Electrical and thermal performance of different core materials applied in wind turbine blades under lightning strikes

© 2019 John Wiley & Sons, Ltd. Wind turbine blades are subject to lightning strikes, which may result in severe damage of the blade materials. The withstanding performance of different blade materials needs to be classified in order to maximize their operational safety. Lightning impulse voltages were applied to model blades with different core materials (polyvinyl chloride [PVC], polyethylene terephthalate [PET], and balsa wood) to characterize the breakdown points (electrically vulnerable areas) on the blades. It has been found that the areas subjected to puncturing are located in the back part (toward the trailing edge) of the sandwich structure, especially at locations close to the main beam. Model blades made of balsa wood are more susceptible to puncturing breakdown than PVC and PET. High impulse currents were imposed at the most probably stricken spots in the impulse voltage tests to compare the severity of damage for PVC, PET, and balsa wood in an attempt to understand the thermal effect of lightning discharge following the final jump. Results show that balsa wood is most resistive to while PVC suffers most damage due to the thermal impact of lightning. Molecular simulation of the chemical degradation process and thermal gas production dynamics was performed at atomic level to explain the damage mechanisms of the three core materials. The performance data of the blade core materials against lightning strike obtained in the present work provide strong guidance on the optimal design of wind turbine blade structure and selection of blade core material