Siemens has launched a new alternating-current (AC) grid access solution at EWEA Offshore conference in Copenhagen for connecting near-shore wind power plants to the grid. It replaces the conventional AC transformer platforms. The new solution consists of an offshore transformer module (OTM) attached directly to a wind turbine, and acts as a distributed transmission asset. Nominally rated in incremental 250 megawatt blocks it can be linked together to provide the required transmission capacity even for very large wind parks. The new device can be installed on a wind turbine foundation separately. As an alternative, it can be installed at the transition piece between foundation and turbine shaft like a balcony. It is suitable for all wind power turbine models.
The substation of the grid access represents an important lever for reaching Siemens’ goal of reducing the costs of wind power generated offshore to below 10 euro cts/kWh by 2020: Construction, transport, installation, operation and maintenance of the platform account for a high portion of the total grid access costs. These costs will be reduced by up to 40 percent with the new solution, which is one third smaller in size and weight compared to a conventional AC platform. This innovation is small and light enough to be mounted together with a turbine on the same foundation. This eliminates the need for a special heavy lift vessel and saves additional costs. Furthermore, installation time will be shortened by around 20 percent, also due to better availability of standard service operation vessels.
Focusing on the core electrical equipment and removing a number of optional ancillary systems made this space and weight reduction possible, which also results in a reduced maintenance regime – no fans and diesel generators are necessary. Moreover, the use of ester liquids instead of mineral oil makes this solution extremely environmentally friendly. Esters liquids have a low flammability and are biodegradable which is very important for operations at sea.
In addition, Siemens offers a wide choice and flexibility to customers, as it has also optimized its conventional platform solution based upon knowledge from more than ten grid connections with AC technology.