Device and method for determining the deflection of a rotor blade of a wind turbine

Abstract

To provide a device and a method for monitoring deflection of a rotor blade of a wind turbine.SOLUTION: The present disclosure relates to methods and systems for measuring deflection of blades of a wind turbine. Examples include a light emission and collection device mounted to a nacelle and configured to emit light in a direction within a substantially vertical plane. Examples include a method for operating a wind turbine including emitting light above a hub, receiving the light when reflected by a blade of the wind turbine, and, if the level of blade deflection is above a threshold, reducing blade loading of the blade before the blade reaches a vertically downward position. Examples include a method for monitoring deflection of a rotor blade of a wind turbine comprising emitting a light sheet, collecting reflections of the emitted light, and determining deflection of the rotor blade by determining a time during which the blade reflects the emitted light sheet.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to devices and methods for monitoring the deflection of rotor blades of wind turbines, and more particularly, to devices and methods for monitoring the deflection of rotor blades of wind turbines using light. [Background technology]

[0002] Modern wind turbines are commonly used to supply electricity to the power grid. This type of wind turbine generally comprises a tower and a rotor disposed on the tower. The rotor, which typically comprises a hub and a number of blades, rotates under the influence of wind on the blades. Said rotation typically generates torque that is transmitted through the rotor shaft to a generator, either directly or by a gearbox. In this way, the generator generates electricity that can be supplied to the power grid.

[0003] The wind turbine hub may be rotatably coupled to the front of the nacelle. The wind turbine hub may be connected to a rotor shaft, which may then be rotatably mounted within the nacelle using one or more rotor shaft bearings located in a frame inside the nacelle. The nacelle is a housing located at the top of the wind turbine tower that houses and protects further components, such as the gearbox (if present) and generator, and, depending on the wind turbine, power converters, and auxiliary systems.

[0004] The trend in the wind turbine industry is to increase the hub height and increase the blade length to capture more wind energy, which makes the blade more flexible.

[0005] The loads on a wind turbine blade should generally be high enough to generate as much energy as possible, but not so high as to overcome the blade's deflection or strain limits. If a wind turbine blade deflects or bends excessively, for example due to a wind gust, it could strike the wind turbine tower and even break. These risks increase with the blade's length. Also, to reduce direct material costs, there is a trend to build blades as light (and therefore flexible) as possible.

[0006] It is known to sense the tips of wind turbine blades so that blade tip clearance, i.e., the distance between the blade tip and the wind turbine tower, can be calculated and adjusted to avoid blade damage or to prevent the blade from hitting the tower. However, existing blade tip sensing methods and devices may not be sufficiently reliable or may require complex and expensive equipment. For example, it may be necessary to install instruments on the blade tips. In some cases, information gathered about blade tip position may be obtained too late to avoid blade damage.

[0007] Examples of the present disclosure provide a device and method for determining the deflection of (the tips of) rotor blades of a wind turbine using light, which at least partially solves the above-mentioned problems. Summary of the Invention

[0008] In a first aspect of the present disclosure, there is provided a wind turbine comprising: a tower; a nacelle on top of the tower; a rotor hub having one or more rotor blades rotatably mounted to the nacelle; and a first light emission collecting device mounted to the nacelle, the first light emission collecting device configured to emit light in a direction substantially in a vertical plane and collect reflections of the emitted light by one of the rotor blades, the first light emission collecting device mounted to the nacelle at a horizontal distance from the tower such that a tip of the blade is detected before or when it exceeds a blade deflection limit.

[0009] According to this aspect, a wind turbine is provided with a simple device that can emit light and collect reflections of previously emitted light in a direction substantially in a vertical plane, thereby avoiding excessive blade deflection and therefore blade breakage and / or blade collision with the wind turbine tower.

[0010] Throughout this disclosure, a light emission collecting device can be understood as a set of at least a light source element and a light receiving element. These light emitters and light sensors may be located together inside a case or device that houses them, such as a laser rangefinder, or they may be separate elements; for example, the light sensor may be a camera and the light emitter may be a laser or light-emitting diode (LED). If the light emitters and light sensors belong to the same device, they may be controlled subordinately, i.e., they may share a control processing unit (CPU) and memory. If the light emitters and light sensors are separate elements, they may not share a CPU and memory. In this case, an additional device, such as a controller mounted in the nacelle, can collect data from both elements and operate on this data. In some examples, the emitters and sensors can be interlinked and communicate with each other as needed, for example, to control the emission of light at specific times and / or frequencies or to perform functionality checks.

[0011] Blade deflection limit or blade deflection threshold may be understood as the deflection or strain limit above which the risk of breakage of the wind turbine blade, or the risk of collision with the wind turbine tower, or generally damage to the blade, is acceptable.

