Assessment of the WRF Wind Farm Parameterization for Easterly Wake Events during the Second Wind Forecast Improvement Project

Skillful wind power forecasts inform wind farm and electric grid operators of future periods of high and low power production that need to be balanced according to high and low electricity demand. Obtaining accurate forecasts in complex terrain is particularly challenging for numerical weather prediction models due to fast vertical accelerations incited by steep terrain and limitations to model resolution and subgrid-scale physical parametrizations. Further, the presence of large numbers of wind turbines can introduce wakes that modify the available wind power. A Wind Farm Parameterization (WFP) has been available in the Weather Research and Forecasting (WRF) model to predict the effects of these wakes on power production. Recent work (Lee and Lundquist 2017) has provided guidelines for optimal use of the WFP in flat terrain, but the presence of complex terrain may affect these recommendations.

Here, we assess the skill of the WRF WFP at predicting wind power from wind farms near the Columbia River Gorge during WFIP2. We focus on strong easterly flow events during which turbine wakes (Fig. 1) are measured by remote sensing devices, and we evaluate the simulations by comparison not only to meteorological measurements but also to turbine power production. Toward providing guidelines for the use of the WFP in complex terrain, our simulations vary model configurations such as vertical resolution as well as model physics options. Specifically, improvements afforded by the use of a new 3D PBL scheme designed for use in complex terrain will be highlighted.

References: Lee, J. C. Y., and J. K. Lundquist, 2017: Evaluation of the wind farm parameterization in the Weather Research and Forecasting model (version 3.8.1) with meteorological and turbine power data. Geosci Model Dev Discuss, 2017, 1–31, doi:10.5194/gmd-2017-128.