Exchange (EEX).

There is a large array of stakeholders that provide services through electricity generation, transmission, distribution and marketing for industrial, commercial, public and residential customers in the United States. It also includes many public institutions that regulate the sector. In 1996, there were 3,195 electric utilities in the United States, of which fewer than 1,000 were engaged in power generation. This leaves a large number of mostly smaller utilities engaged only in power distribution. There were also 65 power marketers. Of all utilities, 2,020 were publicly owned, 932 were rural electric cooperatives, and 243 were investor-owned utilities. The electricity transmission network is controlled by Independent System Operators or Regional Transmission Organizations, which are not-for-profit organizations that are obliged to provide indiscriminate access to various suppliers to promote competition.

The Tres Amigas SuperStation was a project proposed in 2009 to unite North America’s two major power grids and one of its three minor grids, with the goals of enabling faster adoption of renewable energy and increasing the reliability of the U.S. grid.

<span class="mw-page-title-main">Alaska Interconnection</span> American AC power transmission grid

The Alaska Interconnection (ASCC) is an AC power transmission grid in North America that serves Central and Southeast Alaska. While the Alaska Interconnection is often referred to as one interconnected grid, its two parts are not connected to each other through interconnectors, nor are the two grids connected to any other interconnection, making the grids in Alaska isolated circuits. Both grids, though, are managed by the Alaska Systems Coordinating Council (ASCC) as if they were one entity like the other interconnections in North America. ASCC was formed in 1983 and is an affiliate North American Electric Reliability Corporation (NERC) member.

A balancing authority (BA) is an entity in the US electric system that is responsible for grid balancing: resource planning and unit commitment ahead of time, maintenance of the load-interchange-generation balance within a balancing authority area and support for real-time load-frequency control. The balancing authorities are connected by metered high-voltage tie lines and grouped into interconnections:

References

  1. 1 2 When the Grid Was the Grid:The History of North America’s Brief Coast-to-Coast Interconnected Machine -By JULIE COHN
  2. 1 2 3 4 Howland, Ethan (19 October 2021). "Boosting transmission between East, West grids will lower costs: NREL". Utility Dive. Archived from the original on 20 October 2021.
  3. ↑ Borberly, A. and Kreider, J. F. (2001). Distributed Generation: The Power Paradigm for the New Millennium. CRC Press, Boca Raton, Florida. 400 pgs.
  4. ↑ Mazer, A. (2007). Electric Power Planning for Regulated and Deregulated Markets. John Wiley and Sons. Hoboken, NJ.
  5. ↑ . (2001). Glover J. D., Sarma M. S., Overbye T. J. (2010) Power System and Analysis 5th Edition. Cengage Learning. Pg 10.
  6. ↑ FERC:Electric Power Markets: National Overview
  7. ↑ "Home". nerc.com.
  8. 1 2 "Connecting the Grid: DC Ties Serve Critical Role". www.nmppenergy.org. NMPP Energy (Nebraska Municipal Power Pool). 2020-09-01. Retrieved 2020-12-07. HVDC ties in: Miles City, MT; Rapid City, SD; Stegall, NE; Sidney, NE; Lamar, CO; Clovis, NM; Artesia, NM
  9. 1 2 Billy J. Robert: U.S. Transmission System and B2B HVDC Ties, NREL, 2017-01-12
  10. ↑ High-Temp Superconductors To Connect Power Grids
  11. ↑ Visualizing The U.S. Electric Grid
  12. ↑ "Control Area Concepts and Obligations" (PDF). North American Electric Reliability Council. July 1992. Archived from the original (PDF) on January 2, 2011. Retrieved July 18, 2011. Today, in NERC, there are four major interconnected areas: the Eastern Interconnection, the Western Interconnection, the Texas Interconnection, and the Québec Interconnection.
  13. 1 2 "Nearly three quarters of US took steps toward grid modernization in first quarter, study finds". Daily Energy Insider. 2017-05-25. Archived from the original on 2018-05-08. Retrieved 2017-06-05.
  14. ↑ "Five ways to modernize the U.S. electric power grid via Advanced Energy Economy | Solar Builder". Solar Builder Magazine. 2018-08-06. Retrieved 2018-08-30.
  15. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2021-11-24. Retrieved 2021-10-21.{{cite web}}: CS1 maint: archived copy as title (link)
  16. ↑ "Preparing grids for EV buses to enable a sustainable future. A contribution by Anthony Allard, Hitachi Energy Head of North America". Sustainable Bus. 2022-08-12. Retrieved 2022-08-28.
  17. ↑ "Fleet Electrification Provides Great Opportunity — If Done Right". www.utilityproducts.com. 2022-05-13. Retrieved 2022-08-28.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.