Revision of IEC PT Power performance measurements on electricity producing wind turbines TC88 meeting March 2010 Troels Friis Pedersen

17/04/2008Presentation name2Risø DTU, Technical University of Denmark Status, MCR basis for revision First version of IEC December 2005 Revision based on MCR 88/319 Main topics in revision are inclusion of wind shear and turbulence in performance measurements Other issues comprise: air density correction, site calibration, generic versus site specific power curves, obstacle model, topography requirements, lightning protection, lattice tower flow distortion and anemometer classification

17/04/2008Presentation name3Risø DTU, Technical University of Denmark Status, Maintenance team MT was supplemented with additional experts in LIDAR and SODAR technology MT has 41 members, about 25 members participate in meetings Meetings have been held January, May, October 2009 and February 2010 Two major sub-groups established, one on performance methods, and one on measurement methods (LIDAR, SODAR, mast) Seven minor sub-groups on other issues

17/04/2008Presentation name4Risø DTU, Technical University of Denmark Status, shear Shear problems has been documented. Shear has a significant influence on power performance measurements in special cases (up to 5% on AEP) In special cases shears are non-power law profiles, and these may vary very differently above and below hub height A concept of a shear equivalent wind speed has been introduced for analysis A shear normalised hub height wind speed has also been presented (requires a reference shear)

17/04/2008Presentation name5Risø DTU, Technical University of Denmark Status, turbulence A turbulence normalisation method (published 2008) has been tested by several members The turbulence normalisation method primarily changes the power curve at low wind speeds and around power regulation The turbulence normalisation method did not seem to reduce scatter of data

17/04/2008Presentation name6Risø DTU, Technical University of Denmark Status, LIDAR LIDAR’s are appropriate instruments for measurement of shear LIDAR’s are sold in larger numbers (50-100) LIDAR comparisons to met masts (verification measurements) are made systematically on most systems Procedures for comparison of individual LIDAR’s to met masts are considered a necessary part of the standard

17/04/2008Presentation name7Risø DTU, Technical University of Denmark Status, LIDAR LIDAR’s can be positioned right next to met masts LIDAR’s have been tested for performance measurements, but at present stage they must be supplemented by met masts, perhaps not all the way to hub height (traceability) Traceability and uncertainty important issues

17/04/2008Presentation name8Risø DTU, Technical University of Denmark Status, SODAR SODAR’s are also potential instruments for measurements of shear A new generation of SODAR’s are sold in larger numbers (50-100) SODAR’s are used regularly for siting (US) SODAR’s cannot be positioned close to masts Requirements will preferably be based on technical requirements rather than on type of instrument

17/04/2008Presentation name9Risø DTU, Technical University of Denmark Status, Time schedule Present target date April 2010 Meetings planned for June 2010, October 2010 and January 2011 Expected target date April 2011 MT requests TC88 to postpone target date to April 2011