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Advancement in Wind Turbine Technology

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A3: Wind, Wave and Tidal Energy".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 36072

Special Issue Editor

School of Engineering, Robert Gordon University, Aberdeen AB10 7GJ, UK
Interests: computational fluid dynamics; pipeline engineering; multiphase flows; valve engineering; automotive engineering; aerodynamics & hydrodynamics; turbomachinery; renewable energy

Special Issue Information

Dear Colleagues,

Wind turbines are playing a key role in providing clean energy around the world, harnessing onshore and offshore wind energy. The efficient operation of wind turbines is determined by a number of factors such as design, energy extraction, installation, maintenance etc. This journal aims to address the current challenges the wind turbines sector is facing by providing innovative solutions and reporting advances in wind turbine technology from all those with an interest in this field. Contributions across a wide spectrum of scientific and engineering disciplines concerned with technological developments in wind power generation, energy conversion and integration are of great importance for the journal.

This Special Issue seeks to disseminate knowledge on various aspects of the modelling and analysis of wind turbines and to promote fundamental, multidisciplinary and applied research. This Special Issue offers a major opportunity for reporting advancements in wind turbine technologies for realizing the worldwide potential to harness wind energy onshore and offshore. This Special Issue covers, but is not limited to, a wide range of topics, including:

  • Wind farms
  • Digital twins
  • Cost modelling
  • Wake dynamics
  • Control mechanisms
  • Reduced-order modelling
  • Wind-resource estimation
  • Applications and economics
  • Aeroelasticity and aeroacoustics
  • Environmental and legal aspects
  • The estimation of remaining useful life
  • The aerodynamics of rotors and blades
  • Installation and condition monitoring
  • Power generation, storage and transmission
  • Novel wind-turbine designs and optimisation
  • Analytical, empirical and numerical modelling

Dr. Taimoor Asim
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (19 papers)

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Research

16 pages, 14563 KiB  
Article
Primary Frequency Regulation Strategy Based on Rotor Kinetic Energy of Double-Fed Induction Generator and Supercapacitor
by Renting Ma, Shitong Yuan, Xianwei Li, Shuying Guan, Xiangwu Yan and Jiaoxin Jia
Energies 2024, 17(2), 331; https://0-doi-org.brum.beds.ac.uk/10.3390/en17020331 - 09 Jan 2024
Viewed by 491
Abstract
To address the challenge of wind turbines meeting primary frequency regulation requirements, incorporating energy storage devices to handle most of the frequency regulation tasks would result in increased operational costs. When a wind turbine rotor accelerates, it deviates from the maximum power tracking [...] Read more.
To address the challenge of wind turbines meeting primary frequency regulation requirements, incorporating energy storage devices to handle most of the frequency regulation tasks would result in increased operational costs. When a wind turbine rotor accelerates, it deviates from the maximum power tracking point (MPPT), leading to reduced output while retaining significant rotational kinetic energy. Based on this characteristic, a primary frequency regulation strategy is proposed that coordinates the rotor kinetic energy of a double-fed induction generator (DFIG) with supercapacitors (SCs). Supercapacitors provide power support during low-frequency conditions, while accelerating the wind turbine rotor reduces output during high-frequency conditions. Additionally, continuous attention is given to subsequent frequency changes. In case of short-term, low-frequency conditions, stored kinetic energy is released for power support, establishing a mechanism for wind turbine kinetic energy recovery and release. This mechanism reduces charging and discharging requirements for supercapacitors, extends their service life, and considers both wind turbine frequency regulation requirements and economy. Finally, using MATLAB 2020/Simulink platform allows for the verification of the effectiveness and rationality of this proposed method. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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19 pages, 8871 KiB  
Article
Dynamic Performance of Monopile-Supported Wind Turbines (MWTs) under Different Operating and Ground Conditions
by Shaohui Xiao, Hongjun Liu and Kun Lin
Energies 2024, 17(1), 112; https://0-doi-org.brum.beds.ac.uk/10.3390/en17010112 - 24 Dec 2023
Viewed by 526
Abstract
A monopile is the most popular foundation type for wind turbines. However, the dynamic performance of monopile-supported wind turbines under different operating and ground conditions is not fully understood. In this study, an integrated monopile-supported wind turbine model in a wind tunnel was [...] Read more.
