August 2021

n RENEWABLE ENERGY July/August 2021 www.drivesncontrols.com World’s mightiest wind turbines head for the North Sea T he first of 277 massive 13MW wind turbines – the largest in the world – will start being installed next year at the Dogger Bank Wind Farm in the North Sea, 130-290km off the coat of Yorkshire. The multi-billion pound project, a joint venture between SSE Renewables, Equinor and Eni, is being developed in three 1.2GW phases, each capable of producing 6TWh of electricity a year. By the time it is fully operational in 2026, the array is expected to be the world’s biggest wind farm, capable of satisfying 5% of the UK’s electricity demand and powering six million homes. The Dogger Bank farm will make a significant contribution towards the UK government’s aim of sourcing up to a third of its electricity from offshore wind by 2030. The 260m-tall (to the tip of the blade) Haliade-X wind turbines, being designed and built by GE Renewable Energy, will be gargantuan. Their 220m-diameter rotors will sweep an area of 38,000m 2 , and each of the three 107m blades will be twice as long as the wingspan of the Angel of the North sculpture. One turn of the massive rotor could power an typical UK home for more than two days. The wind turbines are being built at a GE factory in France and at a new plant on Teesside which will produce the blades. This plant, due to start production in 2023, could create up to 750 direct jobs and up to 1,500 indirect jobs in the area. Construction activities for the project will be based at Able Seaton port in Hartlepool, which will serve as the hub for all equipment marshalling, installation and commissioning activities, resulting in the creation of around 120 jobs during the construction period. The turbines will be installed in water depths ranging from 18–63m using a special vessel which, when fully extended, will stand taller than the Eiffel tower. When completed, the farm will cover an area of 8,660km2. The AC output from the turbines will be converted offshore to DC and transmitted to the shore via HVDC cables buried in 1.5m- deep trenches. ABB is designing and building 95 medium- voltage converters for the first phase of the project – the company’s biggest-ever order for MV converters. The converters will take the power from the wind turbines and convert it to the right voltage and frequency for the wind farm grid. ABB’s collaboration with GE began in 2017 and the companies have worked closely to optimise the PCS6000 converters, including test operations on a prototype turbine installed at the Port of Rotterdam in The Netherlands. “The selection of the right converter is critical to achieve the performance and reliability that yields the maximum return on investment,”says Chris Poynter, president of ABB Motion’s System Drives division.“And medium-voltage converters are the optimum choice for today’s high-power wind turbines. “Turbines approaching 15MW are around the corner and data obtained from the converter and turbine type tests is supporting our r&d to achieve even higher power,”he adds.“Our advanced converter technology can be scaled up to powers as high as 18MW and we are working closely with stakeholders in the wind industry to keep our development work aligned with their increasing power requirements for future offshore turbines.” Engineers based at an ABB site in Turgi, Switzerland, are leading the project, while the PCS6000 converters will be manufactured in Poland. The first deliveries are scheduled for this summer. At high wind turbine power levels, medium- voltage operation offers clear advantages. The higher voltage means currents are smaller in the electrical drivetrain, which in turn enables the use of less bulky cables, as well as smaller and lighter converters. The MV converters boost turbine efficiency using IGCT (integrated gate-commutated thyristor) power semiconductors. Advanced control algorithms apply an adaptable maximum torque per ampere strategy, optimising the generator’s operating point at all times, depending on the wind speed, while minimising losses in the generator windings. The Global Wind Energy Council expects the world’s offshore wind generating capacity to rise from 29.1GW at the end of 2019, to more than 234GW by 2030. n The world’s largest wind farm, using the world’s most powerful wind turbines, will take shape over the next few years more than 130km off the Yorkshire coast. A key element of the project is the use of MV converters that optimise the generator’s operating point at all wind speeds. Each turn of the turbine blades will produce enough electricity to power a UK home for more than two days 50