Statistical impact of wind-speed ramp events on turbines, via observations and coupled fluid-dynamic and aeroelastic simulations

Abstract. Via 11 years of high-frequency measurements, we calculated the probability space expected offshore wind-speed ramps, recasting it compactly in terms relevant load-driving quantities for horizontal-axis wind turbines. A statistical ensemble events reduced ramp-parameter (ramp acceleration, mean speed after ramp, upper-level shear) was created to capture variability ramp parameters and also allow connection such ramp-driven loads. Constrained Mann-model (CMM) turbulence simulations coupled an aeroelastic model were made each member, a single turbine. Ramp acceleration found dominate maxima thrust-associated loads, with ramp-induced increase 45 %–50 % blade-root flap-wise bending moment tower-base fore–aft moment, plus ∼ 3 per 0.1 m/s2 bulk ramp-acceleration magnitude. The from CMM embedded large-eddy simulation (LES) farm consisting rows nine LES uses actuator-line modeling turbines is model. results indicate that associated them, tend persist through farm. Depending on ramps crossing rated lead maximum which are nearly constant third row further downwind. Where power not achieved, loads primarily depend speed; as winds weaken within farm, can again have U < Vrated. This leads higher than pre-ramp conditions, distance where begin depending inflow Umax⁡ relative For considered here, effect be small amplitude causes Vrated exceeded, but Uafter Vrated, combination cause load maxima. same sensitivity both CMM-aeroelastic LES.