The best “papers of the day” are papers which deal with problems I never thought about although they are quite obvious. This is the case for the paper of Amr M. Abd-Elhady et al. (2014) which deals with the problem of backflow current-overvoltages in wind turbines. I never thought about it, but wind turbines have a high risk of being hit by a lightning due to their size and location. Of course, wind turbines have a grounding system. However, that grounding system depends on the soil resistivity (= how much the soil resists the flow of electricity) which depends on moisture and salt content and temperature. High soil resistivity makes it “difficult to attain low grounding impedance for the utilized electrodes. These increase the ground potential rise (GPR) and make surge arresters operate in reverse direction.” The resulting backflow surge current can damage the equipment (cable, transformers, surge arresters . . .) and therefore needs to be prevented. Using a modelling approach, Amr M. Abd-Elhady et al. analysed which parameters influence the damage caused by lightning and tested an alternative grounding system. For example: The lightning damage is worse when the lightning hits the wind turbine at the negative peak of voltage waveform. Moreover, they compared the damage in “in service” and “out of service” wind turbines and the influence of the number of connected wind turbines in a wind farm. Interestingly, the damage decreases with increasing the number of wind turbines for the non-thunderstruck turbines case and increases with increasing the number of wind turbines for the thunderstruck turbines. So in larger wind farms, the wind turbine which is hit by lightning receives more damage but the surrounded wind turbines are less damaged compared to a small wind farm. High-frequency modeling of Zafarana wind farm and reduction of backflow current-overvoltages
Amr M. Abd-Elhady, Nehmdoh A. Sabiha and Mohamed A. Izzularab International Transactions on Electrical Energy Systems 24.4 (2014): 457-476.
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IdeaI love to increase my general science knowledge by reading papers from different fields of science. Here I share some of them. Archiv
März 2018
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