A monopile is the most popular foundation type for wind turbines. However, the dynamic performance of monopile-supported wind turbines under different operating and ground conditions is not fully understood. In this study, an integrated monopile-supported wind turbine model in a wind tunnel was employed to jointly simulate the operating and ground conditions. A series of wind tunnel tests were designed and performed to investigate the dynamic performance of monopile-supported wind turbines. These tests included seven operating conditions (seven wind speeds and corresponding rotor speeds) and four ground conditions (one fixed ground condition and three deformable ground conditions with different soil relative densities). According to the test results, the structural responses and dynamic characteristics were analyzed and discussed. This shows that the assumption of fixed-base support significantly overestimates the natural frequency but underestimates the global damping ratio. With the increase in soil relative density, the natural frequency slightly increases, while the damping ratio decreases more significantly. With the increase in the wind speed and rotor speed, the increase in global damping is larger on softer ground. A regression analysis was performed to estimate the global damping ratio under different operating and ground conditions. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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18 pages, 5694 KiB  
Article
Study on the Pitch Angle Effect on the Power Coefficient and Blade Fatigue Load of a Vertical Axis Wind Turbine
by Wenxing Hao, Abdulshakur Abdi, Guobiao Wang and Fuzhong Wu
Energies 2023, 16(21), 7279; https://0-doi-org.brum.beds.ac.uk/10.3390/en16217279 - 26 Oct 2023
Viewed by 843
Abstract
For vertical axis wind turbines (VAWTs), the increase of the incoming wind speed higher than the rated value will make the tip speed ratio (TSR) lower and lower, resulting in the blade fatigue load becoming more and more severe and the power coefficient [...] Read more.
For vertical axis wind turbines (VAWTs), the increase of the incoming wind speed higher than the rated value will make the tip speed ratio (TSR) lower and lower, resulting in the blade fatigue load becoming more and more severe and the power coefficient weakening gradually. This paper explores whether varying the pitch with the TSR decrease is necessary for improving the power coefficient and reducing the fatigue load. Specifically, the pitch angle effect on the power coefficient and fatigue load of a VAWT at different TSRs was studied by the computational fluid dynamics method. The results show that the optimal pitch angle in terms of the power coefficient varies with the TSR, which means that varying the pitch with the TSR decrease can improve the power coefficient. Meanwhile, the principle to guide the pitch variation is to avoid flow separation in the downwind zone and minimize the angles of attack (AoAs) in the upwind zone. At the lowest TSR of 1.7 in the present work, varying the pitch from the optimal one in terms of the power coefficient reduced the blade normal force amplitude significantly, which is mainly attributed to avoiding the vortex–blade encounter and minimizing the AoAs in the downwind zone. The vortex–blade encounter at the lowest TSR is an important phenomenon related to the variation of the blade torque and blade normal force and will weaken and disappear with the pitch angle increase. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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14 pages, 5200 KiB  
Article
Experimental Analysis of Oscillatory Vortex Generators in Wind Turbine Blade
by Hector G. Parra, Hernan D. Ceron, William Gomez and Elvis E. Gaona
Energies 2023, 16(11), 4343; https://0-doi-org.brum.beds.ac.uk/10.3390/en16114343 - 26 May 2023
Viewed by 1281
Abstract
Vortex generators are devices that modify the wind behavior near the surface of wind turbine blades. Their use allows the boundary layer shedding transition zone to be varied. Bio-inspired design has been used to improve the efficiency of aerodynamic and hydrodynamic systems by [...] Read more.
Vortex generators are devices that modify the wind behavior near the surface of wind turbine blades. Their use allows the boundary layer shedding transition zone to be varied. Bio-inspired design has been used to improve the efficiency of aerodynamic and hydrodynamic systems by creating devices that use shapes present in animals and plants. In this work, an experimental methodology is proposed to study the effect of bio-inspired vortex generators and their effect on the structural vibration of a blade. In addition, the wind wake generated by the blade with oscillating vortex generators at different oscillation frequencies is analyzed by means of a hot wire anemometer, obtaining appreciable vibration reduction results in the measured 3D acceleration signals for wind velocities between 10 and 15 m/s. Values of the spectral components of the wake velocity measured at higher tunnel wind velocities increase. Spectral variance is reduced at higher tunnel wind velocities. The system analyzed in this paper can contribute in the future to the construction of actuators for vibration compensation systems in wind turbines. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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17 pages, 3528 KiB  
Article
Analysis of DFIG Interval Oscillation Based on Second-Order Sliding Film Damping Control
by Qi Liu, Jiahui Wu, Haiyun Wang, Hua Zhang and Jian Yang
Energies 2023, 16(7), 3091; https://0-doi-org.brum.beds.ac.uk/10.3390/en16073091 - 28 Mar 2023
Viewed by 868
Abstract
This paper takes advantage of the high control flexibility and fast response time of the interfacing power electronic converter for doubly fed wind turbine grid-connected systems to address inter-area oscillations caused by inadequate system damping in power systems. A reactive-power-coordinated damping controller for [...] Read more.