[0012] As used herein, horizontal distance may be understood as the distance measured along the length of the nacelle. If the light collecting device is mounted to the bottom of the nacelle, horizontal distance may refer to the distance along the length of the nacelle between this device and the wind turbine tower. The appropriate distance depends on the tip clearance due to the shape of the tower. If the light collecting device is mounted to the top of the nacelle, horizontal distance may refer to the distance along the length of the nacelle between this device and the tower, measured along the axis between the nacelle rotational axis and the rotor hub.

[0013] A vertical direction may be understood as a direction that is substantially parallel to the wind turbine tower in the absence of tower movement, e.g., in the absence of tower tilt. A vertical plane may be understood as a plane that includes such a vertical direction.

[0014] In a further aspect, a method is provided for operating a wind turbine having a first light emission collecting device mounted to a nacelle, the method including emitting light onto a hub of the wind turbine and receiving the light when reflected by a blade of the wind turbine, the method further including reducing blade load on the blade before the blade reaches a vertically downward position if a level of blade deflection based on the received reflected light exceeds a threshold.

[0015] Emitting light above the hub can be understood as emitting light between 9 o'clock and 3 o'clock, where 9 o'clock and 3 o'clock refer to the position of the wind turbine blades (e.g., 6 o'clock refers to the blades pointing downward).

[0016] In yet a further aspect, a method is provided for monitoring deflection of rotor blades of a wind turbine, wherein a first light emission collecting device is mounted to a nacelle of the wind turbine, the method including emitting a light sheet, collecting reflections of the emitted light, and determining deflection of the rotor blades by determining the time at which the blades reflect the emitted light sheet.

[0017] According to this aspect, not only can the blade deflection be detected but the time of the blade-light sheet interference can be used to better tune the mechanism of blade load reduction. The operation of the wind turbine blades can then be optimized by achieving a suitable compromise between blade load reduction and keeping energy production as high as possible.

[0018] As used herein, a "light sheet" can be understood as a light beam having a higher divergence, i.e., not collimated. Conversely, as used herein, the term "light beam" can be understood as a light beam having a lower divergence, i.e., substantially collimated. Thus, the difference between a light beam and a light sheet as used throughout this disclosure can be divergence or collimation.

[0019] As a visual example, a set of light rays that are substantially parallel among themselves and have a substantially constant width along the length of the set of rays (i.e., the light rays are substantially collimated or substantially non-diverging) can be considered a light beam, while a set of light rays that increase in width with distance from the light source (i.e., the light rays are not collimated and exhibit divergence) can be considered a light sheet. Thus, a light beam can be visualized as a set of light rays traveling in a substantially unidirectional direction, and a light sheet can be visualized as a plane of light, in the sense that the light rays of the light sheet can be visualized as traveling in multiple directions in a plane due to the divergence of the light rays.

[0020] Thus, in this specification, a light beam may be emitted from a light source at an angle of, for example, less than 0.5°, and a light sheet may be emitted from a light source at an angle of, for example, 0.5° or more. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view of an example of a wind turbine. [Figure 2] FIG. 2 is a simplified internal view of an example nacelle of the wind turbine of FIG. 1. [Figure 3]FIG. 1 is a schematic diagram illustrating a front view of an example wind turbine. [Figure 4] FIG. 4 shows a schematic side view of the wind turbine of FIG. 3. [Figure 5] FIG. 5 is a diagram illustrating an example of a vertical distance evolution measured by the light emitting collecting device (LECD) of either of FIGS. 3 and 4. [Figure 6] FIG. 2 shows a schematic front view of another example of a wind turbine. [Figure 7] FIG. 7 shows a schematic side view of the wind turbine of FIG. 6. [Figure 8] 8 is a diagram illustrating an example of the evolution of the intensity of light received by the LECD of either of FIGS. 6 and 7. FIG. [Figure 9] FIG. 2 is a schematic diagram illustrating a side view of a wind turbine according to another example. [Figure 10] 1 illustrates a schematic diagram of an example of a method for operating a wind turbine. [Figure 11] 1 illustrates a schematic diagram of an example of a method for monitoring rotor blade deflection in a wind turbine; DETAILED DESCRIPTION OF THE INVENTION

[0022] Reference will now be made in detail to the embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is presented by way of explanation of the invention, and not as a limitation of the invention. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment may be used in another embodiment to yield still a further embodiment. The present invention, therefore, is defined by the appended claims. of It is intended to encompass all such modifications and variations that fall within its scope.

