*6.1. Conclusions*

Lightning protection is an important aspect of wind energy, since over the expected lifetime of a turbine; at least once a lightning will hit it. Due to the enormous amount of current, without proper protection, it is most likely to result failure to turbine and will cause high repair costs. The protection methods and levels are proposed by standards to achieve the minimal protection suggested, although this protection cannot be taken as guarantee for all cases. As wind turbines keep increase in size to

keep up with the generation demand, as the chance increases, of being hit by a lightning due to their elevation from ground level.

In this paper, a conventional lightning protection concept, previously used for smaller turbine models has been evaluated for possible use for large blades. For the task, simulation software, ANSYS Workbench, Mechanical APDL has been used. In the first three case studies, different conductor cross-section areas have been set for conventional design for full length of the conductor. For the second half of the case studies a hybrid conductor model was evaluated. This design consists of two conductors with different diameters joined together. The higher diameter one covered the tip of the blade and ran down at specific distance from the tip towards the root. The lightning parameters was set according to the current standards, with and additional extreme first and subsequent return stroke current amplitude. Comparing the simulation outcomes has been showed that Case Study C indicated the most promising results among all. In the other hand considering the weight and cost of the extra material, also the possible aerodynamical effects of the conductor around the blade, Case Study E has been appeared to be the most adequate alternative. The design shows grea<sup>t</sup> improvement in reducing the lightning caused effects, compared to Case Study A, therefore the possible damage on the blade. Furthermore, it only requires simple modification of the existing lightning protection concept, minimizing the associated costs, weight, and the possible disturbance in the aerodynamics of the blade.

### *6.2. Recommendations for Future Work*

There are still many factors and values that should be evaluated in order to give full understanding and clarification of the proposed design.


**Author Contributions:** Conceptualization, A.S.A.; Data curation, A.S.A.; Formal analysis, V.M.; Funding acquisition, F.M.-S., A.S.M.S. and J.A.A.-R.; Investigation, V.M. and A.S.A.; Methodology, A.S.A.; Resources, A.S.A.; Software, A.S.A.; Supervision, A.S.A.; Validation, A.S.A.; Visualization, A.S.A. and F.M.-S.; Writing—original draft, V.M.; Writing—review and editing, V.M., A.S.A., F.M.-S., M.Z., M.N.M., A.S.M.S. and J.A.A.-R. All authors have read and agreed to the published version of the manuscript.

**Funding:** Part of the work presented in this research study funded by the Agencia Nacional de Investigación y Desarrollo (through the project Fondecyt regular 1200055 and the project Fondef ID19I10165), project PI\_m\_19\_01 (UTFSM) and by Universiti Kuala Lumpur under the Short Term Research Grant (STRG) STR18022.

**Conflicts of Interest:** The authors declare no conflict of interest.
