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Book Mitigation of Wind Turbine Vortex Interaction Using Disturbance Accommodating Control

Download or read book Mitigation of Wind Turbine Vortex Interaction Using Disturbance Accommodating Control written by and published by DIANE Publishing. This book was released on with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Advances of Science and Technology

Download or read book Advances of Science and Technology written by Mulugeta Admasu Delele and published by Springer Nature. This book was released on 2021 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: This two-volume set constitutes the refereed post-conference proceedings of the 8th International Conference on Advancement of Science and Technology, ICAST 2020, which took place in Bahir Dar, Ethiopia, in October 2020. The 74 revised full papers were carefully reviewed and selected from more than 200 submissions of which 157 were sent out for peer review. The papers present economic and technologic developments in modern societies in 6 tracks: Chemical, food and bio-process engineering; Electrical and computer engineering; IT, computer science and software engineering; Civil, water resources, and environmental engineering; Mechanical and industrial engineering; Material science and engineering.

Book Wind Turbine Wake Interactions

Download or read book Wind Turbine Wake Interactions written by Daniel Curtis Saunders and published by . This book was released on 2017 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing concerns about the environmental impact of fossil fuel energy and improvements in both the cost and performance of wind turbine technologies has spurred a sharp expansion in wind energy generation. However, both the increasing size of wind farms and the increased contribution of wind energy to the overall electricity generation market has created new challenges. As wind farms grow in size and power density, the aerodynamic wake interactions that occur between neighboring turbines become increasingly important in characterizing the unsteady turbine loads and power output of the farm. Turbine wake interactions also impact variability of farm power generation, acting either to increase variability or decrease variability depending on the wind farm control algorithm. In this dissertation, both the unsteady vortex wake loading and the effect of wake interaction on farm power variability are investigated in order to better understand the fundamental physics that govern these processes and to better control wind farm operations to mitigate negative effects of wake interaction. The first part of the dissertation examines the effect of wake interactions between neighboring turbines on the variability in power output of a wind farm, demonstrating that turbine wake interactions can have a beneficial effect on reducing wind farm variability if the farm is properly controlled. In order to balance multiple objectives, such as maximizing farm power generation while reducing power variability, a model predictive control (MPC) technique with a novel farm power variability minimization objective function is utilized. The controller operation is influenced by a number of different time scales, including the MPC time horizon, the delay time between turbines, and the fluctuation time scales inherent in the incident wind. In the current research, a non-linear MPC technique is developed and used to investigate the effect of three time scales on wind farm operation and on variability in farm power output. The goal of the proposed controller is to explore the behavior of an ‘ideal’ farm-level MPC controller with different wind, delay and horizon time scales and to examine the reduction of system power variability that is possible in such a controller by effective use of wake interactions. The second part of the dissertation addresses the unsteady vortex loading on a downstream turbine caused by the interaction of the turbine blades with coherent vortex structures found within the upstream turbine wake. Periodic, stochastic, and transient loads all have an impact on the lifetime of the wind turbine blades and drivetrain. Vortex cutting (or vortex chopping) is a type of stochastic load that is commonly observed when a propeller or blade passes through a vortex structure and the blade width is of the same order of magnitude as the vortex core diameter. A series of Navier-Stokes simulations of vortex cutting with and without axial flow are presented. The goal of this research is to better understand the challenging physics of vortex cutting by the blade rotor, as well as to develop a simple, physics-based, validated expression to characterize the unsteady force induced by vortex.

Book Dissertation Abstracts International

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Disturbance Accommodating Adaptive Control with Application to Wind Turbines

Download or read book Disturbance Accommodating Adaptive Control with Application to Wind Turbines written by Susan Frost and published by BiblioGov. This book was released on 2013-07 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive control techniques are well suited to applications that have unknown modeling parameters and poorly known operating conditions. Many physical systems experience external disturbances that are persistent or continually recurring. Flexible structures and systems with compliance between components often form a class of systems that fail to meet standard requirements for adaptive control. For these classes of systems, a residual mode filter can restore the ability of the adaptive controller to perform in a stable manner. New theory will be presented that enables adaptive control with accommodation of persistent disturbances using residual mode filters. After a short introduction to some of the control challenges of large utility-scale wind turbines, this theory will be applied to a high-fidelity simulation of a wind turbine.

