Uncertainties
Here you define uncertainties in the wind speeds and energy to model their impact on the overall uncertainty in the net yield. The uncertainties are split into three sections: factors representing annual variability, uncertainties in wind speed and energy uncertainties
Uncertainties can be entered for each wind climate used in the energy calculation. Note that only wind climates that are used to initiate turbines in non-neighbour farms are shown.
Tip
To perform a net energy calculation with no uncertainties, set all the mandatory values to zero and ensure no optional values are entered. In this case, only one run of the Net energuy calculation needs to be performed and the P50 Net yield is product(efficiencies)*Gross yield
Interannual Variabilities
Annual Variabilities
Wind speed interannual variability is the variation of mean wind speed from year to year, and frequency distribution interannual variability is the variation in wind flow energy due to changes in the wind direction distribution from year to year. Default values have been provided and can be used if these variabilities are unknown for a site, or if the purpose is a high-level estimate.
Future Annual Variabilities
In this table, custom factors describing the predicted future annual variability in energy may be defined.
Wind climate information
Enter the number of years as long-term reference period, based on the longest long-term reference dataset used in the Long Term Adjustment task.
Enter the number of years as on-site measurement period, using what is shown for the wind climate in the Calculate Wind Climate task.
The corresponding uncertainties are automatically calculated from the specified periods and the Annual Variabilities
Uncertainties on wind speed
A default list of wind speed uncertainties is provided. You can add and remove uncertainty items from the list and define your own categories. The uncertainties to be considered are site-specific and DNV does not provide recommendations on defaults in WindFarmer: Analyst.
- Enter wind speed uncertainties for each wind climate.
Energy Uncertainties
Other uncertainty factors that affect the overall net energy result can be defined in this table, given in energy terms.
