RTE Wins Work on Two UK Offshore Wind HVDC Projects

France-headquartered electricity transmission consultancy and engineering company, RTE international, has been appointed as third-party consultant to conduct joint interaction studies between two HVDC projects in the UK: Sofia Offshore Wind Farm and Dogger Bank C.

Under the contract, RTE international will carry out wide-ranging interaction studies to ensure the connection of both projects to the Lackenby AC substation in the UK.

Although the two large-scale offshore wind farms are being built by different developers, their offshore HVDC export cables will connect to onshore cables that will run seven kilometres to a new converter station – one for each project – now under construction to the North East of Lazenby. Each project will then have a further two kilometres of HVAC cables that will transport power to the existing National Grid substation at Lackenby.

Because of this, RWE, the owner of the 1.4 GW Sofia and SSE Renewables, Equinor, and Eni Plenitude, who are jointly developing the 1.2 GW Dogger Bank C, are working together at the site of their adjacent converter stations and along the shared onshore cable route.

The interaction studies that RTE will perform will investigate the reciprocal interaction between the two projects, which will be operated on the AC onshore side in a close electrical vicinity. The risk-analysis focuses on negative interactions that can cause a deterioration in network performance, potentially leading to system instability.

The studies will use offline EMT simulation methods, as well as in-the-loop hardware, with replicas of both projects being hosted in RTE international’s laboratories in Lyon.

“Integrating offshore wind farms, that are far from the shore, into the power system requires High Voltage Direct Current (HVDC) technology and converter stations. This results in the displacement of conventional power generation, lower system inertia and lower short circuit capacity of the AC system. The AC grids integrated with multiple converters in a close electrical vicinity have the potential to influence each other. The interoperability and stability of the system with a large number of converters is regarded as a key issue in the future power system planning development”, RTE said.

HVDC links for Sofia and Dogger Bank C, rated at 1,320 MW and 1,200 MW respectively, will be connected at the same electrical location simultaneously by two different HVDC manufacturers, Hitachi Energy for Dogger Bank and GE’s Grid Solutions for Sofia.

The work to construct both the converter stations started last year and will take around four years, due to be completed in 2025.

SSE Renewables and Equinor reached financial close on Dogger Bank C in December 2021, setting the third phase of the 3.6 GW Dogger Bank Wind Farm on track to start construction this year with onshore cable installation works.

RWE reached the financial investment decision on the Sofia offshore wind farm in March 2021, with the project breaking ground in the summer, together with Dogger Bank C.

Both offshore wind farms are scheduled to be put into operation in 2026.

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