Book Manipulating the Flow Through Wind Farms to Increase Their Efficiency

Download or read book Manipulating the Flow Through Wind Farms to Increase Their Efficiency written by Daniel Houck and published by . This book was released on 2020 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind farms are adversely affected by the very wakes that are a necessary by-product of their energy extraction process. While turbines that are most upstream produce at or near their maximum power production, those downstream suffer from the reduction in available energy and increase in turbulence created by the upstream turbines. Methods to combat these effects generally either attempt to increase the available energy to the downstream turbines or mitigate the effects of the upstream turbines' wakes. Wake dissipation also requires entrainment of energy from the ambient flow into the wake, so, in fact, wake mitigation and increasing available energy are two sides of the same coin. To explore methods that would improve wind farm efficiency, we performed model-scale wind turbine experiments while recording their power production and measuring the flow. Accurately measuring power production is the subject of the first paper in which a high-accuracy torque transducer was designed and validated to facilitate mechanical power measurements with very low uncertainty. This transducer was necessary to obtain non-intrusive measurements of torque via a calibration to a turbine's current output. In the second paper, a wake mitigation technique, called dynamic induction control, was studied. With this technique, the set point of the turbine is periodically varied in an effort to trigger or accelerate instabilities in its wake. Contrary to existing literature that indicated that the oscillation frequency would be critical, results showed that the amplitude of oscillation, which corresponds to the turbine's rotation rate, had the largest effect. We theorize that switching to higher rotation rates reduces the pitch of the tip vortex helices promoting more destructive interactions among them. Accelerating the decay of the tip vortices allows for greater mixing with the ambient flow and ultimately accelerated wake decay compared to conventional steady operation. Finally, in the last paper, static axial induction control was studied with an array of five turbines while measuring the flow and turbine power in an effort to understand the fluid dynamics associated with the increase in power. In static axial induction control (AIC), upstream turbines are derated in an effort to maximize the total power production of the array, though not all turbines operate at their individual optima. While data from the power production of individual turbines and flow measurements are difficult to interpret, the total power production of the treatment using AIC was successfully increased. Flow measurements indicate that unharvested energy in the array was redistributed to the edges of the wakes as hypothesized.

Book Wake Interaction Modeling Using a Parallelized Free Vortex Wake Model

Download or read book Wake Interaction Modeling Using a Parallelized Free Vortex Wake Model written by Kelsey Shaler and published by . This book was released on 2020 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine-wake interactions pose significant challenges in the development of wind farms. These interactions can lead to an increase in wind energy cost through reduction in wind farm power efficiency as well as a reduction of functional turbine lifetime. The overall objective of this work is to extend and assess a moderatefidelity free vortex wake (FVW) model to capture turbine-wake interactions between multiple turbines. Specific focus areas include: (1) analyzing the effects of turbine-wake interaction; (2) benchmarking of the model against experimental wind farm measurements; and (3) comparing wake interaction effects between the FVW model and a dynamic wake meandering (DWM) model. Results show that FVW produces an increased dynamic response in wake-influenced turbines than FAST.Farm, which is an important factor in fatigue life of turbine blades. Parameter studies for various operating and layout conditions are performed. Analysis focuses on impact of wake interaction on wake structure, rotor power, and blade root bending moments. The parameter study shows expected power trends for all tested parameters. The effects of turbine-wake interactions are analyzed in terms of wake structure, rotor power, and structural response. The FVW model predicts increased unsteadiness in wake-influenced turbine rotor power and out-of-plane blade root bending moment. This could have implications for prediction of turbine life and suggests that the transient as well as average response of turbines should be considered to fully capture the effects of wake interaction. Comparisons between the FVW predictions and experimental measurements of relative rotor power are made over varying yaw angle and freestream velocity. Overall trends are predicted by the FVW approach, with less than 13% error on average when compared to wind farm measurements. These results indicate the FVW method is a useful tool for carrying out improved optimization of wind farms.

