Computer-implemented method and device for aligning a blade load measurement system of a rotor blade of a wind turbine, wind turbine having at least one rotor blade with a strain

Abstract

The blade load acting on the rotor blade is typically determined taking into account the strain acting on the rotor blade detected by the strain sensor. The rotor angle has hitherto been utilized to align the strain sensor. However, the detection of the rotor angle is typically unreliable or imprecise, and therefore, the simple and precise alignment of the strain sensor has hitherto been not sufficiently precise solved. According to the invention, the problem is solved by a computer-implemented method for aligning a first blade load measuring system having at least one strain sensor on a first rotor blade of a wind turbine, comprising the following steps: measuring a first acceleration by means of a first acceleration sensor; determining a first reference bending moment and / or a first reference axial force based on the measured first acceleration; determining a measured first bending moment and / or a measured first axial force based on a measurement value of at least one strain sensor of the first blade load measurement system and a first alignment parameter set associated with the first blade load measurement system and having a first initial alignment parameter value; determining a first deviation of the first reference bending moment and / or the first reference axial force from the measured first bending moment and / or the measured first axial force; alignment parameter values for a first set of alignment parameters for the first blade load measurement system are adjusted such that the first deviation is less than or equal to a threshold value.

Description

Technical Field

[0001] The invention generally relates to a computer-implemented method and an apparatus for aligning a blade load measurement system of a rotor blade of a wind power plant, a wind power plant having at least one rotor blade with a strain sensor, and a computer-readable storage medium. Background Art

[0002] Wind power plants convert wind energy into electrical energy. The wind applies force to at least one rotor blade of a wind power plant's rotor, so that the kinetic energy of the wind is converted into the dynamic rotational energy of the rotor. The rotor drives a generator, which feeds electrical energy into a power grid.

[0003] One or more rotor blades of a wind power plant are increasingly frequently equipped with one or more sensors, such as strain sensors, which are used for control purposes, in particular for load reduction, and / or for monitoring the operation of the plant, in particular for safety and maintenance purposes. The forces and / or moments acting on the rotor blades are determined from the strains measured by the strain sensors. In order to obtain reliable and correct measured values ​​of the strain sensors and thus correct load measurement results, the strain sensors must be calibrated before the strain sensors are put into operation, i.e. the deviations of the load measurement values ​​from the expected values ​​(reference) must be determined and recorded. The calibration parameters for the strain sensors are then set or tuned so that the measured deviations from the expected values ​​are as small as possible or are within defined specifications or tolerance limits.

[0004] To date, in order to calibrate strain sensors for blade load measurement, the mass of the rotor blade, the arrangement of the sensor on the rotor blade, the current rotor angle of the turbine of the wind power plant, the current wind speed and the current pitch angle can be detected. The pitch angle and the current rotor angle are the most important input parameters. The current wind speed is used for filtering means in order to filter out measurements recorded at high wind speeds, which could falsify the measurement results. High wind speeds cause additionally acting moments, which make the calibration inaccurate, so that filtering improves the calibration quality of the strain sensor.

[0005] For the real alignment, controlled and limited operation is implemented with the rotor blades, for example, multiple rotations in the case of low wind speed. In particular, the pitch angle of the rotor blades is controlled and set differently in a targeted manner. Because wind power plants operate at different pitch angles, it is necessary to perform alignment operations at different pitch angles in order to fully describe the characteristics of the strain sensor. The rotor blades are placed in a defined position in which a known force or bending moment acts on the rotor blades. The defined position is, for example, the attitude of the rotor blade perpendicular to or parallel to the ground surface. The position in which the rotor blade is located can be clearly determined by measuring the current rotor angle. In other words, for alignment, the measurement of the rotor angle is definitely required. In the defined position, for example, only gravity acts on the rotor blades. In the case of low wind speed, the aerodynamic forces acting on the rotor blades can be ignored. Taking into account the gravity acting, the position of the strain sensor and the mass of the rotor blade, the bending moment and axial force acting on the rotor blade are determined. At the same time, the strain sensor detects the force or bending moment based on the initial alignment parameter set. Since the acting forces or moments are known, the forces or bending moments measured by the strain sensor are compared with the known forces or bending moments, and the calibration parameter set for the strain sensor is adjusted according to the deviation.

