GE Vernova completes first EGL1 converter transformer

GE Vernova has completed the first of 14 converter transformers being manufactured in Britain for Eastern Green Link 1 (EGL1), a planned 2 GW high-voltage direct-current link between Scotland and England. The first unit has been loaded for transport at its Staffordshire factory and will enter a staged logistics programme before installation at the project’s two converter stations begins in July 2027. The milestone establishes that one major electrical component has reached the end of factory production while the wider transmission scheme remains under construction.

National Grid Electricity Transmission and SP Energy Networks are delivering EGL1 as a joint venture. Its 196 km route will run predominantly offshore between Torness in East Lothian and Hawthorn Pit in County Durham. The link is intended to move power in either direction, expanding transfer capacity between Scotland’s generation resources and demand elsewhere in Britain. National Grid describes a potential electricity transfer equivalent to the needs of around two million homes; that comparison concerns the planned link rating, not electricity already flowing through it.

The transformer will first be taken to storage at Ellesmere Port, after which marine transport will move it towards the relevant converter station. Large power transformers are transported as specialised loads, with their weight distribution, securing points, route clearances and handling limits incorporated into the movement plan. Factory completion therefore changes the equipment’s logistics status, while unloading, positioning and connection at the destination remain separate operations. National Grid has identified the route and installation month without publishing a unit-by-unit transport timetable.

At an HVDC converter station, converter transformers connect the alternating-current transmission network to the power-electronic converter equipment. They transform the voltage required by the converter design and provide a dedicated electrical interface whose insulation, impedance and harmonic characteristics must suit that installation. The converter then controls the exchange of power between the AC system and the direct-current cable. The transformers are essential to the conversion process, but they do not themselves perform AC-to-DC conversion.

EGL1 uses a high-voltage DC transmission arrangement because long submarine connections must manage cable charging effects as well as resistive losses. Direct-current transfer avoids the reactive charging current associated with carrying alternating current along a comparably long submarine cable. Voltage-sourced converters at the terminals will control the exchange with the AC networks, while station protection and controls must coordinate the equipment during energisation, disturbances and changes in transfer direction. Each terminal consequently depends on an integrated system rather than a transformer operating in isolation.

The two converter stations also require valves, cooling equipment, switchgear, transformers, cable terminations, auxiliary systems and communications. Civil structures and equipment foundations must be ready before heavy plant can be placed, and the installed apparatus must then be connected and tested as a coordinated electrical system. Factory acceptance establishes that an individual component satisfies its manufacturing requirements; site acceptance tests verify its installed interfaces, followed by staged station and link commissioning. Those processes are distinct engineering milestones with their own dependencies.

Neither the individual transformer power rating nor its mass and voltage specifications were disclosed with the 20 October update. The project’s 2 GW figure is the planned transfer capacity of the complete link and cannot be assigned to any one of the 14 units. Equally, the number of transformers does not disclose the precise equipment grouping, operating redundancy or control architecture at either station. Those details depend on the terminal designs and protection arrangements, rather than on the overall project headline rating.

The current manufacturing work sits within contracts awarded in December 2023. National Grid and SP Energy Networks awarded approximately £1.8 billion of cable and converter-station contracts, including a £1 billion converter-station contract for GE Vernova and MYTILINEOS, now known as Metlen, and a £750 million cable contract with Prysmian. That historical procurement established suppliers and scope before the latest equipment completion; the first transformer’s departure from the factory is progress on those existing commitments rather than an additional contract award.

Grid reinforcement on Britain’s east coast is intended to reduce bottlenecks that restrict the movement of power from areas with substantial generation to other parts of the network. When a transfer route becomes constrained, the electricity system operator may need to curtail generation on one side and obtain additional output or flexibility elsewhere. Additional capacity can relieve some of those pressures, although the effect in service will depend on network topology, generation and demand patterns, and planned or unexpected outages. Its contribution cannot be measured simply by multiplying the 2 GW rating by hours in a year.

With the first Staffordshire-built transformer complete, GE Vernova’s programme moves towards delivery and installation of the remaining units. The next identifiable site milestone is installation beginning at Hawthorn Pit and Torness from July 2027, followed by connection, protection testing, converter integration and commissioning of the complete transmission route. Only after the terminals, cable and associated network interfaces have been accepted can the project’s designed power-transfer capability become available to system operators.