Book Directory of Southeast Asian studies centers in the United States 1969

Download or read book Directory of Southeast Asian studies centers in the United States 1969 written by and published by . This book was released on with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Periodic Vortical Gust Encounter and Mitigation Using Closed Loop Control

Download or read book Periodic Vortical Gust Encounter and Mitigation Using Closed Loop Control written by Andrew Edward Killian and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contending with gusts has been a problem people have been working on for a very long time, in fact the Wright Brothers' first day of flights was cut short after a gust of wind overturned and damaged their first flyer. Long before airplanes, people contended with gusts when they built sailboats to be resilient and even harness sudden bursts of wind without tipping over. Gusts are ever present in the atmosphere whether that be from weather, terrain, buildings, or other objects. To navigate through the air effectively, gusts must be contended with. While people have been working on this problem for a long time, the issue of understanding gust encounters, and in particular mitigating them has become even more important today. Wind turbines can be made more efficient if their interactions with gusts are better understood, and with the rise of more susceptible aircraft like smaller Uncrewed Aerial Vehicles (UAVs) and even Micro Air Vehicles (MAVs), gust mitigation has become even more important to ensure these new technologies can operate effectively. Due to these vehicles' smaller size, a gust can have a large effect on their stability and the loads they experience. Especially if these vehicles are to operate in complex environments like cities gust mitigation strategies will be essential to their success. Gust mitigation strategies in the past have mainly focused on using unsteady aerodynamic models to predict the forces a wing or flat plate will experience and building an open loop controller from that model to mitigate the gusts. While this method has had success, the use of an open loop controller limits applications to a known gust. This work instead makes use of a closed loop controller that does not necessarily need to know the structure of a gust a priori to mitigate it. Unsteady aerodynamic models are also examined and evaluated as a method of combining the two strategies for possible future controller improvements. A gust generator was designed to produce several periodic vortical gusts for a range of amplitudes and reduced frequencies. Time Resolved PIV (TR-PIV) measurements were captured along with force data while the controller mitigated periodic vortical gusts to examine the flow physics present in a closed loop gust mitigation encounter. When compared to the unmitigated open loop encounters, the closed loop controller was able to mitigate up to 95.7% of the peak open loop forces and up to 62.31% of the periodic disturbance. PIV flow analysis revealed that the controller limited flow separation and LEV formation that was present in open loop at the peak forces. For most of the gust encounter the controller was able to align the plate more closely to the flow to reduce lift deviations. The controller was also able to offset the angle to maintain a positive lift throughout a gust encounter. PIV also revealed that the controller performed best while the vortical gusts approached the plate. During this phase there was a gradual increase in induced Angle of Attack (AoA) it could compensate for. The controller struggled as the vortices crossed the leading edge (LE) of the flat plate rapidly changing the induced AoA as the vertical component of velocity due to the gust changed from one side of the vortex to the other. Three unsteady aerodynamic models, Theodorsen, Wagner, and KuÌ8ssner, are explained and evaluated to see how well they can predict the experimental forces measured in both open and closed loop gust encounters. Using the upstream induced AoA and the angle of the flat plate, the models were all able to predict the general trends in the coefficient of lift CL histories for the range of gusts tested. Wagner, in particular, was also successful in predicting the magnitudes of the forces experienced during the gust encounters with an average error as low as 0.07. The success of the models indicate that they could be leveraged to further improve periodic vortical gust mitigation with a closed loop controller.

Book Demonstration of Wake Steering Through Yaw Control in a Wind Plant Field Experiment Cooperative Research and Development Final Report CRADA Number CRD 16 00629

