Load sensors in wind turbines

Abstract

To provide methods and systems for determining reliability or correct functioning of load sensors in wind turbines.SOLUTION: The present disclosure relates to a method for determining reliability of one or more load sensors in a wind turbine. The method comprises measuring loads with the load sensors during operation of the wind turbine; determining in-plane moments based on the measured loads; selecting the in-plane moments with 1 p frequency; and comparing the selected in-plane moments with theoretical in-plane moments due to the mass of the blade. The method then comprises determining that the load sensors have reduced reliability if the selected in-plane moments deviate from the theoretical in-plane moments by more than a first threshold value. The present disclosure also relates to wind turbine systems incorporating load sensors, and methods for on-line determination of correct functioning of load sensors mounted on a wind turbine blade.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] The present disclosure relates to wind turbines, and more particularly to methods and systems for determining the reliability or accurate functioning of load sensors in wind turbines. The present disclosure particularly relates to determining the functioning of load sensors indicating blade root bending moments.

Background Art

[0002] Modern wind turbines are used to supply electricity to the grid. A wind turbine generally includes a tower with a nacelle supported on top of the tower. A wind turbine rotor comprising a hub and a plurality of wind turbine blades can be rotatably mounted to the nacelle.

[0003] The wind turbine blades can be configured to move by the wind. The hub of the wind turbine can be operatively coupled to the rotor of the generator. When the hub and the blades rotate, the kinetic energy of the wind is converted into the mechanical kinetic energy of the wind turbine rotor and ultimately into electrical energy or power in the generator. The generator may typically be disposed inside the nacelle.

[0004] The wind turbine rotor can be directly coupled to the generator rotor in so-called direct drive wind turbines. Alternatively, the wind turbine rotor may include a main rotor shaft (so-called "low speed shaft") leading to a gearbox. Subsequently, the high speed shaft of the gearbox can drive the generator. Regardless of the topology of the wind turbine, the electrical power output of the generator can be supplied to the power grid. The connection of the generator to the grid can include, for example, converters, transformers, medium voltage lines, etc.

[0005] A wind turbine controller can be configured to determine appropriate actuator setpoints for the wind turbine based on general conditions. Actuator setpoints for modern variable-speed wind turbines include, for example, generator torque and blade pitch angle. By controlling the blade pitch angle and generator torque, the rotor speed, as well as power output, aerodynamic thrust, and further mechanical loads, can be controlled. The objective of the control system is generally to maximize power output while maintaining the load on the wind turbine at an acceptable level.

[0006] As mentioned above, the actuator setpoints for torque and pitch (as well as other actuators such as yaw) can be changed depending on the situation. Important inputs for determining the actuator setpoints include, for example, wind speed and wind direction. Wind speed can be measured directly or indirectly, for example, by using a (generator) rotor speed sensor.

[0007] Wind turbines may also be equipped with load sensors on or within the blades to measure the load on the blades caused, for example, by wind and / or the weight of the blades. Excessively high loads on the blades can cause undesirable rotor speeds, potentially damaging the blades and / or other components of the wind turbine. Blade load sensors allow for the detection of high loads and enable a response by activating the pitch system to reduce the load on the blades, for example. These adjustments to the blades through the pitch system can extend the lifespan of the wind turbine and / or reduce the cost of generating power.

[0008] Therefore, for the safe and efficient operation of wind turbines, it is crucial that load measurements obtained from load sensors are reliable, that is, that they accurately represent the actual load at any given time. Load sensors for measuring the load on wind turbines, particularly wind turbine blades, may include resistance strain gauges, fiber optic strain gauges, or any other known strain sensing systems. The performance of these types of sensors can degrade over time due to the effects of continuous loads, temperature changes, and exposure to different types of ambient conditions and environments.

[0009] Different blade loads can be defined for wind turbine blades: edge-direction loads, span-direction loads, and flap-direction loads. The span-direction refers to the direction along the longitudinal axis of the blade, extending from the root to the tip. The edge-direction refers to the direction along the chord of the section of the wind turbine blade, i.e., extending from the leading edge to the trailing edge. The flap-direction is perpendicular to both the edge-direction and the span-direction.

