The solution enables near-shore wind power plants to be connected to the grid, replacing the conventional AC transformer platforms. It consists of an offshore transformer module (OTM) attached directly to a wind turbine which acts as a distributed transmission asset. It is nominally rated in incremental 250 MW blocks and can be linked together to provide the required transmission capacity even for very large wind farms. It can also be installed on a wind turbine foundation separately or installed at the transition piece between foundation and turbine shaft like a balcony. It is suitable for all wind power turbine models and represents an important lever which Siemens can use to help it achieve its goal of reducing the cost of offshore wind power to below 10 euro cents per kilowatt hour by 2020.
Construction, transport, installation, operation and maintenance of the platform account for a high portion of the total grid access costs. However, according to Siemens, these costs can now be reduced by up to 40 percent thanks to this new solution. The grid access platform is one third smaller in size and weight compared to a conventional AC platform and is therefore small and light enough to be mounted with a turbine on the same foundation. This in turn eliminates the need for a special heavy lift vessel and saves additional costs. It also shortens installation time by around 20 percent, due to the better availability of standard service operation vessels.
In order to achieve this space and weight reduction, Siemens focused on the core electrical equipment while also removing a number of optional ancillary systems. This also helps to reduce the required maintenance regime as no fans and diesel generators are necessary. Ester oil instead of mineral oil increases the solution’s environmental credentials even further, given that ester liquids have a low flammability and are biodegradable.
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