This paper takes advantage of the high control flexibility and fast response time of the interfacing power electronic converter for doubly fed wind turbine grid-connected systems to address inter-area oscillations caused by inadequate system damping in power systems. A reactive-power-coordinated damping controller for a doubly fed induction generator (DFIG) is proposed, and it makes use of second-order sliding-mode technology. The suggested controller improves damping performance by controlling the reactive power. It provides benefits such as a quicker damping rate and resilience to modeling errors and parameter changes. The simulation results indicate the system’s improved performance in inter-area oscillation damping and the robustness of the suggested control technique over a broad range of functional areas. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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17 pages, 9678 KiB  
Article
A Wind Turbine Vibration Monitoring System for Predictive Maintenance Based on Machine Learning Methods Developed under Safely Controlled Laboratory Conditions
by David Pérez Granados, Mauricio Alberto Ortega Ruiz, Joel Moreira Acosta, Sergio Arturo Gama Lara, Roberto Adrián González Domínguez and Pedro Jacinto Páramo Kañetas
Energies 2023, 16(5), 2290; https://0-doi-org.brum.beds.ac.uk/10.3390/en16052290 - 27 Feb 2023
Cited by 2 | Viewed by 2321
Abstract
Wind energy is one of the most relevant clean energies today, so wind turbines must have good health and be reliable in operation. Current wind turbines have slender and elastic structures that can be easily damaged through vibrations and compromise their health; therefore, [...] Read more.
Wind energy is one of the most relevant clean energies today, so wind turbines must have good health and be reliable in operation. Current wind turbines have slender and elastic structures that can be easily damaged through vibrations and compromise their health; therefore, vibration monitoring is essential to ensure safe operation. Here, we present a method for simple wind turbine vibration monitoring in the laboratory by means of an accelerometer placed on a weathervane under different scenarios, with recording of different amplitudes of vibrations caused at a constant speed of 10 km/h. The variables, trends, and data captured during vibration monitoring were then used to implement a prediction system of synthetic failure using machine learning methods such as: Medium Trees, Cubic SVN, Logistic Regression Kernel, Optimized Neural Network, and Bagged Trees, with the last demonstrating an accuracy of up to 0.87%. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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15 pages, 6523 KiB  
Article
Integrated Design and Experimental Validation of a Fixed-Pitch Rotor for Wind Tunnel Testing
by Alessandro Fontanella, Giulia Da Pra and Marco Belloli
Energies 2023, 16(5), 2205; https://0-doi-org.brum.beds.ac.uk/10.3390/en16052205 - 24 Feb 2023
Cited by 3 | Viewed by 1192
Abstract
In this paper we report about the design and validation of a 1.2 m wind turbine rotor with fixed blade pitch. The wind turbine is a scaled version of the DTU 10 MW. Integrated design of dimensional scaling laws, blade aerodynamics, and turbine [...] Read more.
In this paper we report about the design and validation of a 1.2 m wind turbine rotor with fixed blade pitch. The wind turbine is a scaled version of the DTU 10 MW. Integrated design of dimensional scaling laws, blade aerodynamics, and turbine control is carried out to reproduce blade loading and interaction with atmospheric boundary layer of the reference turbine, despite challenges posed by the great reduction in chord-based Reynolds number. The rotor is verified with numerical simulations in OpenFAST and wind tunnel testing. The servo-aerodynamic design approach proposed in this article is shown to be successful for small-scale wind turbine models for use in experiments about wakes and floating wind. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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26 pages, 2067 KiB  
Article
Life Cycle Assessment of Various PMSG-Based Drivetrain Concepts for 15 MW Offshore Wind Turbines Applications
by Farid Khazaeli Moghadam and Nils Desch
Energies 2023, 16(3), 1499; https://0-doi-org.brum.beds.ac.uk/10.3390/en16031499 - 02 Feb 2023
Cited by 4 | Viewed by 2300
Abstract
There are different configurations selected by both industry and academia as the drivetrain for wind turbines in the power range of 10 to 16 MW. The choice of drivetrain system influences the levelized cost of energy, and, as the turbines become larger, and, [...] Read more.
