Operational modal analysis of two wind turbines with foundation problems

Abstract

Towers and foundations of wind turbines are subject to fatigue damage due to the variable wind loading, which they are exposed to during their working life, particularly if they are located at places were very turbulent wind is acting. In the investigation described here, operational modal analysis is applied to identify the dynamic behaviour of a wind turbine showing an anomalous vibration level under normal wind conditions as well as appearance of fatigue cracks at the foundation. With the aim of avoiding these deficiencies, reinforcement of the transition between tower and concrete foundation was decided on. In order to validate the effectiveness of the repairing procedures, operational modal analysis was performed on the wind turbine before and after the foundation reinforcement