scholarly journals Stabilization of the vertical take-off of a rigid flying wing for an airborne wind energy system

2021 ◽  
Author(s):  
H. Fuest ◽  
D. F. Duda ◽  
T. Islam ◽  
T. Ostermann ◽  
D. Moormann
Keyword(s):  
Wind Energy ◽  
Wind Velocity ◽  
Flight Control ◽  
Control Unit ◽  
Energy System ◽  
Horizontal Wind ◽  
Longitudinal Motion ◽  
Strong Wind ◽  
Control Units ◽  
Wind Velocities

AbstractAirborne wind energy is an emerging technology that harvests wind energy with flight systems connected via a tether to the ground. In the project “EnerGlider”, a flying wing is meant to fly fully automated by its own control units. This contribution discusses the challenges to control and trim this flying wing during vertical take-off and landing under the influence of a horizontal wind velocity. High wind velocities can lead to unstable and untrimmed states concerning the longitudinal motion of the flying wing. The paper analyzes the influence of design modifications of thrust vector and elevon area to enhance the flight envelope of the trimmed states to higher wind velocities. Besides, the tether force as additional control unit is considered for strong wind forces. It is demonstrated that a tether force acting behind the center of gravity can significantly enhance the robustness of the flight system concerning wind velocity. Moreover, the unstable flight states emerging during vertical take-off and landing can be stabilized with a flight control.

scholarly journals A Stewart Platform as a FBW Flight Control Unit

2011 ◽  
Vol 62 (4) ◽  
pp. 213-219
Author(s):  
Vasfi Ömürlü ◽  
İbrahim Yildiz
Keyword(s):  
Flight Control ◽  
Degrees Of Freedom ◽  
Force Feedback ◽  
Single Point ◽  
Control Unit ◽  
Stewart Platform ◽  
Rotational Axis ◽  
Control Units ◽  
Feasible Solutions ◽  
Future Work

A Stewart Platform as a FBW Flight Control UnitA variety of flight control units have been put into realization for navigational purposes of spatially moving vehicles (SMV), which is mostly manipulated by 2 or 3 degrees-of-freedom (DOF) joysticks. Since motion in space consists of three translational motions in forward, side and vertical directions and three rotational motions about these axis; with present joystick interfaces, spatial vehicles has to employ more than one navigational control unit to be able to navigate on all required directions. In this study, a 3 × 3 Stewart-Platform-based FBW (Fly-By-Wire) flight control unit with force feedback is presented which will provide single point manipulation of any SMVs along three translational and about three rotational axis. Within the frame of this paper, design, capability and the advantages of the novel system is mentioned. Kinematics of a Stewart Platform (SP) mechanism employed and its motion potentials is presented by simulations and workspace of the system is evaluated. Dynamic analysis by Bond-Graph approach will be mentioned. Mechatronic design of the complete structure is discussed and force reflection capability of the system with simulations is pointed out using stiffness control. Finally, the possible future work of the subject is discussed which may include the feasible solutions of the SP in terms of size and safety when implementing inside a cockpit.

Longitudinal Flight Control for a Novel Airborne Wind Energy System: Robust MIMO Control Design Techniques

2011 ◽  
Author(s):  
Nicholas Tierno ◽  
Nicholas White ◽  
Mario Garcia-Sanz
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Flight Control ◽  
Synchronous Generator ◽  
Energy System ◽  
Polar Coordinate System ◽  
Additional Information ◽  
Wind Energy System ◽  
Aerodynamic Control ◽  
Control Surfaces

This paper deals with the longitudinal flight control for a novel Airborne Wind Energy (AWE) system: the EAGLE System. It is a tethered lighter-than-air flyer wind turbine composed of a blimp, several aerodynamic airfoils (wings) with specific aerodynamic control surfaces (ailerons, elevator, rudder), a counter-rotating aerodynamic rotor for the wind turbine (four identical sections, symmetrically arranged, with three blades each), an electrical synchronous generator attached to the counter-rotating rotors, and a tether to secure the airship and to transmit the generated power. Additional information can be found in US Patent, Provisional Application No. 61/387,432 developed by the authors. The designed system proposed here supports a 2.5 kW generator and flies at approximately 100 meters. The mathematical model developed for the AWE system incorporates a hybrid blimp-airfoil design, modeled using a hybrid Cartesian-polar coordinate system to capture the dynamics of both the airship and the tether, and includes the effect of the counter-rotating aerodynamic rotor of the wind turbine, as well as the aerodynamic control surfaces. This paper presents the design of a robust Multi-Input Multi-Output (MIMO) controller for the 3×3 longitudinal flight dynamics of the tethered airborne wind energy system. The control system is designed by applying sequential MIMO robust Quantitative Feedback Theory (QFT) techniques.

