FAQ

Are wakes and global blockage effects included?

Yes. LES physically models the phenomena of wind, pressure and atmospheric stability and their interaction with wind turbine-induced wake and blockage effects. Therefore, we don't have to rely on non-physical/empirical correction factors for example blockage effects and deep-array effects.

Are external wind farm effects included?

By default, external wind farms are not included in the simulation. However, external wind farms can be added to the simulation; then their effects on the target wind farm will be modelled and included. If you wish to have additional analysis of external effects, you may want to consider making use of Whiffle’s Consulting service. For more information, feel free to send an email to [e-mail].

What is LES?

Large Eddy Simulation (LES) is a Computational Fluid Dynamics (CFD) model for resolving turbulence and is gaining increased attention in the wind energy sector. The benefits of LES to model the wake and global blockage effects of wind farms lie in the fact it can model the interaction between wind farms and the atmospheric boundary layer (ABL). A recent overview on various aspects of the atmospheric flow through wind farms is presented in Stevens and Meneveau’s 2017 paper: Flow Structure and Turbulence in Wind Farms, volume 49.

How does the long-term correction work?

Long term correction aims to correct the estimated AEP from a Whiffle Wind simulation to be representative of the AEP of a longer period, usually 10 or 15 years. This correction is performed by learning the statistical relationship between the wind farm power predicted by the LES and ERA5 wind speed on the LES period. This relationship is then applied to a long term period of 10-15 years of ERA5 wind speed data. This gives an estimate of the mean power that would be predicted by a 10-15 year LES run.

For more information on the long term correction method, please refer to the Long term correction advanced topic page. A paper about the implementation and validation of the long term correction implemented in Whiffle Wind will soon be available here!

Can I perform bias correction based on local measurements?

It’s not possible to perform this directly within Whiffle Wind. However, our consulting service can certainly perform this for you. You can contact Whiffle Consulting via [e-mail].

Can I make an intra-day or day-ahead power forecast?

Yes, but not through Whiffle Wind. We have a separate forecast service that can provide wind and solar power forecasts, wind speed forecasts, and any number of other meteorological forecasts you may be interested in. See our forecasting service for more information here.

What is the uncertainty of Whiffle Wind’s AEP prediction?

Using SCADA data of wind farms, it is possible to make ex-post assessments of Annual Energy Production (AEP) predictions. Based on a small (N ≤ 10) sample of wind farms that Whiffle has modelled, we estimate the mean error of AEP predictions are around 2% (Whiffle’s model tends to underpredict AEP) with a standard deviation of 4%. These numbers are based on raw output from Whiffle Wind without any long-term correction or correction of mean wind speed biases. Therefore, this number represents not only errors in aerodynamic losses, but also errors in the mean wind speed.

What is the resolution and why?

The default resolution of our LES is 100 m x 100 m in the horizontal plane, 25 m vertically close to the ground. Our LES has been extensively validated on a wide range of sites (onshore, offshore, complex terrain) and wind farms for this resolution and provides the best trade-off between cost and accuracy.

If you require other resolutions, please consider Whiffle’s Consultancy service which can be contacted via [e-mail].

What is the mesoscale domain size and resolution?

To bridge the gap between ERA5's 30 km resolution and our 100 m resolution LES, an in-house, GPU-resident meso-scale model is run concurrently to generate the boundary conditions for our LES on the fly. This model is run on a typical meso-scale resolution of 2 km and on a domain of a few hundred kilometers depending on the size of the LES domain.

Is the simulation domain shown on the map the LES domain or the mesoscale domain?

The rectangle drawn on the map within Whiffle Wind represents the LES domain. The LES domain is then nested within the larger mesoscale domain.

Can I easily import an entire wind farm to set-up a simulation?

Yes! For instructions see our Getting Started, Running a Simulation guide here.

Running a simulation

Can I easily import a new turbine type to set-up a simulation?

Yes! For instructions see our Getting Started, Adding a Custom Turbine guide here.

Adding a custom turbine

How much does it cost?

The cost is based upon the domain size and duration of the simulation. To get a general idea of costs:

A 12.8 km x 12.8 km one day simulation will cost around 6 Euro. A 12.8 km x 12.8 km full year simulation will cost around 2000 Euro.

A 51.2 km x 51.2 km one day simulation will cost around 21 Euro. A 51.2 km x 51.2 km full year simulation will cost around 7700 Euro.

Exact costs are shown prior to submitting a run; therefore, you will always know the cost up front.

What is the largest domain that can be simulated?

Currently a 90 km x 90 km domain is the largest. However, we’re working hard to make this even larger! If you need a larger domain, certainly feel free to contact Whiffle’s Consulting service via [e-mail].

How long will it take for the simulation to run?

This depends on the domain size and length of the simulation, as well as how many other simulations have been requested and are in the queue. As a rough guideline, generally a one-day simulation should be available the next day or sooner, and generally a full year simulation should be available the next week or sooner.

How does Whiffle manage the privacy of your data?

Whiffle acknowledges the nature and sensitivity of customer data and is dedicated to safeguarding its privacy through the adoption of contemporary security practices in the Whiffle Wind solution. As part of this commitment, we are currently undergoing the certification process for ISO 27001 and incorporating the NIST Cybersecurity Framework.

If you need more information on how your data will be processed in Whiffle Wind, please contact us at [e-mail].