Individual Blade Pitch Control for the Controls Advanced Research Turbine (CART)

2006 ◽  
Vol 128 (4) ◽  
pp. 498-505 ◽  
Author(s):  
Karl A. Stol ◽  
Wenxin Zhao ◽  
Alan D. Wright
Keyword(s):  
Fatigue Damage ◽  
Linear Time ◽  
Field Testing ◽  
Superior Performance ◽  
Horizontal Axis Wind Turbine ◽  
Pitch Control ◽  
Wind Speeds ◽  
Controller Performance ◽  
The Individual ◽  
Individual Pitch Control

Pitching the individual blades of a horizontal-axis wind turbine allows control of asymmetric aerodynamic loads, which in turn influences structural loads in the nonrotating frame such as tower side-side bending. These loads are not easily controlled by traditional collective pitch algorithms. This paper presents the design of individual pitch control systems for implementation on the Controls Advanced Research Turbine (CART) in Colorado to verify controller performance for load attenuation. The control designs are based on linear time-periodic state-space models of the turbine and use optimal control methods for gain calculation. Comparisons are made between new individual pitch, new collective pitch, and baseline controller performance in both above rated and below rated wind conditions. Results from simulations show the potential of individual pitch to reduce tower side-side fatigue damage in above rated wind speeds (by 70% compared to baseline control) but with no improvement over collective pitch in below rated wind speeds. Fatigue load reductions in tower fore-aft, shaft torsion, and blade flap are also observed. From 13h of field testing, both collective and individual pitch controllers achieve a reduction in fatigue damage. However, the superior performance of individual pitch control observed in simulation was not verified by the field test results.

The Study of Individual Pitch Control on Reducing The Load Fluctuation of Tower Shadow

2011 ◽  
Vol 347-353 ◽  
pp. 2260-2267
Author(s):  
Wei Li ◽  
Hong Li Sun ◽  
Zuo Xia Xing ◽  
Lei Chen
Keyword(s):  
Wind Turbine ◽  
Linear Time ◽  
Pitch Control ◽  
Linear Time Invariant ◽  
Load Fluctuation ◽  
Pitch System ◽  
The Individual ◽  
Time Invariant ◽  
Individual Pitch Control ◽  
Tower Shadow

Load fluctuation of wind turbine under tower shadow was researched，introducing individual pitch control. First，establish the linear time-varying model of the rotor，make it into the linear time invariant model through Coleman transformation. Then，based on this model，achieving the design of individual pitch system with PID controller. Comparing the loads of wind turbine under tower shadow between individual pitch control and collective pitch control and analysing the fatigue damage of wind turbine through rainflow cycle counting.The result shows that load fluctuation of wind turbine using the individual pitch control under tower shadow has better effect and reduces the effect of tower shadow，extend the working life of wind turbine.

Wind Shear and Turbulence Effects on Rotor Fatigue and Loads Control

2003 ◽  
Author(s):  
A. J. Eggers ◽  
R. Digumarthi ◽  
K. Chaney
Keyword(s):  
Fatigue Damage ◽  
Wind Shear ◽  
Drive Train ◽  
Turbulence Level ◽  
Horizontal Axis Wind Turbine ◽  
Pitch Control ◽  
Wind Speeds ◽  
Blade Root ◽  
Fatigue Design ◽  
Turbulence Effects

The effects of wind shear and turbulence on rotor fatigue and loads control are explored for a large horizontal axis wind turbine in variable speed operation from 4 to 20 m/s. Two and three blade rigid rotors are considered over a range of wind shear exponents up to 1.25 and a range of turbulence intensities up to 17%. RMS blade root flatwise moments are predicted to be very substantially increased at higher wind shear, and resultant fatigue damage is increased by many orders of magnitude. Smaller but similar trends occur with increasing turbulence levels. In-plane fatigue damage is driven by 1P gravity loads and exacerbated by turbulence level at higher wind speeds. This damage is higher by one to two orders of magnitude at the roots of the three blade rotor. Individual blade pitch control of fluctuating flatwise moments markedly reduces flatwise fatigue damage due to this source, and to a lesser degree the in-plane damage due to turbulence. The same is true of fluctuating rotor torque moments driven by turbulence and transmitted to the drive train. Blade root moments out of the plane of rotation aggregate to create rotor pitching and yawing moments transmitted to the turbine structure through the drive train to the yaw drive system and the tower. These moments are predicted to be relatively insensitive to turbulence level and essentially proportional to the wind shear exponent for the two blade rotor. Fluctuating moments are substantially reduced with individual blade pitch control, and addition of a teeter degree of freedom should further contribute to this end. Fluctuating pitching and yawing moments of the three blade rotor are substantially less sensitive to wind shear, more sensitive to turbulence level, and substantially lower than those for the two blade rotor. Mean rotor torque and hence power are essentially the same for both rotors, independent of wind shear, and somewhat reduced with individual blade pitch control of fluctuating flatwise moments. The same is true of mean rotor thrust, however fluctuations in rotor thrust are substantially reduced with individual blade pitch control. It appears, on balance, that higher wind shear coupled with turbulence effects should be accounted for in the fatigue design of large, long life turbines. Much more work is required on this problem.

