# Model Based Open-Loop Wind Farm Control Using Active Power for Power Increase and Load Reduction
## 3 Simulation Result
### Flow Field in Wind Farm
Figure 5: Wind flow variation in wind farm with the baseline and proposed wind farm controllers under ambient turbulence intensity of 0.075: (**a**) turbulent wind field variation with the baseline wind farm control (\(\overline{\text{U}}\) = 8 m/s); (**b**) steady wind speed deficit of figure (**a**); (**c**) turbulent wind field variation with the proposed wind farm control (\(\overline{\text{U}}\) = 8 m/s) (**d**) steady wind speed deficit of figure (**c**); (**e**) turbulent wind field variation with the baseline wind farm control (\(\overline{\text{U}}\) = 10.5 m/s); (**f**) steady wind speed deficit of figure (**e**); (**g**) turbulent wind field variation with the proposed wind farm control (\(\overline{\text{U}}\) = 10.5 m/s); and (**h**) steady wind speed deficit of figure (**g**). Red dashed line means the wind deficit profile. Deviation from the flat ends represents larger wind speed deficit. As shown in Figure 5b, where the wind farm control is off, the wake generated between the wind turbines causes significant wind speed reduction, and wake expansion. On the other hand, Figure 5d shows that, if the control is applied to the wind turbine, both effects are much reduced. With the wind speed of 10.5 m/s, similar effects on the wind flow by the wind farm control can be observed in Figure 5e,g or Figure 5f,h. Figure 6 shows exactly the same plots as Figure 5 but with the higher ambient turbulence intensity of 0.21. The higher ambient turbulence intensity can be noticed by severe changes of black and white colors in the figure compared with those in Figure 5. As shown in Figure 6a,c or Figure 6b,d for the mean wind speed of 8 m/s, the wind speed deficit was reduced when the proposed wind farm controller was used. This result is the same as the result of Figure 5. The similar results were obtained for Figure 6e,g or Figure 6f,h that are the cases when the mean wind speed was 10.5 m/s. However, because of the mean wind speed, again, the pitch control was turned on for power regulation, and as the result, the wind speed deficits with the baseline and the proposed controllers were reduced  
Figure 6: Wind flow variation in wind farm with the baseline and proposed wind farm controllers under ambient turbulence intensity of 0.21: (**a**) turbulent wind field variation with the baseline wind farm control (\(\overline{U}\) = 8 m/s); (**b**) steady wind speed deficit of figure (**a**); (**c**) turbulent wind field variation with the proposed wind farm control (\(\overline{U}\) = 8 m/s) (**d**) steady wind speed deficit of figure (**c**); (**e**) turbulent wind field variation with the baseline wind farm control (\(\overline{U}\) = 10.5 m/s); (**f**) steady wind speed deficit of figure (**e**); (**g**) turbulent wind field variation with the proposed wind farm control (\(\overline{U}\) = 10.5 m/s); and (**h**) steady wind speed deficit of figure (**g**). Red dashed line means the wind deficit profile. Deviation from the flat ends represents larger wind speed deficit. compared with those at 8 m/s. It is known that the mixing process of the wind becomes more active with the ambient turbulence intensity, and therefore the wake effect is eliminated more quickly compared with Figure 5. As the result, the difference in wind speed deficit with the baseline controller and the proposed controller in Figure 6 was reduced compared with Figure 5.  
Figure 7a,b shows the wind speed gain for turbines when the mean wind speed is 8 m/s and the turbulence intensities are 0.075 and 0.21, respectively. As shown in the figure, the input wind speed of all wind turbines located downstream is increased by adjusting the power output of the most upstream wind turbine in both cases. However, as the turbulence intensity increases, the wind speed increase percentage decreases by nearly two times. This phenomenon is related to the wind speed recovery due to the mixing process in the wake region, which is known to be in proportion to the ambient turbulence intensity [25; 35].