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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Over the past five years, Shermco Industries has repaired over 1,200 generators ranging from 660kW to 3MW and, although the root failure causes vary, the rate of failures has not substantially declined with the larger turbine designs. A review of the collected data from these repairs has revealed that the occurrence of wind turbine generator failure types actually closely mirrors failure modes in more traditional rotating machines, just at a greater incident rate.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}‘Vibro-wind power’ is the harvesting of energy from the wind as it flows around commercial and residential buildings through the mechanism of vibrating structures. The basic science involves energy extraction from bodies induced to vibrate by the action of fluid flow and vortices around flexible structures. Our approach at Cornell University has been to consider the effects of wind on multiple interacting flexible structures, such as hundreds of small cantilevers mounted to a surface. Other vibro-wind concepts include large, fluttering wind-vane type structures, as well as flag or leaf and tree type flexible structures.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Using its extensive knowledge of wind turbine operation, the Danish firm, AVN Energy, has developed a dynamic program which simulates the performance of hydraulic pitch systems during the emergency stopping of a wind turbine. The simulation program is based on a combination of verified accumulator and hydraulic pitch cylinder models; both accumulators and cylinders are products of AVN Energy. The simulation program is designed to verify the performance of AVN Energy products in a hydraulic pitch system set-up. This means that before building a complete system the customers of AVN Energy are now in a position to test whether their hydraulic pitch system is correctly dimensioned and therefore able to perform the requested emergency stop of the wind turbine.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}The term ‘nanotechnology’ often evokes thoughts of tiny robots operating inside cells, super-fast computers, or satellites tethered to Earth by Herculean cables. Looking beyond these popular myths and the hype, nanomaterials have a real potential to make a significant improvement to the performance of composite materials, including the ones used in wind turbine blades.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Downtime is very expensive and only the most important reasons for stopping a wind turbine generator (WTG) can be accepted today. The costs incurred when the electrical system breaks down increase with the size of the WTG; thus the need to implement protection against damage arising from over-voltages is getting higher. It is becoming more and more common for buyers of WTGs to require surge protective devices (or SPDs). This means that the developer and the wind turbine manufacturer have to ensure that the system is satisfactory according to international standards and reliability demands for a modern WTG. To facilitate this work, the International Electrical Committee (IEC) has published a standard for the selection and use of equipment for surge protection in low-voltage power distribution systems (IEC61643 Low-Voltage Protective Devices: Part 12 Surge protective devices connected to low-voltage power distribution systems – Selection and Application Principles).
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Wind turbines that are sited in the view of radars can cause blind spots for air traffic control (ATC); radar clutter that can result in the loss or corruption of a real aircraft’s position. This equivalent return can appear on a controller’s radar screen as a moving aircraft or, equally disconcerting, as strong false weather. In ATC circles this is described as a false target/false weather and may cause the air traffic controller to re-route aircraft. Thus these false targets create additional work for controllers, and may also have safety implications. Typical issues caused by turbines are circled in Figure 1 which shows (from left to right), false air traffic targets, radar clutter and false weather.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Wind and water energy can be harnessed in two major ways: either with lift turbines or reaction turbines. Lift turbine design has reached a point where only small improvements can be made, usually focusing on increasing the efficiency of the impeller blades. Several efforts have been made to introduce different designs.
