Introducing WakeBlaster
WakeBlaster is a 3rd party wake model, developed and maintained by ProPlanEn (https://www.proplanen.info/). The 3D CFD solver addresses the interaction of wakes with other wakes, and with the atmospheric boundary layer. The model considers the impact of ambient turbulence, air density, wind resource gradients, and atmospheric stability. The computational requirements are higher, by several orders of magnitude, than those of wake models which propagate single wind turbine wakes independently and then superimpose them. To still deliver results quick and cost effective, WakeBlaster is run as a cloud-based service.
Purchasing WakeBlaster credits
To benefit from WakeBlaster, please sign up for the service with ProPlanEn (https://proplanen.info/order-form). ProPlanEn will set up a dedicated environment for your company, and provide an API URL, an API key, and a number of flow case credits per month. Once you have received this information, please ensure that your computer is connected to the internet and proceed with the next step.
Setting up WakeBlaster in Openwind
Next to the entry fields is a test button, which checks that the connection to your WakeBlaster environment can be established.
WakeBlaster is now set up and ready to be used in Openwind.
Running WakeBlaster calculations in Openwind
There are two ways to run a WakeBlaster wake loss calculation from Openwind - in:
•statistical mode - run for all bins, intervals in wind speed and wind direction.
•time series mode - run for all the steps of a time series.
Statistical WakeBlaster calculation in Openwind
In statistical mode, a flow case is calculated for the centre of each bin of a statistical distribution.
A flow case is defined by wind speed, wind direction, and turbulence intensity.
(Settings -> Energy Capture)
•Select WakeBlaster as the wake model.
•Define the resolution of the calculation in wind speed (m/s) and wind direction (degrees).
Pre-set values include neutral stability and air density at a reference point.
Time series WakeBlaster calculation in Openwind
In time series mode, a flow case is also defined by wind speed, wind direction, and turbulence intensity. The resolution in wind speed, wind direction, turbulence, etc. of the wake calculation is infinite in this mode, eliminating rounding or binning errors.
Some optional inputs can be varied for each time step. These include Monin-Obukhov-Length and air density. The turbine operational mode (curtailments) is not yet available as time variable input.
In Settings -> Energy Capture, the user selects WakeBlaster as the wake model for testing.
The number of flow cases used is defined by the length of the time series. The user defines this in the ‘Time Series Settings’.
Figure 136: Time-series energy capture settings showing check-box for using met mast Monin-Obukhov length.
If the time series data includes Monin-Obukhov-Length, the ‘Include effects of time series Monin-Obukhov length (check the Detailed box, in DAWM settings)’ needs to be enabled. In WakeBlaster mode, the DAWM settings can safely be ignored; they will not affect the calculation.
A resource file can be used to describe the spatial wind resource variation. To reduce the need for interpolation of the input data it is then recommended to set the “number of direction steps” equal to the number of direction sectors in the resource file.
Starting the simulation
After setting up the calculations, the user can run Operations -> Energy Capture. Depending on the size of the project, it can take a moment for the input data for WakeBlaster to be prepared, so that the calculation does not start immediately. A dialog then opens, showing the number of flow cases available, and the number of flow cases which are about to be used by this calculation.
Figure 137: Dialog showing available flow cases and required flow cases before starting the simulation
Additional flow cases can be bought from ProPlanEn (https://proplanen.info/order-form).
Once the dialog is confirmed, the calculation initialises. For very large wind farms, the calculation can take several hours. Once all the data have been uploaded to the server and the calculation has started, the computer can meanwhile be shut down or used for other things.
An error message may be shown, if a network connection has been lost during the execution of a calculation and was not recovered automatically. Openwind can reconnect to an existing calculation by running exactly the same calculation again. Instead of the message which informs the user on the flow cases, a message will state that the calculation has been started before. If the user agrees to reuse it, Openwind will reconnect to the calculation (it might still be processing).
Flow plane plots
Flow plane plots can be generated by Openwind from a flow plane log created by WakeBlaster. Flow plane logs are a specific mode of operation in WakeBlaster and are charged at a higher rate of flow case credits per flow case. The resulting plot is loaded as a layer in the main view of Openwind.
Figure 138: Flow plane of the Horns Rev wind farm for 11 m/s and 265 degrees, at hub height
In order to create a flow plane plot, the menu option Operations -> Get WakeBlaster flow case layer needs to be selected. A setup dialog will be opened.
Figure 139: WakeBlaster flow plane setup dialog
All values need to be entered. Most users will be interested in a plot at (one of the) hub height(s). On ‘OK’, the calculation of the flow plane starts. Even though this is just a single flow case, this kind of calculation can take significantly more time than a regular flow case, depending on the size of the calculation domain (essentially, the size of the wind farm).
When the calculation is finished, the plot will automatically be loaded to the main view.
User support
For more help, please contact ProPlanEn (wakeblaster@proplanen.net).