There are different configurations selected by both industry and academia as the drivetrain for wind turbines in the power range of 10 to 16 MW. The choice of drivetrain system influences the levelized cost of energy, and, as the turbines become larger, and, therefore, costlier, there is more potential for the optimization of cost critical systems, like the drivetrain. The latter motivates the utilization of a life cycle assessment approach to profoundly influence the choice of drivetrain technology such that it offers a better compromise between the different aspects in the drivetrain life cycle. To this end, in this paper, various permanent magnet synchronous generator (PMSG)-based drivetrain technologies for 15 MW bottom-fixed and floating offshore wind turbine applications are designed and compared. The technologies under investigation are based on direct-drive, medium- and high-speed generators. The conceptual design of the drivetrain for the three technologies under consideration is investigated and the pros and cons of each technology are assessed and explained by looking, simultaneously, into the design, manufacturing, operation and maintenance. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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25 pages, 19038 KiB  
Article
3D CFD Modelling of Performance of a Vertical Axis Turbine
by Cameron Gerrie, Sheikh Zahidul Islam, Sean Gerrie, Naomi Turner and Taimoor Asim
Energies 2023, 16(3), 1144; https://0-doi-org.brum.beds.ac.uk/10.3390/en16031144 - 20 Jan 2023
Cited by 6 | Viewed by 2307
Abstract
Recently, wind turbine research has switched focus to vertical axis wind turbines due to the extensive research that has been performed on horizontal axis wind turbines and the potential of vertical axis wind turbines in built-up areas. This study aims to analyse the [...] Read more.
Recently, wind turbine research has switched focus to vertical axis wind turbines due to the extensive research that has been performed on horizontal axis wind turbines and the potential of vertical axis wind turbines in built-up areas. This study aims to analyse the performance of a small-scale hybrid vertical axis wind turbine that can switch from functioning as a Darrieus (lift) turbine to a Savonius (drag) turbine by rotating the blades. The turbine was analysed using 3D computational fluid dynamics (CFD) simulations in ANSYS Fluent as the primary method, and the findings were verified using wind tunnel experiments. During the analysis, design parameters such as the blade length, diameter, and number of blades were varied to determine if the design had room for improvement. It was found that the current design of the turbine has an optimal efficiency of 12.5% in the Darrieus configuration, which was found to increase when the diameter or blade length was increased. The Savonius configuration was found to be more efficient at low tip-speed ratios (<0.14), and its efficiency could be increased by adding more blades. The experiments found similar trends to the simulations; however, the efficiencies obtained were on average a tenfold increase from the simulation. Implementing the changes that increased efficiency leads to an increased wake recovery distance, making it less suitable for use in a wind farm. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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15 pages, 3506 KiB  
Article
Design and Validation of Pitch H-Infinity Controller for a Large Wind Turbine
by Yuan Song, Taesu Jeon, Insu Paek and Bayasgalan Dugarjav
Energies 2022, 15(22), 8763; https://0-doi-org.brum.beds.ac.uk/10.3390/en15228763 - 21 Nov 2022
Cited by 4 | Viewed by 1476
Abstract
In this study, a pitch H-infinity control algorithm was developed for variable-speed–variable-pitch (VSVP) wind turbines to improve the rotor standard deviation of the wind turbines under normal and extreme wind conditions. The pitch H-infinity control algorithm only uses H-infinity control in the blade [...] Read more.
In this study, a pitch H-infinity control algorithm was developed for variable-speed–variable-pitch (VSVP) wind turbines to improve the rotor standard deviation of the wind turbines under normal and extreme wind conditions. The pitch H-infinity control algorithm only uses H-infinity control in the blade pitch control loop in the rated power region, and conventional torque gain scheduling algorithms are applied in the partial power region. The performance of this controller was verified using simulations of a 5 MW wind turbine using the commercial aeroelastic simulation code Bladed. The performance of the pitch H-infinity controller was compared with that of the conventional proportional-integral (PI) control algorithm under three different operating conditions: normal operating conditions without sensor noise, normal operating conditions with sensor noise, and extreme operating conditions without sensor noise based on the wind turbine design standard by IEC. Based on the simulation results with two different wind speed regions, namely, the transition region and the rated power region, it was found that the proposed pitch H-infinity controller showed better rotor speed standard deviation performance in the three operating conditions and achieved lower standard deviations of the rotor speed and the electrical power without affecting the mean electrical power. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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18 pages, 4941 KiB  
Article
Improvements to and Experimental Validation of PI Controllers Using a Reference Bias Control Algorithm for Wind Turbines
by Taesu Jeon, Dongmyoung Kim and Insu Paek
Energies 2022, 15(21), 8298; https://0-doi-org.brum.beds.ac.uk/10.3390/en15218298 - 07 Nov 2022
Cited by 3 | Viewed by 1272
Abstract
In this study, a reference bias control (RBC) algorithm for variable speed and variable pitch wind turbines was designed and validated. To improve the performance of conventional PI control algorithms, the RBC algorithm applies biased references to power and pitch angle to the [...] Read more.
