Patent Application
20220364847
The present disclosure relates to the field of measuring three-dimensional shapes of 3D structures, in particular wind turbine structures like wind turbine blades, using optical fibre strain sensors, namely Fibre Bragg Gratings, FBGs.
In the field of measuring 3D shapes using optical fibre strain sensors, namely Fibre Bragg Gratings, there are insufficiencies that the present disclosure addresses. In particular, there are problems relating to shape sensing systems based on FBGs.
The known shape sensing systems are based on multicore arrays of normally 3 cores. The distance between the cores are of microns which means that are not suitable for accuracy along long lengths.
Other known systems use hundreds or thousands FBGs to measure the shape of a small length structure, which means a very costly system with no general commercial application, with the exception of medical research.
The inherent round design of the fibre optic does not allow for the measurement of torsion unless it is bonded to the structure itself, and in that case to measure the shape it is then required the knowledge of the design of the original structure.
In particular, there are also problems relating to shape sensing systems based on FBGs embedded on wind turbine blades.
The use of FBGs embedded on blades has more than 20 years, but its reliability comes under question, due to high stresses of the blades, need for calibration, temperature compensation and design of original blade in order to measure reliable strains. Another issue is that huge composite structures are likely to be different from each other due to manufacturing processes and this affects the quality of measurement.
These reasons can explain that strain sensing on large structures is quite used on research and prototype testing, but not much used on the actual long-term control structures, in particular wind turbine structures due to the lack of reliability from the acquired data and devices.
These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.
The present disclosure relates to the field of measuring three-dimensional shapes of 3D structures, in particular wind turbine structures like wind turbine blades, using optical fibre strain sensors, namely Fibre Bragg Gratings, FBGs.
The present disclosure includes a self-contained 3D shape sensing device and respective operation method comprising three or more single-core parallel optical arrays of FBGs embedded in a discrete composite structure with a predetermined profile, for example a rectangular pliant beam, for measuring the shape and deflection of structures such as wind turbine blades, advantageously without experiencing structural stresses, and without needing to know the exact design and profile of the blade to measure its deformation.
The present disclosure also includes a self-contained shape sensing device method and apparatus based on two or more single-core parallel optical arrays of FBGs embedded in a discrete composite profile for measuring the shape and deflection along the length of a wind turbine blade, advantageously without experiencing stresses from the blade, and having the possibility of being removed and refitted again, being a discrete and independent relative to the structure to be measured.
The device of the present disclosure is thus capable of measuring the original shape and consequent deflections of a wind turbine blade in terms of flapwise, edgewise or torsion. The device of the present disclosure is also capable measuring the original shape and deflection of a structure without knowing its design profile or material. The fibre optic device of the present disclosure is also capable of measuring a precise shape immune to temperature changes.
Advantageously, the measurement device of the present disclosure can be mounted, unmounted and refitted again in the same or a different placement.
Advantageously, the fibre optic device of the present disclosure is capable of measuring shape and deflection of a structure, e.g. a wind turbine blade, without experiencing stresses from the structure, wind turbine blade.
Advantageously, the fibre optic device of the present disclosure is capable of measuring three-dimensional shape of very large structures, for example 150-meter blades, with a reduced number of sensors and sections (for example, 5 to 20) and improved long-term stress resistance, without impairing measurement precision.
Advantageously, the fibre optic device of the present disclosure for measuring shape and deflection can be mounted inside or outside of a wind turbine blade.
The device of the present disclosure can be thus be used to reliably compare the structural behaviour of different blades.
The device of the present disclosure is precise and reliable enough to provide information to control a wind turbine in terms of pitch and yaw controls.
The shape sensor device of the present disclosure can be manufactured on one facility and easily mounted or refitted on a blade in other location, being easily transported when rolled.
The device of the present disclosure includes the following advantages:
It is disclosed a device for measuring a three-dimensional shape of a structure by being slidably coupled to the structure such that the deformation of the structure, except lengthening or shortening, causes a corresponding deformation of the device, comprising:
An embodiment comprises one or more slidable fittings for slidably coupling the beam to the structure to be measured.
An embodiment comprises a conduit for rigidly mounting onto the structure to be measured, wherein the beam is slidably mounted inside the conduit.
Optionally, the device may be rigidly fixed at one location to the structure. In particular, the device may be rigidly fixed to the structure at one of the ends of the beam.
Optionally, the device may be rigidly fixed at two or more locations to the structure. However, in this case the advantages associated with the slidable connection to the structure will no longer be present.
In an embodiment, the beam has a rectangular or quadrangular cross-section and device comprises four said optical fibres arranged in parallel within said beam forming a rectangle-shaped or a square-shaped optical fibre cross-section.
In an embodiment, the device comprises three said optical fibres arranged in parallel within said beam to sense deflection of the beam along a first direction, deflection of the beam along a second direction perpendicular to the first direction, and temperature.
