IEC PT61400-12-3 TC88 meeting March 2010 Jens Carsten Hansen

1. IEC PT61400-12-3 TC88 meeting March 2010 Jens Carsten Hansen

2. Outline • the technical need for the standard • the state of the technology that would be employed • the status of PT61400-12-3 • PT61400-12-3’s recommendation for next steps

3. 1. the technical need for the standard The scopewasadopted by the PT as described by the NP • This third part of IEC 61400-12 specifies a procedure for power performance testing of an entire wind farm. It applies to testing of the overall wind farm power performance related to one or more wind measurement positions. The Technical Specification shall contain a methodology for measuring the overall performance matrix of a wind farm. The measurement methodologies shall include requirements related to test set-up, instrumentation, calibration, uncertainty evaluation, analysis and reporting. • Testing for overall wind farm power performance matrix determines power production of the entire wind farm as function of wind speed related to one or more wind measurement positions for all relevant wind directions (power curves for different wind direction intervals). • This document is not intended for verification of the performance of individual wind turbines due to associated high uncertainties. • The Technical Specification shall deal with the measurement methodology only; the commercial use of the experimentally determined wind farm power performance matrix is outside the scope.

4. 2. the state of the technology that would be employed • An outline of a Technical Specification document has been developed by the PT at Meeting #3, containing brief description of steps needed to measure a Wind Farm Performance Matrix (WFPM) • WFPM for selected wind farms have been determined and presented by PT-members, showing promising results. However methods differ considerably. • Some major concerns identified by the PT : • Promising results have been obtained for 4 wind farms, however these have been with either simple topographic conditions like offshore and flat homogeneous terrain or in the case of complex terrain the wind farm was practically one row with small wake-losses • The method should allow other choices of reference wind speed than met mast anemometer, like nacelle anemometers or wind turbine power data • It has proven impossible to get permission to share data and therefore impossible to test each others methods on a common set of data • No work to test the discussed and proposed methods on a large onshore wind farm has been done yet • It is unclear how an uncertainty measure can be established – the work on uncertainties has been postponed until more clarity regarding the method has been reached • It seems that daily and seasonal variations in external conditions average out over time and that results are reproducible and converge for climatological mean conditions, however, in order to reach such convergence the measurement period must be long.

5. 3. the status of PT61400-12-3 • The work of IEC TC88 PT61400-12-3 was commenced April 2008. The work was commenced 2008. Meetings 1, 2 and 3 were held June 2008, November 2008 and June 2009. • At Meeting 3, a draft outline of the TS and a revised time schedule for the work were agreed upon. A revised NP has been prepared accordingly. • However, a significant amount of basic research and work will be required in order to complete the TS, work that was never funded by any research projects as originally expected. The time schedule of the revised NP aimed at completion of the first CD of the TS by December 2010. This assumed sufficient active participation of a sufficient number of members for this work. Just 9 out of 30 members plus 2 observers participated in Meeting No. 3, which was considered by the participants to be too few. • A poll among all team members for their ongoing commitment showed that 2 members in addition to the Project Leader’s organisation reconfirmed their active participation and willingness to provide work in-between meetings, whereas another 2 have confirmed that they will participate at meetings. From the participation at Meeting 3 it may be expected that yet another 2-4 members may participate throughout the working period.

6. 4. PT61400-12-3’s recommendation for next steps • There is a mismatch between work required and work offered by members. The work required is considerable since no member or group of members have presented a workable proposal for the Technical Specification obtained from previous work. A project for developing a proposal for a Technical Specification as well as access to public wind farm data that can be agreed as sufficient for verification will be needed. • The Project Leader does not find sufficient support in terms of active experts willing to undertake the foreseen work to be able to complete the TS in accordance with the work plan made at Meeting No. 3. • The work of PT 61400-12-3 has been suspended since Meeting No. 3. • A re-start will require that TC88 reappraise the market relevance of the project and that the situation and a rationale for possible continuation of the project are supported by National Committees and the nominated members. This will assume availability of manpower, experts and data to be able to develop a Technical Specification, a situation that seems not to exist at present. • It is the recommendation of the Project Leader to terminate the project 61400-12-3.