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- Category: Articles
A New Type of Direct-Drive Generator
The NewGen is a new type of direct-drive generator for wind turbines, based on the idea of putting the generator bearings adjacent to the air-gap of a large diameter generator. In this way the stiffness requirements of the rotor and the stator are drastically reduced, which leads to large mass savings in the mechanical structure.? These savings then enable a further diameter increase, which leads to further mass reductions in electrically active parts. The design is based on excitation by use of permanent magnets. So far a 140kW pilot-scale generator has been tested with encouraging results. The next step is a full-scale demonstration in a wind turbine. The development is taking place in cooperation with VG Power AB, Vasteras, Sweden.By Staffan Engström, Independent Consultant, Agir Konsult AB, Sweden
- Category: Articles
Maximising the Value of Wind Energy
Wind energy remains the front-runner in the increased use of renewable energy. In the quest for cost-efficient wind energy, the constant availability of strong winds is crucial for every project. This is why, after coastal regions and high mountains, it is important to explore, develop and install near-shore and offshore wind projects. The first 2MW onshore turbines suffered from transformer reliability concerns around 2002. The problems due to vibrations, electric switching surges and overloading were investigated and designs were changed accordingly. Since 2004, step by step, wind energy has increasingly moved offshore.? Again, some reliability concerns were discovered and equipment was replaced. This article summarises the need for higher specifications and more reliable transformers in order to prepare the wind industry business for sustainable growth in offshore multi-megawatt turbines.By Dr Jan Declercq and Raymond Van Schevensteen, Pauwels International NV, Belgium
.- Category: Articles
Making Offshore Access as Easy as Crossing the Street
Accessing offshore wind turbines is critical to keep all systems running. This is especially true when the weather deteriorates, wind speeds pick up and production can be maximised. But offshore these conditions also mean that wave heights increase and access by boat can become impossible. The Ampelmann has been developed to increase the accessibility from a ship, even in high wave conditions. The system uses six hydraulic cylinders (also used in flight simulators) to support a transfer deck and gangway. By measuring the ship motions continuously and controlling the length of the cylinders, the transfer deck stands completely still compared to the wind turbine. Access to the turbine then becomes 'as easy as crossing the street'.By Jan van der Tempel and David Cerda Salzmann, Delft University of Technology Offshore Engineering, the Netherlands
- Category: Articles
Using UAVs for Wind Resource Estimation
Aerial photography can be of great value in the planning process for wind farms, including tasks such as wind resource estimation, verification of area maps and finding routes for transportation. However, this can be a rather expensive tool. A system has been developed to use a small unmanned air vehicle (UAV) to perform such photography tasks by using automated optimised routing and piloting. The goal was to allow inexperienced model airplane pilots to perform aerial photography with the required precision. This article explains the concepts, and the UAV hardware and system software developed within the project, which was conducted at Overspeed GmbH & Co. KG.
By Felix Dierich and Dr Hans-Peter (Igor) Waldl, Overspeed, Germany
.- Category: Articles
A Powerful Tool for Analysing Wind Turbine Rotor Designs
Computational fluid dynamics (CFD) gives a unique insight into the complex flow phenomena that govern the aerodynamics of wind turbines. Through a dedicated research and development effort CFD is steadily reaching a level of maturity where it is becoming indispensable in the analysis of modern wind turbine designs. This article gives an insight into recent developments in wind turbine flow simulations in the Wind Energy Department at Risø National Laboratory, where recent additions to our CFD code have made it possible to model the entire turbine including rotor, tower, nacelle and ground boundary. Here, an investigation carried out into the interaction between the rotor and the tower on a downwind turbine will be presented.By Frederik Zahle, Wind Energy Department, Risø, Denmark
.- Category: Articles
Reducing Structural Mass in Direct-Drive Permanent Magnet Electrical Generators
Direct-drive wind turbines offer the potential for high efficiency and reliability but they require large and heavy electrical generators. Large electrical machines require significant structural material to maintain the small airgap clearance between rotor and stator. This structural mass can be modelled, and optimised by either choosing lightweight materials or by adding to the airgap stiffness or using air-cored topologies. A new topology (the ‘E-generator') combines the structural and active material in a ‘C' core module, which can be supported lightly for high torque machines.By Alasdair McDonald, Institute for Energy Systems, UK
.- Category: Articles
New Techniques and Criteria for the Design of Structural Components
By Daniel Trias, National Renewable Energies Centre (CENER), Spain
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