In this study, a reference bias control (RBC) algorithm for variable speed and variable pitch wind turbines was designed and validated. To improve the performance of conventional PI control algorithms, the RBC algorithm applies biased references to power and pitch angle to the pitch and the torque control loops, respectively. To validate the control performance of the improved RBC algorithm, hardware in the loop simulator (HILS) was conducted using a commercial programmable logic controller (PLC). The performance of a conventional PI control algorithm and the proposed RBC algorithm were compared for the target wind turbine model in terms of both the transition region and the rated power region. In the transition region, the proposed RBC algorithm improved the sudden dips in the generator torque and power, which often occur when using a control algorithm with a switching logic. As a result, the damage equivalent load (DEL) of the main shaft was reduced by 15%. In the rated power region, the rotor speed deviation was reduced by 22% and the power deviation was reduced by 21%. To experimentally validate the control performance and applicability of the RBC algorithm, wind tunnel testing using a wind turbine scaled model was additionally performed. Similarly to the HILS testing result, it was confirmed that the DEL of the main shaft and fluctuation of the rotor speed and power decreased with the proposed RBC algorithm. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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15 pages, 4793 KiB  
Article
Aerodynamic Performance Analysis of Adaptive Drag-Lift Hybrid Type Vertical Axis Wind Turbine
by Qiang Gao, Shuai Lian and Hongwei Yan
Energies 2022, 15(15), 5600; https://0-doi-org.brum.beds.ac.uk/10.3390/en15155600 - 02 Aug 2022
Cited by 4 | Viewed by 1709
Abstract
In recent years, with the continuous development of new energy, how to efficiently use wind energy has received more and more market attention. Due to cost advantages, the development of small wind turbines is accelerating. Among them, the design and research of the [...] Read more.
In recent years, with the continuous development of new energy, how to efficiently use wind energy has received more and more market attention. Due to cost advantages, the development of small wind turbines is accelerating. Among them, the design and research of the airfoil design and research of the lift vertical axis wind turbine has matured, but because of the aerodynamic characteristics of the lift airfoil structure, it is impossible to start itself at low wind speed, resulting in the waste of low wind speed energy. Although the drag wind turbine has good self-starting performance, the wind energy utilization efficiency in the high-speed state is inefficient. Each has its own unique shortcomings, which directly affects the marketization of small wind turbines. In order to solve these problems, this paper presents a drag-lift hybrid type wind turbine structure based on an NACA0018 symmetrical airfoil, which can adaptively change the blade shape. This design can keep the blade in the drag shape under static and low speed conditions, and adaptively change the lift shape with the increase of speed. In addition, through the research method of CFD numerical simulation combined with physical experiments, the proposed wind turbine design is studied and analyzed from multiple angles. At the same time, the “6DOF + dynamic grid” setting is used to study the influence of the opening angle factor of the drag-lift hybrid blade on the self-starting performance, and the study shows that the design of the drag-lift hybrid blade proposed in this paper has a higher self-starting torque and lower starting wind speed than the traditional lifting blade, and it is observed that the drag-lift hybrid blade has the best self-starting performance when the opening angle of the blade is 80°. At the same time, the problem of switching the blade morphology of the drag-lift hybrid blade is also analyzed, along with how to use the spring to control all this adaptively. In order to better analyze the advantages of the drag-lift hybrid design proposed in this paper, a wind tunnel test was also carried out using the physical model, and the relationship between the leaf tip speed ratio and the wind energy utilization rate was obtained, which intuitively showed the improvement of the wind energy utilization rate of the drag-lift hybrid design compared with the traditional lift blade. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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16 pages, 5240 KiB  
Article
Dynamics and Control of an Energy-Efficient, Power-Regenerative, Hydrostatic Wind Turbine Dynamometer
by Biswaranjan Mohanty and Kim A. Stelson
Energies 2022, 15(8), 2868; https://0-doi-org.brum.beds.ac.uk/10.3390/en15082868 - 14 Apr 2022
Cited by 1 | Viewed by 1478
Abstract
Dynamometers are used to evaluate the real-world performances of drivetrains in various loading conditions. Due to its superior power density, high bandwidth, and design flexibility, a hydrostatic power-regenerative dynamometer is an ideal candidate for hydrostatic wind turbine transmission testing. A dynamometer can emulate [...] Read more.
