IEA Wind TCP

The general objectives of Task 31 are:

• To provide a forum to develop, evaluate and improve wind farm flow models in relevant research and operational conditions.
• Build consensus on model evaluation procedures to establish an international V&V framework.

WP1: Benchmarking of models for external wind conditions

WP1 is devoted to the setting up and execution of validation benchmarks for flow models dealing with external wind conditions, i.e. without the presence of turbines. These models range in complexity from mesoscale to microscale, in steady and unsteady conditions, to simulate the interaction of the atmospheric boundary layer with side effects due to terrain and vegetation heterogeneities. Phenomena of interest include the definition of appropriate forcing for microscale models, introducing atmospheric stability in turbulence modeling, roughness changes, simulation of the forest canopy, flow separation in complex terrain, etc. The “wind” validation program will be primarily based on benchmarks generated from NEWA experiments for wind resource assessment and site suitability applications. Stakeholders from IEC 61400-15 will be invited to participate and share quality acceptance criteria aligned with the objectives of the standard. Likewise, the validation plan will address the needs of IEC 61400-12-4 for numerical site calibration.

WP2: Benchmarking of wind farm wake models

WP2 is devoted to the setting up and execution of validation benchmarks for modeling wake interactions within and around wind plants. These models range in complexity from simple single equation wake models derived from similarity theory to more complicated large eddy simulations that are able to directly model the atmospheric boundary layer, surface interaction, and turbulent wake production. Phenomena of interest include: the impact of atmospheric stability on wake dissipation, interaction and meandering, large-scale mesoscale type influences on wind plant wakes, the influence of terrain and surface roughness, the behavior of wakes in yawed turbine operation, the impact of wakes on downstream turbine loads, etc. the wakes validation program will be based on direct observation of wakes in offshore wind farms from the EU and onshore wind farms from the DOE A2e program. Results from the validation studies will help to inform new wake observational campaigns scheduled to begin during Phase 3.

WP3: V&V framework, uncertainty quantification, and best practices

WP3 is devoted to the development of verification and validation strategies and the prioritization of validation efforts. It will also include the formation of best practices for model assessment and for the application of uncertainty quantification (UQ) methods for wind energy applications.

The uncertainty quantification process determines the degree to which output quantities of interest are influenced by the uncertainty in input quantities and parameters. The process depends on a model to propagate the input and parameter uncertainties to the output quantities. Additional uncertainty is introduced by an unquantified or variable error in the model. Model and measurement uncertainty are interconnected and are used together to make decisions that depend on the confidence in a model’s predictive capabilities, particularly in regard to untested regimes.