Bringing wind home for tomorrow’s greener generation

Alternating current (AC) or direct current (DC)? The best grid access solution depends on various factors including output and distance. As the world’s leading partner for offshore wind farm grid connections Siemens Energy has extensive experience in this area.

To date Siemens Energy accounts for 14 offshore grid connections with 6 gigawatts (GW) of alternating current transmission. Four of them (ca. 2.5 GW) with the company’s innovative Offshore Transformer Module (OTM) technology. The modular solution is significantly smaller in size and weight compared to conventional AC platforms. For the grid connection of the 950 megawatts (MW) Moray East Offshore Windfarm project in Scotland, Siemens Energy is connecting in a world’s first three of its Offshore Transformer Modules® (OTM).The greater the distance, the more important it becomes to minimize the unavoidable physical power losses, and this is where DC technology comes into play. To date Siemens Energy received orders for seven offshore grid connections with 6 GW of DC transmission. In the German North Sea alone the company successfully completed five grid connections with two more to come. A total of about seven million households will be supplied with electricity generated from wind power via these seven links. 

While wind turbines were producing 0.5 megawatt (MW) of power at a height of 40 meters in 1990, today’s wind turbines produce 10 MW and beyond requiring higher voltage levels and innovative technologies. To manage the voltage reliably and efficiently step-up transformers are crucial. They convert generated electricity to the requisite voltage level for power transmission on high-voltage lines and cables. 

For on- and offshore wind farms Siemens Energy delivered about 30.000 units of fire-resistant GEAFOL cast-resin transformers for up to 40.5 kilovolt (kV), 1.000 of them for offshore wind projects. More than 2.500 units of the company’s ester fluid immersed FITformer REN transformer were installed in wind offshore applications worldwide. The lightweight and compact transformers can be placed in the wind turbines nacelle and are equipped as Siemens Energy Sensformer, that means they come with inbuilt connectivity and optimized operation.