Model-based aeroelastic analysis and blade load alleviation of offshore wind turbines

Abstract

Offshore wind turbines take advantage of the vast energy resource in open waters but face structuralintegrity challenges specific to their operating environment that require cost-effective load alleviation solutions. This paper introduces a computational methodology for model-based two and three-dimensional design of load alleviation systems on offshore wind turbines. The aero-hydro-servoelastic model is formulated in a convenient state-space representation, coupling a multi-body composite beam description of the main structural elements with unsteady vortex-lattice aerodynamics and Morison's description of the hydrodynamics. The aerodynamics does not require empirical corrections and focuses on a controloriented approach to the modelling. Numerical results show that through trailing-edge flaps actuated by a robust controller, more than 60% reduction in dynamic loading due to atmospheric turbulence can be achieved for the sectional model and close to 13% reduction in blade loads are obtained for the complete three-dimensional floating turbine.

An analysis of the impact of an advanced aero-hydro-servo-elastic model of dynamics on the generator-converter dynamics, for an offshore fixed 5MW PMSG wind turbine

“…For accurate assessment of offshore wind turbines (OWTs) performance, consideration of the stochastic nature of the aerodynamic and hydrodynamic loads acting on the wind turbine is paramount. Modelling of the mechanical aspects of OWTs encompasses consideration of aero, hydro and structure dynamics [13] as well as the non-linear dynamics of the main mechanical components, such as blades, hub, low and high speed shafts, gearbox, etc., as exemplified in Fig. 3.…”

“…The relationship between generator mechanical and electrical ( ge  ) angular speed is given by (12), where the pole-pairs of the generator. The generator electric torque ( e T ), with magnetic flux m  , can be obtained as given by (13). Equations (12) and (13) allow coupling between the generator electric dynamics and the shaft dynamics, i.e.…”

“…The generator electric torque ( e T ), with magnetic flux m  , can be obtained as given by (13). Equations (12) and (13) allow coupling between the generator electric dynamics and the shaft dynamics, i.e. the two-mass model given by (7)- (9).…”

Aeroelastic load control of large and flexible wind turbines through mechanically driven flaps

“…Successful wind tunnel experiment of small scaled wind turbine equipped with smart rotor has demonstrated the effectiveness on mitigating loads by actively controlled trailing-edge flap [10]. Several control schemes, such as MPC [11], H ∞ [12,13], LQG [14] and LQR [15], have been applied to actively adjust trailing-edge flap angle to react to both deterministic loads (such as wind shear and tower shadow) and stochastic loads (such as gusts) [16]. These control methods, however, are active techniques that require sensors, controllers and actuators, which from the design consideration, could be complicated, susceptible to hardware failures, and interrupted by bad weather, which limits the practical application of the smart rotor concept.…”

Effects of leading-edge tubercles on wing flutter speeds

“…The aeroelastic description is based on the integrated framework for the Simulation of High Aspect Ratio Planes (SHARP), which has been previously developed to study the dynamics of flexible aircraft [32] and wind turbines [33,34] for linear stability analysis, time-marching simulations and control synthesis.…”