[0023] FIG. 1 illustrates a perspective view of an example wind turbine 160. As illustrated, the wind turbine 160 includes a tower 170 extending from a support surface 150, a nacelle 161 mounted to the tower 170, and a rotor 115 coupled to the nacelle 161. The rotor 115 includes a rotatable hub 110 and at least one rotor blade 120 coupled to and extending outward from the hub 110. For example, in the illustrated embodiment, the rotor 115 includes three rotor blades 120. However, in alternative embodiments, the rotor 115 may include more or fewer than three rotor blades 120. Each rotor blade 120 may be spaced about the hub 110 to facilitate rotation of the rotor 115 so that kinetic energy from the wind can be converted into usable mechanical energy and, subsequently, electrical energy. For example, the hub 110 may be rotatably coupled to a generator 162 ( FIG. 2 ) positioned within the nacelle 161 to enable the generation of electrical energy.

[0024] 2 shows a simplified interior view of an example nacelle 161 of the wind turbine 160 of FIG. 1. As shown, a generator 162 may be disposed within the nacelle 161. In general, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 to generate electrical power from rotational energy generated by the rotor 115. For example, the rotor 115 may include a main rotor shaft 163 coupled to the hub 110 for rotation therewith. The generator 162 may then be coupled to the rotor shaft 163 such that rotation of the rotor shaft 163 drives the generator 162. For example, in the illustrated embodiment, the generator 162 includes a generator shaft 166 rotatably coupled to the rotor shaft 163 via a gearbox 164.

[0025] It should be understood that the rotor shaft 163, gearbox 164, and generator 162 may generally be supported within the nacelle 161 by a support frame or bedplate 165 positioned at the top of the wind turbine tower 170.

[0026] The nacelle 161 is rotatably coupled to the tower 170 by a yaw system 20 such that the nacelle 161 can rotate about a yaw axis YA. The yaw system 20 comprises a yaw bearing having two bearing components configured to rotate relative to one another. The tower 170 is coupled to one of the bearing components, and a bedplate or support frame 165 of the nacelle 161 is coupled to the other bearing component. The yaw system 20 comprises a ring gear 21, a plurality of yaw drives 22 having motors 23, a gearbox 24, and a pinion 25 for meshing with the ring gear 21 to rotate one of the bearing components relative to the other.

[0027] The blades 120 are coupled to the hub 110 via pitch bearings 100 between the blades 120 and the hub 110. The pitch bearings 100 include an inner ring and an outer ring. The wind turbine blades can be mounted on either the inner bearing ring or the outer bearing ring, with the hub connected to the other. The blades 120 can rotate relative to the hub 110 when the pitch system 107 is activated. Thus, the inner bearing ring can rotate relative to the outer bearing ring. The pitch system 107 of FIG. 2 includes a pinion 108 that meshes with an annular gear 109 provided on the inner bearing ring to rotate the wind turbine blades about the pitch axis PA.

[0028] Figure 3 shows a schematic front view of an example of a wind turbine including a light emission collecting device. Similar to that shown with respect to Figure 1, the wind turbine 160 includes a tower 170, a nacelle 161 on top of the tower 170, and a rotor hub 110 having at least one rotor blade 120 rotatably mounted to the nacelle 161. The wind turbine 160 also includes a first light emission collecting device (LECD) 305 mounted to the nacelle 161, for example, to the top 310 or bottom 315 of the nacelle 161 in Figure 3. In particular, the wind turbine 160 in Figure 3 includes three blades 120 and two LECDs, the first LECD 305 mounted to the bottom 315 of the nacelle 161, and an additional LECD 330 mounted to the top 310 of the nacelle 161.

[0029] In general, there may be any number of LECDs mounted on any side of the nacelle 161. The nacelle 161 may have a top side 310, a bottom side 315, a forward or upstream side 915, an aft or downstream side 910, and two lateral sides 312, 313. Thus, the lateral sides 312, 313 may be substantially parallel to the length of the nacelle 161 and may extend from the forward 915 to the aft 910 of the nacelle 161, rather than the top 310 and bottom 315 of the nacelle 161. In the example of FIG. 3 , any number of LECDs may be mounted on the bottom 315 of the nacelle 161, and any number of LECDs may be mounted on the top 310 of the nacelle 161. In these or some other examples, one or more LECDs may be mounted on either of the lateral sides 312, 313 of the nacelle 161. This can be particularly useful when the LECD emits light above, e.g., upward, the hub 110 to detect excessive blade deflection before the blades 120 pass in front of the tower 170. Mounting on the lateral side of the nacelle 161 can be an option available in all examples throughout this disclosure.

