Simulation Analysis and Safety Risk Assessment of a Wind Turbine Blade Failure Event

ABSTRACT A common concern raised during the permitting of onshore wind farms is the potential risk posed by the release of failed turbine blades. Although there has been extensive analysis of blade throw risk based on simulated trajectories, there is a lack of empirical data with which to calibrate models and assess the true risk to public safety. This paper presents a case study of an actual wind turbine blade failure event caused by a lightning strike in the midwestern United States. The nature of the debris field is described, along with measurements of example blade fragments collected from the site. A blade throw simulation model is used to simulate the release of a representative set of debris, informed by fragment sizes and weights collected from the debris field. The debris field produced by the simulation model is shown to match the debris field observed empirically with reasonable accuracy. Ballistic impact models are used to determine whether any fragments thrown beyond 1.1 times the turbine tip height could have caused injury to a person. This ballistic analysis shows that debris that traveled beyond 1.1 times the tip height had relatively low kinetic energy and would be extremely unlikely to cause injury to a person.