Apparatus and method for determining deflection of a rotor blade of a wind turbine

Abstract

The present disclosure relates to methods and systems for measuring deflection of a blade of a wind turbine. Examples include a light emitting and collecting 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, the method comprising: emitting light above a hub; receiving light as it is reflected by a blade of the wind turbine; and if a level of deflection of the blade is above a threshold, reducing a blade load 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, the method comprising: emitting a sheet of light; collecting reflections of the emitted light; and determining a deflection of the rotor blade by determining a time during which the blade reflects the emitted sheet of light.

Description

Technical Field

[0001] This disclosure relates to apparatus and methods for monitoring the deflection of rotor blades of a wind turbine. More particularly, this disclosure relates to apparatus and methods for using light to monitor the deflection of rotor blades of a wind turbine. Background Technology

[0002] Modern wind turbines are commonly used to supply electricity to the power grid. Such a wind turbine generally consists of a tower and a rotor mounted on the tower. The rotor (which typically includes a hub and multiple blades) is set to rotate by the wind's influence on the blades. This rotation generates torque, which is typically transmitted directly or via a gearbox through the rotor shaft to a generator. In this way, the generator produces electricity that can be supplied to the power grid.

[0003] The wind turbine hub can be rotatably connected to the front of the nacelle. The wind turbine hub can be connected to the rotor shaft, and the rotor shaft can then be rotatably mounted in the nacelle using one or more rotor shaft bearings arranged in a frame located inside the nacelle. The nacelle is a shell arranged on top of the wind turbine tower that houses and protects, for example, gearboxes (if present) and generators, and, depending on the wind turbine, houses and protects other components (such as power converters) and auxiliary systems.

[0004] The trend in the wind turbine industry is to increase hub height and blade length in order to capture more wind energy. As blade length increases, the blades also become more flexible.

[0005] The loads on wind turbine blades should be generally high enough to generate as much energy as possible, but not high enough to overcome the deflection or strain limitations imposed on the blades. If wind turbine blades deflect or bend excessively, for example due to gusts, they can impact the wind turbine tower and even break. These risks increase with the length of the blade. Furthermore, to reduce direct material costs, the trend is towards building blades that are as lightweight (and therefore flexible) as possible.

[0006] It is known that sensing the tips of wind turbine blades allows for the calculation and adjustment of the blade tip clearance (i.e., the distance between the blade tip and the wind turbine tower) to prevent blade breakage or blade impact with the tower. However, existing blade tip sensing methods and devices may not be reliable enough or may require complex and expensive equipment. For example, mounting instruments on the blade tip may be necessary. In some cases, the information collected about the blade tip position may be obtained too late to prevent blade damage.

[0007] Examples of this disclosure provide apparatus and methods for determining the deflection of the rotor blades (tip) of a wind turbine, using light and at least partially addressing the aforementioned problems. Summary of the Invention

[0008] In a first aspect of this disclosure, a wind turbine is provided, comprising a tower, a nacelle located atop the tower, a rotor hub with one or more rotor blades rotatably mounted to the nacelle, and a first light emitting and collecting device mounted to the nacelle. The first light emitting and collecting device is configured to emit light in a direction in a substantially vertical plane and to collect the emitted light reflected by one of the rotor blades; and the first light emitting and collecting device is mounted to the nacelle at a horizontal distance from the tower such that the tip of a blade is detected before or after it exceeds a blade deflection limit.

[0009] According to this aspect, the wind turbine is equipped with a simple device that can avoid excessive blade deflection by emitting light in a direction in a substantially vertical plane and collecting the reflection of the previously emitted light, and thus avoid blade breakage and / or impact between the blade and the wind turbine tower.

[0010] Throughout this disclosure, light emitting and collecting devices can be understood as a group of at least light source elements and light receiving elements. These light emitters and light sensors may be located together, for example, within a housing or device (such as a laser rangefinder) housing them; or they may be separate elements, for example, the light sensor may be a camera, and the light emitter may be a laser or a light-emitting diode (LED). If the light emitter and light sensor belong to the same device, they can be controlled in a dependent manner, i.e., they may share a control processing unit (CPU) and memory. If the light emitter and light sensor are separate elements, they may not share a CPU and memory. In this case, additional devices (such as a controller placed in a cabin) can acquire data from both elements and operate using that data. In some examples, the emitter and sensor may be interconnected and able to communicate with each other as needed to control, for example, light emission or perform functional checks at specific times and / or frequencies.

[0011] The blade deflection limit or blade deflection threshold can be understood as the deflection or strain limit beyond which the risk of blade breakage, collision with the wind turbine tower, or general blade damage is higher than acceptable.