Dynamometers are used to evaluate the real-world performances of drivetrains in various loading conditions. Due to its superior power density, high bandwidth, and design flexibility, a hydrostatic power-regenerative dynamometer is an ideal candidate for hydrostatic wind turbine transmission testing. A dynamometer can emulate the wind turbine rotor dynamics and allow the investigation of the performance of a unique hydrostatic drivetrain without actually building the physical system. The proposed dynamometer is an energy-efficient system with counter-intuitive control challenges. This paper presents the dynamics, control synthesis, and experimental validation of a power-regenerative hydrostatic dynamometer. A fourth-order non-linear model with three inputs was formulated for the dynamometer. The strength of input–output couplings was identified, and two different decoupling controllers were designed and implemented. During wind turbine testing, the synchronous generator turns at a constant speed and the system model is linear. A steady-state decoupling controller was developed for independent control of the drive and transmission. The implemented decoupling controller demonstrated a negligible change in rotor speed for a 40 bar step increase in pressure, but a 20 bar pressure spike for a 4 rpm step change in rotor speed. However, during starting and stopping, the synchronous generator speed is not constant, and the system model is nonlinear. Therefore, a steady-state decoupling controller will not work. Thus, a decentralized controller with feed-forward control and gain scheduling was designed and implemented. A reference command was designed to avoid cavitation, pressure spikes, and power flow reversal during start-up. The experimental results show precise tracking in steady-state and transient operations. The decentralized controller demonstrated a negligible change in rotor speed for a 40 bar step increase in pressure but a 100 bar pressure spike for a 4 rpm step increase in rotor speed. The pressure spike was reduced by 80 bar with the implementation of feed-forward gain. The proposed electro-hydro-mechanical system requires less power and has the potential to reduce energy expenditure by 50%. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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19 pages, 5700 KiB  
Article
Along-Wind Aerodynamic Damping of Wind Turbine Towers: Determination by Wind Tunnel Tests and Impact on Tower Lifetime
by Robert Fontecha, Frank Kemper, Markus Feldmann, Stefan Witter and Ralf Schelenz
Energies 2022, 15(6), 1984; https://0-doi-org.brum.beds.ac.uk/10.3390/en15061984 - 09 Mar 2022
Cited by 2 | Viewed by 1914
Abstract
As wind turbines become larger and their towers more slender, aeroelastic effects play a bigger role in the wind turbine’s dynamic behavior. This study focuses on the along-wind aerodynamic damping of wind turbine towers, which has been determined by wind tunnel experiments using [...] Read more.
As wind turbines become larger and their towers more slender, aeroelastic effects play a bigger role in the wind turbine’s dynamic behavior. This study focuses on the along-wind aerodynamic damping of wind turbine towers, which has been determined by wind tunnel experiments using the forced oscillation method according to Steckley’s approach. Reynolds number scale effects have been considered through surface roughness modifications using sand paper and a dimple pattern, which have been described in detail. The wind tunnel measurements are performed in sub-critical, critical and trans-critical flow regimes, as well as in low- and high-turbulence conditions, which allows for an accurate description of the required relative roughness and Reynolds numbers for achieving trans-critical conditions. The resulting along-wind aerodynamic damping values according to Steckley’s and Holmes’ approaches are compared, and an analytical relation between them is established. Both approaches are then used in aeroelastic multi-body-simulations of an onshore 6 MW reference wind turbine and their impact on the wind turbine lifetime is evaluated through fatigue proofs at the tower base section. Holmes’ approach seems more appropriate for the application in aeroelastic multi-body simulations. A lifetime extension for the wind turbine tower of approximately 0.4% is achieved for the reference wind turbine tower, which roughly corresponds to 1 to 2 months for 20 years of operation. An analytical expression is given for the estimation of the tower’s aerodynamic damping in parked and operating conditions. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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19 pages, 16435 KiB  
Article
Amplitude Control of Stall-Induced Nonlinear Aeroelastic System Based on Iterative Learning Control and Unified Pitch Motion
by Tingrui Liu, Changle Sun, Kang Zhao and Ailing Gong
Energies 2022, 15(3), 787; https://0-doi-org.brum.beds.ac.uk/10.3390/en15030787 - 21 Jan 2022
Cited by 1 | Viewed by 1115
Abstract
In this study, vibration control, a behavior which subordinates to stall-induced nonlinear vibration and amplitude control of a wind turbine’s blade section, based on unified pitch motion driven by slider-linkage mechanism, is investigated by using an iterative learning control (ILC) method. The nonlinear [...] Read more.
