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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Alex Meilan Alstom Renovables España S.L, Spain
Jordi Armet (1) F Fernando Liso (1) Ignasi Simon (1) Alex Meilan (1)
(1) Alstom Renovables España S.L, Barcelona, Spain

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Alex Meilan is the Head of Certification in Alstom (Wind). He studied industrial engineering at Universitat Politécnica de Catalunya (UPC) and took a master in project management at Univeristat de Barcelona (UB). In 1994 he started his career in the automotive sector where he dealt with homologation of vehicles over 10 years. In 1997, he joined Alstom and is currently the head of certification area which covers all modules of wind turbine type certification including design, testing and manufacturing. He has combined his role in Alstom with participations, as a delegate, in IEC standardization and certification committees.


Poster Download poster (10.70 MB)


Case study of nacelle power curve according IEC61400-12-2. Sensitivity analysis of the nacelle anemometer position and wind conditions.


The methodology defined by IEC 61400-12-1 has been the most commonly used for power performance testing. It requires the erection of a temporary meteorological mast at wind turbine location which implies a significant cost, especially for offshore sites. The IEC 61400-12-2 recently developed states guidelines for testing purposes based on nacelle wind speed measurements. Furthermore, it eases the assessment of the power curve for any wind turbine of an existing wind farm.


This study aims to analyse the nacelle power curves (NPC) obtained for ECO122 (2.7MW) wind turbine according to IEC 61400-12-2. Estimated annual energy production (AEP) based on NPC will be shown as well as a brief comparison with results obtained by applying measurement procedure based only on meteorological mast IEC 61400-12-1.

A mobile met mast has been designed for the present study to could analyse the effect on the nacelle roof position/height on the NPC allowing the simultaneous wind measurement at three locations using the two existing anemometers.

Main body of abstract

Using synchronized data acquired from the wind turbine, nacelle anemometers and met mast it has been done several analyses focused on:

•Nacelle transfer function (NTF):

Comparison of the NTF found in each nacelle anemometer position.

•Nacelle power curve (NPC):

Annual energy production is compared for the different anemometer positions together with a full uncertainty analysis using the NTFs to obtain the free wind from the measurements taken by the anemometers.

•Sensitivity analysis of the wind conditions on the NPC:

Thanks to the wide range of wind shear and turbulence intensity observed in the site, it is studied the impact of the wind conditions to the NTF giving a valuable information for future application of the NTF, and NPC, in large amount of wind turbines under different site conditions.


Taking under consideration the anemometer position recommendations of IEC61400-12-2, the results found are in good agreement: less disturbed nacelle wind speed in comparison with the free flow (slope of linear regression closer to one) for the positions located in the middle of the recommended area than the position located in the boundaries. However, in terms of standard deviation, similar results have been found in the three nacelle anemometer positions.

As regards the effect of wind conditions, differences from -7% to 5% of AEP has been found in case of use a NTF found at fixed turbulence intensity and wind shear at different wind regimes.

Learning objectives
The position recommendations of IEC 61400-12-2 are in accordance with our results measuring the wind more similar from the free wind with the anemometer located inside the recommended area. However, after apply the NTF for each cup anemometer position, the correlation found has been good enough to could ensure negligible differences in terms of AEP and uncertainties confirming that the most important point is apply the adequate nacelle transfer function for each case.

Last part of the research, showed that topographical characteristics play also a main role on the NTF and must be treated carefully when choosing the best function for a specific location.