I have been using the NREL 5-MW offshore baseline wind turbine model. I would like to apply an adaptive torque gain control to this model which takes place in the torque-control region 2. Originally this torque gain is a constant (0.0255764) but now it is adaptive. As the model’s technical report says, the range of generator speeds in region 2 is between 871 rpm and 1161.96 rpm, which is a little narrow for my simulation study. Finally I enlarge this range to 670-1161.96 rpm and rearrange Region 1.5 to 515-670 rpm. But I don’t know whether it is allowable theoretically. I appreciate your advice.
I don’t suggest that you lower the operational speeds in Region 1.5 by much. This will effectively widen the range of operational speeds of the turbine, which makes e.g. resonance avoidance with natural frequncies of the structure difficult. What you could do is make Region 1.5 steeper such that Region 2 is wider: say, change Region 1.5 to 670-700 rpm and Region 2 to 700-1161.96 rpm. We realized that Region 1.5 was quite wide after Figure 7-2 in the NREL 5-MW specifications report was made. We thought about changing this at the time, but decided it wasn’t worth it because the improvement in power would have been marginal and unimportant for most conceptual projects.
Thank you very much for your reply. I made this range change because I assume that the optimal torque gain is unknown and decide to find this optimal value via a control algorithm. So I need to start simulation by setting the initial value of torque gain away from its optimal value to observe the improvement of the turbine power. Hence wide Region 1.5 and narrow region 2 bring trouble on simulation study when the torque gain is away from its optimal value to some extent.