OpenFAST based optimization of wind turbine configurations considering aerodynamic performance and fatigue life

In this thesis, a Taguchi-based optimization model was proposed to investigate the interaction of power density with turbine layout configurations and yaw angles in a wind farm setup. The wind speed was assumed to be unidirectional and constant, based on the average wind data at 100 meters height in the Bandırma region of Turkey. For numerical analyses, a three-turbine tandem layout was modeled using the wind farm module Fast.FARM of the open-source aero-servo-elastic solver OpenFAST. In the study, the spacing between downstream turbines was defined as 3D, 4D, and 5D in terms of rotor diameter, while yaw angles for each turbine ranged from -20° to 20° in 5° increments. A design of experiment (DOE) consisting of 81 different scenarios was generated based on these parameters. A mathematical model was fitted to the analysis results using the least squares method, and the optimal configuration yielded a power density of 57.30 W/m². Since the yaw angle of the third turbine had minimal influence on the output, it was recommended to fix it at 0°. Additionally, new scenarios were created by evaluating yaw angles with 10° increments. To define the limits of the spacing factor, two additional experimental designs were developed. For the new designs, the inter-turbine spacing was defined within the ranges of 3D–8D and 1D–5D, each consisting of 25 scenarios. The highest power output, 8.454 MW, was achieved at an 8D spacing, with yaw angles of 20° for the first turbine and 10° for the second. The highest power density, 151.42 W/m², was obtained at a 1D spacing, with yaw angles of 10° and -20° for the first and second turbines, respectively. For both scenarios, fatigue analyses were conducted based on root loads obtained from FAST simulations and evaluated using MLife. The most critical fatigue life was observed in the first turbine in the edgewise direction, with estimated lifespans of 33,9 years for the maximum power density scenario and 38,4 years for the maximum power scenario. In both cases, the intended operational lifespan of 20 years is not exceeded.