Nordsee Ost’s First Turbine Spinning

The first electricity from the Nordsee Ost (North Sea East) offshore wind farm off the German coast is flowing shore-ward. The first of a total of 48 wind turbines has commenced trial operation in the past few days and is already feeding its green electricity into the grid.

Grid operator TenneT had connected the wind farm via its Helwin alpha converter platform at the end of October, so that everything was ready for the first power generation to go ahead.

“By generating our first electricity, we’ve passed a major milestone and gave us ourselves an advanced Christmas present. However we still have our work cut out in the coming months. During the commissioning stage, we’ll be working on electrical fine-tuning with the grid operator, TenneT, and are going to connect all the turbines to the grid, one by one,” explains Marcel Sunier, RWE Innogy’s Project Director for the Nordsee Ost Wind Farm.

He added: “We’ve laid some 200 kilometres of undersea cable in the past few months, and built two substations offshore. So the technical conditions are met for the transmission of electricity to consumers. The trial operation is to show whether everything meshes as it should and whether the wind farm can provide stable feed-in to the grid.”  

The first step was to connect the individual wind turbines with each other. This cabling within the wind farm came together in the internal substation in recent weeks. The electricity from the wind turbines that are already generating enters the substation at 33 kilovolts (kV). There it is stepped up to 155 kV. A high-voltage undersea cable then transmits the electricity to grid operator TenneT’s converter platform Helwin alpha.

To avoid transmission losses, this platform converts alternating current to ± 250 kV D.C. Two export cables then take the direct current to the nearest feed-in point at Büttel, where the onshore converter station first converts it back to AC, then feeds it in to the public grid.

Parallel to the progressive commissioning of the wind turbines, the turbine installation works will be completed. “We’ve completed 47 wind turbines so far. On the last location the tower segments and the nacelle are already standing,” explains Sunier. “However at the moment the wind blows too strong, so we are not able to install the last rotor star. Unfortunately we can only wait and keep the fingers crossed that the weather will change to finish all 48 wind turbines before the end of this year.”

After completion and commissioning on a commercial basis next spring, the Nordsee Ost offshore wind farm will offer around 295 megawatts of installed capacity. This is the equivalent of supplying about 320,000 households for a whole year. Equipped with what are currently the most powerful offshore turbines available, Nordsee Ost is one of the biggest commercial wind power projects off the German coast.

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Press release; Image: RWE