The rapid technological progression of wind turbines not only imposes design challenges but also necessitates continuous advancements in modeling approaches, particularly holistic methods capable of accurately capturing turbine coupling effects. A well-established modeling tool in the wind energy sector is the aero-servo-elastic code HAWC2. Although it is widely used to predict the overall turbine response across a broad range of operating conditions, the drivetrain is typically represented as a single beam.
In the presented work, a more realistic and comprehensive drive train model was developed in HAWC2 to account for additional flexibility effects associated with increasing turbine dimensions and enable the estimation of the main bearing reaction loads. First, a detailed literature review was conducted to analyze current trends regarding drivetrain technology, essential components, and modeling approaches of modern wind turbine drivetrains.
The DTU 10MWRWT and a high-fidelity SIMPACK drivetrain model, developed by researchers from NTNU, were identified as references for the implementation. Additionally, the theoretical foundations of Timoshenko beam elements and multibody formulation used in HAWC2 were studied, as both are essential for constructing a turbine model in HAWC2. In the implementation phase, the overall drivetrain structure and fundamental drivetrain properties, such as the stiffness properties of the main bearings, were extracted from the SIMPACK model and incorporated into HAWC2 through the introduction of additional beam elements. To further increase the fidelity, the first torsional eigenfrequency of the derived structure was tuned to match the dynamics of the reference models. As a final step, the simple HAWC2 drivetrain representation was adjusted to reflect the mass distribution of the developed structure, enabling a direct comparison between the two.
The developed model showed strong performance in predicting main bearing loads under steady conditions, thereby achieving a clear improvement in fidelity compared with the original setup. In contrast, reduced agreement was observed for the torque arms response and under turbulent simulations. The study concludes with a critical evaluation of the model, addressing its limitations and outlining potential directions for further accuracy improvements.