scholarly journals Prognostics-based adaptive control strategy for lifetime control of wind turbines

2021 ◽  
Author(s):  
Edwin Kipchirchir ◽  
Manh Hung Do ◽  
Jackson Githu Njiri ◽  
Dirk Söffker
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategy ◽  
Fatigue Loading ◽  
Operational Reliability ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Time Step ◽  
Damage Level ◽  
Structural Loading

Abstract. Variability of wind profiles in both space and time is responsible for fatigue loading in wind turbine components. Advanced control methods for mitigating structural loading in these components have been proposed in previous works. These also incorporate other objectives like speed and power regulation for above-rated wind speed operation. In recent years, lifetime control and extension strategies have been proposed to guaranty power supply and operational reliability of wind turbines. These control strategies typically rely on a fatigue load evaluation criteria to determine the consumed lifetime of these components, subsequently varying the control set-point to guaranty a desired lifetime of the components. Most of these methods focus on controlling the lifetime of specific structural components of a wind turbine, typically the rotor blade or tower. Additionally, controllers are often designed to be valid about specific operating points, hence exhibit deteriorating performance in varying operating conditions. Therefore, they are not able to guaranty a desired lifetime in varying wind conditions. In this paper an adaptive lifetime control strategy is proposed for controlled ageing of rotor blades to guaranty a desired lifetime, while considering damage accumulation level in the tower. The method relies on an online structural health monitoring system to vary the lifetime controller gains based on a State of Health (SoH) measure by considering the desired lifetime at every time-step. For demonstration, a 1.5 MW National Renewable Energy Laboratory (NREL) reference wind turbine is used. The proposed adaptive lifetime controller regulates structural loading in the rotor blades to guaranty a predefined damage level at the desired lifetime without sacrificing on the speed regulation performance of the wind turbine. Additionally, significant reduction in the tower fatigue damage is observed.

scholarly journals Modeling and simulation of forces applied to the horizontal axis wind turbine rotors by the vortex method coupled with the method of the blade element

2021 ◽  
Vol 12 (1) ◽  
pp. 413
Author(s):  
Ibtissem Barkat ◽  
Abdelouahab Benretem ◽  
Fawaz Massouh ◽  
Issam Meghlaoui ◽  
Ahlem Chebel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farms ◽  
Vortex Method ◽  
Operating Conditions ◽  
Horizontal Axis ◽  
Rotor Blades ◽  
Good Representation ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element

This article aims to study the forces applied to the rotors of horizontal axis wind turbines. The aerodynamics of a turbine are controlled by the flow around the rotor, or estimate of air charges on the rotor blades under various operating conditions and their relation to the structural dynamics of the rotor are critical for design. One of the major challenges in wind turbine aerodynamics is to predict the forces on the blade as various methods, including blade element moment theory (BEM), the approach that is naturally adapted to the simulation of the aerodynamics of wind turbines and the dynamic and models (CFD) that describes with fidelity the flow around the rotor. In our article we proposed a modeling method and a simulation of the forces applied to the horizontal axis wind rotors turbines using the application of the blade elements method to model the rotor and the vortex method of free wake modeling in order to develop a rotor model, which can be used to study wind farms. This model is intended to speed up the calculation, guaranteeing a good representation of the aerodynamic loads exerted by the wind.

Model-Inversion Feedforward Control for Wave Load Reduction in Floating Wind Turbines

2021 ◽  
Author(s):  
Alessandro Fontanella ◽  
Marco Belloli
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategy ◽  
Feedforward Control ◽  
Operating Conditions ◽  
Offshore Wind ◽  
Linear Wave ◽  
Wave Load ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines

Abstract This paper develops a novel feedforward control strategy for reducing structural loads caused by waves in floating offshore wind turbines. The proposed control strategy is based on the inversion of a linear model of the floating wind turbine, and a real-time forecast of the wave obtained from an upstream measurement is utilized to compute a collective pitch control action. Two feedforward controllers are considered: one is designed to cancel the rotor speed oscillations and one to lower the towertop fore-aft shear force. The feedforward control strategies are implemented in a 10MW floating wind turbine, complementing the standard feedback controller for generator speed regulation. Numerical simulations are carried out in FAST, in four operating conditions with realistic wind and waves, proving the proposed feedforward controller effectively mitigates the structural loads caused by waves. In detail, the feedforward action reduces the loads spectra in the frequency range where linear wave is active. The best performance is realized higher winds (the FA force is reduced up to 25% in 22 m/s wind), where the wave excitation is the strongest.

scholarly journals Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5564
Author(s):  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
Michele Messina ◽  
Sebastian Brusca
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Time Step ◽  
Vertical Axis Wind Turbines ◽  
2D Model

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

scholarly journals Monitoring Wind Turbine Gearbox with Echo State Network Modeling and Dynamic Threshold Using SCADA Vibration Data

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 982 ◽  
Author(s):  
Xin Wu ◽  
Hong Wang ◽  
Guoqian Jiang ◽  
Ping Xie ◽  
Xiaoli Li
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Operating Conditions ◽  
Dynamic Threshold ◽  
Detection Accuracy ◽  
Echo State Network ◽  
Monitoring Method ◽  
Vibration Data ◽  
Static Monitoring ◽  
Threshold Monitoring

