| Part of a series on |
| Power engineering |
|---|
| Electric power conversion |
| Electric power infrastructure |
| Electric power systems components |
An interconnector (also known as a DC tie in the USA [1] ) is a structure which enables high voltage DC electricity to flow between electrical grids. An electrical interconnector allows electricity to flow between separate AC networks, or to link synchronous grids. [2] [3] They can be formed of submarine power cables or underground power cables or overhead power lines.
The longest interconnection as of July 2022 was the 2,210 km Hami - Zhengzhou delivering 8 GW of high voltage direct current power. The longest proposed connector is the 3,800 km, 3.6 GW Xlinks Morocco-UK Power Project. [4]
Interconnectors allow the trading of electricity between territories. For example, the East–West Interconnector allows the trading of electricity between Great Britain and Ireland. A territory which generates more energy than it requires for its own activities can therefore sell surplus energy to a neighbouring territory.
Interconnectors also provide increased resilience. Within the European Union there is a movement towards a single market for energy, which makes interconnectors viable. [5] They are essential to achieve security of supply. [6] As such, the Nordic and Baltic energy exchange Nord Pool Spot rely on multiple interconnectors. The fullest possible implementation of this is the proposed European super grid which would include numerous interconnectors between national networks.
Interconnectors are used to increase the security of the energy supply and to manage peak demand. They enable cross-border access to the producers and consumers of electricity, thus increasing the competition in energy markets. They also help integrate more electricity generated from renewable sources, [7] thus reducing the use of fossil fuel power plants and CO2 emissions. Interconnectors aid adaptation to changing demand patterns such as the uptake of electric vehicles.
Interconnectors may run across a land border or connect two land areas separated by water. As of July 2022 there are at least 35 international connectors and many more intra-national connectors, see high-voltage direct-current (HVDC) projects.
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.
A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems.
The National Grid is the high-voltage electric power transmission network serving Great Britain, connecting power stations and major substations, and ensuring that electricity generated anywhere on the grid can be used to satisfy demand elsewhere. The network serves the majority of Great Britain and some of the surrounding islands. It does not cover Northern Ireland, which is part of the Irish single electricity market.
NorNed is a 580-kilometre (360 mi) long high-voltage direct current submarine power cable between Feda in Norway and the seaport of Eemshaven in the Netherlands, which interconnects both countries' electrical grids. It was once the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the NorNed cable is a bipolar HVDC link with a voltage of ±450 kV and a capacity of 700 MW. NorNed is a joint project of the Norwegian transmission system operator Statnett and its Dutch counterpart TenneT. The cable system itself and the two converter stations were produced by ABB.
Murraylink is an Australian high voltage direct current electricity transmission link between Berri in South Australia and Red Cliffs in Victoria, connecting the two state electricity grids. Murraylink was commissioned in 2002 and is believed to be the world's longest underground transmission system and cost more than A$177 million. It was built by TransEnergie Australia, a subsidiary of Hydro-Québec. It was sold to the Australian Pipeline Trust in March 2006 for A$153 million. In December 2008 ownership of Murraylink was transferred to the newly formed Energy Infrastructure Investments Group, while APA continued as the operator. The ownership of EII is APA with 19.9%, with the balance with Japan-based Marubeni Corporation with 49.9% and Osaka Gas with 30.2%.
A submarine power cable is a transmission cable for carrying electric power below the surface of the water. These are called "submarine" because they usually carry electric power beneath salt water but it is also possible to use submarine power cables beneath fresh water. Examples of the latter exist that connect the mainland with large islands in the St. Lawrence River.
The East–West Interconnector is a 500 MW high-voltage direct current submarine and subsoil power cable which connects the Irish and British electricity markets. The project was developed by the Irish national grid operator EirGrid.
The synchronous grid of Continental Europe is the largest synchronous electrical grid in the world. It is interconnected as a single phase-locked 50 Hz mains frequency electricity grid that supplies over 400 million customers in 24 countries, including most of the European Union. In 2009, 667 GW of production capacity was connected to the grid, providing approximately 80 GW of operating reserve margin. The transmission system operators operating this grid formed the Union for the Coordination of Transmission of Electricity (UCTE), now part of the European Network of Transmission System Operators for Electricity (ENTSO-E).
TenneT is a transmission system operator in the Netherlands and in a large part of Germany.
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).
A super grid or supergrid is a wide-area transmission network, generally trans-continental or multinational, that is intended to make possible the trade of high volumes of electricity across great distances. It is sometimes also referred to as a "mega grid". Super grids typically are proposed to use high-voltage direct current (HVDC) to transmit electricity long distances. The latest generation of HVDC power lines can transmit energy with losses of only 1.6% per 1,000 km.
BritNed is a 1,000 MW high-voltage direct-current (HVDC) submarine power cable between the Isle of Grain in Kent, the United Kingdom; and Maasvlakte in Rotterdam, the Netherlands.
The North Sea Link is a 1,400 MW high-voltage direct current submarine power cable between Norway and the United Kingdom.
The EuroAsia Interconnector is a planned HVDC interconnector between the Greek, Cypriot, and Israeli power grids via the world's longest submarine power cable, with a length of 310 kilometres (190 mi) from Israel to Cyprus and 898 kilometres (558 mi) from Cyprus to Greece for a total of 1,208 kilometres (751 mi). Connecting Kofinou, Cyprus to Hadera, Israel and Korakias, Crete, Greece, the EuroAsia Interconnector is a major Project of Common Interest (PCI) of the European Union and a priority Electricity Highway Interconnector Project as an energy highway bridging Asia and Europe. Regulatory approval of electricity interconnection between Cyprus and Greece was completed on October 10, 2017.
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 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.
The Celtic Interconnector is a 700 MW high-voltage direct current (HVDC) submarine power cable under construction between the southern coast of Ireland and the north-west coast of France. It will be the first such interconnector between the two countries.
Icelink is a proposed electricity interconnector between Iceland and the United Kingdom via Great Britain. At 1,000 to 1,200 km, the 800–1,200 MW high-voltage direct current (HVDC) link would be the longest sub-sea power interconnector in the world.
EuroAfrica Interconnector is a planned HVDC interconnector and submarine power cable between the Greek, Cypriot, and Egypt power grids. The Interconnector is an energy highway bridging Africa and Europe. It will have a capacity to transmit 2,000 megawatts of electricity in either direction. Annual transmission capacity will be rated at 17.5 TWh, much more than the annual production at the Aswan Dam power stations. President of Egypt Abdel Fattah el-Sisi, President of Cyprus Nicos Anastasiades and Prime Minister of Greece Kyriakos Mitsotakis, issued a joint declaration at the conclusion of the 7th Trilateral Summit, held in Cairo on October 8, 2019, in which they expressed their desire to continue strengthening their cooperation in matters of energy. In particular, the joint declaration by the three leaders stated they recognised the importance of establishing an electrical grid between Egypt, Cyprus and Greece, building on the framework agreement between the Egyptian Electricity Holding Company and the Euro Africa Interconnector Company on 22 May 2019.
The Xlinks Morocco-UK Power Project is a proposal to create 10.5 GW of renewable generation, 20 GWh of battery storage and a 3.6 GW high-voltage direct current interconnector to carry solar and wind-generated electricity from the Kingdom of Morocco to the United Kingdom. Morocco has far more consistent weather, and so should provide consistent solar power even in midwinter.