CREYAP 2021
In partnership with:
How does your model perform? Take part in our latest CREYAP and find out!
Since 2011, WindEurope has been a proud supporter of comparison and benchmarking exercises that can help the industry improve its modelling and analysis capabilities.
CREYAP stands for “Comparison of Resource and Energy Yield Assessment Procedures”. Courtesy of Ørsted and DTU, Technical University of Denmark, this fifth edition – the third to focus on offshore wind – aims to investigate new themes which have become relevant in the wind energy sector during the most recent years and which were not included in the previous CREYAPs. The latest CREYAP was run in 2015, and this new CREYAP exercise will allow us to assess how the wind energy sector has developed and understand where wind analysts need to focus to continue developing this area.
Scope
The 2021 CREYAP exercise will be based on the operating Walney Extension offshore wind farm, which consists of 40 MHI-Vestas 8.25 MW wind turbines and 47 Siemens Gamesa 7 MW wind turbines. Using the data provided, the participants (organisations/teams) will estimate the net energy yield for the Walney Extension wind farm, accounting for wind speed variations over time and across the site, and for turbine interaction losses.
The exercise is supposed to provide a realistic estimate of the Walney Extension wind farm energy yield. It is intended not only as a comparative exercise, using public information about the wind farm, but also as a benchmark exercise gauging how well the industry can estimate actual offshore wind farm energy yields.
To focus the exercise on the different modelling applied by the different participants, all participants will receive and apply the same wind measurement data from the site, which have been provided by Ørsted and quality assessed and filtered by DTU Wind Energy.
Themes
From previous CREYAP exercises for offshore wind farms, the following themes have been identified as important: uncertainty estimation and calculation, turbine interaction modelling, long-term extrapolation methods, systematic operational losses estimation, vertical extrapolation and tall turbines, horizontal extrapolation, stability and challenging climatology, wind conditions and site suitability.
The CREYAP 2021 exercise will include these new themes:
- Significance of wind farm size and turbine interaction losses.
- Stability effects on energy yield and wake loss (optional for participants).
- Time series of energy production (optional for participants).
Moreover, the exercise will be similar to previous CREYAP exercises and report on:
- Wind farm statistics – how accurately can wind farm energy yield be estimated?
- What are the overall biases of offshore wind farm energy yield estimates?
- Detailed wind farm statistics – how well can the energy yields of individual wind turbines be predicted?
- Uncertainty estimates – what are the participants’ uncertainty estimates?
- Detailed profile of participants – what is the influence of the human factor?
- What are the main characteristics of the participants?
Timeline
| 3 May 2021 | Data pack and instructions available for download |
| 28 June 2021 | Deadline to submit results (send output template back to techworkshops[a]windeurope.org) |
| July-August 2021 | DTU to:
|
| 10 September 2021 | Results presented at the WindEurope Technology Workshop: “Resource Assessment & Analysis of Operating Wind Farms 2021″ |
Still some questions?
You downloaded the datapack, you read the instructions, and something is still unclear? We are at your disposal to answer any question you may have on the exercise, but BEFORE you email us, please check out our ‘Questions and Answers‘ page, we might already have answered it! 🙂 Otherwise, you can email your questions to techworkshops[a]windeurope.org.
Resources
Energy yield assessment process
All participants will apply the same input data and follow the main steps in the energy yield assessment process. However, the different participants will apply different modelling and therefore derive different results. This will allow for specific comparisons of the different results and modelling.
Methodology
DTU Wind Energy will apply the following methodology:
- The energy yield assessment process is the framework for data collection and data analyses
- N participants make estimates for one wind farm
- Input data are provided and therefore the same, modelling is optional and therefore different
- Mean and spread compared for each main step in the energy yield assessment process
- For Net yield, mean and spread also compared to observations (SCADA data)
- Open exercises, no formal participant requirements (everyone can participate)
- Results may not reflect industry
- Blind tests with independent and unbiased evaluation by DTU Wind Energy
- Participant identities unknown to evaluator, communication to any participant through WindEurope
- Results based on group statistics
- Limited data in forms and groups
- Statistics may be sensitive to outliers
- Non-parametric and normal statistics
- Definition
- Bias ≡ difference between estimates and observations
References
A summary of CREYAP exercises from 2011-15 is given below; these publications have been downloaded more than 6,000 times from orbit.dtu.dk at DTU.
- Mortensen, N. G., Nielsen, M., & Ejsing Jørgensen, H. (2015). Comparison of Resource and Energy Yield Assessment Procedures 2011-2015: What have we learned and what needs to be done? EWEA 2015, Paris, France, 17-20 November. Presentation
References for offshore wind farms are:
- Mortensen, N. G., Nielsen, M., & Ejsing Jørgensen, H. (2013). First Offshore Comparative Resource and Energy Yield Assessment Procedures (CREYAP). EWEA Offshore 2013, Frankfurt, Germany, 19-21 November.
- Mortensen, N. G., & Nielsen, M. (2015). Offshore CREYAP Part 2 – preliminary results. EWEA Offshore Conference 2015, Copenhagen, Denmark, 10-12 March.
- Mortensen, N. G., & Nielsen, M. (2015). Offshore CREYAP Part 2 – final results. EWEA Technology Workshop, Helsinki, Finland, 2-3 June.
- Mortensen, N. G., Nielsen, M., & Ejsing Jørgensen, H. (2015). EWEA CREYAP benchmark exercises: summary for offshore wind farm cases. Wind Energy Denmark 2015, Herning, Denmark, 22-23 September.
References for onshore wind farms are:
- Mortensen, N. G., & Ejsing Jørgensen, H. (2011). Comparison of resource and energy yield assessment procedures. EWEA Wind Resource Assessment Technology Workshop, Brussels, Belgium, 10-11 May.
- Mortensen, N. G., Ejsing Jørgensen, H., Anderson, M., & Hutton, K-A. (2012). Comparison of resource and energy yield assessment procedures. EWEA 2012, Copenhagen, Denmark, 16-19 April.
- Mortensen, N. G., & Ejsing Jørgensen, H. (2013). Comparative Resource and Energy Yield Assessment Procedures (CREYAP) Pt. II. EWEA Technology Workshop: Resource Assessment, Dublin, Ireland, 26 June.
- Anderson, M., & Mortensen, N. G. (2013). Comparative Resource and Energy Yield Assessment Procedures (CREYAP) Pt. II. AWEA Wind Resource & Project Energy Assessment Seminar, Las Vegas, United States, 10-12 December.
- Mortensen, N. G., Ejsing Jørgensen, H. & Nielsen, M. (2014). How well can the industry predict the wind resources? Overview of the results from EWEA CREYAP exercises. Danish Wind Industry Annual Event 2014, Herning, Denmark, 26-27 March.