[0012] In this paper, horizontal distance can be understood as the distance measured along the length of the nacelle. If the light emitting and collecting device is mounted at the bottom of the nacelle, the horizontal distance can refer to the distance along the length of the nacelle between the device and the wind turbine tower. A suitable distance depends on the end clearance caused by the tower geometry. If the light emitting and collecting device is mounted at the top of the nacelle, the horizontal distance can refer to the distance along the length of the nacelle between the device and the tower, measured along the axis between the axis of rotation of the nacelle and the rotor hub.

[0013] The vertical direction can be understood as a direction that is substantially parallel to the wind turbine tower without tower movement (e.g., without tower swaying). A vertical plane can be understood as a plane that includes such a vertical direction.

[0014] In another aspect, a method is provided for operating a wind turbine having a first light emitting and collecting device mounted to a nacelle. The method includes: emitting light above the hub of the wind turbine; and receiving the light as it is reflected by the blades of the wind turbine. The method further includes: reducing the blade load on the blades before they reach a vertically downward position if the level of blade deflection based on the received reflected light is above 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 blade (e.g., 6 o'clock refers to the blade pointing downwards).

[0016] In another aspect, a method for monitoring the deflection of rotor blades of a wind turbine is provided, wherein a first light emitting and collecting device is mounted to the nacelle of the wind turbine. The method includes: emitting a light plate; collecting the reflection of the emitted light; and determining the deflection of the rotor blades by determining the time during which the blades reflect the emitted light plate.

[0017] Based on this, blade deflection can not only be detected, but the timing of the blade-optical-sheet interference can be used to better adjust the mechanism for reducing blade load. Then, the operation of the wind turbine blade can be optimized by striking a suitable trade-off between reducing blade load and maintaining the highest possible energy production.

[0018] In this document, "light sheet" can be understood as a beam of light with high divergence (i.e., it is not collimated). Conversely, in this document, the term "beam" can be understood as a beam of light with low divergence, i.e., a beam that is substantially collimated. Thus, the difference between a beam and a light sheet as used throughout this disclosure can be divergence or collimation.

[0019] As a visual example, a group of light rays that are substantially parallel to each other and have a substantially constant width along the length of the group (i.e., the rays are substantially collimated or substantially non-divergent) can be considered a light beam, but a group of light rays whose width increases with distance from the emission source (i.e., the rays are not collimated and exhibit divergence) can be considered a light sheet. Thus, a light beam can be visualized as a group of light rays traveling substantially in one direction, and a light sheet can be visualized as a plane of light in which the light rays can be visualized as traveling in more than one direction within the plane due to the divergence of the light rays.

[0020] Therefore, in this paper, the light beam may be emitted from the light source at an angle of less than 0.5°, for example, and the light sheet may be emitted from the light source at an angle equal to or greater than 0.5°, for example.

[0021] Technical Solution 1. A method for operating a wind turbine, the wind turbine having a first light emitting and collecting device installed in the nacelle, the method comprising: Light is emitted above the hub of the wind turbine; Receive the light when it is reflected by the blades of the wind turbine; and If the level of blade deflection based on the received reflected light is higher than a threshold, the blade load of the blade is reduced before the blade reaches a vertically downward position.

[0022] Technical Solution 2. The method according to Technical Solution 1, wherein reducing the blade load includes at least one of the following: reducing the rotor speed; pitching one or more of the blades; and activating the aerodynamic actuator.

[0023] Technical solution 3. The method according to technical solution 1 or 2, wherein the emitted light comprises emitting light in a substantially vertical plane.

[0024] Technical Solution 4. The method according to any of Technical Solutions 1-3, wherein the emitted light comprises emitting light upward from the cabin.

[0025] Technical Solution 5. The method according to any of Technical Solutions 1-3, wherein the emitted light comprises an emitting light sheet, and the level of blade deflection is determined at least in part based on the time during which the blade interferes with the light sheet.

[0026] Technical Solution 6. The method according to Technical Solution 5, wherein determining the time during which the blade reflects the emitted light sheet includes measuring the light intensity of the reflected light received by the first light emitting and collecting device.

[0027] Technical Solution 7. The method according to Technical Solution 1 or 2, wherein the emitted light comprises emitting a substantially collimated beam.

[0028] Technical Solution 8. The method according to any of Technical Solutions 1-7, wherein the emitted light is located in a region of the electromagnetic spectrum that is different from the visible region of the electromagnetic spectrum.

[0029] Technical Solution 9. The method according to any of Technical Solutions 1-9, wherein the first light emitting and collecting device is configured to measure the distance between the first light emitting and collecting device and the position of reflection.

