Wind Turbine’s Tower-Nacelle Model with MR Tuned Mass Damper
The laboratory model of wind turbine’s tower-nacelle system consists of vertically oriented titanium (Ti Gr.5) rod 1 (representing wind-turbine’s tower), and a set of steel plates 2 (representing nacelle and turbine assemblies) fixed to the top of the rod 1, with Magnetorheological Tuned Mass Damper 3 (MR TMD) embedded. Titanium rod is rigidly mounted to the steel foundation frame 4. MR TMD 3 is an additional mass moving horizontally along linear bearing guides, connected with the assembly representing nacelle via spring and Lord’s RD 1097-1 MR damper in parallel. MR TMD operates along the same direction as vibration excitation applied to the system. Force generated by vibration excitation system, i.e. force exciter TMS 2060E 5 with drive train assembly 6 of changeable leverage (enabling changeable force / velocity amplitudes, and displacement range) may be applied either to the rod 1 (modelling the tower, as in the picture) or to the set of steel plates 2 modelling nacelle/turbine. Excitation signal is generated by LDS Dactron 7 and amplified by TMS 2100E21-400 8.
Measurement and control system consists of laser vibrometer with its controller 9, laser displacement transducer 10, LVDT relative displacement transducer 11, tensometric stress transducers 12, force and acceleration transducers (not apparent in the picture) as well as transducers supply/conditioning system including MR damper signal amplifier 13, and measuring-control PC 14 with Windows XP/MATLAB/Simulink/RT-CON applications.
The laboratory test rig gives the possibility to model wind turbine’s tower vibration under various excitation sources as variable wind conditions, including wind shear, Karman vortices, blade passing effect, rotating elements unbalance, sea waves, ice, etc. Several vibration control algorithms are tested with the help of this rig. MR damper, which force depends on the current fed to its coil, serves as an actuator of the control system. With the use of the MR damper, standard TMD linear damping algorithm may be realised as well as other dedicated solutions as ground-hook and its improvements, nonlinear damping, sliding mode, optimal and fuzzy control, etc. Moreover, the rig may be laid down on the horizontally excited platform to model vibration due to seismic, or sea waves (for buoy-floating structures).
Several didactic activities for Faculty of Energy and Fuels are realised using this test rig, including e.g.:
- tower-nacelle system behaviour demonstration under several excitation source models (as specified above) and various frequency values, especially in relation with system natural frequencies,
- determination of MR damper dissipation energy for each vibration period in relation with the excitation frequency and MR damper control current.
Project financed by the Polish National Science Centre (Narodowe Centrum Nauki) (contract no. 2286/B/T02/2011/40).