[0030] The first LECD 305 is configured to emit light in a direction in a substantially vertical plane and collect reflections of the emitted light by one of the rotor blades. In some examples, the first LECD 305 is configured to emit light in a substantially vertical direction, such as upward or downward. As shown in FIG. 3 , the first LECD 305 emits light downward and can collect the reflected upward light that is reflected off the ground 320. In some examples, the ground 320 can correspond to the support surface 150 in FIG. 1 . However, in some circumstances, the blade can deform to such an extent that at least the tip of the blade reaches a position where the light beam from the LECD 305 to the ground is interrupted and reflected.

[0031] In some examples, particles in the ground 320 and / or air, for example in dusty or foggy conditions, may absorb a portion of the emitted and / or reflected light, thereby complicating detection of one or more reflections of the emitted light. To facilitate detection of the light reflected by the ground 320, the emitted light may be split, for example, into two portions so that each portion can be detected by a different light sensor. In one example, the first LECD 305 may include two light-receiving elements for this purpose, such as a primary light sensor and a secondary light sensor. In another example, the secondary light-receiving element may be provided as an element independent of the first LECD 305. In both examples, the secondary sensor may be used to indicate a failure of the light emitter and / or the primary light sensor or to confirm that they are functioning properly.

[0032] Figure 4 schematically illustrates a side view of the wind turbine of Figure 3. As shown in Figure 4, the first LECD 305 is mounted to the nacelle 161 at a horizontal distance 405 of the tower 170 such that the tip 410 of the blade 120 is detected before or when it exceeds the blade deflection limit. Thus, detection of the tip 410 of the blade 120 can provide a warning that the blade 120 is approaching the tower 170 too closely and may collide with the tower 170. Therefore, preventative measures can be taken to avoid such a collision or generally to avoid damage to the blade 120.

[0033] The first LECD 305 may be configured to emit a substantially collimated light beam 325. The first LECD 305 may include one or more lenses to obtain the collimated light beam 325. The first LECD 305 may also be configured to measure a distance in a substantially vertical plane 415 between the first LECD 305 and the location of the reflection. In some examples, the first LECD 305 may be configured to obtain a location where the one or more reflections occur. The distance in the substantially vertical plane may be the substantially vertical distance 415 in some examples. In some other examples, the distance in the substantially vertical plane may be a substantially horizontal distance. In still other examples, the distance in the substantially vertical plane may be a distance in a substantially vertical plane having an angle (greater than 0°) with respect to either the vertical direction or the horizontal direction.

[0034] 3 and 4, the light may be reflected off the ground 320. The measurement of vertical distance 415 may be registered and recorded in the memory of the first LECD 305. In one example, the first LECD 305 may be a laser range finder.

[0035] 5 schematically illustrates an example of the evolution over time of a measured vertical distance 415, i.e., a distance representing the distance between the LECD and the reflection point in this particular example. Thus, when the distance between the LECD and the location of the reflection of the emitted light is not a vertical distance, the following may apply: The vertical distance 415 (VD) may be measured indirectly. For example, the first LECD 305 may quantify the time it takes for the emitted collimated light beam 325 to hit the ground 320, then be reflected and detected by the first LECD 305. This time value may then be converted into a value for the vertical distance 415.

[0036] Each of the lines 505, 510, 515 represents a number of measured vertical distances 415. The case of line 505 represents the case where no interference between the light beam 325 and the blade 120 was detected, which is why the measured vertical distances 415 provide a substantially constant value over time.

[0037] However, two other lines 510 and 515 show cases where interference of blade 120 with light beam 325 is detected. Such interference causes a decrease in measured vertical distance 415. Thus, three interferences are shown in Figure 5. Lines 505, 510, and 515 may correspond to the deployment of the blade in cases 121, 122, and 123 of Figure 4, respectively. In deflection case 121, the blade does not interfere with light beam 325, but interference does occur in cases 122 and 123.

[0038] Additionally, the variation (reduction) in vertical distance 415 may be correlated with blade deflection (e.g., distance 407 between blade 120 and tower 170, see FIG. 4 ) and used to determine which load reduction measures to take. For example, different load reduction measures may be implemented for the cases of lines 510 and 515. In some instances, no measures are necessary even if the blade reflects light. In other instances, operational changes such as pitching or rotor speed reduction may be implemented. Also, action may be taken immediately upon detecting interference, or after several blade passes and / or blade interference, depending, for example, on how large the deflection of blade 120 may be.

[0039] For example, in some instances, blade load reduction may occur after monitoring multiple passes of the same blade 120. In some of these instances, a statistical evaluation of the interference of the blade 120 with the light emitted by the first LECD 305 may be performed over time to determine whether to react and, if so, how to react. In some other instances, a single pass, e.g., a single interference event of the blade 120 with the emitted light, may be used to determine whether to react and how to react. These options may also be combined, e.g., one of them may be used during a particular period of time and the other may be used during a later or at least partially overlapping period of time.