[0030] Technical Solution 10. The method according to any of Technical Solutions 1-9, wherein the wind turbine further includes a positioning sensor attached to the nacelle, and the method further includes determining the position and / or orientation of the nacelle.

[0031] Technical Solution 11. The method according to any of Technical Solutions 1-10, wherein the first light emitting and collecting device is rotatably mounted to the cabin in such a way that the light oscillating in the cabin is emitted in a substantially vertical plane and more particularly in a substantially vertical direction.

[0032] Technical Solution 12. A wind turbine, comprising a tower, a nacelle located on top of the tower, a rotor hub with one or more rotor blades rotatably mounted to the nacelle, and a first light emitting and collecting device mounted to the nacelle; The first light emitting and collecting device is configured to emit light in a substantially vertical plane and to collect the emitted light reflected by one of the rotor blades; and The first light emitting and collecting device is installed at a horizontal distance from the tower to the nacelle, so that the tip of the blade is detected before or when it exceeds the blade deflection limit.

[0033] Technical solution 13. The wind turbine according to technical solution 12, wherein the first light emitting and collecting device is configured as a light emitting sheet.

[0034] Technical Solution 14. The wind turbine according to Technical Solution 12 or 13 further includes a processor configured to measure the time during which light emitted therefrom is reflected by the blades.

[0035] Technical Solution 15. The wind turbine according to any of Technical Solutions 12-14, wherein one or more rotor blades include a reflective coating located at their tips. Attached Figure Description

[0036] Figure 1 A perspective view illustrating an example of a wind turbine; Figure 2 Illustration Figure 1 A simplified interior view of an example wind turbine nacelle; Figure 3 A schematic front view of an example of a wind turbine; Figure 4 schematic diagram Figure 3 A side view of a wind turbine; Figure 5 schematically depicting by Figure 3 and Figure 4 An example of the evolution of vertical distance measured by any light emitting and collecting device (LECD); Figure 6 A schematic front view of another example of a wind turbine is shown. Figure 7 schematic diagram Figure 6 A side view of a wind turbine; Figure 8 schematically representing by Figure 6 and Figure 7 Examples of the evolution of the strength received by any LECD; Figure 9 The illustration is a schematic side view of a wind turbine according to another example; Figure 10 This illustration schematically depicts an example of a method for operating a wind turbine; and Figure 11 The illustration schematically depicts an example of a method for monitoring the deflection of rotor blades in a wind turbine. Detailed Implementation

[0037] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, and not as a limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the invention without departing from its scope. For example, a feature partially illustrated or described as one embodiment may be used with another embodiment to produce yet another embodiment. Thus, it is intended that the invention cover such modifications and variations as fall within the scope of the appended claims.

[0038] Figure 1The illustration shows a perspective view of an example wind turbine 160. As shown, the wind turbine 160 includes a tower 170 extending from a support surface 150, a nacelle 161 mounted on 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 apart around the hub 110 to allow the rotor 115 to rotate so that kinetic energy can be converted from wind into usable mechanical energy and subsequently into electrical energy. For example, the hub 110 may be rotatably coupled to a generator 162 located within the nacelle 161. Figure 2 ), to allow the generation of electrical energy.

[0039] Figure 2 Illustration Figure 1 A simplified internal view of an example of the nacelle 161 of a wind turbine 160. As shown, a generator 162 may be disposed within the nacelle 161. Generally, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 to generate electrical power from the rotational energy generated by the rotor 115. For example, the rotor 115 may include a main rotor shaft 163 coupled to a hub 110 for rotating together with the hub 110. 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.

[0040] It should be recognized that the rotor shaft 163, gearbox 164 and generator 162 can be generally supported within the nacelle 161 by a support frame or base plate 165 positioned on top of the wind turbine tower 170.

[0041] The nacelle 161 is rotatably connected to the tower 170 via a yaw system 20 in a manner that allows the nacelle 161 to rotate about a yaw axis YA. The yaw system 20 includes a yaw bearing having two bearing members configured to rotate relative to each other. The tower 170 is connected to one of the bearing members, and the base plate or support frame 165 of the nacelle 161 is connected to the other bearing member. The yaw system 20 includes a ring gear 21 and a plurality of yaw actuators 22, each having a motor 23, a gearbox 24, and a pinion 25 for meshing with the ring gear 21 to rotate one of the bearing members relative to the other.

