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Latest Issue
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- Category: Articles
Active Flap Systems Coming Closer to Market
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The idea of active flap systems on wind turbine blades is to reduce the variable loading on the blades by continuously adjusting the shape of the trailing edge of the blade to counteract the fluctuating loads from the wind. The reduction in loading means that a larger rotor can be mounted on the same turbine platform and the power production can be increased. In this way the cost of energy (COE) can be reduced, which is the overall goal with the new smart blade control.
By Helge Aagaard Madsen, Research Specialist, DTU Wind Energy, Denmark
- Category: Articles
Ring-Shaped Bearingless Generator with Buoyant Rotor and Modular Structure
In wind turbines, bearing failures have been a continuing problem and have accounted for a significant proportion of all failures. Bearing-related downtime is among the highest of all components of wind turbines. The location of wind turbines is moving offshore. However, to access offshore sites is difficult and thus wind turbines with high reliability and availability are required. Direct-drive wind generators are argued to have higher reliability and availability than geared generators. However, direct-drive generators require a large diameter, which results in a large mass and high cost, in order to get a high torque rating compared to geared generators. It is disadvantageous in terms of manufacture and maintenance to construct direct-drive generators with a large diameter as a one-body structure. In scaling up the power of direct-drive generators, the structural part becomes dominant in the total mass of the generators. Therefore, it is necessary to find a solution to significantly reduce bearing failures and structural mass, and to facilitate manufacture and maintenance for large direct-drive wind generators.
By Dr Deok-je Bang, Korea Electrotechnology Research Institute, South Korea
- Category: Articles
AWES Could Potentially Halve Offshore Wind LCOE
UK-based Kite Power Solutions (KPS) is one of a handful of developers of airborne wind 
energy systems (AWES) who are pushing forward a technology to challenge the conventional horizontal axis wind turbines (HAWTs) in the utility-scale offshore market. Floating offshore AWES could potentially halve offshore wind levelised cost of energy (LCOE) compared with HAWTs. In this article, David Ainsworth of KPS explains the challenges in bringing this novel technology to market in the next ten years.
By David Ainsworth, Business Development Director, Kite Power Solutions, UK
- Category: Articles
Reliable Verification of Design Parameters at Prototype and Serial Turbines
For reasons of cost reduction, modern large wind turbines and blades are designed to use less material and to make use of new materials. They are designed using new simulation tools and smaller safety factors, going beyond established knowledge. Therefore, turbine type certification requires simulation validation by real-life prototype measurements to prove that design dimensions (e.g. clearance between blade tip and tower), parameters and assumptions assure safe operation during the planned service life. For safe and reliable operation, every serial turbine also has to comply with certified design parameters. This keeps O&M costs and lifetime consumption low, despite unmanned 24/7 operation in remote areas. Hence, highly accurate but also cost efficient and safe measuring methods are needed to avoid excess fatigue loads, such as those from resonance issues related to the tower’s natural frequencies or intolerably high rotor imbalance and blade angle deviation. For these applications, video-based analysis is a suitable method to measure motion and vibration.
By Anke Grunwald, Christoph Heilmann and Michael Melsheimer, BerlinWind GmbH, Germany
- Category: Articles
Assessing Long-Term Hub Height Wind Specifications
Numerous wind energy yield assessments are based on measurements carried out with a met mast located at a lower height than the hub of the planned wind turbine. This article deals with the issue of vertical extrapolation of measured wind characteristics. It benchmarks four distinct empirical extrapolation methods based on a simple measurement set-up – two heights of anemometers, a wind vane, a short-term measurement of a remote sensing device (lidar, sodar) and different assumptions about the wind shear (α). These methods were tested on nine of Maïa Eolis’ 80-metre met masts in France and benchmarked to a WAsP calculation.
By Olivier Coupiac, Maïa Eolis, France
- Category: Articles
First Reference to Help Ensure Decisions are Rational and Unbiased
The Top 30 Wind Turbine Faults chart is a database of the most significant failure mechanisms, identified through a failure modes and effects analysis (FMEA), which is validated and regularly updated using information available in the public domain and Lloyd’s Register’s experience of working with wind farm operators. This provides a basis for intelligent decision-making during new product design, sensor selection, configuration of condition monitoring software, SCADA specification, O&M management specification and O&M task prioritisation.
By Mark Spring, Senior Wind Loading Specialist, Lloyd’s Register, UK
- Category: Articles
The Multiple Facets of this Subject, Challenges and Latest Advances
Noise is one of the environmental impacts of a wind farm that requires attention, and can in some cases represent a key constraint on the farm’s operation. Regulation and therefore control of this noise has tended to focus on the level or ‘loudness’ of the noise, which is challenging in itself to measure. But recently increasing attention has been given to features in the noise (in other words its character). Objective measures of these aspects have been developed but they still require careful and time-consuming analysis. Advances in the capabilities of sound measuring equipment are, however, helping practitioners and wind farm operators to obtain results more directly.
By Matthew Cand, Executive Acoustic Engineer, Hoare Lea Acoustics, UK
