On the Attachment of Dart Lightning Leaders to Wind Turbines
(English)In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046Article in journal (Other academic) Submitted
Wind turbines are prone to damages due to lightning strikes and the blades are one of the most vulnerable components. Even though the blade tip is usually protected in standard designs,lightning damages several meters away from it have also beenobserved in field studies. However, these damages inboard fromthe tip cannot be explained by the attachment of downwardstepped leaders or the initiation of upward lightning alone. In this paper, the attachment of dart leaders in an upward lightning flashis investigated as a mechanism of strikes to inboard sections of the blade and the nacelle. Dart leaders in an upward lightning flashuse the channel previously ionized by the preceding stroke or thecontinuous current. The analysis is performed with the self-consistent leader inception and propagation model SLIM. A commercial wind turbine with 45 m long blades and hub height of 80 m is analysed as a case study. The impact of the prospective return stroke peak current, the rotation angle of the blade and the wind on the location of lightning strikes on this mechanism is analysed. The probability of lightning attachment of dart leaders along the blade for the case study is also calculated. It is shown that the dart leader attachment is a mechanism that can explain lightning strikes to the nacelle and to the inboard region several meters away from the blade tip. However, this mechanism cannot explain the lightning strikes observed in the close vicinity of theblade tip (in the region between 1.5 and 6 m from it). The modelling study here also shows that for the turbine under consideration, nacelle receptors intercept most of dart leaders,around 73%, even if the initial continuous currents flow to the blade tip. Overall, it is estimated that around 80% of strikes inupward lightning flashes attach to the tip receptor of the blade.
Place, publisher, year, edition, pages
dart lightning leaders, lightning attachment, lightning damages, wind turbines
Other Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-197277OAI: oai:DiVA.org:kth-197277DiVA: diva2:1050954
QC 201612012016-11-302016-11-302016-12-01Bibliographically approved