In this study, vibration control, a behavior which subordinates to stall-induced nonlinear vibration and amplitude control of a wind turbine’s blade section, based on unified pitch motion driven by slider-linkage mechanism, is investigated by using an iterative learning control (ILC) method. The nonlinear dynamical system is a nonlinear aeroelastic system. The aeroelastic system equations consist of three parts: the nonlinear structural equations derived by using Lagrange’s equations, the improved stall-induced nonlinear ONERA (ISNO) aerodynamic equations, and the pitch control equation. The ISNO model is not only suitable for the actual external pitch motion, but also suitable for the solution by using an ILC algorithm due to its fitted nonlinear aerodynamic coefficients. The ILC algorithm used here is an improved iterative learning algorithm (IILC) which considers the large-range, linearized, residual terms, and realizes gain adaptive tuning based on PID controller. On the one hand, it can control the amplitude of an unsteady flutter through trajectory tracking. On the other hand, when the preset value of the amplitude of the ideal trajectory is very small, it can make the system directly tend to convergence and stability of a nonlinear aeroelastic system. To simplify the extremely difficult iterative process, the pitch movement can track the elastic twist displacement in time, thus simplifying the aeroelastic equations and accelerating the IILC iteration process. Therefore, amplitude control for flap-wise/lead-lag displacements is realized by the unified pitch motion and the trajectory tracking controlled by using the IILC algorithm. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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21 pages, 6629 KiB  
Article
Parametric Analysis Using CFD to Study the Impact of Geometric and Numerical Modeling on the Performance of a Small Scale Horizontal Axis Wind Turbine
by Muhammad Salman Siddiqui, Muhammad Hamza Khalid, Abdul Waheed Badar, Muhammed Saeed and Taimoor Asim
Energies 2022, 15(2), 505; https://0-doi-org.brum.beds.ac.uk/10.3390/en15020505 - 11 Jan 2022
Cited by 12 | Viewed by 2824
Abstract
The reliance on Computational Fluid Dynamics (CFD) simulations has drastically increased over time to evaluate the aerodynamic performance of small-scale wind turbines. With the rapid variability in customer demand, industrial requirements, economic constraints, and time limitations associated with the design and development of [...] Read more.
The reliance on Computational Fluid Dynamics (CFD) simulations has drastically increased over time to evaluate the aerodynamic performance of small-scale wind turbines. With the rapid variability in customer demand, industrial requirements, economic constraints, and time limitations associated with the design and development of small-scale wind turbines, the trade-off between computational resources and the simulation’s numerical accuracy may vary significantly. In the context of wind turbine design and analysis, high fidelity simulation under full geometric and numerical complexity is more accurate but pose significant demands from a computational standpoint. There is a need to understand and quantify performance deterioration of high fidelity simulations under reduced geometric or numerical approximation on a single small scale turbine model. In the present work, the flow past a small-scale Horizontal Axis Wind Turbine (HAWT) was simulated under various geometric and numerical configurations. The geometric complexity was varied based on stationary and rotating turbine conditions. In the stationary case, simple 2D airfoil, 2.5D blade, 3D blade sections are evaluated, while rotational effects are introduced for the configuration 3D blade, rotor only, and the full-scale wind turbine with and without the inclusion of a nacelle and tower. In terms of numerical complexity, the Single Reference Frame (SRF), Multiple Reference Frames (MRF), and the Sliding Meshing Interface (SMI) is analyzed over Tip Speed Ratios (TSR) of 3, 6, 10. The quantification of aerodynamic coefficients of the blade (Cl, Cd) and turbine (Cp, Ct) was conducted along with the discussion on wake patterns in comparison with experimental data. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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15 pages, 3574 KiB  
Article
Experimental Validation of a Hydrostatic Transmission for Community Wind Turbines
by Biswaranjan Mohanty and Kim A. Stelson
Energies 2022, 15(1), 376; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010376 - 05 Jan 2022
Cited by 9 | Viewed by 1831
Abstract
Hydrostatic transmissions are commonly used in heavy-duty equipment for their design flexibility and superior power density. Compared to a conventional wind turbine transmission, a hydrostatic transmission (HST) is a lighter, more reliable, cheaper, continuously variable alternative for a wind turbine. In this paper, [...] Read more.
Hydrostatic transmissions are commonly used in heavy-duty equipment for their design flexibility and superior power density. Compared to a conventional wind turbine transmission, a hydrostatic transmission (HST) is a lighter, more reliable, cheaper, continuously variable alternative for a wind turbine. In this paper, for the first time, a validated dynamical model and controlled experiment have been used to analyze the performance of a hydrostatic transmission with a fixed-displacement pump and a variable-displacement motor for community wind turbines. From the dynamics of the HST, a pressure control strategy is designed to maximize the power capture. A hardware-in-the-loop simulation is developed to experimentally validate the performance and efficiency of the HST drive train control in a 60 kW virtual wind turbine environment. The HST turbine is extensively evaluated under steady and time-varying wind on a state-of-the-art power regenerative hydrostatic dynamometer. The proposed controller tracks the optimal tip-speed ratio to maximize power capture. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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23 pages, 12762 KiB  
Article
Structural Modeling and Failure Assessment of Spar-Type Substructure for 5 MW Floating Offshore Wind Turbine under Extreme Conditions in the East Sea
by Kwangtae Ha, Jun-Bae Kim, Youngjae Yu and Hyoung-Seock Seo
Energies 2021, 14(20), 6571; https://0-doi-org.brum.beds.ac.uk/10.3390/en14206571 - 12 Oct 2021
Cited by 6 | Viewed by 3468
Abstract
Not only the driving for offshore wind energy capacity of 12 GW by Korea’s Renewable Energy 2030 plan but also the need for the rejuvenation of existing world-class shipbuilders’ infrastructures is drawing much attention to offshore wind energy in Korea, especially to the [...] Read more.
Not only the driving for offshore wind energy capacity of 12 GW by Korea’s Renewable Energy 2030 plan but also the need for the rejuvenation of existing world-class shipbuilders’ infrastructures is drawing much attention to offshore wind energy in Korea, especially to the diverse substructures. Considering the deep-sea environment in the East Sea, this paper presents detailed modeling and analysis of spar-type substructure for a 5 MW floating offshore wind turbine (FOWT). This process uses a fully coupled integrated load analysis, which was carried out using FAST, a widely used integrated load analysis software developed by NREL, coupled with an in-house hydrodynamic code (UOU code). The environmental design loads were calculated from data recorded over three years at the Ulsan Marine buoy point according to the ABS and DNVGL standards. The total 12 maximum cases from DLC 6.1 were selected to evaluate the structural integrity of the spar-type substructure under the three co-directional conditions (45°, 135°, and 315°) of wind and wave. A three-dimensional (3D) structural finite element (FE) model incorporating the wind turbine tower and floating structure bolted joint connection was constructed in FEGate (pre/post-structural analysis module based on MSC NASTRAN for ship and offshore structures). The FEM analysis applied the external loads such as the structural loads due to the inertial acceleration, buoyancy, and gravity, and the environmental loads due to the wind, wave, and current. The three-dimensional FE analysis results from the MSC Nastran software showed that the designed spar-type substructure had enough strength to endure the extreme limitation in the East Sea based on the von Mises criteria. The current process of this study would be applicable to the other substructures such as the submersible type. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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26 pages, 8938 KiB  
Article
On the Accuracy of uRANS and LES-Based CFD Modeling Approaches for Rotor and Wake Aerodynamics of the (New) MEXICO Wind Turbine Rotor Phase-III
by Shantanu Purohit, Ijaz Fazil Syed Ahmed Kabir and E. Y. K. Ng
Energies 2021, 14(16), 5198; https://0-doi-org.brum.beds.ac.uk/10.3390/en14165198 - 23 Aug 2021
Cited by 13 | Viewed by 3061
Abstract
This work presents a comparison study of the CFD modeling with two different turbulence modeling approaches viz. unsteady RANS and LES, on a full-scale model of the (New) MEXICO rotor wind turbine. The main emphasis of the paper is on the rotor and [...] Read more.
This work presents a comparison study of the CFD modeling with two different turbulence modeling approaches viz. unsteady RANS and LES, on a full-scale model of the (New) MEXICO rotor wind turbine. The main emphasis of the paper is on the rotor and wake aerodynamics. Simulations are carried out for the three wind speeds considered in the MEXICO experiment (10, 15, and 24 ms−1). The results of uRANS and LES are compared against the (New) MEXICO experimental measurements of pressure distributions, axial, radial, and azimuth traverse of three velocity components. The near wake characteristics and vorticity are also analyzed. The pressure distribution results show that the LES can predict the onset of flow separation more accurately than uRANS when the turbine operates in the stall condition. The LES can compute the flow structures in wake significantly better than the uRANS for the stall condition of the blade. For the design condition, the mean absolute error in axial and radial velocity components along radial traverse is less than 10% for both the modeling approaches, whereas tangential component error is less than 2% from the LES approach. The results also reveal that wake recovers faster in the uRANS approach, requiring further research of the far wake region using both CFD modeling approaches. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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