Higuera specifically notes that the instrumentation of onshore, concrete wind turbine foundations with optical fibre sensors could provide valuable structural health monitoring data during construction and operation.
Previous research in this area has included FBG strain gauges in blades, wind turbine towers, foundation piles, gearboxes, accelerometers, and for temperature and generator current measurements. highlight the value of FBG sensors for fatigue and damage-detection in wind turbine components. present optical fibre sensors for modern structural health monitoring applications, emphasising examples of best practice for asset-monitoring in industries ranging from energy to transportation. Review papers discussing the fundamental theory and early industrial deployments of FBGs include those by Rao, Kersey, as well as Hill and Meltz, who highlight applications within structural health monitoring. Monitoring requires sensor data, and the transformation of fibre Bragg gratings (FBGs) into sensing transducers is an established, yet active field of research. Structural health monitoring of wind turbine components is observed as a potential area to improve operations and maintenance procedures, monitor fatigue damage, and thus assist lifetime extension decision making. The work demonstrates that real-time foundation monitoring is not only achievable, but that it has the potential to help operators and policymakers quantify the conservatism of their existing design codes.
During this time, measured foundation strains did not exceed 95 μϵ, and showed a strong correlation with both measured tower displacements and the results of a foundation finite element model. In this paper, we outline the sensors’ design, characterisation and installation, and present 67 days of operational data. Selected reinforcement bars were instrumented with metal packaged optical fibre strain sensors prior to concrete casting. This paper presents the initial results of a real-time strain monitoring campaign for an operating wind turbine foundation.
While there are industry drivers to shift towards more economical foundation designs, making this transition safely will require new monitoring techniques, so that the uncertainties around structural health can be reduced. Onshore wind turbine foundations are generally over-engineered as their internal stress states are challenging to directly monitor during operation.