scholarly journals Estimating Wind Velocities in Mountain Lee Waves Using Sailplane Flight Data*

2010 ◽  
Vol 27 (1) ◽  
pp. 147-158 ◽  
Author(s):  
R. P. Millane ◽  
G. D. Stirling ◽  
R. G. Brown ◽  
N. Zhang ◽  
V. L. Lo ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Sierra Nevada ◽  
General Circulation ◽  
Three Dimensional ◽  
Horizontal Wind ◽  
Atmospheric Gravity Wave ◽  
Mountain Waves ◽  
Lee Waves ◽  
Wind Velocities ◽  
Using Data

Abstract Mountain lee waves are a form of atmospheric gravity wave that is generated by flow over mountain topography. Mountain lee waves are of considerable interest, because they can produce drag that affects the general circulation, windstorms, and clear-air turbulence that can be an aviation hazard, and they can affect ozone abundance through mixing and inducing polar stratospheric clouds. There are difficulties, however, in measuring the three-dimensional wind velocities in high-altitude mountain waves. Mountain waves are routinely used by sailplane pilots to gain altitude. Methods are described for estimating three-dimensional wind velocities in mountain waves using data collected during sailplane flights. The data used are the logged sailplane position and airspeed (sailplane speed relative to the local air mass). An algorithm is described to postprocess this data to estimate the three-dimensional wind velocity along the flight path, based on an assumption of a slowly varying horizontal wind velocity. The method can be applied to data from dedicated flights or potentially to existing flight records used as sensors of opportunity. The methods described are applied to data from a sailplane flight in lee waves of the Sierra Nevada in California.

Lab-Scale Experimental Crosswind Flight Control System Prototyping for an Airborne Wind Energy System

2016 ◽  
Author(s):  
Mitchell Cobb ◽  
Christopher Vermillion ◽  
Hosam Fathy
Keyword(s):  
Wind Energy ◽  
Flight Control ◽  
Energy System ◽  
Experimental Setup ◽  
Flight Control System ◽  
Wind Energy System ◽  
Stationary Operation ◽  
Wind Energy Systems ◽  
Scale Control

This paper presents an original experimental setup for controlling and measuring the crosswind flight of airborne wind energy systems in a laboratory environment. Execution of cross-wind flight patterns, which is achieved in this work through the asymmetric motion of three tethers, enables dramatic increases in energy generation compared with stationary operation. Achievement of crosswind flight in the 1:100-scale experimental framework described herein allows for rapid, inexpensive, and dynamically scalable characterization of new control algorithms without recourse to expensive full-scale prototyping. This work is the first example of successful lab-scale control and measurement of crosswind motion for an airborne wind energy system. Specifically, this paper presents the experimental setup, crosswind flight control strategy, and experimental results for a model of the Altaeros Buoyant Airborne Turbine (BAT). The results demonstrate that crosswind flight control can achieve nearly 50 percent more power production then stationary operation, while also demonstrating the potential of the experimental framework for further algorithm development.

scholarly journals A deep CNN model for medium-range spatio-temporal wind speed prediction for wind energy applications

2021 ◽  
Author(s):  
Daan Scheepens ◽  
Katerina Hlavackova-Schindler ◽  
Claudia Plant ◽  
Irene Schicker
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Velocity ◽  
Wind Farms ◽  
Relative Vorticity ◽  
Horizontal Wind ◽  
Energy Applications ◽  
Wind Speed Prediction ◽  
Speed Prediction ◽  
Deep Cnn

