Siemens Energy has been selected by MHI Vestas Offshore Wind (MHI Vestas) to deliver 114 low-loss 66kV distribution transformers for the Seagreen Offshore Wind Farm in Scotland.
With an installed capacity of 1,075 mw, the Seagreen offshore wind farm will be Scotland’s single largest source of renewable energy and is forecast to provide low carbon energy for around 1.3 million homes.
The solution has been specifically designed to pass through the opening in the tower base without disassembly. Earlier Siemens Energy’s compact transformers also helped to enable the Deutsche Bucht offshore wind farm (see picture) in the German North Sea, together with MHI Vestas Offshore Wind.
The fluid immersed distribution transformers will complement 114 MHI Vestas’ 10-mw turbines that the company will deliver to the wind farm located 27 km from the Angus coastline in Scotland.
The solution has been specifically designed for MHI Vestas’ needs for a lightweight and compact solution that passes through the opening in the tower base without disassembly.
The low-loss distribution transformers were designed to meet high efficiency requirements. The transformer voltage class of up to 72.5kV will enable larger power capacities, such as provided by MHI Vestas’ 10MW offshore wind turbines, while keeping energy losses low.
After commissioning, the distribution transformers will transform the voltage from the low voltage of produced electricity to the medium voltage level of 66kV needed to feed the offshore transmission substation before going to mainland with an even higher voltage. It is anticipated that the Seagreen Offshore Wind Farm will be operational by 2022/2023.
The solution has been specifically designed for MHI Vestas’ needs for a lightweight and compact solution that passes through the opening in the tower base without disassembly. To combine the compactness with challenging and diverging efficiency requirements a newly developed core design, an innovative cooling solution as well as a highly efficient winding arrangement were implemented.
The transformers will be filled with safe and biodegradable ester insulation fluid as an environmentally friendly and operationally safe alternative to conventional mineral oil. The transformers have been vibration tested to ensure they reliably cope with the highly demanding service conditions and strong vibration typical for wind power applications. In addition, a short circuit test was conducted to ensure the transformers can withstand potential short circuits.
Photo (courtesy: MHI Vestas Offshore Wind) shows the Deutsche Bucht offshore wind farm in the German North Sea. Siemens Energy supplied compact transformers to this wind farm as well.
