Revision of IEC PT61400-12-1Power performance measurements on electricity producing wind turbines TC88 meeting March 2010

Troels Friis Pedersen

17/04/2008Presentation name2 Risø DTU, Technical University of Denmark

Status, MCR basis for revision

• First version of IEC61400-12-1 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 name3 Risø 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 name4 Risø 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 name5 Risø 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 name6 Risø 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 name7 Risø 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 name8 Risø 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 name9 Risø 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