A load basis consist of approximately 1000 different simulations, covering normal production in different turbulence conditions, start-up and shutdown situations, fault situations and extreme wind loading in storm situations etc. In order to enable and keep an overview of these simulations, an Excel spreadsheet with build-in macro functions is combined with a tool for handling distributed computing on multiple computers. Once the turbine is defined with respect to structure, aerodynamics and control, the load case setup is handled it generating individual input files based on a master file. It is in this context that the interaction between HAWC2 and WAsP Engineering occurs, since WAsP Engineering will deliver the site-specific parameters for each surrounding wind sector, including weibull parameters used for post processing of fatigue loads in particular. The calculation time is close to real time on a 3GHz CPU (for a land based turbine), which is obtained using a Newmark beta solution scheme together with Newton-Raphson iterations within each time-step. The code is limited to Windows 32, primarily caused by its use of DLLs, although execution on Linux platforms works well using the WINE Windows Emulator. The source code is not public, but through the general DLL interface a lot of external coding can be performed by the user as described here.
