With its 175 Siemens wind turbines and a total capacity of 630 MW, the London Array offshore wind farm will following completion be the largest of its kind in the world. After Siemens Energy was already appointed to supply the turbines for the wind farm, the company also received the order to connect London Array to the power supply network. Purchasers are Dong Energy, E.ON and Masdar, the wind farm’s owners. The order volume is EUR128 million. The wind farm is scheduled to be completed by 2012 and will be hooked up to London’s power supply network via the Siemens grid connection.

The wind farm is being erected in the Thames estuary approximately 20 km off the Kent and Essex coasts. An option is also provided for uprating London Array to as much as 1000 MW. The wind farm will thus become the first in the 1-gigawatt class. That will be sufficient to supply 750,000 British households with eco-friendly electricity, which is equivalent to approximately a quarter of the population of Greater London. “Offshore wind farms of this size place particular demands in terms of grid access. We not only have the requisite technology and know-how but also a wealth of experience in connecting offshore wind farms to the grid,” said Udo Niehage, CEO of the Power Transmission Division of Siemens Energy.

Siemens will supply the electrical equipment for two offshore substation platforms, which will be installed right at the wind farm. The substations bundle the power generated by the 175 Siemens SWT-3.6 wind turbines, each rated at 3.6 MW, before it is transported via high-voltage subsea cable to the coast. On each of the platforms there are two 180-MVA transformers and medium-voltage switchgear. The requisite protection and instrumentation and control equipment is also installed on the platforms. Distribution over two platforms has the advantage that the cable routes within the wind farm are short, and power transmission losses are kept as low as possible to enhance the wind farm’s energy efficiency.