Experimental Dynamic Investigation of a Small-Scale Wind Turbine

Investigation of Wind Turbines (WTs) structural behavior has gained crucial importance in recent decades due to the ever-increasing complexity that these systems feature. System identification techniques can be used at several stages of WTs life cycle to maximize performance and ensure safety as well as reliability. Within the design and certification phases, dynamic properties of WT components can be retrieved through dedicated data-driven methods. This helps gaining insights about the system structural behavior and allows to update numerical models which can be used during the WT operational life to help predicting its operational response. Data-driven methods can be also implemented in the field, where dedicated algorithms can be used to monitor the structural performance of the WT in operation. This work focuses on the implementation and execution of the mentioned strategies for a small-scale WT. An extensive test campaign is conducted on subcomponents of the WT for modal characterization via Experimental Modal Analysis (EMA). The latter is also used to determine the entire system modal properties. An operational test campaign is then carried out to monitor the small-scale WT structural response in different rotating conditions. Operational Modal Analysis (OMA) is exploited to extract operational modal parameters. Additionally, Order Based Modal Analysis (OBMA) techniques are also put in place to account for non-stationary operating conditions within the evaluation process of the rotating WT modal properties. The outcome of the presented study builds a solid baseline for potential hybrid Structural Health Monitoring (SHM) strategies, i.e., involving the combination of data-driven approaches with prevalidated numerical models.