[0040] If the blade deflection is acceptable, for example, if one or more blades 120 are not detected for a period of time, then in some instances the operating power may be increased. In some of these instances, the power may be increased above the nameplate rating.

[0041] Mounting a first LECD 305 configured to emit a light beam 325 and collect its reflection can be an easy and inexpensive way to detect deflection of the blade 120. Additionally, this can be a convenient method compared to prior art systems that use specific equipment on the blade tip 410 or tower 170.

[0042] In some examples, the blades may include a paint or coating on at least a section including the blade tip to ensure effective reflection of light emitted by the LECD.

[0043] 3 and 4 also show LECD 330 mounted on top 310 of nacelle 161. In this case, when LECD 330 emits light above, e.g., upward, hub 110, the distance, e.g., vertical distance, between LECD 330 and where the reflection occurs can be measured only when blade 120 interferes with light beam 325. Such a measurement can trigger preventative measures that can be adapted depending on the magnitude of the measured vertical distance.

[0044] The measured distance, for example the value of the upper vertical distance, can help to predict a possible collision between the blade 120 and the tower 170 and reduce the blade load to avoid it.

[0045] FIG. 6 schematically illustrates a front view of another example of a wind turbine including a light emission collecting device. In the example of FIG. 6, the first LECD 305 is configured to emit a light sheet 605. In one example, the light sheet 605 may be generated by a cylindrical lens that diverges the light beam. In another example, the light sheet 605 may be generated by a rotating or oscillating mirror that rapidly deflects the light beam, covering a specific angle in a substantially negligible time. The light sheet 605 may be emitted in a substantially vertical direction in some examples. In some other examples, other emission directions may be used.

[0046] The first LECD 305 or a processor coupled to the first LECD may also be configured to measure the intensity of the received light. That is, the first LECD may emit light 605 and receive light, and the received light may partially include a reflection of the emitted light 605. If the blade 120 does not interfere with the light sheet 605, the received light intensity does not change. However, if the blade 120 intersects with the light sheet 605, it may increase the reflection and scattering of light, thus increasing the light received by the first LECD 305. Thus, the first LECD 305 may detect that the blade 120 is interfering with the light sheet 605 and that preventative measures may need to be taken to avoid excessive blade deflection.

[0047] In this specification, a change in light intensity may be understood as a variation, for example an increase, in the amount of light relative to the amount of light previously received.

[0048] In some examples, modulation techniques can be used to distinguish between blade 120 crossings and other undesired detections that may cause false positives, such as birds or flying plastic bags. In this case, the intensity can be time-averaged and the pulse frequency filtered. In some examples, color filtering, or general wavelength filtering, can be used to help in this regard. Additionally, in some examples, rotor position and / or rotor speed can identify detected intensity fluctuations, allowing undesired detections to be discarded.

[0049] A schematic diagram of the evolution of the intensity received by an LECD (e.g., the first LECD 305 in FIG. 6 ) over time as the rotor 115 and blades 120 rotate can be illustrated in FIG. 8 . FIG. 8 illustrates case a), where there is no intersection, i.e., no interference, between the blades 120 and the light sheet 605. In such a case, a substantially constant received intensity value may be measured. Line 901 illustrates a number of unfiltered measurements, and line 902 illustrates a number of high-pass filtered measurements. A high-pass filter can be used to filter out standard intensity measurements. By applying the high-pass filter, deviations from the normal or default situation are registered and highlighted.

[0050] 8 also shows case b) where blades 120 intersect with light sheet 605, thus causing fluctuations in the measurements of received light intensity as explained above. In case b), interference between three blades 120 and light sheet 605 is detected.

[0051] The duration of different values ​​of measured light intensity and / or the magnitude of the change in intensity may be correlated with the distance 407 between the blade 120 and the tower and used to trigger measures to prevent damage to the blade 120, such as a collision between the blade 120 and the tower 170. Thus, the LECD or a processor coupled to the LECD may be configured to measure the time it takes for emitted light to be reflected by the blade 120.

[0052] As described above, the wind turbine 160 may further include an additional LECD 330. The additional LECD may, in some examples, be mounted to the top 310 or bottom 315 of the nacelle 161. Like the first LECD 305, the additional LECD may be configured to emit light in a direction in a substantially vertical plane, such as the substantially vertical direction 415, and to collect reflections of the emitted light by one of the rotor blades. In some examples, the first LECD 305 and the additional LECD 330 may be mounted on the same side of the nacelle 161. For example, FIG. 7, which schematically illustrates a side view of the wind turbine of FIG. 6, shows the first LECD 305 and the additional LECD 330 mounted on the bottom 315 of the nacelle 161. In these or other examples, for example, in FIGS. 3 and 4, the first LECD 305 and the additional LECD 330 may be mounted on opposite sides of the nacelle 161. FIG. 7 shows two additional LECDs 330, one mounted on the same side (bottom 315) as the first LECD 305 and the other mounted on the opposite side (top 310).

