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Brake application to lock generator
Dear David,
While trying to reproduce the simulation results of the free decay test in the literature, I encountered some problems locking the generator.
As you can see from the load case 1.3 description in Figure 1, how can I achieve the requirement of “generator is locked, the DOFs of platform and mooring lines are enabled “
I’ve tried to change the value of maximum brake torque in the BRAKE MODEL table as shown in Figure 2, but in my results, the range of pitch is much smaller than the literature, and didn’t change too much before and after I changed the brake setting.
Would you please point out what’s the mistake in my simulation and give me some ideas?
Best Regards,
Easey
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Hello Easey,
if you want to model a locked rotor, you can simply set the RPM to zero and enable “Always Fixed”. In this way the rotor will behave as locked.
You were trying to use the brake to achieve the same behavior. However, for this to work the controller needs to send a “brake activation” signal to the turbine, upon which the brake will be activated. If no brake signal is coming from the controller the “brake torque” setting will not have any effect.
BR,
David
Hi David,
When I set the RPM to zero, may I confirm that the rotor’s DOF is also zero?
If not, how can I turn off the DOFs of the blade, tower and rotor?
Best Regards,
Easey
Hi Easey,
when the rpm is set to zero the rotor is fixed and cannot rotate. You could interpret this as the rotational DoF being deactivated.
Disabling DoF’s of the structural model is not possible. In fact, each node of the structural model has 3 translational and 3 rotational DoF’s. However, you can increase the stiffness (using the STIFFTUNER parameter) of a structural component so that it behaves essentially as “rigid”. It is also possible to remove the tower completely by removing the TWRFILE parameter from the main structural input file. Doing this constrains the rotor nacelle assembly (RNA) at the defined tower height, removing all DoF’s of the tower nodes.
BR,
David
