Regardless of generator rotational limit, is there any limitation for rotor rotational speed?
I mean where the rotor rated rotational speed(12.1rpm) come from? Is it come from generator rotational speed limitations or depend on other factors?
Can the rotor rotational speed be 14rpm but with lower gear box ratio(83) the generator speed be 1173rpm?
Rotor speed is typically limited to limit tip speed (and hence noise emissions) at rated power. The NREL 5-MW turbine limits the tip speed limit to 80 m/s, which is common.
What about generator torque rated value?
How it is determined?
Suppose the generator speed is less than the rated speed, in this way can the generator torque be higher than rated? (e.g 50KN.m)
The combination of rated speed and rated torque are designed to achieve the desired rated power.
For turbines designed to operate with constant power above rated wind speed (as opposed to constant torque above rated wind speed), it is possible to have a generator torque that is higher than rated torque over a small range of generator speeds below rated speed. To avoid overloading the generator, the NREL 5-MW torque controller places a torque limit at 10% above rated torque.