3.1.4. Drivetrain Damper

The torque controller also includes a drivetrain damper to damp unwanted oscillation of the turbine shaft due to e.g., excitation of its torsional eigenfrequency. The drivetrain damper is implemented as a proportional term *kdmp* to the band-passed rotor speed signal Ω*BPF*:

$$Q\_{dmp} = k\_{dmp} \cdot \Omega\_{BPF}.\tag{11}$$

The equation of the band-pass filter is given in Equation (A3). *Qdmp* is added to *QPID* to obtain the total output torque of the controller:

$$Q\_{\mathcal{S}^{\rm ren}}(t) = Q\_{\mathcal{d}mp}(t) + Q\_{PID}(t). \tag{12}$$
