IEA Wind Task 31: Initial results of a new comparison metrics simulation challenge for wind resource assessment in complex terrain
Creators: name: Barber, Sarah
Publisher: name: Zenodo
Year: 2020
Subjects: wind energy
wind resource assessment
simulation challenge
complex terrain

description: This poster was presented at the online WindEurope Wind Resource Assessment Workshop in June 2019. For a given wind resource assessment project, the modeller is faced with a difficult choice of a wide range of simulation tools with varying accuracies and costs. In order to help modellers choose the most cost-effective tool for a given project, a new method for estimating the accuracy, or skill, and cost of wind modelling tools has been developed (Wind Energy Science, in Review). This involves the modeller estimating scores for a range of weighted parameters relating to the skill and cost of the tool, using a pre-defined template. An initial study applying this method to a range of tools for the Bolund Hill experiment and comparing predicted skill and cost scores (estimated before carrying out the simulations) to the actual skill and cost scores (established after carrying out the simulations) has shown that the method works well for modelling microscale effects (Wind Energy Science, in Review). However, further studies are required for a wide range of input conditions and project types in order to develop project-specific transfer functions between the predicted and actual cost and skill scores. Additionally, the method needs extending for calculating all wind directions and the Annual Energy Production (AEP). Therefore, a new comparison metrics simulation challenge for wind resource assessment in complex terrain was designed. The goal of Stage 1 of this challenge is to collect comparison metrics data regarding the skill and cost scores of a range of different simulation tools for a complex terrain site, both before and after carrying out new simulations. Participants will be asked to submit simulation results as well as estimations of various parameters relating to the cost and skill scores in a pre-defined template. The detailed design of Stage 1 will be presented at TORQUE2020 (in review). This present work involves an analysis of some initial results of Stage 1 of the challenge. The Perdigão site in Portugal was chosen for Stage 1 of the challenge, due to the volume and quality of available measurement data, the complexity of the terrain and the relative lack of simulations already carried out. The site consists of flow over two parallel ridges with SE–NW orientation, which are 4 km long and 500–550 m tall and separated by about 1.5 km. An initial analysis has been undertaken by carrying out simulations using the wind resource tool <em>WAsP</em> as well as in-house adaptions of the generic flow modelling tools <em>ANSYS Fluent</em> and <em>Palabos LBM</em>. The results shows that <em>WAsP</em> is not capable of modelling the 90<sup>o</sup> turning of the flow between the ridges, as is observed in the measurement data, and therefore loses out on accuracy despite its extremely low costs. Additionally, the parameters defined to estimate the skill and cost scores of each model were found to compare well to the actual skill and cost scores obtained by comparing the simulation results with the measurements.