IEA Wind Task 32 Comparative Exercise:

Power curve verification in complex terrain using nacelle mounted lidar

November 2019 - November 2020

Exercise leader: Rozenn Wagner (DTU Wind Energy)

Organization team: Luke Simmons (DNV GL), Ioannis Antoniou (Siemens Gamesa Renewable Energy), Andy Clifton (U. Stuttgart).

Background to the exercise

IEA Wind Task 32 Workshop 14 will focus on the use of nacelle mounted lidars for wind turbine power curve verification (PCV) in complex terrain.

A new standard (IEC 61400-50-3) for wind measurement using nacelle-mounted lidars is currently under development. This standard will describe the prescribed calibration procedure , the sources of uncertainty to be accounted for and the measurement methodology highlighting specific requirements for nacelle mounted lidars. However, the scope of this standard is limited to applications in flat terrain or offshore.

We therefore propose to build evidence of application in complex terrain based on actual measurement campaigns, leading to a Task 32 workshop on the theme (Workshop 14). The objective of WS14 is to present and discuss possible ways of using nacelle mounted lidars to fulfill the needs for a practical and reliable method for PCV in complex terrain. The primary objective is to prepare a proposal for an addendum to IEC 61400-50-3 to extend the scope to moderately complex terrain - a short term solution - including actual practice of the method or part of it. The secondary objective is to discuss all possible methods and their challenges/needs for further development, which would lead to a long term solution.

Comparative Exercise

In preparation to the workshop and to ensure a high-level discussion, we invite owners of complex terrain nacelle lidar datasets to participate in an exercise to evaluate 2 methods.

Method 1: site calibration and power curve measurement using a nacelle lidar. This method follows requirements from the IEC 61400-12-1: 2005 as close as possible while replacing the met mast with a nacelle lidar. The wind speed is measured at hub height at 2.5D upstream of the rotor. A detailed guideline is given in Annex A in the summary document on this page. Additional modifications to the method are welcome but results should include strict application of Annex A in addition to any modified approach so that results can be compared. 

Method 2: the wind speed is reconstructed from the LOS speed measured by the nacelle lidar at 3 or 4 distances between 0.5D and 1D upstream of the rotor and using a simple induction model (no site calibration). This is similar to the approach developed and tested in the UniTTe project (see Wagner R et al., WESC2019) and discussed in IEA task 32 WS11 (see Nygaard NG, WESC 2019).

Who should participate in the exercise?

We therefore invite anyone who is planning or currently running a measurement campaign using a nacelle mounted lidar to either try out one or both methods on her/his own dataset.

In this exercise, each participant works on his/her own dataset. Only normalized results will be shared. The group provides and discusses the methods.  The results will first be discussed amongst the exercise participants through several video conference calls. The lessons learned will then be presented and discussed within a broader audience in Workshop 14 in 2020. Participants in the workshop will be have the opportunity to present their results and learnings. The workshop learnings and conclusions are expected to be published or presented at a conference and form the basis for a proposal to PT 61400-50-3.

The minimum requirements to participate to the exercise are:

  • Power curve measurement using a nacelle lidar in moderately complex terrain.
  • Site calibration.
  • An independent wind speed measurement (e.g. met mast or ground based lidar) is recommended.

More details are provided in the attached document.

Taking part in the comparative exercise

You can take part in the comparative exercise if you have a dataset or expect to have one by February 2020.

If you are interested in participating, please email Rozenn Wagner.


The following timeline is a draft and subject to revision without notice. We also welcome your feedback.

Please check back for updates!

DateWhat will happen?  
Before 1st November 2019

Show interest

 If you are interested in participating, please contact Rozenn Wagner (DTU).
Mid November

Conference call #1

Registered participants will be invited to a conference call to briefly present their dataset, discuss the exercise, and clarify the methods.
Mid January 2020

Conference call #2

Participants will be invited to a second conference call to confirm participation, check upon status of measurement campaigns to be used in the exercise, clarify exercise
April 2020 

Follow up conference calls

Status follow up to check upon progress and clarify requested results to be delivered. 
May 2020

Workshop (limited to exercise participants)

People who have submitted results will be invited to a conference call/workshop where the results will be presented and discussed
September 2020

Adjusted results submission

November 2020

IEA Task 32 Workshop 14

Presentation of results obtained from suggested method, presentation of other methods, discussion about main challenges and pros and cons of different method.

The objective of the workshop is to provide 1) recommended practice for 2 to open the scope of IEC 61400-50-3 version 2 to complex terrain, 2) identify requirements for development of eventual other methods.