[0053] When multiple LECDs are mounted in nacelle 161, the LECDs can emit light beam 325 or light sheet 605 independently of what the other LECDs emit. That is, all LECDs in the set of LECDs may emit light beam 325, may emit light sheet 605, or some of them may emit light beam 325 and some of them may emit light sheet 605 differently than those that may emit light beam 325.

[0054] Any of the wind turbine blades 120 disclosed herein may include reflective paint on their tips 410. The reflective paint may help increase the signal-to-noise ratio (SNR) of light reflected by the blade tips 410.

[0055] When exposed to wind, the nacelle 161 and / or wind turbine tower 170 may tilt, i.e., oscillate back and forth. This tilt may deflect the light emitted by the LECD from a substantially vertical plane when there is no load on the wind turbine 160. Thus, a false alarm or indication may occur that the blades 120 are excessively deflecting when they are actually moving acceptably. The opposite may also occur, i.e., blade deflection may be excessive, but such a risk may be overlooked. This may be particularly relevant when the LECD is emitting a light sheet 605.

[0056] A possible solution to this problem is illustrated in FIG. 9 , which schematically illustrates a side view of a wind turbine including another example light emitting collecting device. The wind turbine 160 can include a first positioning sensor 905 (depicted as a triangle) mounted to the bottom of the nacelle 161 and configured to detect tilt of the nacelle 161 and / or the tower 170. The first LECD 305 can be configured to adjust the direction of the emitted light to maintain the direction of the emitted light in a substantially vertical plane. In some examples, the first LECD 305 can be configured to adjust the direction of the emitted light to maintain a substantially vertical direction of the emitted light.

[0057] To this end, in some examples, the first LECD 305 may be rotatably mounted (to the nacelle 161) such that when the nacelle vibrates, light is emitted in a direction in a substantially vertical plane, more specifically in a substantially vertical direction. The movement of the first LECD 305 may be similar to the movement of a pendulum. In some of these examples, the first LECD 305 may be rotatably mounted to the nacelle 161 such that the LECD always points substantially vertically downward, also like a pendulum. One or more LECDs may move in this manner, for example, one or more additional LECDs may be rotatable as shown.

[0058] The first positioning sensor 905 may be mounted near the aft or downstream side 910 of the nacelle 161, as in FIG. 9 . In other examples, it may be mounted closest to the forward or upstream side 915 of the nacelle 161. The positioning sensor 905 may measure a distance to the ground 320 or any other reference. A reference value for this distance may be readily known by the positioning sensor 905. If the positioning sensor 905 measures a distance different from the reference value, this may indicate that the nacelle 161 and / or tower 170 are tilting.

[0059] In some examples, variations in distance values ​​measured by one or more positioning sensors (e.g., first sensor 905 and additional sensor 920 as in FIG. 9 ) can be used to rotate the LECD so that a substantially vertical direction of the emitted light can be maintained.

[0060] In any of these examples or some other examples, any values ​​obtained by an inclinometer mounted within the nacelle 161 may be used to adjust the direction of the emitted light. Measurements of thrust, rotor imbalance, or bending loads on the blades 120 or main (rotor) shaft may also be used in this regard.

[0061] In some other examples, instead of rotating the LECD, variations in distance values ​​measured by one or more positioning sensors 905, 920 may be used to correct the information collected by the LECD 305.

[0062] In one example, a controller (not shown) in the nacelle 161 can collect information from the LECD 305 and the positioning devices 905, 920 and make any necessary corrections therein. In another example, the measurements of the positioning sensors 905, 920 may be sent to the LECD 305 so that the LECD can make the appropriate corrections.

[0063] 10 schematically illustrates an example of a method for operating a wind turbine 160. In one aspect, a method is provided for operating a wind turbine having a first light emitting collecting device 305 mounted to a nacelle 161. The first LECD 305 may, in some examples, be mounted on top of the nacelle 161.

[0064] The method includes emitting light onto a hub of a wind turbine at block 1000. The method further includes receiving the light when reflected by a blade 120 of the wind turbine 160 at block 1010, i.e., receiving at least a portion of the previously emitted light that is reflected by the blade 120. The method further includes, if a level of blade deflection based on the received reflected light exceeds a threshold (block 1030), reducing blade load on the blade 120 before the blade 120 reaches a vertically downward position at block 1040.

