Dear @Emanuel.Rergis,
Regarding scripts that automate the generation of input files and executing TurbSim and OpenFAST simulations for IEC DLCs, see my post dated Aug 31, 2022 in the following forum topic: Wind & Wave data - #67 by Jason.Jonkman .
Can you clarify what the low-frequency excitation is caused by? Are these system natural frequencies or excitation frequencies, e.g., harmonics of the rotor speed? Are you running an OpenFAST model provided by NREL (e.g., from the r-test); if so, which one? Or is this a model that you created yourself? What is the rotor speed the wind turbine is spinning at for this case?
Best regards,