Effect of Shaft Damping on the Dynamic Performance of a Wind Turbine Drivetrain: A Two-Mass System Approach

Wind turbine drivetrains are flexible mechanical systems prone to torsional oscillations, particularly when modeled as a two-mass system consisting of rotor inertia, generator inertia, and a flexible shaft. These oscillations can increase mechanical stresses, accelerate fatigue damage, and reduce power quality if not properly controlled. Shaft damping plays a critical role in shaping the dynamic response of the drivetrain, but it also introduces a trade-off between vibration suppression and energy efficiency.

This paper investigates the effect of shaft damping on the dynamic performance of a wind turbine drivetrain modeled as a two-mass system. Transfer function models for rotor speed, generator speed, and shaft torque were derived, and both time-domain and frequency-domain analyses were performed. Step responses were used to evaluate transient metrics such as overshoot, oscillation amplitude, and settling time, while Bode diagrams captured resonance behavior and frequency sensitivity. The cumulative energy dissipated in the shaft was also computed to assess efficiency impacts.

The results show that low shaft damping produces sharp resonance peaks and sustained oscillations, leading to poor dynamic stability. Increasing damping reduces oscillations, suppresses resonant modes, and improves torque transmission smoothness. However, higher damping levels also result in greater energy dissipation, reducing drivetrain efficiency. These findings highlight the need for optimal damping selection to balance mechanical stability with energy performance. This study provides insights into the design and optimization of wind turbine drivetrains, contributing to improved reliability and overall system performance.