Wind Shear and Turbulence Effects on Rotor Fatigue and Loads Control

2003 ◽  
Vol 125 (4) ◽  
pp. 402-409 ◽  
Author(s):  
A. J. Eggers, ◽  
R. Digumarthi ◽  
K. Chaney
Keyword(s):  
Fatigue Damage ◽  
Wind Shear ◽  
Drive Train ◽  
Turbulence Level ◽  
Horizontal Axis Wind Turbine ◽  
Pitch Control ◽  
Wind Speeds ◽  
Blade Root ◽  
Turbulence Effects ◽  
Rigid Rotors

The effects of wind shear and turbulence on rotor fatigue and loads control are explored for a large horizontal axis wind turbine in variable speed operation at wind speeds from 4 to 20 m/s. Two- and three-blade rigid rotors are considered over a range of wind shear exponents up to 1.25 and a range of turbulence intensities up to 17%. RMS blade root flatwise moments are predicted to be very substantially increased at higher wind shear, and resultant fatigue damage is increased by many orders of magnitude. Smaller but similar trends occur with increasing turbulence levels. In-plane fatigue damage is driven by 1P gravity loads and exacerbated by turbulence level at higher wind speeds. This damage is higher by one to two orders of magnitude at the roots of the three-blade rotor compared with the two-blade rotor. Individual blade pitch control of fluctuating flatwise moments markedly reduces flatwise fatigue damage due to this source, and, to a lesser degree, the in-plane damage due to turbulence. The same is true of fluctuating rotor torque moments driven by turbulence and transmitted to the drive train. Blade root moments out of the plane of rotation aggregate to create rotor pitching and yawing moments transmitted to the turbine structure through the drive train to the yaw drive system and the tower. These moments are predicted to be relatively insensitive to turbulence level and essentially proportional to the wind shear exponent for the two-blade rotor. Fluctuating moments are substantially reduced with individual blade pitch control, and addition of a teeter degree-of-freedom should further contribute to this end. Fluctuating pitching and yawing moments of the three-blade rotor are substantially less sensitive to wind shear, more sensitive to turbulence level, and substantially lower than those for the two-blade rotor. Mean rotor torque and, hence, power are essentially the same for both rotors, independent of wind shear, and are somewhat reduced with individual blade pitch control of fluctuating flatwise moments. The same is true of mean rotor thrust; however fluctuations in rotor thrust are substantially reduced with individual blade pitch control.

Field testing of multi-variable individual pitch control on a utility-scale wind turbine

2021 ◽  
Vol 170 ◽  
pp. 1245-1256
Author(s):  
Daniel Ossmann ◽  
Peter Seiler ◽  
Christopher Milliren ◽  
Alan Danker
Keyword(s):  
Wind Turbine ◽  
Field Testing ◽  
Pitch Control ◽  
Utility Scale ◽  
Individual Pitch Control

Research on Joint Power and Loads Control for Large Scale Directly Driven Wind Turbines

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
JuChuan Dai ◽  
Deshun Liu ◽  
Yanping Hu ◽  
Xiangbing Shen
Keyword(s):  
Wind Turbines ◽  
Control Strategy ◽  
Pitch Angle ◽  
Large Scale ◽  
Synchronous Generator ◽  
Joint Power ◽  
Pitch Control ◽  
The Difference ◽  
The Individual ◽  
Individual Pitch Control

Emphasis of this article is on the dynamic characteristics analysis of individual pitch control for MW scale directly driven wind turbines with permanent magnet synchronous generator (PMSG). The pitch control objectives were analyzed and the objective expressions were deduced, including power expression, loads expression, and vibration expressions of blade and tower. Then, both the collective pitch control aiming at power control and the individual pitch control strategy aiming at joint power and loads control were analyzed, too. The blade root bending moments and the actual capture power of wind rotor were employed to be the control variables. The power was calculated based on the conventional measured parameters of wind turbines. In order to reflect the difference between the pitch angle command value and the actual value, the pitch actuator dynamic model was used. The research results show that both the collective pitch control strategy and the proposed individual pitch control strategy can effectively control the power injected into grid; moreover, the individual pitch control can reduce fatigue loads; while in the process of individual pitch control, the actual variation of blade pitch angle is closely related to not only the inflow speed but also the blade azimuth angle; individual pitch control strategy can reduce the variation amplitude of flapwise moments, but has little influence on the edgewise moments.

scholarly journals Wind Turbine Collective and Individual Pitch Control Using Quantitative Feedback Theory

