Experimental setup and sensor comparison: towards accelerometer-based detection of flying animal collisions with wind turbines

Mitigating climate change and preserving biodiversity are both crucial to maintain Earth’s habitability for future generations. While wind energy turbines are urgently needed for sustainable power generation, the threat they pose to their surrounding ecosystems must be closely investigated. Especially birds and bats are highly prone to die by colliding with wind turbines or due to barotrauma caused by flying in the direct proximity of the rotor blades. Therefore, to develop a measurement setup which reliably counts impacts on rotor blades is indispensable to establish effective preventive measures. In this work we developed a test setup designed to resemble the conditions of a bat or bird strike to perform preliminary experimentes. Furthermore, we investigated four different sensors, comprising a piezoelectric microphone, as well as a piezoelectric and two capacitive accelerometers, in regard of their feasibility for the intended use case by comparing signal-to-noise ratios and cross-correlations. Material- and structure-related parameters such as wave propagation velocities and damping factors have also been evaluated to obtain initial insights into their behavior. Since the impact onset detection algorithm is of high importance when investigating impact locations, we compared three different approaches in regard of their reproducibility and precision. The results indicate that the piezoelectric acceleration sensor and the more sensitive capacitive sensor are well suited for further development and that the proposed setup provides a reliable basis for detailed analysis of the distinct signal characteristics. Additionally, the onset detection method based on calculating an energy signal and extracting the maximum amplitude of the impact appears to be the most precise method for the application described.