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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.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}In the long term, European electricity will dominantly be supplied by solar and wind power. Both power sources fluctuate with the weather, so we will inevitably have to think carefully about the infrastructure of Europe’s future power supply system. A Supergrid (on and offshore) will have to be in place besides new flexible units and storage facilities to balance fluctuations and to transfer wind and solar energy from places where they are abundant. Furthermore, to alleviate the inherent seasonal characteristics of wind and solar power generation in Europe and to secure the power supply, large-scale storage will be needed. A study that has been funded by Siemens AG shows that an optimal mix of solar and wind power generation exists which determines a minimum investment into storage and transmission capacities.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}The experiments agreed as part of the DANAERO project should decrease the uncertainty of several mechanisms characterising wind turbine rotor flow. They were set up to reveal mechanisms such as:
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Increasing the reliability of drive trains for wind turbines of an ever-increasing size requires dedicated simulation models that can provide more insight into the internal gearbox dynamics at the early stages of the design process. These drive train models should contain more than the typical one or two degrees of freedom in standard wind turbine design codes. Therefore, Hansen Transmissions chose to develop detailed multibody models of wind turbine gearboxes.
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{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}While most vendors promote availability in the 97 to 98% range for their machines, and most investors have come to expect that, a recent analysis by Garrad Hassan discovered that levels of true availability are a percentage point or two below that level. Furthermore, turbines operating in North America average in the 94 to 95% range.
