A pioneering offshore wind measurement campaign by leading renewable energy consultancy, SgurrEnergy, part of Wood Group, has completed the first ever power performance assessment (PPA) using a scanning lidar deployed on the transition piece of an AREVA M5000 offshore wind turbine.

This success has huge implications for the offshore wind industry as this study shows that PPAs can successfully be conducted from the transition piece of offshore wind turbines, providing opportunity for simplified and more cost effective offshore measurement campaigns.

With ease of access, downtime should be less and therefore cost will be significantly lower. In addition, installation on the transition piece allows reference to guidance, standards and recommended practices developed for onshore, ground-based lidar measurements, supporting confidence in the results. A device measuring from the transition piece is easier to deploy and decommission, and facilitates easy access for maintenance.

The locations of the other wind turbines in the wind farm are fixed relative to the transition piece, but change in the reference frame of the nacelle as it yaws in response to changes in wind direction. As a consequence, a device on the transition piece can test the power curves of multiple turbines, in contrast to a device on the nacelle which can only test the power curve of the turbine on which it is installed. Therefore mounting the device on the transition piece can drive down the costs of the tests much further, and less than 1% of the cost of a comparable meteorological (met) mast based test.  The accuracy of this method has been demonstrated by comparison with results using an offshore met mast.

Dr Peter Clive, senior scientist at SgurrEnergy, commented: “The results of this pioneering campaign will have a significant effect on how the offshore wind industry can use lidar to assess their wind turbines.

This campaign shows how the industry can assess the performance of wind turbines and reduce risks with easy and reliable measurements.”

This method was presented in a poster at EWEA’s Annual Conference in Barcelona in March and the poster won the EWEA 2014 industry poster award.

These results come as part of a wider year-long campaign which has seen three of SgurrEnergy’s Galion Lidar devices deployed on an AREVA M5000-116 wind turbine in the alpha ventus site in the North Sea.  Two G4000 Offshore Galion Lidars were deployed on the nacelle of the wind turbine and one on the transition piece.

The campaign began in early 2013 and confirmed the reliability and accuracy of the wind turbines against expected performance and measurements which included a PPA, wind shear and visualisation of the inflow wind field and wakes.

SgurrEnergy
www.sgurrenergy.com
 
Wood Group 
www.woodgroup.com