Wind Farm Energy Studies with WindSim
Istos Renewables has already been using WindSim since February 2008. WindSim is the leading wind farm simulation software that is based on Computational Fluid Dynamics code, which combines advanced numerical processing with exciting 3D imaging.
The engineers of Istos Renewables were properly trained in WindSim headquarters in Norway. They have extensive experience in using the software and have conducted validation experiments that compare the performance of the CFD model with real data, in order to identify sensitive parameters affecting the simulation results. In this way, uncertainties are reduced by using as input the most appropriate data and solution parameters.
According to bibliography, linear models (WaSP, Windfarmer etc.) fail to predict and describe correctly the downwind side of a hill where turbulent disturbances and flow separation exist. Further experiments and applications have shown that the linear theory can give good results on the upwind side and crest of a hill
when ground inclination does not exceed 22°.
On the other hand, modern CFD codes overcome these obstacles, because they solve the (non linear) Navier-Stokes equations.
Finally, WindSim CFD software, unlike other commercially available software applications, can make the forecast of the following important properties that relate to the adequacy of wind park design:
- Wind flow inclination as to the horizontal level=inflow angle (it must not exceed -8 / +8 degrees based on standards).
- Turbulence Intensity for various direction sectors
- Wind shear coefficient (it can also predict negative values unlike most linear software applications).
What does Istos Renewables offer?
As part of the energy study, we can undertake and offer everything that a potential investor or a financial institution needs to know about a project:
- Implementation of high resolution terrain (up to 5x5m), which improves the accuracy of the results
- Assessment of wind shear
- Optimum citing of wind turbines considering maximum power production with minimum wake losses, as well as the limitations imposed by IEC-61400-1 standard
- Correlation with nearby masts and satellite data as well, and calculation of long-term variability of wind (up to 30 years) (Measure, Correlate, Predict.)
- Calculation of long-term characteristics of the wind, like the characteristic turbulence intensity and extreme wind speed of 50 years (at least 3 years of measurements are necessary)
- Based on the above, the most appropriate wind turbine class for each specific location can be found
- Selection of the most efficient wind turbine model and size for each site
- Analysis of uncertainties in the assessment of the annual energy yield of a project and calculation of P50, P75 and P90.
Finally, in conjunction with Lidar technology for measurements up to 200m, a wind resource map can be accurately generated at the hub height of a wind park project.