Performance Enhancement of Lightning Protection Systems for Offshore Wind Turbine Blades

When offshore wind turbines are polluted with salt, their surface characteristics change. Pollution affects the performance of the protection systems which can result in damages when it is hit by lightning. In this paper, two lightning protection systems (metallic cap and receptor methods), commonly in use, are applied on a full scale polluted offshore wind turbine to compare their performance. The lightning attachment to the offshore wind turbine blade is studied by analyzing the variations in maximum electric field strength required for the initiation of upward leader due to a vertical tri-pole cloud charge distribution. The computation is done for a polluted Vestas V100, 2 MW wind turbine. A new protection system (enhanced method) with higher lightning protection efficiency is developed. The performance of the metallic cap was then enhanced by adding a receptor at the middle of the blade. This modification has a significant impact on the electric field distribution of the blade. The new method was compared with the metallic cap and the tip receptor. The proposed method can markedly improve the lightning protection performance of offshore wind turbines. The results of the point of initiation of upward leader coincides with experimental data from lightning discharge attachments.