Fragility analysis of large-scale wind turbines under the combination of seismic and aerodynamic loads

The objective of this paper is to research the fragility of large-scale wind turbines considering the combination of seismic and aerodynamic loads. According to the International Electrotechnical Commission (IEC) 61400-1 and pushover analysis, the critical moment and displacement for wind turbines were proposed. The moment based and displacement based fragility curves under different wind speeds were obtained by using multiple stripe analysis (MSA) approach and compared between the first scenario of normal operation condition with the baseline control system (BCS) working and the second scenario of parked condition. The simulation results indicate that the effect of aerodynamic damping on structural response of a wind turbine during normal operation results in a reduction in the maximum values of dynamic response compared to the parked condition, which causes that the probability of exceeding limit state in the first scenario is less than that in the second scenario. It illustrates that, a wind turbine subjected to the combination of seismic and aerodynamic loads in normal operation condition is safer than in parked condition. Finally, it can be concluded that the fragility of large scale wind turbines can be reduced by keeping the BCS working when earthquake happens.