[0006] For example, EP 2 531 722 A1 teaches a method for in-situ alignment of a load sensor of a wind turbine. Here, the rotor azimuth angle and the angle of attack of a first wind turbine blade are first determined. In a next step, the load in a first cross section of the first wind turbine blade is measured using a first load sensor. Based on the rotor azimuth angle and the angle of attack, a theoretical load acting on the blade is calculated. The measured load is compared with the calculated theoretical load, and the first load sensor is aligned based on the comparison.

[0007] Problems to be solved by the present invention

[0008] A disadvantage of the previously described methods for adjusting strain sensors is that the current rotor angle of the turbine of the wind turbine must be detected. However, the rotor angle cannot usually be measured unambiguously, because due to deficiencies in the measurement technology, an angular offset occurs between the actual and measured rotor angle. If interference signals occur or the detected signal of the rotor angle is unreliable or inaccurate, this affects the adjustment of the strain sensor.

[0009] Based on the prior art described, the object of the present invention is to overcome the mentioned disadvantages. It is desirable to be able to calibrate the strain sensor precisely and reliably, in particular without measuring or using the rotor angle. Summary of the invention

[0010] The object is achieved by a computer-implemented method for calibrating a first blade load measuring system having at least one strain sensor at a first rotor blade of a wind turbine according to claim 1. In this case, a simple and precise calibration of the blade load measuring system is possible, and the measurement or use of the rotor angle or the use of the rotor angle is dispensed with in the calibration method. Furthermore, the object is achieved by a device for calibrating a first blade load measuring system having at least one strain sensor at a first rotor blade of a wind turbine according to claim 9, by a wind turbine according to claim 13, and by a computer-readable storage medium according to claim 14.

[0011] In particular, the object is achieved by a computer-implemented method for calibrating a first blade load measuring system having at least one strain sensor on a first rotor blade of a wind power plant, the method comprising the following steps:

[0012] a) measuring a first acceleration by means of a first acceleration sensor;

[0013] b) determining a first reference bending moment and / or a first reference axial force based on the measured first acceleration;

[0014] c) determining a measured first bending moment and / or a measured first axial force based on measurement values ​​of at least one strain sensor of the first blade load measurement system and a first set of alignment parameters associated with the first blade load measurement system and having first initial alignment parameter values;

[0015] d) determining a first deviation of the first reference bending moment and / or the first reference axial force from the measured first bending moment and / or the measured first axial force;

[0016] e) adjusting the values ​​of the tuning parameters of the first tuning parameter set for the first blade load measurement system so that the first deviation is less than or equal to a threshold value.

[0017] One idea of ​​the invention is therefore to calibrate the blade load measuring system without using the rotor angle of the wind power plant.

[0018] Acceleration based alignment may be suitable for improving the accuracy of the alignment.

[0019] The blade load measurement system can be understood in particular as a strain sensor system, which includes at least one strain sensor, in particular a plurality of strain sensors, in particular at least three, more particularly at least four strain sensors. At least one strain sensor can be configured as a strain sensor that measures one or more strains in one direction. The strain sensor can preferably be positioned and oriented so that it measures one or more strains in the direction of the blade axis. To this end, the strain sensor can be arranged in any first plane of the rotor blade cross section. The plane of the rotor blade cross section can be understood in particular as a plane passing through the cross section of the rotor blade, which plane is orthogonal to the blade axis of the rotor blade. In particular, the strain sensor can be configured to measure multiple strains in the direction of the blade axis, which are necessary for determining the axial force and / or the bending moment. In particular, if the strain sensor is capable of measuring only one strain in the direction of the blade axis, the blade load measurement system can include multiple strain sensors that can also detect strains in the direction of the blade axis. The strain sensors can in principle be arranged in any plane that is the same or different from each other. For example, the strain sensors can each be arranged in a common plane of the rotor blade cross section, for example, in a first plane, or in multiple planes of the rotor blade cross section that are spaced apart from each other.

[0020] The first acceleration sensor can detect a first acceleration acting in the rotating rotor hub. The first acceleration sensor can be, for example, an acceleration sensor system that measures accelerations in three orthogonal spatial directions. For example, the first acceleration sensor can be provided by a 6-DOF acceleration sensor.