In an embodiment, the device comprises four said optical fibres arranged in parallel within said beam to sense deflection of the beam along a first direction, deflection of the beam along a second direction perpendicular to the first direction, torsion of the beam, and temperature.
It is also disclosed a wind turbine blade or wind turbine tower comprising the device according to any of the disclosed embodiments.
In an embodiment, the device is installed inside the blade or mounted outside the blade, in particular on the trailing edge.
In an embodiment, the pliant beam comprises a plurality of parallel recesses along the length of the pliant beam.
The recesses are located at the external upper and lower surfaces of the pliant beam to embed the optical sensors and the optical fibres. With these recesses, the optical fibres and in particular the optical sensors are only affected by the shape or deflection or torsion of the pliant beam and not by other stresses external to the beam, when said beam is applied on the structure. Preferably, the optical fibre is embedded in a recess at a predetermined depth such that the optical fibre is not flush with the beam surface, in order to better protect the optical fibre from external stresses or pressures. Advantageously, the optical fibre is embedded in the recess and fixed using an adhesive, preferably an adhesive resin, more preferably an epoxy resin.
It is also disclosed a method for measuring a three-dimensional shape of a structure by using a device slidably coupled to the structure such that the deformation of the structure, except lengthening or shortening, causes a corresponding deformation of the device, the device comprising:
An embodiment of the disclosed method comprises the previous application of one or more slidable fittings to the structure for slidably coupling the beam to the structure to be measured.
An embodiment of the disclosed method comprises the previous rigidly mounting of a conduit onto the structure to be measured, wherein the beam is subsequently slidably arranged inside the conduit.
In an embodiment, the device comprises three said optical fibres arranged in parallel within said beam, and the method comprises determining deflection of the beam along a first direction, deflection of the beam along a second direction perpendicular to the first direction, and temperature.
In an embodiment, the device comprises four said optical fibres arranged in parallel within said beam, and the method comprises determining deflection of the beam along a first direction, deflection of the beam along a second direction perpendicular to the first direction, torsion of the beam, and temperature.
In an embodiment of the method, the device is previously installed inside the blade or mounted outside the blade, in particular on the blade trailing edge.
The beam may be made in polymer or may also be made from a composite material like a polymer base comprising embedded fibres, such as a glass-fibre based composite, for example using a polyvinyl-based polymer.
It is also disclosed a computer-implemented method for measuring a three-dimensional shape of a structure, using data obtained from a device slidably coupled to the structure such that the deformation of the structure, except lengthening or shortening, causes a corresponding deformation of the device, the device comprising:
It is also disclosed a non-transitory storage media including program instructions for implementing a method for measuring a three-dimensional shape of a structure, the program instructions including instructions executable by a data processor to carry out the method of any of the disclosed embodiments.
The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.
The present disclosure relates to the field of measuring three-dimensional shapes of 3D structures, in particular wind turbine structures like wind turbine blades, using optical fibre strain sensors, namely Fibre Bragg Gratings, FBGs.
The present disclosure relates to a system comprised of a composite beam acting as a base layer with 2 or more arrays of parallel FBGs embedded along the composite beam.
In an embodiment, the beam can be between 1 to 200 meters with 5 to +20 sensorized sections.
In an embodiment, the device is fixed to the structure to precisely replicate the same shape of the structure onto the beam and then we can just measure the shape of the beam using the embedded FBGs.
In an embodiment, the beam shall be fixed on one of the ends and free on the rest, so that the beam does not experience the stresses of the structure when deflecting.
In an embodiment, the beam is arranged to slide through fixation pieces that are fixed to the structure.
In an embodiment, the shape sensor can be applied to the interior of the blade or on the outside of an existing blade.
In an embodiment, when the beam deflects, the FBGs on one of the sides will experience more strain then the FBGs on the other side, and the difference of strains is used to measure the curvature on each section. The knowledge of the composition and design of the beam allows for the extrapolation of shape for the rest of the beam between sections.
In an embodiment, the disclosure allows for the re-use of the same shape sensor device in different structures, and it allows the re-fitting on the same position, if needed.
In an embodiment, the use of 3 or 4 parallel arrays allows for the measurement of flapwise, edgewise deflection, torsion and with temperature compensation.
In an embodiment, by not being fixed or bonded to the structure, but free to move on one of the ends, allows the beam not to experience the stresses from the structure, only experiencing the shape and deflection.
In an embodiment, the higher the transversal distance between arrays and respective FBGs allows for a higher accuracy in terms of shape and deflection.
In an embodiment, the sensor of
In an embodiment,
In an embodiment,
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In an embodiment,
In preferred embodiment, the number of recesses are 2 or more for the measurement of the shape and deflection in two dimensional shapes structure.
In an embodiment, the recesses are 3 or more for the measurement of the torsion in three dimensional shapes.
The term “comprising” whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof.
The above described embodiments are combinable.
The following claims further set out particular embodiments of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 115813 | Oct 2019 | PT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/059285 | 10/2/2020 | WO |