[0042] The blade 120 is connected to the hub 110 via a pitch bearing 100 located between the blade 120 and the hub 110. The pitch bearing 100 includes an inner ring and an outer ring. The wind turbine blade may be attached to either the inner or outer bearing ring, while the hub is connected to the other. When the pitch system 107 is actuated, the blade 120 can perform a relative rotational movement relative to the hub 110. The inner bearing ring can therefore perform a rotational movement relative to the outer bearing ring. Figure 2 The pitch system 107 includes a pinion 108 that meshes with an annular gear 109 disposed on an inner bearing ring to set the wind turbine blades to rotate about the pitch axis PA.

[0043] Figure 3 This schematic diagram shows a front view of an example wind turbine including light emitting and collecting devices. (Similar to...) Figure 1 As indicated, the wind turbine 160 includes a tower 170, a nacelle 161 located on top of the tower 170, and a rotor hub 110 with at least one rotor blade 120 rotatably mounted to the nacelle 161. The wind turbine 160 also includes components mounted to the nacelle 161 (e.g., in…). Figure 3 A first light emitting and collecting device (LECD) 305 is installed in the top 310 or bottom 315 of the nacelle 161. Specifically, Figure 3 The wind turbine 160 includes three blades 120 and two LECDs, a 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.

[0044] Generally, any number of LECDs can be installed 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, a rear or downstream side 910, and two lateral sides 312, 313. The lateral sides 312, 313 can therefore be substantially parallel to the length of the nacelle 161 and can extend from the forward portion 915 of the nacelle 161 to the rear portion 910 of the nacelle 161, rather than the top 310 and bottom 315 of the nacelle 161. Figure 3 In the examples, any number of LECDs may be mounted to the bottom 315 of nacelle 161, and any number of LECDs may be mounted to the top 310 of nacelle 161. In these examples, or some other examples, one or more LECDs may be mounted to any of the lateral sides 312, 313 of nacelle 161. This is particularly useful when the LECDs are projecting light upwards above hub 110, for example, to detect excessive blade deflection before blade 120 passes in front of tower 170. Mounting on the lateral sides of nacelle 161 is an option that can be used throughout all the examples of this disclosure.

[0045] The first LECD 305 is configured to emit light in a substantially vertical direction and to collect the emitted light by reflection from one of the rotor blades. In some examples, the first LECD 305 is configured to emit light in a substantially vertical direction (e.g., upward or downward). Figure 3 As shown, the first LECD 305 emits light downwards, and the first LECD 305 can collect the reflected light that has been reflected up from the ground 320. In some examples, the ground 320 may correspond to... Figure 1 The supporting surface 150. However, in some cases, the blade can be deformed to such a degree that at least the tip of the blade reaches the position where the light beam from LECD 305 to the ground is intercepted and reflected.

[0046] In some examples, the ground 320 and / or airborne particles (e.g., under dusty or foggy conditions) may absorb portions of the emitted and / or reflected light, thereby complicating the detection of one or more reflections of the emitted light. To facilitate the detection of light reflected by the ground 320, the emitted light may, for example, be divided into two parts, such that each part can be detected by a different light sensor. In one example, for this purpose, the first LECD 305 may include two light receiving elements, such as a primary light sensor and an auxiliary light sensor. In another example, the auxiliary light receiving element may be a component not belonging to the first LECD 305. In both examples, the auxiliary sensor can be used to indicate a malfunction of the light emitter and / or the primary light sensor or to confirm the correct operation of the light emitter and / or the primary light sensor.

[0047] Figure 4 schematic diagram Figure 3 A side view of a wind turbine. (Example) Figure 4 As shown, the first LECD 305 is mounted to the nacelle 161 at a horizontal distance 405 from the tower 170, such that the tip 410 of the blade 120 is detected before or when it exceeds the blade deflection limit. The detection of the tip 410 of the blade 120 thus warns that the blade 120 may be too close to the tower 170, potentially causing it to collide with the tower 170. Therefore, preventative actions can be taken to avoid such a collision, or substantially prevent damage to the blade 120.

[0048] The first LECD 305 may be configured to emit a substantially collimated beam 325. The first LECD 305 may include one or more lenses for obtaining the collimated beam 325. The first LECD 305 may also be configured to measure a distance 415 in a substantially vertical plane between the first LECD 305 and the location of reflection. In some examples, the first LECD 305 may be configured to obtain the location where one or more reflections occur. In some examples, the distance in the substantially vertical plane may be a substantially vertical distance 415. 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 the substantially vertical plane having any angle (greater than 0°) relative to either the vertical or horizontal direction.

[0049] exist Figure 3 and Figure 4 In this configuration, light can be reflected off the ground at 320°. The measured vertical distance 415 can be registered and recorded in the memory of the first LECD 305. In this example, the first LECD 305 can be a laser rangefinder.

