4.2.1. Controller Signals

Figure 9 shows the averaged normalized standard deviation of the controller signals as a function of the average wind speed for the calculations with the DTU and the TUB controllers. The normalization is done with respect to the calculations with the DTU controller. We can see in this figure that the averaged standard deviations of the rotor speed and pitch angle are very similar with both controllers. The main difference is seen for Ω in wind speed bins of 12 m/s and higher. Here, the *σ*¯(Ω) of the calculations with TUBCon are consistently higher than with the DTU controller. The reason for this can be seen in Figure 9c. Here we can see that *σ*¯(*P*) is considerably smaller for the TUBCon calculations compared to the calculations with the DTU controller. The torque controller objective was constant power for both controllers. The fact that *σ*¯(*P*) is smaller in the TUBCon simulations indicates a more aggressive constant power enforcement of this controller. This comes at the expense of larger torque and rotor speed fluctuations when compared to the calculations with the DTU controller. We note that even though the differences in the normalized *σ*¯(*P*) are large, the absolute differences in the variation of the generator power were small. The large relative differences seen in wind speed bins of 14 m/s and higher arise because the generator power is mostly constant and the values of *σ*¯(*P*) are small for both controllers.

**Figure 9.** Normalized average standard deviations of controller signals vs. wind speed. (**a**) Rotor speed; (**b**) Pitch angle; (**c**) Generator power. Nomenclature of the signals is found in Table 5.