Download or read book Demonstration of Wake Steering Through Yaw Control in a Wind Plant Field Experiment Cooperative Research and Development Final Report CRADA Number CRD 16 00629 written by and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last few decades, wind energy has evolved into a large international industry involving major players in the manufacturing, construction, and utility sectors. Coinciding with the industry's growth, significant innovation in the technology has resulted in larger turbines with lower associated costs of energy and more complex designs in all subsystems. However, as the deployment of the technology has grown and its role within the electricity sector become more prominent, so have the expectations of the technology in terms of performance, reliability, and cost. The industry currently partitions its efforts into separate paths for turbine design, plant design and development, finance, grid interaction and operation, mitigation of adverse community and environmental impacts, and other areas. One prominent area where this partition is evident is in wind turbine control. Traditionally, each wind turbine in a wind plant has been controlled separately - via its own internal controller using only its own sensors. However, wind turbines in a plant interact with each other through the plant-level fluid dynamics. Wake losses (due to upstream turbines extracting energy from the winds and "waking" downstream turbines) can be up to 10% or even 20% of the gross energy production (if each turbine experienced the free stream wind inflow to the plant). A series of studies and experiments have demonstrated that there is potential for improving energy output at existing plants through plant control methods which seek to optimize total wind plant energy production over the current "greedy" approach where each turbine maximizes its own production. Wake steering induced by yaw offsets (turning the turbine to be out of the plane perpendicular to wind inflow) for upstream turbines has shown significant promise in simulations and wind tunnel experiments. In simulation studies, annual energy production has been shown to increase by 2% or more depending on the particular aspects of the wind plant (turbine spacing, meteorological conditions, etc). This project seeks to demonstrate the potential of plant-level controls via wake steering at a commercial wind plant. This is an important step towards commercialization and industry adoption of this plant-level modeling and analysis capability.

Book Separation Flow Control with Vortex Generator Jets Employed in an Aft loaded Low pressure Turbine Cascade with Simulated Upstream Wakes

Download or read book Separation Flow Control with Vortex Generator Jets Employed in an Aft loaded Low pressure Turbine Cascade with Simulated Upstream Wakes written by Kyle Adler Gompertz and published by . This book was released on 2009 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Detailed pressure and velocity measurements were acquired at Rec = 20,000 with 3% inlet free stream turbulence intensity to study the effects of position, phase and forcing frequency of vortex generator jets employed on an aft-loaded low-pressure turbine blade in the presence of impinging wakes. The L1A blade has a design Zweifel coefficient of 1.34 and a suction peak at 58% axial chord, making it an aft-loaded pressure distribution. At this Reynolds number, the blade exhibits a non-reattaching separation region beginning at 60% axial chord under steady flow conditions without upstream wakes. Wakes shed by an upstream vane row are simulated with a moving row of cylindrical bars at a flow coefficient of 0.91. Impinging wakes thin the separation zone and delay separation by triggering transition in the separated shear layer, although the flow does not reattach. Instead, at sufficiently high forcing frequencies, a new time-mean separated shear layer position is established which begins at approximately 72%Cx. Reductions in area-averaged wake total pressure loss of more than 75% were documented. One objective of this study was to compare pulsed flow control using two rows of discrete vortex generator jets (VGJs). The VGJs are located at 59%Cx, approximately the peak Cp location, and at 72%Cx. Effective separation control was achieved at both locations. In both cases, wake total pressure loss decreased 35% from the wake only level and the shape of the Cp distribution indicates that the cascade recovers its high Reynolds number (attached flow) performance. The most effective separation control was achieved when actuating at 59%Cx where the VGJ disturbance dominates the dynamics of the separated shear layer, with the wake disturbance assuming a secondary role only. On the other hand, when actuating at 72%Cx, the efficacy of VGJ actuation is derived from the relative mean shear layer position and jet penetration. When the pulsed jet actuation (25% duty cycle) was initiated at the 72%Cx location, synchronization with the wake passing frequency (8.7Hz) was critical to produce the most effective separation control. A 20% improvement in effectiveness over the wake-only level was obtained by aligning the jet actuation between wake events. A range of blowing ratios was investigated at both locations to maximize separation reduction with minimal mass flow. The optimal control parameter set for VGJ actuation at 72%Cx does not represent a reduction in required mass flow compared to the optimal parameter set for actuation at 59%Cx. Differences in the fundamental physics of the jet interaction with the separated shear layer are discussed and implications for the application of flow control in a full engine demonstrator are reviewed. Evidence suggests that flow control using VGJs will be effective in the highly unsteady LPT environment of an operating gas turbine, provided the VGJ location and amplitude are adapted for the specific blade profile.