[0050] Figure 5 An example illustrating the evolution of the measured vertical distance 415 (i.e., in this particular example, the distance between the LECD and the reflection point) over time is given. The following explanation thus applies when the distance between the LECD and the location where the emitted light is reflected is not a vertical distance. The vertical distance 415 (VD) can be measured indirectly. For example, the first LECD 305 can quantify the time taken for the emitted collimated beam 325 to strike the ground 320 and then be reflected and detected by the first LECD 315. This time value can then be converted into a value for the vertical distance 415.

[0051] Each of lines 505, 510, and 515 represents multiple measured vertical distances 415. Line 505 indicates a situation where interference between beam 325 and blade 120 has not yet been detected. This is why the measured vertical distance 415 gives a substantially constant value over time.

[0052] However, the other two lines 510 and 515 illustrate the situation where interference of blade 120 with beam 325 has been detected. This interference causes a reduction in the measured vertical distance 415. Therefore, in Figure 5 Three types of interference are shown. Lines 505, 510, and 515 can respectively correspond to the blade's interference at... Figure 4 The evolution under cases 121, 122, and 123. In deflection case 121, the blade does not interfere with beam 325, but interference occurs in cases 122 and 123.

[0053] Additionally, the change (descent) in the vertical distance 415 can be related to blade deflection (e.g., the distance 407 between blade 120 and tower 170, see...). Figure 4 This information is relevant and used to determine which load reduction measures to take. For example, different load reduction measures can be implemented for line 510 and line 515. In some examples, no action is necessary even if the blades reflect light. In other examples, operational changes such as pitching or reducing rotor speed can be made. Moreover, depending on the extent of the deflection of blade 120, action can be taken immediately after interference is detected, or after several blade passes and / or blade interferences.

[0054] For example, in some examples, a reduction in blade load can be performed after the same blade 120 has been monitored passing over multiple times. In some of these examples, a statistical evaluation of the interference of blade 120 with light emitted by the first LECD 305 over time can be performed to determine whether to respond and, if so, how to respond. In some other examples, a single pass (e.g., a single interference event of blade 120 with the emitted light) can be used to determine whether and how to respond. These options can be combined; for example, one option can be used during a certain time period, and another can be used during a later time period or at least partially overlapping time periods.

[0055] If blade deflection is acceptable, for example, if one or more blades 120 are not detected during a certain period, then in some examples, the operating power can be increased. In some of these examples, the power can be increased to exceed the nameplate rating.

[0056] The first LECD 305, configured to emit a beam 325 and collect its reflection, provides an easy and inexpensive way to detect the deflection of the blade 120. Furthermore, it is a more convenient method compared to existing systems that employ specific equipment located on the blade tip 410 or on the tower 170.

[0057] In some examples, the blade may include paint or coating at least in the section including the blade tip to ensure effective reflection of light emitted by the LECD.

[0058] Figure 3 and Figure 4The diagram also illustrates a LECD 330 mounted on the top 310 of the nacelle 161. In this case, when the LECD 330 emits light, for example upwards, above the hub 110, the distance (e.g., vertical distance) between the LECD 330 and the point where reflection occurs can be measured only when the blade 120 interferes with the beam 325. Such a measurement can trigger preventative action, which can be adjusted depending on the value of the measured vertical distance.

[0059] The measured distance (e.g., the upward vertical distance) can help anticipate a possible collision between blade 120 and tower 170 and reduce blade load to avoid such a collision.

[0060] Figure 6 The schematic illustration shows a front view of another example of a wind turbine, including light-emitting and collecting devices. Figure 6 In one example, the first LECD 305 is configured to emit a light sheet 605. In this 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 vibrating mirror that rapidly deflects the light beam, thereby covering an angle in a substantially negligible time. In some examples, the light sheet 605 may emit in a substantially vertical direction. In some other examples, other emission directions may be used.

[0061] The first LECD 305, or a processor coupled to the first LECD, can also be configured to measure the intensity of the received light. That is, the first LECD can emit light 605 and receive light, wherein the received light may partially include reflections of the emitted light 605. If the blade 120 does not interfere with the light plate 605, the received intensity remains unchanged. However, if the blade 120 intersects with the light plate 605, the blade 120 can increase light reflection and scattering, and thus increase the light received by the first LECD 305. Therefore, the first LECD 305 can detect that the blade 120 is positively interfering with the light plate 605, and preventative action may be necessary to avoid excessive blade deflection.

[0062] In this paper, a change in light intensity can be understood as a change in the amount of light relative to the previously received amount of light, such as an increase.