[0010] With respect to a wind turbine rotor, the load can be decomposed into in-plane loads (loads tangential to the rotor plane) and out-of-plane loads (loads perpendicular to the rotor plane). The rotor plane may, in this specification, be defined as a plane perpendicular to the rotor axis of rotation and passing through the center of the blades at the blade root.

[0011] Blade load sensors can be calibrated to maintain their accuracy in measuring the load on the blades. Calibration typically involves establishing a correspondence between the readings produced by the blade load sensor and a reference value, according to a calibration pattern (i.e., specific conditions for calibration). If any inconsistencies occur in the calibration process, appropriate adjustments can be made to the load sensor to improve its accuracy.

[0012] Blade load sensors are known to be manually calibrated at the factory, for example, by statically pulling the blades to obtain specific conditions for calibration. This manual calibration is usually performed before the blades are mounted on the wind turbine. However, over time, the load sensors may need to be recalibrated.

[0013] European Patent No. 2615303 discloses a method for calibrating one or more load sensors on the blades of a wind turbine, the wind turbine comprising a main generator, a power-electronic converter connected to the main generator, and a rotor operably connected to the main generator and supporting the blades. The method includes operating the power-electronic converter to set the blades to at least one predetermined condition by operating the main generator as a motor, measuring the load at the predetermined condition using the blade load sensors, and calibrating the blade load sensors taking the measured load into account.

[0014] Such methods can be implemented, in particular, after the normal operation of a wind turbine has been interrupted.

[0015] It is also known that blade load sensors can be manually calibrated by manually (i.e., mechanically) operating the wind turbine to set the blades to a specific position (e.g., horizontal position) at a specific pitch angle when the blades are mounted on the wind turbine. This manual calibration allows for periodic recalibration of the load sensors. However, this type of calibration can be time-consuming and can be particularly expensive for offshore wind turbines because the operator needs to go to the location where the wind turbine is situated.

[0016] It is also known that automatic calibration of blade load sensors during wind turbine operation is performed by recording data (or display or load measurement) from the blade load sensor for several minutes. For example, data from the load sensor can be recorded when predetermined conditions for calibration are met during idle operation of the wind turbine in low wind conditions. Some of these predetermined conditions can be obtained several hours or days after idle operation of the wind turbine. Therefore, a disadvantage of this type of calibration may be that it can be time-consuming depending on the wind conditions.

[0017] This disclosure provides examples of methods and systems for determining the reliability or accurate function of a load sensor, which solves at least some of the aforementioned disadvantages. [Overview of the project]

[0018] In a first embodiment, a method is provided for determining the reliability of one or more load sensors in a wind turbine. The method includes measuring the load using the load sensors during the operation of the wind turbine and determining the in-plane moment of one or more blades having the rotor rotation speed frequency based on the measured load. The method then further includes comparing the in-plane moment having the rotor rotation speed frequency with a theoretical in-plane moment attributable to the mass of the blade and determining that the reliability of the load sensor is reduced if the in-plane moment having the rotor rotation speed frequency deviates from the theoretical in-plane moment by a first threshold.

[0019] According to this embodiment, the reliability or accurate function of the load sensor can be determined during the operation of the wind turbine, i.e., it is not necessary to interrupt the operation of the wind turbine or set it to specific conditions so that it can be determined whether the load sensor is accurately indicating the load. The measured load may be measured as an in-plane moment, or converted to an in-plane moment. The in-plane moment at any given moment during operation is a combination of the load and the aerodynamic load attributable to the blade mass. However, the blade mass provides the same moment throughout all rotations of the blade. At the 12 o'clock and 6 o'clock positions, the blade mass does not contribute to the bending moment. However, at the 3 o'clock and 9 o'clock positions, the bending moment attributable to the blade mass is maximum (in one direction and in opposite directions). The blade mass has a clearly defined contribution at the 1p frequency, i.e., the variation in moment attributable to the mass has the same frequency as the rotor rotation speed. In this point, the rotor refers to the wind turbine rotor, not the generator rotor. The generator rotor can have the same rotational speed in the case of a directly driven wind turbine, but it can have a very different speed in the case of a wind turbine with a gearbox.

[0020] The terms “1p frequency” and “rotor rotation speed frequency” can be used interchangeably throughout this disclosure.

