Room:
Egbert-von-Hoyer Hall
Topic:
I. New concepts and configurations
Form of presentation:
Oral
Duration:
120 Minutes
Chaired by: P.W. Cheng, D.T. Griffith
10:30
Simulation of an offshore wind farm using fluid power for centralized electricity generation
Antonio Jarquin Laguna | Delft University of Technology | Netherlands
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Author:
Antonio Jarquin Laguna | Delft University of Technology | Netherlands
A centralized approach for electricity generation within a wind farm is explored through the use of fluid power technology. This concept considers a new way of generation, collection and transmission of wind energy inside a wind farm, in which electrical conversion does not occur during any intermediate conversion step before the energy has reached the offshore platform. A numerical model was developed to capture the relevant physics from the dynamic interaction between different turbines coupled to a common hydraulic network and controller. This paper presents time-domain simulation results for an hypothetical hydraulic wind farm subject to turbulent wind conditions. Results indicate that the individual turbines are able to operate within operational limits with the current pressure control concept. Despite the stochastic turbulent wind input and wake effects, the hydraulic wind farm is able to produce electricity with reasonable performance in both below and above rated conditions.
10:50
Aerodynamic and inertial tuning of passive devices for load alleviation on wind turbines
Pierluigi Montinari | Politecnico di Milano | Italy
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Authors:
Pierluigi Montinari | Politecnico di Milano | Italy
Alessandro Croce | Italy
Carlo Luigi Bottasso | Italy
Federico Gualdoni | Italy
Carlo Emanuele Riboldi | Italy
This paper describes tuning concepts for passive devices aimed at load alleviation in wind turbines. Two types of tuning are considered: inertial and aerodynamic. The first concept is illustrated with reference to a passive flap, while the second with reference to a passive tip. In both cases, the goal is to reduce loads with devices that are as simple as possible, and do not require sensors nor actuators. The main features and critical issues of each concept are highlighted and illustrated with reference to a large conceptual 10 MW wind turbine.
11:10
A Numerical Investigation to Identify Dimensionless Parameters for Dual-Rotor Horizontal Axis Wind Turbines
Kenny Lee Slew | Carleton University | Canada
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Authors:
Kenny Lee Slew | Carleton University | Canada
Michael Miller | Canada
Edgar Matida | Canada
A numerical study was carried out to identify non-dimensional parameters for dual-rotor horizontal axis wind turbines (DRWTs). Based on some important DRWT parameters such as the rotor speeds, rotor diameters and the distance between the rotors, three dimensionless parameters were derived from the Buckingham Pi theorem. Hypothetical DRWT models were created using geometrically-scaled NREL Phase VI rotor geometry and operating conditions in order to confirm the validity of these parameters. The performance of each turbine was simulated using DR_HAWT, an in-house prediction tool for single and dual-rotor wind turbines created by the current authors. The variation in normalized output power as a function of the dimensionless parameters suggests that an improved performance of DRWTs can be obtained at lower diameter and gap ratios. The NREL rotor equipped with a 5 m geometrically-scaled upwind rotor can generate about 88% of the combined power output of two equivalent single-rotors.
11:30
Downscaling of Airborne Wind Energy Systems
Uwe Fechner | Delft University of Technology | Netherlands
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Authors:
Uwe Fechner | Delft University of Technology | Netherlands
Roland Schmehl | Netherlands
Airborne wind energy systems provide a novel solution to harvest wind energy from higher altitudes. The use of a lightweight tether in place of an expensive tower provides a cost advantage, next to the higher capacity factor and much lower total mass. This paper investigates the scaling effects of airborne wind energy systems. For airborne wind energy systems the yield is defined per square meter wing area. In this paper the dependency of the energy yield on the nominal generator power for systems in the range of 1 kW to 1 MW is investigated. For the location Cabauw, The Netherlands, it is shown, that a generator of just 1.4 kW nominal power and a total system mass of less then 30 kg has the theoretical potential to harvest energy at only twice the price per kWh of large scale airborne wind energy systems. This would make airborne wind energy systems an attractive choice for small scale remote and mobile applications as soon as the remaining challenges for commercialization are solved.
11:50
Numerical study on aerodynamic damping of floating vertical axis wind turbines
Dr. Zhengshun Cheng | NTNU | Norway
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Authors:
Dr. Zhengshun Cheng | NTNU | Norway
Helge Aagaard Madsen | Norway
Zhen Gao | Norway
Torgeir Moan | Norway
Due to its potential impact on fatigue damage, the aerodynamic damping should be considered in the preliminary design of a floating VAWT based on the frequency domain method. However, currently the study on aerodynamic damping of floating VAWTs is very limited. In this study, the aerodynamic damping of floating VAWTs was studied in a fully coupled manner, and its influential factors and its effects on the motions, especially the pitch motion, were demonstrated. Three straight-bladed floating VAWTs with identical solidity and with a blade number varying from two to four were considered. The aerodynamic damping under steady and turbulent wind conditions were estimated using fully coupled aero-hydro-servo-elastic time domain simulations. It is found that the aerodynamic damping ratio of the considered floating VAWTs ranges from 1.8% to 5.3%. Moreover, the aerodynamic damping is almost independent of the rotor azimuth angle, and is to some extent sensitive to the blade number.
12:10
A study of rotor and platform design trade-offs for large-scale floating vertical axis wind turbines
Dr. D. Todd Griffith | Sandia National Laboratories | United States
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Authors:
Dr. D. Todd Griffith | Sandia National Laboratories | United States
Matthew Barone | United States
Joshua Paquette | United States
Brian Owens | United States
Diana Bull | United States
Vertical axis wind turbines are receiving significant attention for offshore siting. In general, offshore wind offers proximity to large populations centers, a vast & more consistent wind resource, and a scale-up opportunity, to name a few beneficial characteristics. On the other hand, offshore wind suffers from high levelized cost of energy (LCOE) and in particular high balance of system (BoS) costs owing to accessibility challenges and limited project experience. To address these challenges associated with offshore wind, Sandia National Laboratories is researching large-scale (MW class) offshore floating vertical axis wind turbines (VAWTs). The motivation for this work is that floating VAWTs are a potential transformative technology solution to reduce offshore wind LCOE in deep-water locations. This paper explores performance and cost trade-offs within the design space for floating VAWTs between the configurations for the rotor and platform.