North Sea Wind Farm to Use State-of-the-Art HVDC Transmission System

The proposed 1.4 GW Sofia wind array to be located in the North Sea off the coast of Britain is to have a high voltage direct current (HVDC) transmission system. The wind scheme's transmission providers are a joint venture between GE Renewable Energy’s Grid Solutions and Sembcorp Marine. The wind farm, developed by RWE Renewables, is one of the largest offshore projects in the world, being planned for placement on the Dogger Bank, a shallow sea area about 120 miles from the English coast.

RWE is the UK's second largest generator of electricity and its subsidiary RWE Renewables runs nine offshore wind farms in the country currently, with one more on the drawing board in addition to Sofia. GE’s Grid Solutions is providing the engineering, procurement, construction and installation of two HVDC converter platforms capable of transmitting 1,400 megawatts (MW) of power at 320 kilovolts (kV). Innovative converter modules and a new cutting edge control system are going to be utilized for Sofia.

These offshore converter stations are to be built and installed by Sembcorp Marine. It will comprise a 10,000 tons installation attached to a jacket foundation piled into the seabed. The onshore converter station modifies the electricity generated by the wind farm to 400 kV before it enters the UK's onshore national grid. This facility will be the most powerful offshore converter station to date and will be installed some 131 miles from the coast, so will also be the most remote.

Sven Utermöhlen, Chief Operating Officer Wind Offshore Global of RWE Renewables, says, “We are keen to support the growth of both onshore and offshore wind energy in UK, one of our core markets in Europe. The choice of GE’s Grid Solutions and Sembcorp Marine for the supply of the electrical system is an important statement of our commitment to grow our renewables portfolio in the UK and reflects our ambition to strive for continuous innovation in the development, construction and operation of our offshore wind farms.”

The timescale for the construction of this project is: onshore work including substations to start next year, with offshore installations in 2023. The turbines for the wind farm will be 100 of the 14 MW Siemens Gamesa 14-222 DD models, a very powerful next-generation offshore turbine.