The annual wind potential measurements can give only estimation on the output of a wind farm if it was built and operated the given period.
2EN undertakes the preparation of bank compliant energy studies on wind farms in complex terrain, using specialized tools and implementing the following processes.
Long-term correlation of wind potential
The energy calculations for estimating long-term average annual energy production of the farm (including the uncertainty) require the knowledge of a long-term trend of the wind potential in the region.
To determine the trend of the annual variation in mean wind speed, data from reference stations with at least ten years of recording are being used.
Estimation of uncertainty in wind speed measurement
One of the important factors that introduce uncertainty in the energy calculations is the uncertainty in measuring the wind speed, contributed by the following factors:
- The quality of the wind potential measurements
- The uncertainty of estimating the exponential profile of wind shear
- Quality in digital terrain mapping and hence accuracy in mapping the flow field to calculate wind distribution at the turbines' positions
- Annual variation in mean wind speed in the area of the wind farm installation
Flow field analysis & modelling
Energy flow calculations using CFD simulation models (WindSim software) in order to create a wind atlas for the selected heights.
Wind farm energy production estimation
- Identification of type and size of wind turbines
- Application of power curves of the turbines
- Energy production losses evaluation
- Estimation of annual energy production per turbine position.
Estimation of uncertainty on energy calculations
Energy production calculations use various assumptions that introduce uncertainty.
- Wind speed measurement uncertainty
- Digital terrain model accuracy
- Energy production losses due to transmission network
- Uncertainty in the estimation of losses due to wake effect while modelling
- Uncertainty of the wind turbine power curve