[0063] In some examples, modulation techniques can be used to distinguish between blade 120° intersections and other unwanted detections that could cause false alarms (e.g., birds or fluttering plastic bags). In this case, the intensity can be time-averaged and pulse frequency filtered. In some examples, color filtering or substantially wavelength filtering can be used to assist in this process. Additionally, in some examples, rotor position and / or rotor speed can allow for the differentiation of detected intensity changes and the rejection of unwanted detections.

[0064] By LECD (e.g., Figure 6 A schematic representation of the evolution of the intensity received by the first LECD 305 over time (during which the rotor 115 and blade 120 rotate) can be found in Figure 8 Described in the text. Figure 8 The illustration shows case a), where there is no intersection (i.e., interference) between blade 120 and light plate 605. In this case, a substantially constant value of the intensity of the received light can be measured. Line 901 depicts multiple unfiltered measurements, while line 902 depicts multiple high-pass filtered measurements. The high-pass filter can be used to filter out standard intensity measurements. By applying the high-pass filter, deviations from the normal or default conditions are registered and highlighted.

[0065] Figure 8 The diagram also illustrates case b), where blade 120 has intersected with light plate 605, thus causing a change in the measured value of the received light intensity as explained above. In case b), interference has been detected between three blades 120 and light plate 605.

[0066] The duration of the measured light intensity variations and / or the magnitude of the change in intensity can be correlated with the distance 407 between the blade 120 and the tower, and used to trigger actions 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 can be configured to measure the time during which emitted light is reflected by the blade 120.

[0067] As previously commented, the wind turbine 160 may further include an additional LECD 330. In some examples, the additional LECD may 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 substantially vertical direction (e.g., in a substantially vertical direction 415) and configured to collect the emitted light reflected 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, Figure 7 (its schematic diagram) Figure 6 A side view of the wind turbine shows the first LECD 305 and an additional LECD 330 mounted to the bottom 315 of the nacelle 161. In these examples or others, for example, in Figure 3 and Figure 4 In the middle, the first LECD 305 and the additional LECD 330 can be installed on the opposite side of the cabin 161. Figure 7Two additional LECDs 330 are shown, one mounted on the same side (bottom 315) and the other mounted on the side opposite to the first LECD 305 (top 310).

[0068] When more than one LECD is installed in the nacelle 161, the LECD can emit beam 325 or light sheet 605 independently of the other LECDs. That is, all LECDs in the group can emit beam 325 or light sheet 605, or some LECDs in the group can emit beam 325, and some LECDs in the group that are different from the LECDs that can emit beam 325 can emit light sheet 605.

[0069] Any of the blades 120 of a wind turbine as disclosed herein may include a reflective coating located at its tip 410. This reflective coating may help increase the signal-to-noise ratio (SNR) of light reflected by the blade tip 410.

[0070] When exposed to wind, the nacelle 161 and / or the wind turbine tower 170 may oscillate, i.e., oscillate in the fore-and-aft direction. In the absence of a load on the wind turbine 160, this oscillation can cause the light emitted by the LECD to deviate from a substantially vertical plane. Therefore, a false alarm or indication may occur that the blades 120 are excessively deflected when they are actually performing acceptablely. Conversely, the blades may deflect excessively, but the danger may be missed. This is particularly relevant when the LECD emits light from the sheet 605.

[0071] Possible solutions to this problem are Figure 9 Described in the text. Figure 9 The schematic illustration shows a side view of a wind turbine including light emitting and collecting devices according to another example. The wind turbine 160 may include a first positioning sensor 905 (drawn as a triangle) attached to the bottom of the nacelle 161 and configured to detect the swaying of the nacelle 161 and / or the tower 170. A first LECD 305 may 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 may be configured to adjust the direction of the emitted light to maintain the emitted light in a substantially vertical direction.

[0072] Therefore, in some examples, the first LECD 305 can be rotatably mounted (to the nacelle 161) such that it is launched in a substantially vertical plane during nacelle oscillations, and more particularly in a substantially vertical direction. The movement of the first LECD 305 can be analogous to the movement of a pendulum. In some of these examples, the first LECD 305 can be rotatably mounted to the nacelle 161 such that the LECD again, like a pendulum, always points substantially vertically downwards. One or more LECDs can be represented in this manner; for example, one or more additional LECDs can be rotatable as just indicated.

[0073] The first positioning sensor 905 can be like Figure 9 In one example, the first positioning sensor 905 may be positioned as close as possible to the rear or downstream side 910 of the cabin 161. In other examples, the first positioning sensor 905 may be positioned as close as possible to the front or upstream side 915 of the cabin 161. The positioning sensor 905 may measure the distance to the ground 320 or to any other reference location. A reference value for this distance can be easily obtained by the positioning sensor 905. If the positioning sensor 905 measures a distance different from the reference value, this may indicate that the cabin 161 and / or the tower 170 are swaying.

