Optimization of Turbine Tilt in a Wind Farm

Wind farm power production is severely affected by upstream turbines creating wakes of slower wind speeds that overlap the rotor swept areas of downstream turbines. By optimizing the tilt angle of the turbines in a farm, wakes may be deflected away from downstream turbines, increasing the overall energy production.   In this study, we optimized the tilt angle of turbines in a wind farm to maximize energy production. We used an analytic wake model modified to consider wake deflection from tilt, and gradient-based optimization. We considered optimizing the tilt angle of each turbine assuming that it remained fixed for the lifetime of the farm. We also considered active tilt control.   Preliminary results with a simple five-turbine row show that a large tilt angle of 25 degrees in the front upstream turbine increases the power production of the five turbines by about 14 % compared to the power production with no tilt in the front turbine. Considering a whole wind farm and wind distribution also showed promising results with an increase in the annual energy production(AEP) by aboutc14.9% using active tilt control.                 The preliminary results indicate that the tilt angle in an upstream turbine around 20 to 25 degrees can increase the total power production of a row of 5 turbines in line with the wind direction by about 11% compared to having no tilt in the upstream turbine. Five turbines spaced 5 rotor diameters apart had around a 14% gain in power production with a tilt angle in the front turbine of about 23 degrees. Whereas spacing them 9 rotor diameters apart had around a 10% gain in power production with a tilt angle of about 22 degrees. Therefore, it appears that tilt optimization can have a larger impact on wind farms that have smaller spacing between turbines because the wakes don’t have as long to recover. Preliminary optimizations with fixed tilt and active tilt control further revealed that tilt capabilities in wind turbines can be advantageous to increasing the AEP of a wind farm even when considering an entire wind distribution. Optimization of the AEP of the Princess Amalia wind farm resulted in a 4.5% increase in AEP with fixed tilt angles and a 14.9% increase in AEP with active tilt control. For our final conference paper, we will make several additions and improvements to our current state. First, we will include the turbulence as a function of height. A major benefit of vertical wake deflection is being able to dissipate the turbine wakes faster with ground effects. A turbulence distribution will approximate this phenomenon. Second, we will include parameterized elements of the curled wake model to more accurately model effects that tilt has on the wake of the wind turbine. These adjustments will be tuned and verified with SOWFA simulations. The current wake model underestimates the amount of deflection of the wake and wake recovery due to tilt. Therefore when the wake model is more complete it should predict even larger increases in AEP using tilt. Third, we will optimize the tilt angle of turbines for several wind farm scenarios. We will consider several wind farm layouts, turbine spacings, and wind distributions to understand the benefits of tilt optimization in different circumstances. As mentioned before, we will consider fixed tilt angle optimization, as well as active tilt control.