The Wind Due Diligence Report is produced by Vaisala 3TIER Services using its NWP modeling platform, which combines on-site observations with mesoscale and microscale weather simulation models. We primarily employ an NWP model called WRF (Weather Research and Forecasting). This model is widely supported and continually enhanced by the global atmospheric science and research community. Our in-house developed microscale model, TVM, allows us to calculate the effects of small-scale terrain, roughness, and blocking effects at a very fine resolution without the high computing costs of WRF. The output from this modeling system is a four-dimensional dataset of modeled historical weather for each met tower and wind turbine location.
Model output is statistically calibrated using quality-controlled observations from the site met towers in a process known as MOS (Model Output Statistics) correction. This technique is applied after conducting a detailed quality control analysis of the met tower observations, which incorporates information gathered during the project site visit. MOS then uses multi-linear regression equations to remove bias and adjust the variance of the raw model output. The MOS equation for each met tower is trained during the observational period of record and then applied over the entire time period of the NWP derived dataset.
MOS-corrected long-term wind speed data and the manufacturer specified power curve are used to compute long-term time series of power at each turbine location. Site-specific loss factors are then applied to derive the net power values. Finally, net probability of exceedance values are computed based on the results of the site-specific uncertainty analysis.
In order to perform the analysis, the client must provide all available met tower observations and the boundaries of the project area. If a turbine layout has been defined, then the specifications of the layout are required as well.