Development and implementation of a continuous dynamic monitoring system in a wind turbine

Wind turbines are highly dynamic structural systems, prone to degradation along their expected lifetime of operation. In this context, dynamic monitoring systems represent a good option to continuously assess the condition of these structures. This paper presents the works performed to prepare the implementation of a dynamic monitoring system at a utility-scale wind turbine located at the north of Portugal. These preliminary studies included the development of an ambient vibration test and the construction of a numerical model of the wind turbine to help interpret the experimental results. The implemented procedure within the monitoring system permits to continuously track the wind turbine modal properties under several operating conditions using automated techniques of operational modal analysis. The outputs of this monitoring processing allow to deeply comprehend the dynamic behavior of wind turbine structures under real operating conditions. The results obtained during the monitoring period of 1 year reflected the suitability of the implemented monitoring system to continuously identify the modal parameters of the most important vibration modes along the whole operating regime of the turbine. The continuous assessment of these properties, namely the natural frequency values, can thus be used as unique features to evaluate the presence of damage in the wind turbine structure.