[0021] By selecting an in-plane moment with a rotor rotation speed frequency and comparing the selected in-plane moment with the theoretical in-plane moment attributable to the blade mass, the deviation between the two indicates a potential malfunction of the load sensor. If such a potential malfunction is detected, different measures can be taken to reduce the risk of the load sensor malfunctioning.

[0022] Non-limiting examples of this disclosure are described below with reference to the attached drawings. [Brief explanation of the drawing]

[0023] [Figure 1]Perspective view of a wind turbine according to one example. [Figure 2] Detailed internal view of a nacelle of a wind turbine according to one example. [Figure 3A] Diagram schematically showing an example of a method for determining the reliability of one or more load sensors in a wind turbine. [Figure 3B] Diagram schematically showing an example of a method for determining the reliability of one or more load sensors in a wind turbine. [Figure 3C] Diagram schematically showing an example of a method for determining the reliability of one or more load sensors in a wind turbine. [Figure 3D] Diagram schematically showing an example of a method for determining the reliability of one or more load sensors in a wind turbine. [Figure 3E] Diagram schematically showing an example of a method for determining the reliability of one or more load sensors in a wind turbine. [Figure 4A] Diagram schematically showing an example of a comparison between a theoretical in-plane moment due to the mass of a rotor blade and a measured in-plane moment having a 1p frequency. [Figure 4B] Diagram schematically showing an example of a comparison between a theoretical in-plane moment due to the mass of a rotor blade and a measured in-plane moment having a 1p frequency. [Figure 5A] Diagram schematically showing another example of how a comparison between a theoretical in-plane moment due to the mass of a rotor blade and a measured in-plane moment having a 1p frequency can be performed. [Figure 5B] Diagram schematically showing another example of how a comparison between a theoretical in-plane moment due to the mass of a rotor blade and a measured in-plane moment having a 1p frequency can be performed. [Figure 6] Diagram schematically showing a method for on-line determining the exact function of a load sensor mounted on a wind turbine blade.

Embodiments for Carrying Out the Invention

[0024] In these diagrams, the same reference numerals are used to indicate matching elements.

[0025] Figure 1 shows a perspective view of an example of a 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 the hub 110 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 rotor blades 120 than three. Each rotor blade 120 may be spaced around the hub 110 to facilitate the rotation of the rotor 115 and to allow kinetic energy from the wind to be converted into usable mechanical energy, and subsequently electrical energy. For example, the hub 110 may be rotatably coupled to a generator 162 (Figure 2) positioned within the nacelle 161, enabling the generation of electrical energy.

[0026] Figure 2 shows a simplified internal view of an example of the nacelle 161 of the wind turbine 160 of Figure 1. As shown, the generator 162 may be located within the nacelle 161. Generally, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 to generate electricity from the 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 together with the hub 110. The generator 162 may then be coupled to the rotor shaft 163 so that the 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 through a gearbox 164.

[0027] It should be understood that the rotor shaft 163, gearbox 164, and generator 162 can generally be supported within the nacelle 161 by a support frame or bed plate 165 positioned at the top of the wind turbine tower 170.

[0028] The nacelle 161 is rotatably coupled to the tower 170 by a yaw system 20 so that the nacelle 161 can rotate around the yaw axis YA. The yaw system 20 comprises a yaw bearing having two bearing components configured to rotate relative to the other. The tower 170 is coupled to one of the bearing components, and the bed plate or support frame 165 of the nacelle 161 is coupled to the other bearing component. The yaw system 20 comprises an annular gear 21, a plurality of yaw drive units 22 having motors 23, a gearbox 24, and a pinion 25 for meshing with the annular gear 21 to rotate one of the bearing components relative to the other.

[0029] The blade 120 is coupled to the hub 110 via a pitch bearing 100 between the blade 120 and the hub 110. The pitch bearing 100 comprises an inner ring and an outer ring. The wind turbine blade can be mounted on either the inner bearing ring or the outer bearing ring, and the hub is connected to the other. When the pitch system 107 is actuated, the blade 120 can perform rotational motion relative to the hub 110. Thus, the inner bearing ring can perform rotational motion relative to the outer bearing ring. The pitch system 107 in Figure 2 comprises a pinion 108 that meshes with an annular gear 109 provided on the inner bearing ring to rotate the wind turbine blade around the pitch axis PA.