[0065] In some examples, the method may further include determining a level of blade deflection before testing whether the level of blade deflection based on the received reflected light in block 1030 exceeds a threshold value.

[0066] In some examples, reducing blade loading may include at least one of reducing rotor speed, pitching one or more of the blades, and actuating aerodynamic actuators (if provided on the blades). The actuators on the blades may include one or more of flaps, spoilers, and pitching tips. Blade pitching may be individual (for a single blade) or collective (for all blades). Reducing rotor speed may include modifying generator torque and / or mechanically braking in the event of an emergency or severe fault. In some cases, reducing rotor speed may include ceasing operation of the wind turbine.

[0067] In some examples, the light may be emitted substantially in a direction within a substantially vertical plane, e.g., vertically. This may include emitting light vertically downward or vertically upward, as shown in the previous examples. For example, in one example, emitting light (block 1000) includes emitting light upward (vertically) from the nacelle 161. In other examples, the light may be polarized relative to the vertical plane.

[0068] In some examples, emitting light (block 1000) includes emitting a light sheet 605, and the level of blade deflection is determined based at least in part on the time one of the blades 120 interferes with the light sheet 605. The discussion regarding FIG. 8 may apply.

[0069] In some examples, emitting light (Block 1000) includes emitting a substantially collimated light beam 325.

[0070] In some instances, the emitted light is in a region of the electromagnetic spectrum different from the visible region of the electromagnetic spectrum, which can reduce the visual impact on people and animals.

[0071] Additionally, the wavelength of the emitted light can be selected such that, after filtering the light received by the light sensor, light corresponding to one or more reflections of the emitted light can be easily detected. In some examples, the emitted light is in a different region of the electromagnetic spectrum than light emitted by the sun. This can be particularly useful for avoiding blinding of the light sensor by the sun.

[0072] In some examples, the first LECD 305 is configured to measure a distance 415 between the first LECD 305 and the location of the reflection. The discussion regarding Figure 5 may apply.

[0073] FIG. 11 shows a schematic diagram of an example of a method for monitoring the deflection of a rotor blade of a wind turbine.

[0074] The first light emission collecting device 305 is mounted to a nacelle 161 of the wind turbine 160, e.g., the top 310 or bottom 315 of the nacelle 161. The method includes, at block 1100, emitting a light sheet 605. The light sheet 605 may, in some examples, be emitted in a direction within a substantially vertical plane. In some of these examples, the light sheet 605 may be emitted in a substantially vertical direction, e.g., upward or downward. The method further includes, at block 1110, collecting reflections of the emitted light and, at block 1130, determining a deflection of the rotor blade by determining a time at which the blade 120 reflects the emitted light sheet (block 1120). The discussion regarding FIG. 8 may apply.

[0075] The rotational speed of the rotor 115 can be used to determine the deflection of the rotor blades 120, in addition to the interference time with the light sheet 605. In some examples, multiple light sheets 605 may be emitted, which may allow for multiple measurements to be taken of portions of the blades 120 that may interfere with the light sheet, such as the location of the interference along the length of the blades 120. Thus, the accuracy of the blade deflection calculation may be increased, for example, if the rotor 115 does not maintain a substantially constant rotational speed.

[0076] In some examples, the wind turbine may further include positioning sensors 905, 920 mounted to the nacelle 161 (e.g., as shown with reference to FIG. 9 ), and the method may further include determining a position and / or orientation of the nacelle 161. The position and / or orientation of the nacelle 161 may be taken into account when determining blade deflection.

[0077] In some examples, the first light emitting collecting device 305 may be rotatably mounted to the nacelle 161 such that when the nacelle 161 vibrates, light is emitted in a substantially vertical plane, more specifically in a substantially vertical direction.

[0078] In some examples, wind turbine 160 may include one or more additional light emission collecting devices, e.g., additional LECDs 330, mounted in nacelle 161, e.g., on top 310 or bottom 315 of nacelle 161, and determining deflection of rotor blades 120 includes collecting reflections of emitted light of first light emission collecting device 305 and additional light emission collecting device 330. First light emission collecting device 305 and additional light emission collecting device 330 may be mounted on the same side or on opposite sides of nacelle 161, for example.

[0079] In some examples, determining the time at which the blades 120 reflect the emitted light sheet 605 may include measuring the light intensity of the light received by the first light emission collecting device 305. In particular, if the light is emitted above, e.g., upward, the hub 110, the intensity of the received light may be a good measure for determining the interference of the blades 120 and the light sheet 605.

