The WTDTA1 component is a simplified model for the purpose of emulating the behavior of torsional mode oscillations. The wind turbine shaft damping coefficient (Dshaft) in the drive-train model represents the net damping of the torsional mode seen in the post fault electrical power response. In real equipment, the drive train oscillation are damped through active control signals, much different from the simple two mass drive train model represents in the WTDTA1 component. Thus, the drive-train is not a real physical representation of the real drive-train.
The modelling of such devices is based, mainly, on the following references: