Blade-Pitch Control for Wind Turbine Load Reductions PDF Download

Author: Wai Hou (Alan) Lio
Publisher: Springer
ISBN: 3319755323
Category : Technology & Engineering
Languages : en
Pages : 193

View

Book Description
This thesis investigates the use of blade-pitch control and real-time wind measurements to reduce the structural loads on the rotors and blades of wind turbines. The first part of the thesis studies the main similarities between the various classes of current blade-pitch control strategies, which have to date remained overlooked by mainstream literature. It also investigates the feasibility of an estimator design that extracts the turbine tower motion signal from the blade load measurements. In turn, the second part of the thesis proposes a novel model predictive control layer in the control architecture that enables an existing controller to incorporate the upcoming wind information and constraint-handling features. This thesis provides essential clarifications of and systematic design guidelines for these topics, which can benefit the design of wind turbines and, it is hoped, inspire the development of more innovative mechanical load-reduction solutions in the field of wind energy.

Author: Wai Hou (Alan) Lio
Publisher: Springer
ISBN: 9783319755311
Category : Science
Languages : en
Pages : 174

View

Book Description
This thesis investigates the use of blade-pitch control and real-time wind measurements to reduce the structural loads on the rotors and blades of wind turbines. The first part of the thesis studies the main similarities between the various classes of current blade-pitch control strategies, which have to date remained overlooked by mainstream literature. It also investigates the feasibility of an estimator design that extracts the turbine tower motion signal from the blade load measurements. In turn, the second part of the thesis proposes a novel model predictive control layer in the control architecture that enables an existing controller to incorporate the upcoming wind information and constraint-handling features. This thesis provides essential clarifications of and systematic design guidelines for these topics, which can benefit the design of wind turbines and, it is hoped, inspire the development of more innovative mechanical load-reduction solutions in the field of wind energy.

Author: Martin Shan
Publisher: Fraunhofer Verlag
ISBN: 9783839613696
Category : Technology & Engineering
Languages : en
Pages : 0

View

Book Description
In wind turbine engineering, it is a well-known fact that mechanical loading of the structural components, as tower and blades, can be heavily influenced by means of control. This work provides a comprehensive discussion on systematic control design for active load reduction. A review of the established approaches for load reducing pitch control is given. The basic idea is to adjust the blade pitch angles to provide active damping of structural loads or to compensate for periodic load components. A survey on rating and cost of wind turbine structural components is given to sketch the potential impacts of control design on Cost-of-Energy. Special focus in a separate chapter is given to the major trade-off between load reductions and rating of the pitch actuator system. In the main part, a pragmatic approach to systematic control design by use of modern multi-variable control design methods is introduced. Linear models in combination with disturbance spectra are applied to allow for fast and transparent optimization of the controllers. Exemplarily, this hierarchical control design / controller tuning approach is demonstrated for two different types of load reducing pitch controllers.

Author: Martin O. L. Hansen
Publisher: Routledge
ISBN: 1136572260
Category : Technology & Engineering
Languages : en
Pages : 192

View

Book Description
Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The new material includes a description of the effects of the dynamics and how this can be modelled in an ?aeroelastic code?, which is widely used in the design and verification of modern wind turbines. Further, the description of how to calculate the vibration of the whole construction, as well as the time varying loads, has been substantially updated.

Author: Tony Burton
Publisher: John Wiley & Sons
ISBN: 9780471489979
Category : Technology & Engineering
Languages : en
Pages : 648

View

Book Description
As environmental concerns have focused attention on the generation of electricity from clean and renewable sources wind energy has become the world's fastest growing energy source. The Wind Energy Handbook draws on the authors' collective industrial and academic experience to highlight the interdisciplinary nature of wind energy research and provide a comprehensive treatment of wind energy for electricity generation. Features include: An authoritative overview of wind turbine technology and wind farm design and development In-depth examination of the aerodynamics and performance of land-based horizontal axis wind turbines A survey of alternative machine architectures and an introduction to the design of the key components Description of the wind resource in terms of wind speed frequency distribution and the structure of turbulence Coverage of site wind speed prediction techniques Discussions of wind farm siting constraints and the assessment of environmental impact The integration of wind farms into the electrical power system, including power quality and system stability Functions of wind turbine controllers and design and analysis techniques With coverage ranging from practical concerns about component design to the economic importance of sustainable power sources, the Wind Energy Handbook will be an asset to engineers, turbine designers, wind energy consultants and graduate engineering students.

Author: Katherine D. Van Ness
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

View

Book Description
Cost and reliability remain among the main barriers limiting widespread adoption ofriverine, estuarine, or ocean current turbine power generation. In particular, structural loads are significantly greater than for wind turbines with equivalent power output, which contributes to higher costs. Compounded with uncertainties about hydrodynamic loads, this can contribute to structural failure or excessive and expensive safety factors. Consequently, control strategies to mitigate structural loads and reduce cost are of considerable importance. Load reduction is of particular interest when currents exceed a certain threshold (i.e., theturbine-specific “rated speed”), and a control strategy is implemented to maintain a constant power output. Most fixed-pitch turbines will use a speed control strategy, increasing or decreasing the rotation rate to achieve the efficiency required for power regulation. However, these “overspeed” and “underspeed” control strategies correspond to large increases in thrust or torque, respectively, that require overdesigning the turbine blades or generator. Blade pitch control circumvents this trade-off, as decreased angles of attack simultaneously reduce thrust and torque. This does, however, require actuators to change blade pitch. While active pitch control is the conventional standard for wind turbines in these above-rated conditions, similar variable blade pitch mechanisms have not yet been uniformly adopted by marine current technology developers due to the higher cost of inspection, maintenance, and repairs relative to wind turbines. For this reason, passive adaptive blade pitch control, in which blades are designed to elastically deform under load without an actuator, sensor, or control logic, is conceptually attractive. Improved understanding of the loading associated with both speed and pitch control strategies is critical to optimizing a design for minimal cost and maximal reliability. Therefore, the overarching goal of this work is to experimentally investigate active and passive pitch control methods, characterize their potential for load reduction, and establish appropriate scaling relations for passive adaptive blades. The three underlying objectives supporting this goal are outlined below. The first objective is to demonstrate active blade pitch control in above-rated flow conditionsand compare the measured turbine loads to those observed with overspeed and underspeed control in order to develop our understanding of the trade-offs associated with each. To this end, we experimentally characterized power performance and turbine loading over a range of blade pitch settings and tip-speed ratios for a three-bladed axial-flow turbine. We then implemented a control strategy to maintain power output in time-varying currents using blade pitch control and compared the turbine performance under this control strategy to overspeed and underspeed control strategies for a fixed pitch turbine. The experiments were conducted with a laboratory-scale 0.45-m diameter turbine in an open channel flume with a 35% blockage ratio. During pitch characterization experiments, inflow velocity was maintained at 0.8 m/s with 4% turbulence intensity. During time-varying inflow experiments, currents varied from 0.7-0.8 m/s over a 20-minute period, while a proportional controller regulated either blade pitch or rotor speed, and we recorded turbine power output and turbine loads. In this velocity range, where turbine performance is independent of Reynolds number, we demonstrate that pitch control substantially reduces torque requirements relative to underspeed control and streamwise turbine loads relative to overspeed control. Additional tests were conducted for underspeed control and pitch control in a Reynolds-dependent regime with time-varying inflow between 0.4-0.5 m/s and 0.5-0.6 m/s. These cases suggest that blade pitch control could provide even greater benefits relative to speed control in small-scale applications. The second objective is to develop our understanding of passive adaptive blade fabricationand the effect of fiber orientation to inform a passive pitch control design. By tailoring the ply angle in a unidirectional carbon fiber blade, a desired twist can be induced in response to bending of the blade under load. In developing this form of passive adaptive control, a fundamental question is how to non-dimensionalize the fluid-structure interaction to make laboratory-scale experiments relevant to full-scale applications. To address these questions, we first conducted an experimental investigation into the effect of fiber angle on blade performance and blade deformation during turbine operation. The composite blades were fabricated with 0°, 2.5°, 5°, and 10° fiber orientations, where a positive fiber orientation results in a reduced angle of attack as load increases (i.e., a “pitch-to-feather” control strategy). Blades were tested in a recirculating flume at 0.7 m/s (Rec = 5.3 · 104 − 2.0 · 105) while measuring force and torque on the rotor. Simultaneously, a high-speed camera observed in-situ deflection and twist at the blade tip. Results show a greater reduction in CP and CT for blades with larger fiber orientations relative to the neutral blade set, while even small fiber orientations were observed to limit thrust at high tip-speed ratios. To explore the correct non-dimensional scaling for this physical process, we performed a set of Cauchyscaled experiments using blades with identical bend-twist couplings but different bending stiffness. These results demonstrate that the Cauchy number is a meaningful parameter for scaling passive adaptive current turbine blades and to model steady-state hydrodynamic and hydroelastic behavior. The third and final objective is to implement passive pitch control to develop our understandingof the trade-offs between speed, active pitch, and passive pitch control methods. Two passive blade pitch control strategies for the same lab-scale turbine were developed and tested experimentally in a recirculating flume. The goal of the control is to regulate mechanical power, while minimizing rotor loads, when flow conditions exceed the rated condition. Both strategies used the 5° fiber blade set from the aforementioned study. One control strategy combined passive adaptive blades with overspeed control (actuating rotational speed above the tip-speed ratio corresponding to peak efficiency) while the other combined passive adaptive blades with active pitch control (actuating blade pitch using motors at the blade root). Both strategies were implemented in linearly increasing inflow from 0.7 m/s to 0.8 m/s and compared to control strategies using rigid, aluminum blades under the same flow conditions. The passive adaptive blades combined with active pitch control show no improvement in steady-state load reductions relative to rigid blades used with active pitch control. However, the passive adaptive blades combined with overspeed control show reduced torque and only a 12% increase in thrust relative to the rated flow condition. This indicates that passive adaptive blades combined with overspeed control can be an effective strategy in currents above the rated flow speed, removing the need for an active pitch mechanism in some applications. In addition to measuring turbine loads, deflection and twist of the passive adaptive blades during experimental testing were observed using a high-speed camera to support our understanding of the bend-twist behavior during turbine operation over a range of flow speeds, rotation rates, and preset pitch angles. Overall, active and passive pitch control strategies for Region III are shown to offer significantload reductions in thrust and torque relative to rigid blade speed control strategies. While controller selection is discussed primarily relative to their associated loads, we discuss additional considerations including blade design, channel blockage, range and frequency of flow variation, and Reynolds-number. These discussions underline the value of future investigations into active and passive pitch control for smoothing high-frequency loads and scaling between lab- and full-scale passive adaptive rotors, among other work.

Author: Olimpo Anaya-Lara
Publisher: John Wiley & Sons
ISBN: 1119097789
Category : Science
Languages : en
Pages : 459

View

Book Description
A COMPREHENSIVE REFERENCE TO THE MOST RECENT ADVANCEMENTS IN OFFSHORE WIND TECHNOLOGY Offshore Wind Energy Technology offers a reference based on the research material developed by the acclaimed Norwegian Research Centre for Offshore Wind Technology (NOWITECH) and material developed by the expert authors over the last 20 years. This comprehensive text covers critical topics such as wind energy conversion systems technology, control systems, grid connection and system integration, and novel structures including bottom-fixed and floating. The text also reviews the most current operation and maintenance strategies as well as technologies and design tools for novel offshore wind energy concepts. The text contains a wealth of mathematical derivations, tables, graphs, worked examples, and illustrative case studies. Authoritative and accessible, Offshore Wind Energy Technology: Contains coverage of electricity markets for offshore wind energy and then discusses the challenges posed by the cost and limited opportunities Discusses novel offshore wind turbine structures and floaters Features an analysis of the stochastic dynamics of offshore/marine structures Describes the logistics of planning, designing, building, and connecting an offshore wind farm Written for students and professionals in the field, Offshore Wind Energy Technology is a definitive resource that reviews all facets of offshore wind energy technology and grid connection.

Author: Abdel Ghani Aissaoui
Publisher: BoD – Books on Demand
ISBN: 9535124951
Category : Technology & Engineering
Languages : en
Pages : 354

View

Book Description
Renewable energies constitute excellent solutions to both the increase of energy consumption and environment problems. Among these energies, wind energy is very interesting. Wind energy is the subject of advanced research. In the development of wind turbine, the design of its different structures is very important. It will ensure: the robustness of the system, the energy efficiency, the optimal cost and the high reliability. The use of advanced control technology and new technology products allows bringing the wind energy conversion system in its optimal operating mode. Different strategies of control can be applied on generators, systems relating to blades, etc. in order to extract maximal power from the wind. The goal of this book is to present recent works on design, control and applications in wind energy conversion systems.

Author: Gijs van Kuik
Publisher: Springer
ISBN: 3319469193
Category : Technology & Engineering
Languages : en
Pages : 111

View

Book Description
This book presents the view of European wind energy experts on the long-term research challenges to be solved in order to develop wind energy beyond the applications of today and tomorrow. By this book, the European Academy of Wind Energy (eawe), representing universities and institutes with a significant wind energy programme in 14 countries, wants to: identify current technological and scientific barriers and to stimulate new creative ideas to overcome these barriers define priorities for future scientific research rethink our scientific view of wind energy stimulate the cooperation among researchers in fundamental and applied sciences towards wind energy research The eawe has discussed these long-term research with an explicit focus on a longer-term perspective, in contrast to research agendas addressing short- to medium-term research activities. In other words, this long-term research agenda is driven by problems and curiosity, addressing basic research and fundamental knowledge in 11 research areas, ranging from physics and design to environmental and societal aspects. Because of the very nature of this initiative, this document does not intend to be permanent or complete. It shows the vision of the experts of the European Academy of Wind Energy, but other views may be possible. The eawe sincerely hopes that it will spur an even more intensive discussion worldwide within the wind energy community.

Author: Wiesław Ostachowicz
Publisher: Springer
ISBN: 3319390953
Category : Technology & Engineering
Languages : en
Pages : 432

View

Book Description
This book provides a holistic, interdisciplinary overview of offshore wind energy, and is a must-read for advanced researchers. Topics, from the design and analysis of future turbines, to the decommissioning of wind farms, are covered. The scope of the work ranges from analytical, numerical and experimental advancements in structural and fluid mechanics, to novel developments in risk, safety & reliability engineering for offshore wind.The core objective of the current work is to make offshore wind energy more competitive, by improving the reliability, and operations and maintenance (O&M) strategies of wind turbines. The research was carried out under the auspices of the EU-funded project, MARE-WINT. The project provided a unique opportunity for a group of researchers to work closely together, undergo multidisciplinary doctoral training, and conduct research in the area of offshore wind energy generation. Contributions from expert, external authors are also included, and the complete work seeks to bridge the gap between research and a rapidly-evolving industry.