Summary

This Annex facilitates an international collaboration organised under the International Energy Agency (IEA) Implementing Agreement for Co-operation in the Research and Development of Wind Turbine Systems.

The overall objective of the Annex is to assist the planning and design of wind farms by facilitating a coordinated effort to develop wind farm models suitable for use in combination with software packages for simulation and analysis of power system stability.

The Annex was started in 2002 and ran through 2007. It is carried out on a cost- and task-shared basis. The participants contribute with financial support to the Operating Agent and carry out activities, supply information and join meetings as required to meet the Annex objectives.

Access to detailed reports and database is restricted to the Annex participants.

Immediate Objectives

The effort comprises the following immediate objectives:

• Establishment of an international forum for exchanging knowledge and experience within the field of wind farm modelling for power system studies.

• Development, description and validation of wind farm models. Here, the wind farm models are expected to being developed by the individual participants of the Annex, whereas the description and validation will be coordinated by the Annex as to give the state of the art and to pinpoint key issues for further development. 

• Set-up and operation of a common database for benchmark testing of wind turbine and wind farm models as an aid for securing good quality models.

Common Activities

A)
An international forum for exchanging knowledge and experience within the field of wind farm modelling for power system studies will be initiated through the execution of this proposed Annex supported specifically by organisation of a series of workshops and meetings. Themes for the workshops may include:

• Presentation of Annex status and plans

• Presentation of wind farm models including comparisons against measurements

• In-depth discussions on needs for improvements and further developments

The workshops and meetings are scheduled to take place on an annual basis and will possibly be coordinated with other wind energy events to try to attract involvement of all major players, including manufactures and utilities.

B)
Through discussions at workshops and meetings, a procedure for benchmark testing using data from the common database (see below) will be specified to provide a common basis for model validation. The Annex participants are then expected to test their models accordingly and provide validation results in the form of reports or papers. These will be topics for discussions at the workshops where key issues for further model development will be pinpointed.

C)
The set-up and operation of a common database for benchmark testing of wind turbine and wind farm models is considered crucial for the further efficient development of good quality wind farm models. As to set-up the database, the following activities are scheduled:

• Identification of a set of wind turbines and wind farms to be included in the database. The wind turbines and wind farms should constitute a representative collection with regards to wind turbine types (fixed speed, variable speed, etc), wind farm size and site conditions (turbulence level, grid characteristics, etc.).

• Identification and set-up of database structure.

• Gather technical data required for accurate modelling of the wind turbines and wind farms. The data should constitute detailed wind turbine data, internal grid specifications and grid connection characteristics.

• Collect measurement data from the wind turbines and wind farms as required for verification of models. The data should include measurements of metrological conditions (wind speed and direction) and electrical characteristics (active and reactive power, voltage and currents) at the common connection point of the wind farm and at a number of the individual wind turbines within the farm. Preferably the data should contain measurements taken both during continuous operation at different wind speed conditions and during special events such as short-circuit faults, generator switching and capacitor energizing. The required sample rate may vary from about 1 Hz with regards to metrological conditions to about 20 Hz during continuous operation and several kHz during special events.

The data will be gathered as provided by the Annex participants that they may already have on file or may collect through their relevant ongoing projects, subject to the applicable intellectual property provisions set forth in this Annex. It may also be considered to take a common initiative with regards to acquiring data, e.g. by contacting wind turbine manufactures as to get technical data, though the Annex will not be responsible for making measurements.

Participants Works

The Annex will make extensive use of data, models and knowledge present within the group of participants. The participants have all been active within the field for several years, and will contribute to the Annex carrying on their experience and through their relevant on-going projects.

All the participants will deliver reports to the Operating Agent as required for the Operating Agent to prepare progress reports, status reports and final report to the Executive Committee on the work carried out under this Annex.

Reports

EWEC'06  Session: Dynamic models of wind farms for power system studies - IEA Wind R&D Annex 21

Dynamic models of wind farms for power system studies - status by IEA Wind R&D Annex 21 
Paper presented at EWEC'04, 22-25 November 2004, London, UK

Annex XXI Seminar Presentations, NREL, CO, USA, 11 November 2003 (file size: 10 MB)

IEA Wind Task 21, Final Technical Report 2007

• IEA R&D WIND

• IEA Annex XXI e-room