Replacement of M5000 nacelles at alpha ventus completed (Germany)

The replacement of the six AREVA wind nacelles has been completed at Germany’s first offshore windfarm, alpha ventus. All twelve wind power turbines can be put back into full operation. Work on the nacelle exchange began in September and was completed successfully today.

An increase in the temperature of the sliding bearings of the AREVA Wind M5000 power turbines was noticed in the spring, causing two turbines to be taken out of operation. As per the AREVA maintenance concept, a replacement of the turbine house, or so-called nacelle, was required in order to change the sliding bearings. First, the two out of service turbines at positions AV07 and AV09 in the farm were replaced so that they could be put back into operation successfully. Afterwards, the turbines at positions AV 08, 10, 12 and 11 in the farm were replaced.

Up until their replacement, the turbines continued to feed power into the grid at partially reduced maximum capacity. The replacement procedure for each turbine took only a few hours, starting with the removal of the rotor and of the old nacelle and finishing with the placing of the new nacelle and remounting of the rotor. This was followed by the electro-technical work required for their restarting as well as test runs up to their nominal output of 5 MW. For the transport of the new nacelles from Eemshaven to the offshore test field and for the nacelle exchange, special, tried and tested ships were used, such as the jack-up barges JB 114 and the Sea Worker.

Dr. Claus Burkhardt, Director of Offshore Operations, Energy and Environmental Engineering at EWE, DOTI Director and Overall Project Leader of alpha ventus: “As the operating company, we are very pleased that the nacelle replacement, despite weather-related delays, could be completed successfully in a relatively short time frame. Unfortunately, we recently had only ten turbines available. Now all twelve turbines can once again supply the grid with power.The repair work so soon after the construction and commissioning were not caused by genuine offshore-related problems but by a rise in temperature in the sliding bearings.

Naturally, the offshore conditions remain generally – and of course as well for the replacement of the nacelles – the main challenge with the logistics and weather conditions at sea. Together with the contractor, AREVA Wind, we implemented the know-how we acquired during the construction phase to facilitate an expedient offshore solution. We consider the nacelle exchange to be additional learning experience that can be utilised in future offshore projects as well as presumably incorporated into the production and maintenance concepts of turbine manufacturers.”

On 16 November 2010 it will have been one year since the last of the twelve offshore turbines was completed after a seven month long construction phase to erect the wind power turbines. With the Federal Environment Minister presiding, the commissioning ceremony for alpha ventus followed on 27 April. Despite successive commissioning, trial operations, downtime and repair work, the twelve, 5 MW class turbines have generated over 140 gigawatt hours of electricity as of October.


Source: alpha-ventus,October 12, 2010;