Welcome to Task 32 Summary Page

OPERATING AGENT ORGANIZATION
ForWind - Center for Wind Energy Research
Research Group Wind Energy Systems
Carl von Ossietzky University of Oldenburg

OA Representative:
Martin KÜHN
ForWind - Center for Wind Energy Research
Research Group Wind Energy Systems
Carl von Ossietzky University of Oldenburg
Marie-Curie-Str. 1, D-26129 Oldenburg,
GERMANY
Phone: +49 (441) 36116 - 571
Fax: +49 (441) 36116 - 739
Cell: +49 151 401 33774
Email: martin.kuehn@forwind.de

Overview

The participants in this research task will

• Exchange experience from research activities and measurement projects on the performance of lidar devices and associated measurement techniques

• Continue the development of an “IEA Recommended Practices for Remote Sensing Measurements“ (Action 59th Topical Expert meeting) and refine it during the course of the task in the three areas:

a) measurement techniques
b) resource assessment
c) power curve measurements and load estimation

• Identify areas for further research and development as well as standardization needs.

The assessment of lidar technologies by participants will

• Identify technical aspects which differentiate lidar systems with respect to conventional anemometry (errors, accuracy, repeatability)
• Evaluate the performance of lidar systems for resource assessment and prediction of the annual energy production, namely, wind speed, turbulence, stability, and boundary -layer characteristics in flat as well as complex terrain, and offshore
• Evaluate lidar-based power curve measurement methods during simple and complex inflow conditions through benchmark studies with new lidar-based measurement techniques and conventional procedures
• Define possible approaches to estimate the inflow conditions related to mechanical loads of wind turbines by means of lidar systems

The competences gained in the new IEA Task will be collected and summarized in an IEA Wind Recommended Practices for LIDAR measurements that will be published in two editions. The first edition expected in 2012 will deal with the standard practices for the assessment on wind conditions in flat terrain. The second edition will include recommendations to improve lidar measured wind and turbulence accuracy and will contain recommendations for lidar applications suitable for flat terrain as well as complex flow conditions (to be published in 2014).

Background
A great deal of work has been performed in the last years towards verification of lidar systems as replacement of conventional anemometry. This is the basis for the confidence on the technology and the spreading of new ideas regarding to different applications of the systems today. One of the first special applications in wind energy was the support of the control system of the wind turbine (Harris 2006). Shortly afterwards the advantages were recognized and the application extended to the measurement of boundary layer profiles (Peña 2009), of complex flow fields (Bingöl 2010a-b, Käsler 2010) in complex terrain and in wind farms. This rapid development has been created by a great effort of the research community in collaboration with the industry and is reflected in several research projects with extensive use of lidar systems, in particular, UpWind WP6 (EU), NORSEWind (EU), WindScanner.dk (DK), RAVE-LIDAR (DE) and others.

At the beginning of this effort, five manufacturers worldwide provide commercial wind lidar systems, namely Leosphere (FR), Natural Power (GB), Sgurr Energy (GB), Catch-the-Wind (US) and Lockheed Martin (US). In addition other systems, which are in development or are used for special application areas in research such as the WindScanner research infrastructure of Risø DTU, the nacelle-based lidar scanner of the University of Stuttgart (DE), the long-range lidar of the DLR – German Aerospace Agency (DE), Mitsubishi Electric Company (JP) among others.

These companies and institutes should develop their systems in conjunction with researchers and the wind energy industry. This will ensure provision of useful requirements, suitable specifications of the systems, and potential new applications of the technology.

A main issue in development of large wind farms is the lack of sufficient measurement data of a complete three-dimensional wind field to which a turbine is exposed in the field. Conventional anemometry permits only measurements at a few discrete points. In this respect the remote sensing techniques, and specially the scanning wind lidar systems, offer a big step towards more comprehensive measurements (Mikkelsen 2009).

However, using lidar systems poses challenges to all actors and especially to the wind energy community. Mainly, the character and retrieval of the measurements is rather different than the conventional and standardized anemometry. For instance, the principle of measurements at a single or at a few points has to be replaced by volumetric or multiple-point measurement perspectives (Lindelöw 2007). This can only be achieved with a gradual understanding and quantification of the real capabilities of the remote sensing based wind lidar systems.

IEA Wind Task 32 will gives the wind community the opportunity to assess and establish good quality comparisons with respect to conventional meteorological mast based anemometry at the most basic level (single-point). Also, more comprehensive measurements of the boundary -layer wind and turbulence profiles will be addressed and evaluated. Finally wind lidar applications, ground-based and wind turbine integrated, will be evaluated in the fields of power curve assessments as well as load estimation.

Approach

Participants
The activities planned for this IEA Wind Task is based on the availability of lidar measurements and on a constructive exchange of experience with lidar among the parties. Therefore, in addition to any obligations listed in the IEA Wind Agreement, Participants are required to prove their
competence with lidar technique towards the Operating Agent and the subtask coordinators.
Moreover, they have to provide data taken in accordance with the prescribed procedure that will
be defined in the initial workshop.

Participants will be divided in two categories:
• active members who can participate to all of the planned activities (meetings, workshops, recommended practices, dissemination of results);
• observers who can participate to all of the planned activities, except those involving the preparation of the final documents (“IEA Recommended Practices for LIDAR Measurements,“ 1st and 2nd edition).

Since the final documents have to be neutral, lidar manufacturers will be accepted as observers only. However, their contribution is considered of fundamental importance in other task activities.

The initial workshop and the two intermediate workshops planned adjacent to the International Symposium for the Advancement of Boundary Layer Remote Sensing (ISARS) 2012 and 2014 will be open to other IEA Wind Participants in order to share knowledge across the entire remote sensing community. Participants will formally join the IEA Wind Task at its activity by signature of the consortium agreement. As a rule the parties interested in becoming a Participant may join one workshop or progress meeting without signature of the consortium agreement once they have proven their competence with lidar technique towards the Operating Agent and the subtask coordinators prior to the meeting. Further tasks will be defined separately for each Participant at the initial and the following workshops.