Presentations

Abstract

Wind turbines undergo a wide range of exposures and stress conditions over their operational lifetime. While monitoring of wind turbines are often carried out on towers, or even blades, there are several practical challenges in assessing the foundations of such turbines. This paper presents foundation inspection and subsequent monitoring of an end of life wind farm in Ireland. The turbine had to be closed down and the foundation was required to be excavated during the process. Inspection and initial experiments for durability were carried out. Subsequently, a vibrating wire strin gauge was implemented in the turbine's foundation for long term monitoring with related data loggers. There were some initial inspections and tests related to other monitoring sensors as well, Doppler vibrometry, non-contact measurements from drones and through accelerometers. The turbine was required to be closed down during the process and the implementation required extensive project management and planning. The paper demonstrates how such monitoring considerations, designs and implementation can be carried out for end of life turbines. It allows for direct measurement of reinforcement strains on operational turbines over a long term. These measurements subsequently link back to structural assessments and even contribute to digital twins. On the other hand, they provide a clear possibility of evidence based assessment of degradation of such turbines over time and whether at a farm level such degradation are consistent or not. The instrumentation also allows for determining whether a representative turbine can be chosen amongst a set of wind turbines in a farm and extensive instrumenetation can then be carried out on it to obtain insights into lifetime performance and safety at a farm level.