[0074] In some examples, the positioning is achieved by one or more positioning sensors (e.g., such as...). Figure 9 The change in the distance value measured by the first sensor 905 and the additional sensor 920 can be used to rotate the LECD so that the emitted light can be kept in a substantially vertical direction.

[0075] In any of these examples, or in some other examples, any value obtained by the inclinometer placed in nacelle 161 can be used to adjust the direction of the emitted light. At this point, measurements of thrust, rotor imbalance, or the bending load on blade 120 or the main (rotor) shaft can also be used.

[0076] In some other examples, instead of rotating the LECD, changes in distance values ​​measured by one or more positioning sensors 905, 920 can be used to modify the information collected by the LECD 305.

[0077] In one example, a controller (not shown) in cabin 161 can acquire information from LECD 305 and positioning devices 905, 920, and can perform necessary corrections within that information. In another example, measurements from positioning sensors 905, 920 can be sent to LECD 305, allowing LECD to make appropriate corrections.

[0078] Figure 10An example of a method for operating a wind turbine 160 is schematically illustrated. In one aspect, a method is provided for operating a wind turbine having a first light emitting and collecting device 305 mounted to a nacelle 161. In some examples, the first LECD 305 may be mounted to the top of the nacelle 161.

[0079] The method includes emitting light above the hub of the wind turbine at block 1000. The method further includes receiving light at block 1010 when the light is reflected by the blades 120 of the wind turbine 160; that is, receiving at least a portion of the previously emitted light that has been reflected by the blades 120. The method further includes reducing the blade load of the blades 120 at block 1040 before the blades 120 reach a vertically downward position if the level of blade deflection based on the received reflected light is above a threshold (block 1030).

[0080] In some examples, the method may further include determining the level of blade deflection before testing at box 1030 whether the level of blade deflection based on the received reflected light is above a threshold.

[0081] In some examples, reducing blade load may include at least one of the following: reducing rotor speed; pitch control of one or more blades; and activation of aerodynamic actuators if they are located on the blades. Actuators on the blades may include one or more flaps, spoilers, and pitch tips. Pitch control may be individual (for a single blade) or collective (for all blades). Reducing rotor speed may include: altering generator torque and / or mechanical braking in emergency or severe disturbance situations. In some cases, reducing rotor speed may include stopping the operation of the wind turbine.

[0082] In some examples, light may be emitted in a direction that is substantially vertical within a plane (e.g., in a vertical direction). This may include emitting light vertically downwards or vertically upwards, as illustrated in previous examples. For example, in one example, the emitted light (box 1000) includes emitting light upwards from nacelle 161 (vertically). In other examples, the light may be deviated from the vertical plane.

[0083] In some examples, the emitted light (box 1000) includes an emitting light plate 605, and the level of blade deflection is determined at least in part based on the timing of an interferometer plate 605 within the blade 120. (This relates to...) Figure 8 The explanation is applicable.

[0084] In some examples, the emitted light (box 1000) includes an emitted, substantially collimated beam 325.

[0085] In some examples, the emitted light is located in a region of the electromagnetic spectrum that is different from the visible region of the electromagnetic spectrum. This reduces the visual impact on humans and animals.

[0086] Furthermore, 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 located in a region of the electromagnetic spectrum different from that emitted by the sun. This can be particularly helpful in avoiding the light sensor's inability to recognize light due to the sun.

[0087] 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. (This relates to...) Figure 5 The explanation is applicable.

[0088] Figure 11 This illustration shows an example of a method for monitoring the deflection of rotor blades in a wind turbine.

[0089] A first light emitting and collecting device 305 is mounted to the nacelle 161 of the wind turbine 160, for example, to the top 310 or bottom 315 of the nacelle 161. The method includes emitting a light sheet 605 at frame 1100. In some examples, the light sheet 605 may 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: collecting the reflection of the emitted light at frame 1110; and determining the deflection of the rotor blades at frame 1130 by determining the time during which the blades 120 reflect the emitted light sheet (frame 1120). This relates to... Figure 8 The explanation is applicable.

[0090] In addition to the timing of the interferometer 605, the rotational speed of the rotor 115 can be used to determine the deflection of the rotor blades 120. In some examples, more than one interferometer 605 may be emitted. This allows for obtaining multiple measurements of portions of the interferometer on the blade 120 (e.g., the location of the interference along the length of the blade 120). Therefore, for example, if the rotor 115 does not maintain a substantially constant rotational speed, the accuracy of the blade deflection calculation can be improved.

