Abstract
The following study conducted on offshore wind farms (WFs) located in the North Sea and in the Baltic Sea. The lightning strokes of 13 WFs over the period of about 8…10 years were analyzed before and after their construction using the lightning location system (LLS) of EUropean Cooperation for Lightning Detection (EUCLID) [1]. Many WFs were excluded from the observation because they were constructed just recently. A detection efficiency (DE) of any LLS for ground-to-cloud flashes (upward lightning) in some cases is very low compared to cloud-to-ground flashes (downward lightning). In [2] the DE of 43% is reported and explained by the fact that the ground-to-cloud lightning currents are often an initial continuous current only (ICConly), free from any superimposed impulse currents and therefore cannot be detected by LLS at all. This type of flashes is often occurred at tall structures (> 100 m) and could pose a risk to wind turbines (WTs) because of their enormous high transferred charge values which can easily exceed 300 As. This specific type of ground-to-cloud flashes are not covered by this study because of the limitation of the LLS. The data obtained during current initial investigation can be used for design and test of lightning protection system (LPS) for WT. The IEC 61400-24 Ed.2.0 (CD) [3] recommends to consider the same maximum values of lightning parameters for offshore WT as for onshore WT, since “there is no evidence of lightning parameters being significantly different offshore”. Our investigation clearly shows that this is not the case. Also, the distance from the coast has an influence on the lightning parameters. Finally, cumulative probability distributions of lightning current peak values obtained for offshore WFs are compared with corresponding curves for onshore WFs presented in [4].
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call