Estimation and Control of Wind Turbine Tower Vibrations Based on Individual Blade-Pitch Strategies
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Citations
Load control optimization method for offshore wind turbine based on LTR
Super-short Term Wind Speed Prediction based on Artificial Neural Networks for Wind Turbine Control Applications
Optimization of Pitch Control Parameters for a Wind Turbine Based on Tower Active Damping Control
Study Method of Pitch-Angle Control on Load and the Performance of a Floating Offshore Wind Turbine by Experiments
Individual Blade Pitch Control with Wind Preview Information for Floating Offshore Wind Turbines
References
Definition of a 5-MW Reference Wind Turbine for Offshore System Development
Wind Energy Handbook
Individual Blade Pitch Control for Load Reduction
Related Papers (5)
Frequently Asked Questions (15)
Q2. What is the simplest way to model the blade and tower?
Owing to variable blade geometry, the wind-induced forces are not uniformly distributed on the blades and to model such forces, blade element/momentum theory is adopted [13], where the blade is discretised into small elements.
Q3. What is the key benefit of the individual pitch-based design?
The key benefit of the individual-pitch-based design is that it is decoupled from the existing CPC loop, owing to the inherent properties of the Coleman transforms.
Q4. What is the key challenge of the tower damping system?
The key challenge is to separate the existing IPC loop and the tower damping control loop, which is particularly important since the tower estimate is also dependent upon the blade load measurements.
Q5. What is the contribution of the paper?
The contributions of this paper lay in the extraction of useful additional information from existing blade load sensors and7 100 105 110 115 120 125 130Time t [s]161718192021W in d S p ee d v (t ) [ms− 1 ](a) Hub-height wind speed.
Q6. What is the heuristic switching policy used to overcome the transition between wind conditions?
The following heuristic switching policy was employed to overcome the transition between wind conditions:ẋfa(t) = ∑κρκ(t)ẋfa,κ(t), ∑κρκ(t) = 1, (14)6where κ ∈ {1, 2} is the index of observers designed in the below-rated and above-rated wind conditions, whilst ρκ ∈ R denotes the weighting on the tower estimate of the κ-th estimator.
Q7. What is the spectra of the model output?
Rnd is defined as follows:ξ̇w(t) = Awξw(t) +Bww(t), dcm(t) = Cwξw(t), (6)where the system matrices {Aw, Bw, Cw} are determined by fitting the spectra of the model output to the known spectra of the wind speed disturbances.
Q8. What is the bending moment of the blade and tower?
This work implicitly assumes the tower is a prismatic beam so that the ratio between rotation and displacement is 23h , where h ∈ R is the height of the tower [3].
Q9. What is the simplest way to model the aerodynamic forces of the blade and tower?
The nonlinear aerodynamic forcing functions on the blade and tower are typically linearised around the operating wind conditions to obtain the perturbation forces, f̃M (θ̃i, ṽi) : R × R → R and f̃x(θ̃col, ṽcol) : R × R → R, defined as follows:f̃M (θ̃i, ṽi) = dfMdθ∣ ∣ ∣ ∣θ∗,v∗ θ̃i(t) +dfMdv∣ ∣ ∣ ∣θ∗,v∗ ṽi,(t), (1c)f̃x(θ̃col, ṽcol) = dfxdθ∣ ∣ ∣ ∣θ∗,v∗ θ̃col(t) +dfx dv∣ ∣ ∣ ∣θ∗,v∗ ṽcol(t), (1d)where dfM dθ , dfx dθ ∈ R and dfM dv , dfx dv ∈ R are the variations of the forcing with respect to the pitch angle and apparent wind speed.
Q10. What is the correct treatment of the Coleman Transforms?
Theorem 3.1: Assuming a fixed rotor speed and Coleman transformations (4), the linear time-varying system (3) can be transformed into the following LTI form:ξ̇(t) = Aξξ(t) +Bξucm(t) +Bξddcm(t),ycm(t) = Cξξ(t), (5)where ycm(t) = [M̃col(t), M̃tilt(t), M̃yaw(t)]
Q11. What are the natural frequencies of the blade and tower?
The damping ratio of the blade and tower are ζb, ζt ∈ R and ωb, ωt ∈ R are the respective natural frequencies of the blade and tower.
Q12. What is the angle of the blade and tower?
The azimuthal angle of each blade is defined as [φ1(t), φ2(t), φ3(t)] := [φ(t), φ(t) + 2π 3 , φ(t) + 4π 3 ], where φ(t) is the angle of the first blade from the horizontal yaw axis with respect to the clockwise direction.
Q13. What is the error magnitude of the proposed method?
In addition, in Figure 6d, it is clearly seen that the error auto-correlation of the proposed method was closer to zero, suggesting its residual was almost white noise.
Q14. What is the effect of the wind on the blade and tower?
Since the focus of this work is on the blade disturbance induced by the wind, the effect of the wind perturbations upon the blade, ṽi(t) in (1), can be approximated by averaging the apparent wind speed perturbations ṽi,l(t) along the blade, as follows:ṽi(t) ≈ 1L∑lṽi,l(t),= ṽ∞,i(t)− ˙̃xfa(t) + kϕ ˙̃xfa(t) sin ( φi(t) ) .
Q15. What is the effect of the individual-pitch-based design on the turbine structure?
Compared to the collective pitch-based design, the individual-pitch-controller imposed slightly larger tilt and yaw loads at the tower resonant frequency, upon the non-rotating turbine structure.