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Title: Assessing the blockage effect of wind turbines and wind farms using an analytical vortex model

Abstract

Wind farm blockage effects are currently neglected in the prediction of wind farm energy yield, typically leading to an overestimation of the production. This work presents a novel method to assess wind farm production, while accounting for blockage effects. We apply a vortex model, based on a cylindrical wake, to assess induction effects. We present variations of the model to account for finite wake length, finite tip-speed ratios, and the proximity to the ground. The results are applied to single rotors in aligned and yawed conditions and to different wind farm layouts. We provide far-field approximations for faster estimates of the velocity field. Further, this article includes a new methodology to couple the induction model to engineering wake models, such as the ones present in the FLOw Redirection and Induction in Steady State (FLORIS). We compare the results to actuator disk simulations for various operating conditions of a single turbine and different wind farm layouts. We found that the mean relative error of the model in the induction zone is typically around 0.2% compared with actuator disk simulations. The computational time of the velocity field using the analytical vortex model is three orders of magnitude less than the one obtainedmore » with the actuator disk simulation.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Technical Univ. of Denmark, Roskilde (Denmark)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind Energy Technologies Office (EE-4W)
OSTI Identifier:
1660123
Report Number(s):
NREL/JA-5000-76525
Journal ID: ISSN 1095-4244; MainId:7199;UUID:c34e637a-ef20-4826-8e62-0768a1f50269;MainAdminID:15135
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Wind Energy
Additional Journal Information:
Journal Volume: 23; Journal Issue: 11; Journal ID: ISSN 1095-4244
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; induction zone; wind farm blockage; vortex models; actuator disk

Citation Formats

Branlard, Emmanuel, and Meyer Forsting, Alexander R. Assessing the blockage effect of wind turbines and wind farms using an analytical vortex model. United States: N. p., 2020. Web. https://doi.org/10.1002/we.2546.
Branlard, Emmanuel, & Meyer Forsting, Alexander R. Assessing the blockage effect of wind turbines and wind farms using an analytical vortex model. United States. https://doi.org/10.1002/we.2546
Branlard, Emmanuel, and Meyer Forsting, Alexander R. Thu . "Assessing the blockage effect of wind turbines and wind farms using an analytical vortex model". United States. https://doi.org/10.1002/we.2546. https://www.osti.gov/servlets/purl/1660123.
@article{osti_1660123,
title = {Assessing the blockage effect of wind turbines and wind farms using an analytical vortex model},
author = {Branlard, Emmanuel and Meyer Forsting, Alexander R.},
abstractNote = {Wind farm blockage effects are currently neglected in the prediction of wind farm energy yield, typically leading to an overestimation of the production. This work presents a novel method to assess wind farm production, while accounting for blockage effects. We apply a vortex model, based on a cylindrical wake, to assess induction effects. We present variations of the model to account for finite wake length, finite tip-speed ratios, and the proximity to the ground. The results are applied to single rotors in aligned and yawed conditions and to different wind farm layouts. We provide far-field approximations for faster estimates of the velocity field. Further, this article includes a new methodology to couple the induction model to engineering wake models, such as the ones present in the FLOw Redirection and Induction in Steady State (FLORIS). We compare the results to actuator disk simulations for various operating conditions of a single turbine and different wind farm layouts. We found that the mean relative error of the model in the induction zone is typically around 0.2% compared with actuator disk simulations. The computational time of the velocity field using the analytical vortex model is three orders of magnitude less than the one obtained with the actuator disk simulation.},
doi = {10.1002/we.2546},
journal = {Wind Energy},
number = 11,
volume = 23,
place = {United States},
year = {2020},
month = {7}
}

Journal Article:
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