[0030] The energy generated by the generator can be delivered to a converter that adapts the generator's output power to the requirements of the power grid. The electromechanical unit may have electrical phases, for example, three electrical phases. The converter may be located inside the nacelle, inside the tower, or outside.

[0031] Figure 3A schematically illustrates an example of a method for determining the reliability of one or more load sensors in a wind turbine. The method includes measuring the load using the load sensors during the operation of the wind turbine in block 200. In block 210, an in-plane moment based on the measured load is determined. Next, in block 220, an in-plane moment with a frequency of 1p is selected. In block 230, the selected in-plane moment is compared with the theoretical in-plane moment attributable to the blade mass. Next, in block 240, if the selected in-plane moment deviates from the theoretical in-plane moment by a first threshold, it can be determined that the reliability of the load sensor has decreased.

[0032] The steps of the method, or various examples of the block in Figure 3A, will be explained with reference to Figures 3B to 3E.

[0033] In some examples, measuring the load on block 200 may include measuring the flap direction moment and the edge direction moment. A standard wind turbine blade can incorporate a suitable load sensor. The load sensor may be a strain gauge. Depending on where and how the load sensor is mounted, the strain may be measured in different directions. The load can also be determined using a sensor placed on the hub or any other (indirect) blade support.

[0034] Edge-direction and flap-direction loads can be used to control wind turbines. Figure 3B shows measurements of flap-direction and edge-direction moments for three blades of a wind turbine over several full rotations.

[0035] In block 210, the edge direction moment and flap direction moment can be converted into in-plane moment and out-of-plane moment based on the blade pitch angle. Since the load on the rotor wind turbine blade is an in-plane load and not an out-of-plane load, this method only needs to consider the in-plane moment. The results for three blades can be seen in Figure 3C.

[0036] In block 220, selecting an in-plane moment having a rotor rotation speed frequency may include filtering the in-plane moment determined using a peak filter. A peak filter is a frequency filter configured to pass a narrow band of frequencies and block all other frequencies. In this respect, a peak filter is essentially a very narrow bandpass filter. Figure 3D schematically shows the measured load in the frequency domain and how the peak filter can select an in-plane moment with a 1p frequency. The results of the filtering can be seen in Figure 3E, which shows in-plane modes with a 1p frequency during several full rotations of the wind turbine rotor for three blades of a wind turbine.

[0037] The comparison of theoretical in-plane moments due to the blade's mass can be determined based on the rotor blade's azimuth position.

[0038] In block 240, if the selected in-plane moment deviates from the theoretical in-plane moment by a first threshold, it can be determined that the reliability of the load sensor has decreased.

[0039] In some examples, the method may further include generating a first warning if the load sensor's reliability is compromised. A first threshold indicating a malfunction can be defined. If the threshold is exceeded, different actions may be taken. Maintenance may be planned to replace or recalibrate the load sensor. Alternatively, the wind turbine's operation may be down-rate because the load sensor's readings are not as reliable as they should be, i.e., the load on the wind turbine may be consciously reduced at the expense of power generation. In other examples, if the load sensor is determined to be unreliable, the wind turbine's operation may be shut down.

[0040] In some examples, the method may further include determining whether the selected in-plane moment deviates from the theoretical in-plane moment by a second threshold, the second threshold being higher than the first threshold. In these examples, the first threshold may generate a warning signal (the operator becomes aware of a potential problem, and operation may continue as usual or with some modifications), while passing the second threshold indicates a more serious warning (e.g., interruption of operation).

[0041] In some examples, the threshold may be a percentage of the absolute value of the theoretical in-plane moment. In some examples, comparing the selected in-plane moment with the theoretical in-plane moment attributable to the blade's mass involves determining the root mean square value of the selected in-plane moment. These examples are illustrated with reference to Figures 4 and 5.