[0091] In some examples, the wind turbine may further include positioning sensors 905, 920 attached to the nacelle 161 (e.g., as referenced). Figure 9 As illustrated, the method may further include determining the 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.

[0092] In some examples, the first light emitting and collecting device 305 can be rotatably mounted to the nacelle 161 in such a way that the light oscillates in the nacelle 161 is emitted in a substantially vertical plane and more particularly in a substantially vertical direction.

[0093] In some examples, the wind turbine 160 may include one or more additional light emitting and collecting devices, such as an additional LECD 330, mounted to the nacelle 161 (e.g., mounted to the top 310 or bottom 315 of the nacelle 161), and determining the deflection of the rotor blades 120 includes collecting the reflection of light emitted by the first light emitting and collecting device 305 and the additional light emitting and collecting device 330. The first light emitting and collecting device 305 and the additional light emitting and collecting device 330 may, for example, be mounted on the same side of the nacelle 161 or on opposite sides.

[0094] In some examples, determining the time during which the blade 120 reflects the emitted light plate 605 may include measuring the light intensity received by the first light emitting and collecting device 305. In particular, if the light is emitted, for example, upward above the hub 110, the intensity of the received light may be a good measure for determining the interference of the blade 120 with the light plate 605.

[0095] This written description 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 apparatus or system and performing any incorporated methods). The patentability of the invention is defined by the claims and may include other examples that would occur to those skilled in the art. If such other examples have structural elements that are no different from the literal language of the claims, then such other examples are intended to be within the scope of the claims. Aspects from the various embodiments described may be mixed and matched by those skilled in the art to construct additional embodiments and techniques in accordance with the principles of this application. If reference numerals relating to the drawings are placed in brackets in the claims, such reference numerals are merely for the purpose of improving the comprehensibility of the claims and should not be construed as limiting the scope of the claims.

Claims

1. A method for operating a wind turbine, the wind turbine having a first light emitting and collecting device mounted to a nacelle, the method comprising: Light is emitted above the hub of the wind turbine, wherein the emitted light includes an emitting light sheet, the light sheet being light that travels in more than one direction in a plane; Receive the light when it is reflected by the blades of the wind turbine; and If the level of blade deflection based on the received reflected light is higher than a threshold, the blade load of the blade is reduced before the blade reaches a vertically downward position. The characteristic feature is that the level of blade deflection is determined at least in part based on the time during which the blade interferes with the optical sheet.

2. The method according to claim 1, wherein, Reducing blade load includes at least one of the following: reducing rotor speed; pitching one or more of the blades; and activating the aerodynamic actuator.

3. The method according to claim 1 or 2, wherein, The emitted light includes light emitted in a substantially vertical plane.

4. The method according to claim 1 or 2, wherein, The emitted light includes light emitted upward from the cabin.

5. The method according to claim 1 or 2, wherein, Determining the time during which the blade reflects the emitted light sheet includes measuring the light intensity of the reflected light received by the first light emitting and collecting device.

6. The method according to claim 1 or 2, wherein, The emitted light is located in a region of the electromagnetic spectrum that is different from the visible region of the electromagnetic spectrum.

7. The method according to claim 1 or 2, wherein, The first light emitting and collecting device is configured to measure the distance between the first light emitting and collecting device and the position of reflection.

8. The method according to claim 1 or 2, wherein, The wind turbine further includes a positioning sensor attached to the nacelle, and the method further includes determining the position and / or orientation of the nacelle.

9. The method according to claim 1 or 2, wherein, The first light emitting and collecting device is rotatably mounted to the cabin such that light oscillating in the cabin is emitted in a substantially vertical direction in a substantially vertical plane.

10. A wind turbine, comprising a tower, a nacelle located on top of the tower, a rotor hub having one or more rotor blades rotatably mounted to the nacelle, and a first light emitting and collecting device mounted to the nacelle; in, The first light emitting and collecting device is configured to emit light in a direction in a substantially vertical plane and to collect the emitted light reflected by one of the rotor blades; The first light emitting and collecting device is installed at a horizontal distance from the nacelle on the tower, such that the tip of the blade is detected before or after it exceeds the blade deflection limit; and The first light emitting and collecting device is configured to emit a light sheet, wherein the light sheet is light that travels in more than one direction in a plane; The wind turbine is characterized by including a processor configured to measure the time during which light emitted therefrom is reflected by the blades.

11. The wind turbine according to claim 10, wherein, One or more rotor blades include a reflective coating located at their tips.

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