Optimization Design of Composite Wind Turbine Blades Integrating Lightning Strike Analysis

This paper presents an optimization procedure which integrates lightning strike analysis into design reliable and economical composite wind turbine blades. A high-fidelity 5-MW composite wind turbine blade is applied into the lightning strike analysis and the optimization procedure under four different lightning severity levels. The lightning-strike-induced electric field along the wind turbine blade at the top vertical position is calculated using finite element analysis. The dielectric breakdown strength of the composite wind turbine blade is considered as a function of laminate thickness. The lightning safety ratio is then calculated as the ratio between the dielectric breakdown strength and the magnitude of the lightning-strike-induced electric field. Subjected to the lightning constraints and fatigue constraints, the optimization procedure minimizes the total composite material cost by fine-tuning the laminate thickness design variables of the blade model. Both the lightning strike analysis and the optimization results indicate that the blade tip is the most vulnerable region against lightning strike damage. The obtained optimum designs under the four lightning severity levels increase the lightning safety ratio by 36% – 45% and increase the fatigue life more than 15 times compared with the initial blade design.