[0042] Figure 4A shows a comparison of in-plane moments at which the mass of a wind turbine blade is at which the in-plane moment at 1p frequency is due. The bandwidth can be defined around the theoretical moment at which the blade mass is due, as shown by the dotted line. The bandwidth may also be defined as the ratio of the theoretical moment at which the blade mass is due. The bandwidth may also be a given fixed value. As long as the moment at 1p frequency derived from actual measurements remains within the bandwidth (as in Figure 4A), the load sensor can be considered to be functioning correctly. As mentioned above, more than one bandwidth can be defined in the example.

[0043] Figure 4B shows an example where a load sensor is determined to be unreliable or untrustworthy. In various cases, the load derived from the measurements falls outside the defined bandwidth.

[0044] Figures 5A and 5B schematically illustrate alternative examples. The example in Figure 5 shows another comparison between measured and theoretical moments. For a 1p in-plane moment, the root mean square (RMS) of the deviation from the theoretical moment should be nearly constant if only the blade mass is actually measured. Actual measurements will inevitably oscillate to some extent, for example, due to the unavoidable vibration of the blade. The root mean square (RMS) of the difference between the theoretical in-plane 1p load and the measured in-plane 1p load can be used for comparison with a threshold. In the example in Figure 5A, the RMS values ​​remain well within the defined bandwidth, i.e., the deviation is below the given threshold. On the other hand, in Figure 5B, it can be seen that for all three blades, the RMS exceeds the given threshold. Malfunction of different load sensors for different blades can be concluded.

[0045] Furthermore, when comparing RMS values ​​to determine deviations from theoretical curves or theoretical loads, two or more thresholds or two or more bandwidths can be defined.

[0046] During wind turbine operation, both examples in Figures 4 and 5 can be used simultaneously, or one of the examples can be selected. In some examples, the comparison in Figure 4 can be used, in particular, for low-speed rotation of the wind turbine, while measurements after interruption of operation and the comparison in Figure 5 can be used for steady-state operation above the minimum rotor speed.

[0047] In a further aspect of the present disclosure, a wind turbine system is provided. The system comprises a wind turbine 160 including a wind turbine rotor 115 having a plurality of blades 120. The system includes a plurality of load sensors for measuring the load on the blades and a control system. The control system may be configured to receive signals from the load sensors during operation, determine in-plane moments for one or more blades, select in-plane moments with a 1p frequency for one or more blades, and compare the selected in-plane moments with theoretical in-plane moments attributable to the mass of one or more blades.

[0048] The control system may be further configured to generate a warning signal if the selected in-plane moment deviates from the theoretical in-plane moment by a predefined threshold.

[0049] In some examples, each blade may be equipped with a strain gauge. Suitable strain gauges may include resistance foil strain gauges. Resistance strain gauges can be attached to the blade using a suitable adhesive, such as an epoxy adhesive. Other types of strain gauges and sensors, such as piezoelectric resistors, capacitive strain gauges, or fiber optics, can also be used to measure strain along the optical fiber.

[0050] In some cases, strain gauges can be mounted to measure edge-direction loads and flap-direction loads.

[0051] In some examples, the load sensor may be mounted inside or near the base of the blade. In one example, measurements from a load sensor on a blade not located at the base can be extrapolated to show the moment at the base of the blade. In another example, the sensor may be mounted at a suitable location on the hub instead of on the blade.

[0052] In some examples, the control system may be located away from the wind turbine. The control system may be part of the SCADA system at the wind power plant, or it may be located in a remote control center. In some examples, the wind turbine controller itself may incorporate a function to determine potential malfunctions or loss of reliability of the load sensors.

[0053] In a further embodiment, referring to Figure 6, a method is provided for determining the precise function of a load sensor mounted on a wind turbine blade online. As used herein, "online" means that the method can be performed during the standard operation of the wind turbine, i.e., without interrupting the operation of the wind turbine and without reproducing a specific load or rotational speed scenario.

[0054] The method may include measuring edge-direction strain and flap-direction strain in the wind turbine blade in block 300. In block 310, the edge-direction bending moment and flap-direction bending moment in the wind turbine blade can be determined based on the measured strains. In block 320, the edge-direction bending moment and flap-direction bending moment can be converted into measured in-plane moment and measured out-of-plane moment on the wind turbine blade. In block 330, a peak filter can be applied to determine the measured in-plane moment having a 1p frequency. In block 340, the azimuth angle of the rotor blade is determined, and in block 350, based on the azimuth angle, the theoretical variation of the moment due to the mass of the rotor blade can be determined. In block 360, the theoretical variation of the moment due to the mass of the rotor blade can be compared with the in-plane moment having a 1p frequency.

