Abstract This paper deals with the aeroelastic instabilities that have occurred and may still occur for modern commercial wind turbines: stall‐induced vibrations stall‐turbines, classical flutter pitch‐regulated turbines. A review of previous works is combined derivations analytical stability limits typical blade sections show fundamental mechanisms these instabilities. The risk mainly related to airfoil characteristics, effective direction structural damping; whereas tip speed, torsional...

Abstract The theory and results of two experimental methods for estimating the modal damping a wind turbine during operation are presented. Estimations aeroelastic operational modes (including effects aerodynamic forces) give quantitative view stability characteristics turbine. In first method estimation is based on assumption that mode can be excited by harmonic force at its natural frequency, whereby decaying response after end excitation gives an estimate damping. Simulations experiments...

ABSTRACT Vertical wind shear is one of the dominating causes load variations on blades a horizontal axis turbine. To alleviate varying loads, turbine control systems have been augmented with sensors and actuators for individual pitch control. However, loads caused by vertical can also be affected through yaw misalignment. Recent studies focused improving alignment to increase power capture at below rated speeds. In this study, potential alleviating blade induced misalignment assessed. The...

Abstract Stall‐induced edgewise blade vibrations have occasionally been observed on three‐bladed wind turbines over the last decade. Experiments and numerical simulations shown that these are related to certain vibration modes of turbines. A recent experiment with a 600 kW turbine has backward whirling mode associated is less aerodynamically damped than corresponding forward mode. In this article shapes particular analysed, based simplified model described in multi‐blade formulation. It...

Abstract A design tool for performing aeroelastic stability analysis of wind turbines is presented in this paper. The method behind described a general form, as independent the particular modelling possible. Here, structure modelled by Finite beam Element Method, and aerodynamic loads are Blade Momentum coupled with Beddoes‐Leishman type dynamic stall model state‐space formulation. linearization equations motion performed about steady‐state equilibrium, where deterministic forcing turbine...

It is investigated how the nonlinear geometric coupling between torsion and flapwise bending of backward swept blades affects their static dynamic aeroelastic properties. A geometrically co-rotational finite beam element formulation coupled with Blade Element Momentum method used to compute steady state blade deflection aerodynamic power thrust (assuming uniform wind neglecting tower shadow gravity effects) a different sweep shapes. linearization this model addition an unsteady frequencies,...

We introduce an optimized Markov chain Monte Carlo (MCMC) technique for solving integer least-squares (ILS) problems, which include maximum likelihood (ML) detection in multiple-input multiple-output (MIMO) systems. Two factors contribute to its speed of finding the optimal solution: probability encountering solution when has converged stationary distribution, and mixing time MCMC detector. First, we compute "temperature" parameter value, so that once mixed there is a polynomially small (...

In this paper we study a Markov Chain Monte Carlo (MCMC) Gibbs sampler for solving the integer least-squares problem. digital communication problem is equivalent to performing maximum likelihood (ML) detection in multiple-input multiple-output (MIMO) systems. While use of MCMC methods such problems has already been proposed, our method novel that optimize "temperature" parameter so steady state, i.e. after chain mixed, there only polynomially (rather than exponentially) small probability...

ABSTRACT When extracting energy from the wind using horizontal axis turbines, ability to align rotor with mean direction is crucial. In previous work, a method for estimating yaw error based on measurements spinner mounted light detection and ranging (LIDAR) device was developed tested. this study, simulation parameter space extended include higher levels of turbulence intensity. Furthermore, applied experimental data compared met‐mast corrected calibration that not discovered during work....

One of the primary criteria for extracting energy from wind using horizontal axis upwind turbines is ability to align rotor with dominating direction. The conventional way estimating direction incoming flow by transducers placed atop nacelle and downwind rotor. Recent studies have suggested methods based on advanced measurement technologies inflow improving yaw alignment. In this study, potential increased power output improved alignment investigated assessing performance a current control...

This study presents a wind turbine controller able to handle both hard and soft constraints, typically on actuators but also other components of the turbine, if needed. An issue especially relevant during extreme events or for under-dimensioned actuators. The presented is based model predictive control, control method well suited constraint handling. performance an operating gust compared that proportional–integral with integrator anti-windup. Furthermore, controller's capability operate in...

Abstract. This paper presents the integration of a near-wake model for trailing vorticity, which is based on prescribed-wake lifting-line proposed by Beddoes(1987), with blade element momentum (BEM)-based far-wake and 2-D shed vorticity model. The resulting coupled aerodynamics validated against lifting-surface computations performed using free-wake panel code. focus description numerical stability, computation speed accuracy unsteady simulations. To stabilize model, it has to be iterated...

Abstract Aeroelasticity is a key issue in the continuing development of wind turbines towards large, flexible, highly optimized machines. The steadily increasing technology level reflected not necessarily by complexity turbines, but knowledge and advanced principles that are taken into account during design process incorporated final design. This article examines some main uncertainties within aeroelastic modelling have been hard to resolve over years research, also presents perspectives for...

The effects of bend–twist coupling on the aeroelastic modal properties and stability limits a two-dimensional blade section in attached flow are investigated. Bend–twist is introduced stiffness matrix structural model. model coupled with an unsteady aerodynamic linearised state–space formulation. A numerical study performed using parameters representative for wind turbine blades. It shown that damping edgewise mode primarily influenced by work lift which close to antiphase, making sensitive...

Abstract Wind turbine multidisciplinary design optimization is currently the focus of several investigations because it has showed potential in reducing cost energy. This approach requires fast methods to evaluate wind loads with a sufficiently high level fidelity. paper presents method estimate fatigue damage suited for applications. The utilizes high‐order linear model. model comprehends detailed description and controller. computed spectral applied power densities sensor responses...

This work presents an integrated multidisciplinary wind turbine optimization framework utilizing state-of-the-art aeroelastic and strutural tools, capable of simultaneous design the outer geometry internal structure blade. The is utilized to a 10 MW rotor constrained not exceed loads existing reference turbine. results show that through combined geometric tailoring aerodynamic shape blade it possible achieve significant passive load alleviation allows for 9% longer with increase in AEP 8.7%,...