An interconnector (also known as a DC tie in the USA) is a structure which enables high-voltage DC electricity to flow between
electrical grid
An electrical grid (or electricity network) 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 tran ...
s, connecting separate AC networks, or linking synchronous grids. It may be formed of
overhead power line
An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large distances. It consists of one or more conductors (commonly multiples of three) suspended by towers or poles. ...
s.
The longest interconnection as of July 2022 was the Hami - Zhengzhou delivering 8 GW of
high voltage direct current
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. Most HVDC links use voltages betwe ...
trading
Trade involves the transfer of goods and services from one person or entity to another, often in exchange for money. Economists refer to a system or network that allows trade as a market (economics), market.
Traders generally negotiate throu ...
of electricity between territories. For example, the East–West Interconnector allows the trading of electricity between
Great Britain
Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...
and
Ireland
Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
. 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
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
there is a movement towards a
single market
A single market, sometimes called common market or internal market, is a type of trade bloc in which most trade barriers have been removed (for goods) with some common policies on product regulation, and freedom of movement of the factors of pr ...
for energy, which makes interconnectors viable. They are essential to achieve security of supply. As such, the Nordic and Baltic energy exchange
Nord Pool Spot
Nord Pool AS is a pan-European power exchange. Nord Pool has its main office in Oslo and further offices in Stockholm, Helsinki, Tallinn and London
London is the Capital city, capital and List of urban areas in the United Kingdom, lar ...
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,GB/France : un projet d’interconnexion dans les tuyaux... de la justice www.lemondedelenergie.com thus reducing the use of fossil fuel power plants and emissions. Interconnectors aid adaptation to changing demand patterns such as the uptake of electric vehicles.
Infrastructure
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.
Variable-frequency transformer
A variable-frequency transformer (VFT) is used to transmit electricity between two ( asynchronous or synchronous) alternating current frequency domains. The VFT is a relatively recent development. Most asynchronous grid inter-ties use high-voltage ...