[0055] In some examples, a load sensor may be determined to function correctly if the measured in-plane moment with a frequency of 1p substantially corresponds to the theoretical variation of the moment attributable to the rotor blade mass. Whether the measured in-plane moment substantially corresponds to the theoretical variation along the rotor rotation can be determined in various ways. One or more thresholds can be used, and these thresholds may be defined in different ways.

[0056] In some examples, the method may include generating a warning if a measured in-plane moment having a frequency of 1p deviates by a first threshold from the theoretical variation of the moment attributable to the rotor blade mass. Such a warning signal may be transmitted to an operator at a remote control center and / or to a wind turbine controller or SCADA system to implement predefined actions in response to such a warning signal.

[0057] In some examples, the method may further include downscaling the wind turbine when a warning is generated.

[0058] In some examples, the edge-direction bending moment and flap-direction bending moment in a wind turbine blade can be determined at the location of a sensor on the blade, and these can be converted into edge-direction bending moment and flap-direction bending moment at the root of the blade.

[0059] The order of the method steps shown in Figures 3A and 6 should not necessarily be considered sequential. In particular, the determination of the azimuth angle does not need to be performed at a specific point in time compared to the measurement of the load. The measured load and azimuth angle only need to be correlated in time to make a meaningful comparison. The method may also be performed continuously during the operation of the wind turbine. The steps may be performed at frequencies above 1 Hz, specifically above 10 Hz.

[0060] Examples of the methods disclosed herein can be implemented in hardware, software, firmware, or combinations thereof.

[0061] Those skilled in the art will further understand that the various exemplary logic blocks, modules, circuits, and algorithmic steps described in connection with the disclosure herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly demonstrate this hardware- and software compatibility, various exemplary components, blocks, modules, circuits, and steps are generally described above in relation to their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in various ways for each specific application.

[0062] The various exemplary logic blocks, modules, and circuits described in connection with the disclosure herein may be realized or implemented using one or more general-purpose processors, digital signal processors (DSPs), cloud computing architectures, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but instead, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be realized as, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other combination of computing devices that are such configurations.

[0063] This disclosure also relates to a computing system adapted to perform any of the methods disclosed herein.

[0064] This disclosure also relates to a computer program or computer program product which includes instructions (code) that, when executed, perform any of the methods disclosed herein.

[0065] A computer program may be in the form of object code, such as source code, object code, code intermediate source, and partially compiled forms, or any other form suitable for use in process implementation. A carrier may be any entity or device capable of carrying a computer program.

[0066] When implemented in software / firmware, the functionality may be stored as one or more instructions or codes on or transmitted through a computer-readable medium. Computer-readable medium includes both computer storage media and communication media, including any media that facilitate the transfer of computer programs from one location to another. Storage media can be any available media that can be accessed by a general-purpose or dedicated computer. Such computer-readable media may include, but are not limited to, RAM, ROM, EEPROM, CD / DVD or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other media that can be used to carry or store desired program code means in the form of instructions or data structures, and can be accessed by a general-purpose or dedicated computer or general-purpose or dedicated processor. Any connection is also appropriately referred to as computer-readable medium. For example, if software / firmware is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used herein, the terms "disk" and "disc" include compact discs (CDs), laser discs, optical discs, digital multipurpose discs (DVDs), floppy disks, and Blu-ray discs, where a disk typically reproduces data magnetically, and a disc reproduces data optically using a laser. Any combination of the above should also be included within the scope of computer-readable media.