2017 ◽  
Author(s):  
Laura H. Wheeler ◽  
Mario Garcia-Sanz
Keyword(s):  
Wind Turbine ◽  
Quantitative Feedback Theory ◽  
Harmonic Frequency ◽  
Mechanical Loads ◽  
Pitch Control ◽  
Wind Turbine Control ◽  
Mechanical Fatigue ◽  
Horizontal Axis Wind Turbines ◽  
The Individual ◽  
Individual Pitch Control

Individual pitch control is an innovative technique in wind turbine control. It has the potential of reducing the asymmetric mechanical loads on the blades in large multi-megawatt turbines. As the mechanical fatigue is reduced, the lifetime of the turbine can be significantly extended. This work develops an individual pitch control for the National Renewable Energy Laboratory’s (NREL) 5 MW reference wind turbine. The individual pitch controller works along with a collective pitch controller, designed using Quantitative Feedback Theory (QFT) robust control. Simulations of the complete individual and collective pitch control system are conducted with the NREL’s computer-aided engineering tool for horizontal axis wind turbines (FAST). They show that the addition of the individual pitch controller significantly reduces the loads on the tilt and yaw directions in the nacelle and tower of the turbine at 1P and 3P frequencies, and on the blades at the 2P harmonic frequency.

scholarly journals Implementation and Validation of an Advanced Wind Energy Controller in Aero-Servo-Elastic Simulations Using the Lifting Line Free Vortex Wake Model

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 783 ◽  
Author(s):  
Sebastian Perez-Becker ◽  
David Marten ◽  
Christian Navid Nayeri ◽  
Christian Oliver Paschereit
Keyword(s):  
Wind Turbine ◽  
Open Source ◽  
Control Strategy ◽  
Vortex Wake ◽  
Load Reduction ◽  
Free Vortex ◽  
Pitch Control ◽  
The Individual ◽  
Individual Pitch Control ◽  
Lifting Line

Accurate and reproducible aeroelastic load calculations are indispensable for designing modern multi-MW wind turbines. They are also essential for assessing the load reduction capabilities of advanced wind turbine control strategies. In this paper, we contribute to this topic by introducing the TUB Controller, an advanced open-source wind turbine controller capable of performing full load calculations. It is compatible with the aeroelastic software QBlade, which features a lifting line free vortex wake aerodynamic model. The paper describes in detail the controller and includes a validation study against an established open-source controller from the literature. Both controllers show comparable performance with our chosen metrics. Furthermore, we analyze the advanced load reduction capabilities of the individual pitch control strategy included in the TUB Controller. Turbulent wind simulations with the DTU 10 MW Reference Wind Turbine featuring the individual pitch control strategy show a decrease in the out-of-plane and torsional blade root bending moment fatigue loads of 14% and 9.4% respectively compared to a baseline controller.

The Realization of Individual Pitch Control

2013 ◽  
Vol 291-294 ◽  
pp. 477-480
Author(s):  
Lei Chen ◽  
Zhen Luo
Keyword(s):  
Pitch Angle ◽  
Control Algorithm ◽  
Bending Moment ◽  
Pitch Control ◽  
Blade Root ◽  
Pi Controllers ◽  
Out Of Plane ◽  
The Individual ◽  
Individual Pitch Control ◽  
Yaw Moment

This paper describes the classical individual pitch control algorithm. Firstly, transform the out-of-plane bending moment of each blade in the rotational coordinate to the hub loads proportional to the tilt and yaw moment in the fixed coordinate. Secondly, design the PI controllers to minimize the load. And then attach the increment pitch angle to the collective one. Simulations in the Bladed show that the individual pitch control can minimize the loads not only in hub tilt and yaw, but also in blade root.

Individual Pitch Control for Wind Turbine Load Reduction Including Wake Modeling

2010 ◽  
Author(s):  
Zhongzhou Yang ◽  
Yaoyu Li ◽  
John E. Seem
Keyword(s):  
Wind Turbine ◽  
Wind Profile ◽  
Load Reduction ◽  
Pitch Control ◽  
Wind Speeds ◽  
Speed Regulation ◽  
Wake Interaction ◽  
Wake Model ◽  
Asymmetric Load ◽  
Individual Pitch Control

Individual Pitch Control (IPC) can greatly benefit the load reduction for wind turbine above the rated power. This research investigates advanced IPC schemes with the wake interaction included. The Jensen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction, and a switched control strategy is thus developed based on the composite wind profile. The wind profile was generated by modifying the TurbSim codes. The state-space models of wind turbine were generated via FAST. Based on such model, individual pitch controllers were designed following the disturbance accommodating control (DAC) framework for regions of different wind speeds. Simulation results showed that the proposed switching DAC can better reject the wake induced asymmetric load than the single DAC, in addition to the rejection of wind shear disturbance, hub-height wind disturbance. The improvement was observed for rotor speed regulation and reduction in steady loads and fatigue loads in 2P of the tower-base yaw moment.

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