<p>The amount of wind farms and wind power production in Europe, on-shore and off-shore, increased rapidly in the past years. To ensure grid stability, omit fees in energy trading, and on-time (re)scheduling of maintenance tasks accurate predictions of wind speed and wind energy is needed. Especially for the prediction range of +48 hours up to 2 weeks ahead at least hourly predictions are envisioned by the users. However, these are either not covered by the high-resolution models or are on a spatial and temporal course scale. </p><p>To address this as a first step we therefore propose a deep CNN based model for wind speed prediction  using the ECMWF ERA5 to train our model using at least seven wind-related temporal variables, i.e. divergence, geopotential, potential vorticity, temperature, relative vorticity, vertical wind velocity and horizontal wind velocity.</p><p>The input of the CNN is represented by  the 3-dim tensor (size of the 2-dim figures x time shots), one for each variable. The CNN  outputs the most probable of the six categories in which the wind speed will be during the following 96 hours, in 6h intervals. Different combinations of input data are investigated in terms of temporal input.</p><p>We analyse the influence of prediction range on the predicted category as well as the relevance of each of the wind-related variables in the prediction of this category.  The model will be tested and applied to the ECMWF IFS forecasts over Austria. The ensure a higher spatial and temporal resolution an additional step will be used for downscaling the CNN directly to a 1 km grid.</p><p>This work is performed as part of the MEDEA project, which is funded by the Austrian Climate Research Program.</p>

Numerical simulation of wind characteristics at bridge site considering thermal effects

2017 ◽  
Vol 21 (9) ◽  
pp. 1313-1326 ◽  
Author(s):  
Mingjin Zhang ◽  
Yongle Li ◽  
Bin Wang ◽  
Sen Ren
Keyword(s):  
Numerical Simulation ◽  
Wind Velocity ◽  
Wind Field ◽  
Thermal Effects ◽  
Surface Wind ◽  
Horizontal Wind ◽  
Bridge Site ◽  
Western Sichuan ◽  
Wind Velocities ◽  
Wind Characteristics

In order to study the variation of wind field characteristics under the influence of thermal effects at a bridge site in a deep-cutting gorge with high-altitude and temperature difference, the simulation of natural convection was realized by adding momentum source terms in FLUENT. And the correctness of the simulation results was verified. Then, choosing Dadu River Bridge located at a deep-cutting gorge in western Sichuan as an engineering background, combined with the variation of temperature tested at the bridge site, the numerical simulation of the wind field characteristics at the bridge site was carried out under the influence of the thermal effects. The influences of different thermal factors on the surface wind characteristics of bridge site area were discussed. The wind characteristics at the bridge site under the combined action of different wind velocities and thermal effects were analyzed. As shown in the results, the maximum vertical wind velocity caused by the thermal effects at the height of main girder is 3.0 m/s, and the maximum horizontal wind velocity is 6.4 m/s. When the upcoming wind velocity is greater than 5.0 m/s, the thermal effects have been significantly reduced, and the wind field at the bridge site is mainly influenced by the upcoming wind velocity, wind direction, and local terrain. Under the influence of thermal, the surface temperature distribution at the bridge site is significantly uneven, which are obviously different from the case of not considering the thermal effects.

scholarly journals Implementation of Maximum Power Point Tracking Based on Variable Speed Forecasting for Wind Energy Systems

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 158 ◽  
Author(s):  
Yujia Zhang ◽  
Lei Zhang ◽  
Yongwen Liu
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Velocity ◽  
Bat Algorithm ◽  
Energy System ◽  
Maximum Power ◽  
State Feedback Control ◽  
Control Technique ◽  
Point Tracking

In order to precisely control the wind power generation systems under nonlinear variable wind velocity, this paper proposes a novel maximum power tracking (MPPT) strategy for wind turbine systems based on a hybrid wind velocity forecasting algorithm. The proposed algorithm adapts the bat algorithm and improved extreme learning machine (BA-ELM) for forecasting wind speed to alleviate the slow response of anemometers and sensors, considering that the change of wind speed requires a very short response time. In the controlling strategy, to optimize the output power, a state feedback control technique is proposed to achieve the rotor flux and rotor speed tracking purpose based on MPPT algorithm. This method could decouple the current and voltage of induction generator to track the reference of stator current and flux linkage. By adjusting the wind turbine mechanical speed, the wind energy system could operate at the optimal rotational speed and achieve the maximal power. Simulation results verified the effectiveness of the proposed technique.

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