[0021] A measured first acceleration may be understood in particular to be an acceleration which comprises acceleration components in a plurality of spatial directions, in particular in three, in particular orthogonal spatial directions.

[0022] According to the invention, the first reference bending moment and / or the first reference axial force is determined based on the measured first acceleration.

[0023] The first reference bending moment and / or the first reference axial force is determined in particular without taking the rotor angle into account.

[0024] Whether the measured first bending moment and / or the measured first axial force are taken into account for the calibration can be dependent in particular on the number of strain sensors. For example, when three strain sensors are used, the measured first axial force can be taken into account. If four strain sensors are used, for example, the measured first bending moment can be used, or alternatively the measured first axial force and the measured first bending moment can be used.

[0025] According to the invention, the measured first bending moment and / or the measured first axial force is determined based on measurement values ​​of at least one strain sensor of the first blade load measurement system and initial alignment parameter values ​​of a first alignment parameter set associated with the first blade load measurement system.

[0026] The first reference bending moment and / or the first reference axial force may be compared to the measured first bending moment and the measured first axial force, and a first deviation between the first reference bending moment and / or the first reference axial force and the measured first bending moment and / or the measured first axial force may be determined.

[0027] The alignment parameter values ​​of the first alignment parameter set are determined based on the first deviation, such that the first deviation is less than or equal to a threshold value. If the first deviation is less than or equal to a defined threshold value, the alignment parameter values ​​of the first alignment parameter set are selected for alignment. For example, the threshold value may indicate a first deviation of at most 5.00%, preferably at most 3.00%, more preferably at most 1.00%.

[0028] The first alignment parameter set for the first blade load measurement system may comprise one or more suitable parameters for aligning the first blade load measurement system or the strain sensor. The initial alignment parameter values ​​of the first alignment parameter set may be arbitrarily specified parameter values. When suitable alignment parameter values ​​are specified as initial alignment parameter values, the calculation time may be shortened. For example, particularly initial alignment parameter values ​​of an alignment parameter set of a structurally and functionally similar wind power installation may be used. Optionally, particularly initial alignment parameter values ​​determined from the stiffness of the first rotor blade and / or the position of the first strain sensor and / or the wavelength of the first strain sensor may be used.

[0029] Based on the adjusted alignment parameters of the alignment matrix, bending moments in the load reference plane and / or axial forces acting orthogonally to the load reference plane can be determined in mutually orthogonal load vectors.

[0030] The first axial force can describe the force acting along the blade axis from the hub center toward the blade tip. In addition, the force acting in the center of gravity of the first rotor blade can be determined from the measured first acceleration and the mass of the first rotor blade. In addition, the first bending moment can be determined based on the gravity and the distance of the center of gravity of the rotor blade from the hub center. The mass and center of gravity of the first rotor blade can be obtained, for example, from the data page of the first rotor blade or by weighing the rotor blade in the step of manufacturing the rotor blade or before installing the first rotor blade. This has the advantage that the first bending moment and / or the first axial force about the blade flange can be inferred in a simple manner only from the mass of the first rotor blade, the distance of the center of gravity from the blade flange and the measured first acceleration. In addition, the design mass distribution can also be used to determine the center of gravity and mass for each blade radius position so as to adjust the bending moment and / or axial force about the blade section.

[0031] As already described, the wind power installation may include at least one first rotor blade. In addition, the wind power installation may include a plurality of, in particular two, more in particular three rotor blades. The rotor blades may each be arranged uniformly around the hub at an angular offset relative to each other. If, for example, two rotor blades are provided, the two rotor blades may be arranged at an angular offset of 180° relative to each other. If, for example, three rotor blades are provided, the three rotor blades may be arranged at an angular offset of 120° relative to each other. The rotor blades may be identical or at least approximately identical in terms of their size, their mass, their mass distribution and their center of gravity and thus their static moment, i.e. the product of the mass and the distance of the center of gravity from a reference point. The deviation is preferably at most 5%, preferably at most 2%, more preferably 1%.

