Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

'Wind Theft' from Onshore Wind Turbine Arrays: Sensitivity to Wind Farm Parameterization and Resolution

Title'Wind Theft' from Onshore Wind Turbine Arrays: Sensitivity to Wind Farm Parameterization and Resolution
Publication TypeJournal Article
Year of Publication2020
JournalJournal of Applied Meteorology and Climatology
Volume59
Number1
Pages153-174
Abstract / Summary

High-resolution simulations are conducted with the Weather Research and Forecasting model to evaluate the sensitivity of wake effects and power production from two wind farm parametrizations (the commonly used Fitch scheme and the more recently developed Explicit Wake Parameterization (EWP)) to the resolution at which the model is applied. The simulations are conducted for a 9-month period for a domain encompassing much of the US Midwest. The two horizontal resolutions considered at 4 by 4 km and 2 by 2 km grid cells, and the two vertical discretizations employ either 41 or 57 vertical layers (with the latter having double the number in the lowest 1km). Higher wind speeds are observed close to the wind turbine hub-height when a larger number of vertical layers are employed (12 in the lowest 200 m, versus six), which contributes to higher power production from both wind farm schemes. Differences in gross capacity factors for wind turbine power production from the two wind farm parameterizations and with resolution are most strongly manifest under stable conditions (i.e. at night). The spatial extent of wind farm wakes when defined as the area affected by velocity deficits near to wind turbine hub-heights in excess of 2% of the simulation without wind turbines are considerably larger in simulations with the Fitch scheme. This spatial extent is generally reduced by increasing the horizontal resolution and/or increasing the number of vertical levels. These results have important applications to projections of expected annual energy production from new wind turbine arrays constructed in the wind shadow from existing wind farms.

URLhttp://dx.doi.org/10.1175/jamc-d-19-0235.1
DOI10.1175/jamc-d-19-0235.1
Journal: Journal of Applied Meteorology and Climatology
Year of Publication: 2020
Volume: 59
Number: 1
Pages: 153-174
Publication Date: 01/2020

High-resolution simulations are conducted with the Weather Research and Forecasting model to evaluate the sensitivity of wake effects and power production from two wind farm parametrizations (the commonly used Fitch scheme and the more recently developed Explicit Wake Parameterization (EWP)) to the resolution at which the model is applied. The simulations are conducted for a 9-month period for a domain encompassing much of the US Midwest. The two horizontal resolutions considered at 4 by 4 km and 2 by 2 km grid cells, and the two vertical discretizations employ either 41 or 57 vertical layers (with the latter having double the number in the lowest 1km). Higher wind speeds are observed close to the wind turbine hub-height when a larger number of vertical layers are employed (12 in the lowest 200 m, versus six), which contributes to higher power production from both wind farm schemes. Differences in gross capacity factors for wind turbine power production from the two wind farm parameterizations and with resolution are most strongly manifest under stable conditions (i.e. at night). The spatial extent of wind farm wakes when defined as the area affected by velocity deficits near to wind turbine hub-heights in excess of 2% of the simulation without wind turbines are considerably larger in simulations with the Fitch scheme. This spatial extent is generally reduced by increasing the horizontal resolution and/or increasing the number of vertical levels. These results have important applications to projections of expected annual energy production from new wind turbine arrays constructed in the wind shadow from existing wind farms.

DOI: 10.1175/jamc-d-19-0235.1
Citation:
Pryor, S, T Shepherd, P Volker, A Hahmann, and S Pryor.  2020.  "'Wind Theft' from Onshore Wind Turbine Arrays: Sensitivity to Wind Farm Parameterization and Resolution."  Journal of Applied Meteorology and Climatology 59(1): 153-174.  https://doi.org/10.1175/jamc-d-19-0235.1.