Dynamics Analysis of Flexible Rotors in Ground‐Based Test Platform for Large‐Capacity Offshore Wind Turbines

To address the safe operation challenges of ultra‐long flexible rotors in large‐capacity offshore wind turbine ground‐based test platforms, this study proposes a system‐level modelling method based on the Timoshenko beam shaft element model. Taking the combined shafting of Fujian's 25 MW offshore wind power ground test platform and the International Energy Agency (IEA) 22 MW standard offshore wind turbine as the research object, it comprehensively considers the shaft's bending deformation, shear deformation, rotational inertia and gyroscopic effect, constructs a rotor dynamics model via the finite element method, and analyses natural modes, critical speeds and natural frequencies—with comparative verification against commercial software numerical models. Results show high consistency in vibration patterns and calculation outcomes. Additionally, Campbell diagram analysis and bearing stiffness research clarify the system's safe operation range and suitable bearing stiffness parameters, enriching the theoretical system for rotating system analysis and optimisation and providing theoretical support for test platform design optimisation and safe operation.