Health monitoring of wind turbine gearboxes has gained considerable attention as wind turbines become larger in size and move to more inaccessible locations. To improve the reliability, extend the lifetime of the turbines, and reduce the operation and maintenance cost caused by the gearbox faults, data-driven condition motoring techniques have been widely investigated, where various sensor monitoring data (such as power, temperature, and pressure, etc.) have been modeled and analyzed. However, wind turbines often work in complex and dynamic operating conditions, such as variable speeds and loads, thus the traditional static monitoring method relying on a certain fixed threshold will lead to unsatisfactory monitoring performance, typically high false alarms and missed detections. To address this issue, this paper proposes a reliable monitoring model for wind turbine gearboxes based on echo state network (ESN) modeling and the dynamic threshold scheme, with a focus on supervisory control and data acquisition (SCADA) vibration data. The aim of the proposed approach is to build the turbine normal behavior model only using normal SCADA vibration data, and then to analyze the unseen SCADA vibration data to detect potential faults based on the model residual evaluation and the dynamic threshold setting. To better capture temporal information inherent in monitored sensor data, the echo state network (ESN) is used to model the complex vibration data due to its simple and fast training ability and powerful learning capability. Additionally, a dynamic threshold monitoring scheme with a sliding window technique is designed to determine dynamic control limits to address the issue of the low detection accuracy and poor adaptability caused by the traditional static monitoring methods. The effectiveness of the proposed monitoring method is verified using the collected SCADA vibration data from a wind farm located at Inner Mongolia in China. The results demonstrated that the proposed method can achieve improved detection accuracy and reliability compared with the traditional static threshold monitoring method.

Study on a global control strategy for rotation speed with different work states in variable-speed constant-frequency wind turbines

2011 ◽  
Vol 225 (7) ◽  
pp. 968-976 ◽  
Author(s):  
G Zheng ◽  
H Xu ◽  
X Wang ◽  
J Zou
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategy ◽  
Control Strategies ◽  
Stable Operation ◽  
Constant Frequency ◽  
Global Control ◽  
Control Rules ◽  
The Individual ◽  
And Control

This paper studies the operation of wind turbines in terms of three phases: start-up phase, power-generation phase, and shutdown phase. Relationships between the operational phase and control rules for the speed of rotation are derived for each of these phases. Taking into account the characteristics of the control strategies in the different operational phases, a global control strategy is designed to ensure the stable operation of the wind turbine in all phases. The results of simulations are presented that indicate that the proposed algorithm can control the individual phases when considered in isolation and also when they are considered in combination. Thus, a global control strategy for a wind turbine that is based on a single algorithm is presented which could have significant implications on the control and use of wind turbines.

Importance of Shear in Site Assessment of Wind Turbine Fatigue Loads

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
René M. M. Slot ◽  
Lasse Svenningsen ◽  
John D. Sørensen ◽  
Morten L. Thøgersen
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Reliability ◽  
Turbine Blades ◽  
Structural Response ◽  
Fatigue Loading ◽  
Worst Case ◽  
Shear Model ◽  
Wind Climate

Wind turbines are subjected to fatigue loading during their entire lifetime due to the fluctuating excitation from the wind. To predict the fatigue damage, the design standard IEC 61400-1 describes how to parametrize an on-site specific wind climate using the wind speed, turbulence, wind shear, air density, and flow inclination. In this framework, shear is currently modeled by its mean value, accounting for neither its natural variance nor its wind speed dependence. This very simple model may lead to inaccurate fatigue assessment of wind turbine components, whose structural response is nonlinear with shear. Here we show how this is the case for flapwise bending of blades, where the current shear model leads to inaccurate and in worst case nonconservative fatigue assessments. Based on an optimization study, we suggest modeling shear as a wind speed dependent 60% quantile. Using measurements from almost one hundred sites, we document that the suggested model leads to accurate and consistent fatigue assessments of wind turbine blades, without compromising other main components such as the tower and the shaft. The proposed shear model is intended as a replacement to the mean shear, and should be used alongside the current IEC models for the remaining climate parameters. Given the large number of investigated sites, a basis for evaluating the uncertainty related to using a simplified statistical wind climate is provided. This can be used in further research when assessing the structural reliability of wind turbines by a probabilistic or semiprobabilistic approach.

scholarly journals Numerical study of various geometries of breakwaters for the installation of floating wind turbines

2016 ◽  
Vol 13 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Keyvan Esmaeelpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Rasoul Bayani
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Numerical Study ◽  
Energy Resources ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Renewable Energy Resources ◽  
Time Step ◽  
Set Up ◽  
The Right

The everyday growing populations all over the world and the necessity of increase in consumption of fossil energies have made the human to discover new energy resources, which are clean, cheap and renewable. Wind energy is one of the renewable energy resources. Considerable wind speed has made settling of wind turbines at sea beneficial and appealing. For this purpose, choosing the appropriate plates to set up wind turbines on the surface of sea is necessary. Regarding the installation condition, by choosing suitable geometry for floating breakwaters, offshore wind turbine can be mounted on them. Suitable geometry of breakwater for multifunctional usage could be selected with analyzing and comparing pressure, force and moment produced by incoming waves. In this article, we implement boundary element method to solve governing differential equations by assuming potential flow. On the other hand, for promoting free surface in each time step, we employed Euler-Lagrangian method. Finally, to find the appropriate geometry for installing the wind turbine on the breakwater, moment and wave profile next to the right and left side of breakwater body are calculated. Among simulated geometries, breakwater with trapezoid geometry which its larger base is placed in the water has more sustainability and it is the most suitable geometry for wind turbine installation.