[0032] In an advantageous embodiment, the method may include calibrating a second blade load measurement system having at least one strain sensor at a second rotor blade, the method comprising the following steps:

[0033] a) determining a second acceleration associated with the second rotor blade based on the measured first acceleration while taking into account an angular offset between the first rotor blade and the second rotor blade;

[0034] b) determining a second reference bending moment and / or a second reference axial force based on the second acceleration;

[0035] c) determining a measured second bending moment and / or a measured second axial force based on measurement values ​​of at least one strain sensor of the second blade load measurement system and a second set of alignment parameters associated with the second blade load measurement system and having second initial alignment parameters;

[0036] d) determining a second deviation of the second reference bending moment and / or the second reference axial force from the measured second bending moment and / or the measured second axial force;

[0037] e) adjusting the values ​​of the tuning parameters of the second tuning parameter set for the second blade load measurement system so that the second deviation is less than or equal to the threshold value.

[0038] The second acceleration is associated with the second rotor blade and is determined from the measured first acceleration taking into account the angular offset between the first rotor blade and the second rotor blade. In other words, the second acceleration is a transformation of the measured first acceleration from the first rotor blade to the second rotor blade in relation to the angle between the rotor blades. From the second acceleration, a second reference bending moment and / or a second reference axial force can be determined. The second reference bending moment and / or the second reference axial force typically relate to the blade flange, but can also relate to any other location on the second rotor blade.

[0039] At least one second blade load measuring system with at least one strain sensor is arranged at the second rotor blade, which determines a measured second bending moment and / or a measured second axial force. The same conditions apply for the type and positioning of the second strain sensor as for the at least one strain sensor of the first blade load measuring system at the first rotor blade.

[0040] The second deviation can be ascertained by comparing a second reference bending moment and / or a second reference axial force with the measured second bending moment and / or the measured second axial force.

[0041] Based on the second deviation, the alignment parameter values ​​of the second alignment parameter set are adjusted so that the second deviation is less than or equal to a threshold value. The threshold value for the second deviation may in particular correspond to the threshold value for the first deviation.

[0042] Simply by measuring the first acceleration by means of the first acceleration sensor, the blade load measurement system at the second rotor blade can also be adjusted in a simple manner via the angular offset between the rotor blades on the basis of the number of rotor blades.

[0043] The second alignment parameter set for the second blade load measurement system may include one or more suitable parameters for aligning the second blade load measurement system or the strain sensor. The initial alignment parameter values ​​of the second alignment parameter set may be arbitrarily specified parameter values. When suitable alignment parameter values ​​are specified as initial alignment parameter values, the calculation time may be shortened. For example, particularly initial alignment parameter values ​​of an alignment parameter set of a structurally and functionally similar wind power installation may be used. Optionally, particularly initial alignment parameter values ​​determined from the stiffness of the second rotor blade and / or the position of the second strain sensor and / or the wavelength of the second strain sensor may be used.

[0044] In an advantageous embodiment, steps a) to d) may be repeatedly performed, in particular at least 50 times, more particularly at least 100 times, more particularly at least 1000 times, more particularly at least 10000 times, and instead of step e), the tuning parameter value is adjusted so that the first deviation or the second deviation detected in step d) is less than or equal to a threshold value, wherein a different pitch angle and / or a different acceleration is detected in each repetition.

[0045] For example, step a) to step d) can be performed at a predetermined number of times or at a predetermined time interval. Not only the time interval of step a) to step d), but also the number of repetitions is not limited in principle. For the purpose of improving the accuracy of the alignment, the time interval of step a) to step d) and / or the number of repetitions can be specified as a minimum value. Similarly, for the purpose of time and cost reduction, the time interval of step a) to step d) and / or the number of repetitions can be limited to a maximum value. Similarly, the time interval of step a) to step d) and / or the number of repetitions can be interrupted and continued at another time. This has the advantage that the alignment method can be interrupted when the operation of the wind power facility cannot be reliably performed for the purpose of alignment due to external environmental influences. The total time interval can be, for example, at least two minutes, preferably at least ten minutes, more preferably at least 15 minutes and / or at most one hour, preferably at most 45 minutes, more preferably at most 30 minutes. The time interval of step a) to step d) or the number of repetitions can be determined in particular according to the frequency with which the measured first acceleration is discarded. The first deviations or second deviations determined in step d) can be combined, for example, into a common first deviation or a common second deviation, for example in the form of a matrix or a vector comprising the first deviations or the second deviations. By first repeatedly performing steps a) to d), a certain amount of data, in particular first deviations or second deviations, can be collected, based on which the first set of alignment parameters can be determined and selected. This allows alignment to be performed at a later time, according to a predetermined time interval or a predetermined number of executions.

