Turbulent Wind |
 
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Turbulent Wind |
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The turbulent wind test cases comprise a series of individual simulations, each of which has a mean wind speed between cut-in (3 m/s) and cut-out (25 m/s). Full-field wind turbulence is simulated, according to IEC 61400-1 standard (class 1B). The wind field files are generated by TurbSim, a component module of OpenFAST, using the Kaimal spectrum (IECKAI) and extreme turbulence (1ETM) options. These test cases are representative of real-world power production conditions. Each wind condition is analysed for 10 minutes simulation time. OpenFAST and OrcaFlex support the specification of non-zero initial rotor speeds in dynamic simulations, thereby reducing initial transience and increasing overall solver efficiency. This also tends to assist the numerical stability of the control system. Hence anticipated mean values of rotor speed and blade pitch angle are specified as user inputs. Flexcom does not yet offer this option, so rotors always start with zero angular velocity. To align the turbulent simulations as closely as possible, preliminary steady-wind simulations are run with Flexcom, followed by the actual turbulent simulations. Results are presented in the form of statistical values (mean and standard deviation, the latter as shaded) at each wind speed (upper three rows of plots). Sample time histories for the largest wind speed (25 m/s) are also included for additional insight (lower three rows of plots).
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