Dynamic Load Response Analysis on Yaw Bearing of Wind Turbine to Turbulent Wind

2019 ◽  
Author(s):  
Jianwen Xu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Gumbel Distribution ◽  
Operating Conditions ◽  
Likelihood Method ◽  
Coupled Analysis ◽  
Response Analysis ◽  
Turbulent Wind ◽  
Load Response ◽  
Yaw Bearing

Abstract Wind turbines are subjected to dynamic loads during their service life. The yaw bearing is an important part which also bears these loads. In this study, a series of 5-megawatt (MW) wind turbines are analyzed for their dynamic response under normal operating conditions while exposed to turbulent wind. These models are Onshore, Monopile, ITI Barge, Spar, Tension-Leg Platform (TLP), Semi-Submerisible. TurbSim is used to prescribe turbulent-wind inflow and a time domain FAST code is applied in order to conduct the Aero-Hydro-Servo-Elastic coupled analysis on the yaw loads of the wind turbines. Three different average wind velocities are examined to compare the load response of the wind turbine to turbulent wind on the yaw bearing. A Gumbel distribution coupled maximum likelihood method is used to predict ultimate loads. And the rain flow counting algorithm, the linear cumulative damage law and S-N curve theory are used to predict the damage equivalent load. The results should aid the fatigue design of yaw bearing and the yaw control system according to different wind turbine design.

Experimental Comparison of Three Floating Wind Turbine Concepts

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Andrew J. Goupee ◽  
Bonjun J. Koo ◽  
Richard W. Kimball ◽  
Kostas F. Lambrakos ◽  
Habib J. Dagher
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Operating Conditions ◽  
Scale Model ◽  
Experimental Comparison ◽  
System Response ◽  
Advantages And Disadvantages ◽  
Floating Wind Turbine ◽  
Wind Resource

Beyond many of Earth's coasts exists a vast deepwater wind resource that can be tapped to provide substantial amounts of clean, renewable energy. However, much of this resource resides in waters deeper than 60 m where current fixed bottom wind turbine technology is no longer economically viable. As a result, many are looking to floating wind turbines as a means of harnessing this deepwater offshore wind resource. The preferred floating platform technology for this application, however, is currently up for debate. To begin the process of assessing the unique behavior of various platform concepts for floating wind turbines, 1/50th scale model tests in a wind/wave basin were performed at the Maritime Research Institute Netherlands (MARIN) of three floating wind turbine concepts. The Froude scaled tests simulated the response of the 126 m rotor diameter National Renewable Energy Lab (NREL) 5 MW, horizontal axis Reference Wind Turbine attached via a flexible tower in turn to three distinct platforms, these being a tension leg-platform, a spar-buoy, and a semisubmersible. A large number of tests were performed ranging from simple free-decay tests to complex operating conditions with irregular sea states and dynamic winds. The high-quality wind environments, unique to these tests, were realized in the offshore basin via a novel wind machine, which exhibited low swirl and turbulence intensity in the flow field. Recorded data from the floating wind turbine models include rotor torque and position, tower top and base forces and moments, mooring line tensions, six-axis platform motions, and accelerations at key locations on the nacelle, tower, and platform. A comprehensive overview of the test program, including basic system identification results, is covered in previously published works. In this paper, the results of a comprehensive data analysis are presented, which illuminate the unique coupled system behavior of the three floating wind turbines subjected to combined wind and wave environments. The relative performance of each of the three systems is discussed with an emphasis placed on global motions, flexible tower dynamics, and mooring system response. The results demonstrate the unique advantages and disadvantages of each floating wind turbine platform.

Comparison of the Frequency Control Strategy of Wind Turbines and its Optimization Scheme

2012 ◽  
Vol 608-609 ◽  
pp. 494-499 ◽  
Author(s):  
Xin Shou Tian ◽  
Yue Hui Huang ◽  
Xiao Yan Xu ◽  
Wei Sheng Wang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategy ◽  
Control Method ◽  
Frequency Control ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Optimization Scheme ◽  
Typical Frequency ◽  
General Method

In order to improve the frequency stability of grid, new control strategy for wind turbines need to be developed with high wind power penetration. This work analyzes the requirements of frequency control for wind turbines in some countries, and the characteristics and methods of typical frequency control strategy are analyzed. To meet the requirements of frequency control of wind turbine and to improve wind energy utilization efficiency, a method of optimization scheme of frequency control on wind turbine is given in the paper, and the operating curve of wind turbine with the control method is determined, at the same time this work gives a general method about how to determine some key parameters.

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