ABB will supply 100 transformers for the 950 megawatt (MW) wind farm. The compact transformers will be installed inside the turbine towers to step up the generated voltage to 66 kilovolt (kV) so that power can be carried ashore with minimal transmission losses.
Located 22 kilometres off the coast of Scotland in the Moray Firth, the 295 square kilometre wind farm will be equipped with 100 MHI Vestas turbines that are 204 metres tall to the tip of the blades. Each turbine is capable of generating 9.5 MW, providing the wind farm with a total capacity of 950 MW, enough clean power to supply up to a million homes.
A key benefit of the project for developer Moray Offshore Renewable Power is that it will deliver power at £57.50 per megawatt-hour (MWh), which is less than half the cost of power generated by other similar offshore wind farms being delivered today.
Driving down the cost of offshore wind
The strong and consistent wind offshore means that electricity production at offshore wind farms is more stable and reliable than onshore installations. However, the tough marine environment means that development of offshore wind was relatively costly when offshore sites were first delivered.
However, according to WindEurope, the cost of investment has fallen sharply since 2015, thanks in part to larger and more efficient turbines and greater expertise and introduction of new technology in the supply chain.
WindSTAR transformers
ABB’s WindSTAR transformers are one example of innovation in the supply chain. The units are specially designed for the offshore wind industry. Not only can they fit inside the tower of a large and powerful turbine, but they can withstand the sudden movements and strong vibrations that could be experienced inside a wind turbine. And they have been built to withstand the corrosive effects of the salty marine environment.
They also protect the environment as their core and windings are insulated by a safe and biodegradable ester fluid, which can handle high temperatures while minimising the impact on the marine ecosystem in the case of an oil leak or spillage.
From the perspective of installation into the wind turbines, WindSTAR transformers are lightweight and compact, and designed with the physical dimensions of turbine towers in mind, with a robust but slender tank.
However, with the main objective of an offshore wind farm being to generate electrical power, the most important benefits of the WindSTAR are electrical. The units are designed to cope with the natural variation in electrical loading from gusts of wind.
At the same time, Moray Offshore Renewable Power wants to maximise efficiency and has opted for a transformer that will transmit power ashore at 66 kV rather than the previous best-in-class of 33 kV. The higher voltage enhances energy efficiency as it enables the current to be reduced while transmitting the same level of power.
“ABB transformers are a critical factor in offshore wind electricity generation, helping to ensure an economically feasible and sustainable future for the industry,” said Laurent Favre, managing director of ABB’s Transformers business line, part of the company’s Power Grids business. “Our innovative WindSTAR transformers are specially designed to meet specific application needs under the mechanical and structural constraints of offshore wind farms.”
Building the relationship with MHI Vestas
The new contract for Moray East builds on ABB’s existing relationship with MHI Vestas, which has installed WindSTAR transformers at several other offshore wind projects.
One of these sites is the WindFloat Atlantic windfarm in Portugal, where MHI Vestas supplied the world’s largest and most powerful floating wind turbines to be deployed to date. The 190 metre tall, 8.4 MW turbines are capable of withstanding 17 metre waves.
WindSTAR units were also selected for 9.5 MW turbines supplied by MHI Vestas at the Borssele wind farm in the Netherlands.
In the UK, WindSTAR transformers are in operation at the 258 MW Burbo Bank
Extension offshore windfarm in the Irish Sea, where they have been installed inside MHI Vestas’ 8 MW turbines.