[0080] This specification uses examples to disclose the invention, including preferred embodiments, and also enables any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples may include any embodiment having structural elements that do not deviate from the literal language of the claims. 、 Those skilled in the art will appreciate that various embodiments described above may be readily apparent to those skilled in the art. Mr. Other known equivalents for may be mixed and matched to construct further embodiments and techniques consistent with the principles of the present application. Where reference signs relating to the drawings are placed within parentheses in the claims, these are merely to enhance the clarity of the claims and should not be construed as limiting the scope of the claims. [Explanation of symbols]

[0081] 20 Yaw System 21 Annular Gear 22 Yaw drive unit 23 Motor 24 Gearbox 25 Pinion 100 pitch bearing 107 Pitch System 108 Pinion 109 Annular Gear 110 rotor hub 115 rotor 120 rotor blades 121 cases 122 cases 123 cases 150 Support surface 160 wind turbines 161 Nacelle 162 Generator 163 Main rotor shaft 164 Gearbox 165 Support frame, bed plate 166 Generator shaft 170 Tower 305 First Light Emitting Collecting Device (LECD) 310 upper side, upper 312 Lateral side 313 Lateral side 315 bottom side, bottom 320 Ground 325 Light Beam 330 Additional LECD, Light Emitting Collecting Device 405 horizontal distance 407 distance 410 Blade Tip 415 Perpendicular Plane Distance, Vertical Distance, Vertical Direction 505 line 510 line 515 line 605 Light Sheet, Light 901 line 902 line 905 Positioning device, first positioning sensor 910 Rear, downstream side 915 Front, upstream side 920 Positioning devices, additional sensors, positioning sensors 1000 blocks 1010 Block 1030 Block 1040 blocks 1100 Block 1110 Block 1120 Block 1130 Block

Claims

1. 1. A method for operating a wind turbine (160) having a first light collecting device (305) mounted to a nacelle (161), the method comprising: a step (1000) of emitting light (1000) towards a space above a hub (110) of the wind turbine (160), the step (1000) of emitting light (1000) comprising emitting (1100) a light sheet (605); receiving (1010) the reflected light when the light is reflected by the blades (120) of the wind turbine (160); If the level of blade deflection based on the received reflected light exceeds a threshold (1030), reducing the blade load (1040) of the blade (120) before the blade (120) reaches a vertically downward position; It contains A method wherein the level of blade deflection is determined based at least in part on the time the blade (120) interacts with the light sheet (605).

2. The method of claim 1, wherein the step (1040) of reducing the blade load includes at least one of reducing rotor speed, pitching one or more of the blades (120), and activating an aerodynamic actuator, wherein the aerodynamic actuator is selected from one or more of a flap, a spoiler, and a pitching tip.

3. 3. The method of claim 1 or claim 2, wherein the step of emitting light (1000) comprises emitting light in a substantially vertical plane.

4. The method of any one of claims 1 to 3, wherein the step of emitting light (1000) comprises emitting light upward from the nacelle (161).

5. 5. The method of claim 1, wherein determining (1120) the time it takes the blade (120) to reflect the emitted light comprises measuring the light intensity of the reflected light received by the first light emission collecting device (305).

6. 3. The method of claim 1 or claim 2, wherein the step of emitting light (1000) comprises emitting a substantially collimated light beam (325).

7. 7. The method of claim 1, wherein the emitted light is in a region of the electromagnetic spectrum different from the visible region of the electromagnetic spectrum.

8. 8. The method of claim 1, wherein the first light emission collecting device (305) is configured to measure a distance (415) between the first light emission collecting device (305) and a location of reflection.

9. 9. The method of claim 1, wherein the wind turbine further comprises a positioning sensor mounted on the nacelle, the method further comprising determining a position and / or an orientation of the nacelle.

10. 10. The method of any one of claims 1 to 9, wherein the first light emission collecting device (305) is rotatably mounted to the nacelle (161) such that when the nacelle (161) vibrates, light is emitted in a substantially vertical plane and in a substantially vertical direction.

11. 1. A wind turbine (160) comprising: a tower (170); a nacelle (161) on top of the tower (170); a rotor hub (110) having one or more rotor blades (120) rotatably mounted to the nacelle (161); and a first light collecting device (305) mounted to the nacelle (161), the first light emission collecting device (305) is configured to emit light in a direction substantially in a vertical plane and to collect reflections of the emitted light by one of the rotor blades (120); the first light collecting device (305) is mounted on the nacelle (161) at a horizontal distance (405) from the tower (170) so as to detect before or when the tips (410) of the blades (120) exceed a blade deflection limit; the first luminescence collecting device (305) is configured to emit a light sheet (605); The wind turbine (160), wherein the wind turbine (160) comprises a processor configured to measure the time the emitted light is reflected by the blades (120).

12. The wind turbine (160) of claim 11, wherein the at least one rotor blade (120) includes reflective paint on a tip (410) thereof.

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