[0067] This specification discloses the present invention, including preferred embodiments, using examples, and enables those skilled in the art to practice the invention, including by fabricating and using any device or system and by carrying out any incorporated method. The patentable scope of the present invention is defined by the claims and may include other embodiments that a person skilled in the art may conceive. Such other embodiments are intended to be within the claims if they have structural elements that do not differ from the language of the claims, or if they include equivalent structural elements that do not substantially differ from the language of the claims. A person skilled in the art may construct further embodiments and techniques in accordance with the principles of this application by combining and adapting aspects from the various embodiments described above and other known equivalents for each such aspect. Where reference numerals related to the drawings are placed in parentheses within the claims, those reference numerals are merely for clarity of the claims and should not be construed as limiting the claims. [Explanation of Symbols]

[0068] 20 Yaw System 21 Ring gear 22 Yaw drive device 23 Motor 24 Gearbox 25 pinion 100 pitch bearing 107 Pitch System 108 pinion 109 Ring gear 110 Hub 115 Wind turbine rotor 120 rotor blades 150 Support surface 160 Wind Turbine 161 Nacer 162 Generators 163 Rotor shaft, main rotor shaft 164 Gearbox 165 Support frame, bed plate 166 Generator shaft 170 Wind Turbine Towers PA pitch axis YA yaw axis

Claims

1. A method for determining the reliability of one or more load sensors in a wind turbine (160), The load (200) is measured using the load sensor while the wind turbine (160) is in operation, Based on the measured load, the in-plane moment of one or more blades (120) having the rotor rotation speed frequency is determined (210, 220), The in-plane moment having the rotor rotation speed frequency is compared with the theoretical in-plane moment attributable to the mass of the blade (120) (230), If the in-plane moment having the rotor rotation speed frequency deviates from the theoretical in-plane moment by a first threshold, it is determined that the reliability of the load sensor has decreased (240) Methods that include...

2. The method according to claim 1, wherein the measurement of the load (200) includes measuring the flap direction moment and the edge direction moment (300).

3. The method according to claim 2, wherein the flap direction moment and the edge direction moment are converted into in-plane moment and out-of-plane moment (320) based on the pitch angle of the blade (120).

4. Determining the in-plane moment having the rotor rotation speed frequency (210, 220) is, Based on the measured load, the in-plane moment is determined (210), Selecting the in-plane moment having the rotor rotation speed frequency (220) The method according to any one of claims 1 to 3, including

5. The method according to claim 4, wherein the selection of the in-plane moment having a rotor rotation speed frequency (220) includes filtering the determined in-plane moment of the blade (120) using a peak filter (330).

6. The method according to any one of claims 1 to 5, wherein the theoretical in-plane moment due to the mass of the blade (120) is determined based on the azimuth position of the blade (120).

7. The method according to any one of claims 1 to 6, wherein the threshold is the ratio of the absolute values ​​of the theoretical in-plane moments.

8. The method according to any one of claims 1 to 7, wherein the determined in-plane moment is compared with the theoretical in-plane moment attributable to the mass of the blade (120) (230), and the root mean square value of the determined in-plane moment is determined.

9. The method according to any one of claims 1 to 8, further comprising generating a first warning signal if the reliability of the load sensor deteriorates.

10. The method according to claim 9, further comprising determining whether the determined in-plane moment of the blade (120) deviates from the theoretical in-plane moment of the blade (120) by a second threshold, wherein the second threshold is higher than the first threshold.

11. The method according to claim 10, further comprising interrupting the operation of the wind turbine (160) if the determined in-plane moment of the blade (120) deviates from the theoretical in-plane moment of the blade (120) by more than the second threshold.

12. It is a wind turbine system, A wind turbine (160) including a wind turbine rotor (115) having multiple blades (120), Multiple load sensors for measuring the load on the blade (120), During operation, receive a signal from the load sensor, The in-plane moment for one or more of the blades (120) is determined (210), Select the in-plane moment (220) having the rotor rotation speed frequency for one or more blades (120), The selected in-plane moment is compared with the theoretical in-plane moment attributable to the mass of one or more blades (120) (230), If the selected in-plane moment deviates from the theoretical in-plane moment by a predetermined threshold, a warning signal is generated. A control system configured as follows: A wind turbine system equipped with the following features.

13. The system according to claim 12, wherein each of the blades (120) is equipped with a strain gauge.

14. The system according to claim 13, wherein the strain gauge is mounted to measure edge-direction load and flap-direction load.

15. The system according to any one of claims 12 to 14, wherein the load sensor is mounted in or near the base portion of the blade (120).

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