[0046] In an advantageous embodiment, the pitch angle and / or a defined pitch angle, in particular a different pitch angle, can be used before step a). For example, a pitch angle signal detected by a wind power plant in accordance with a standard can be used. Wind power plants usually operate at different pitch angles. By setting a defined pitch angle, in particular by setting different pitch angles, the first rotor blade can be placed in an aerodynamic posture that is good in terms of energy and safety technology at any time, so that the rotor of the wind power plant always reliably operates at an optimal operating point. In addition, by determining the pitch angle, critical operating states of the wind power plant can be identified. By setting a defined pitch angle, damage to the wind power plant during the calibration of the first blade load sensor can be avoided.

[0047] In an advantageous embodiment, when the wind speed exceeds a wind speed threshold, the first acceleration measured by the first acceleration sensor is discarded. The wind speed prevailing in the surroundings of the wind power facility can be measured by means of a sensor for detecting the wind speed, which can be arranged at or near the wind power facility. The measured wind speed can be compared with a prescribed wind speed threshold for the maximum wind speed. If the measured current wind speed is less than the wind speed threshold for the maximum wind speed, the measured first acceleration can be used to further adjust the blade load measurement system. If the wind speed is equal to or greater than the wind speed threshold for the maximum wind speed, the measured first acceleration can be discarded. In the described manner, it can be ensured that the first reference bending moment is not too strongly affected by the wind force that occurs and is thereby distorted. The wind speed threshold for the maximum wind speed can be, for example, 10 m / s, preferably 8 m / s, more preferably 5 m / s, more preferably 3 m / s.

[0048] In a preferred embodiment, the first acceleration sensor can measure acceleration in at least one, in particular two, more in particular three spatial directions and / or is formed by an inertial measurement unit, and / or the acceleration sensor, preferably two, more preferably three acceleration sensors are arranged in the hub of the wind power plant.

[0049] The first acceleration sensor can determine positive and negative translational accelerations along one, in particular two, and more in particular all three spatial directions, namely in the x-direction, the y-direction, and the z-direction. Therefore, the measured first acceleration can include accelerations in at least one, in particular two, and more in particular three directions of the x-direction, the y-direction, and the z-direction. By using more than one first acceleration sensor, the measuring system can be designed to be functionally redundant, whereby when one acceleration sensor fails, another acceleration sensor can assume the measuring function. For this purpose, the acceleration sensors are functionally and structurally identical. In addition, the accuracy of the measurement can be improved by comparing the measured values ​​of the individual acceleration sensors with each other in order to identify differences and thus possible measurement errors and obtain correct measured values.

[0050] The first acceleration sensor can be arranged in particular in the hub of the rotor. In particular, the first acceleration sensor can be oriented such that it can measure an acceleration in the direction of the blade axis of the first rotor blade. The first acceleration sensor can also measure two further accelerations orthogonal to the measured first acceleration.

[0051] In each rotor blade attitude, different forces and moments may act on the rotor blade, which forces and moments should be correctly detected by the blade load measurement system. It is therefore necessary to determine an acceleration associated with the rotor blade attitude in a one-to-one correspondence with the first acceleration sensor. The measured first acceleration may be associated with the first rotor blade attitude of the first rotor blade. The measured second acceleration may be associated with the second rotor blade attitude of the second rotor blade, wherein the second rotor blade may be arranged around the hub at a certain angle offset relative to the first rotor blade. Multiple rotor blade attitudes may be associated with the measured acceleration. The acceleration associated with the rotor blade attitude may be described, for example, via an acceleration vector, wherein the vector includes accelerations in three orthogonal spatial directions. Based on the measured acceleration, the bending moment and the axial force may be directly obtained via the known center of gravity orientation and the mass of the blade.

[0052] If the first acceleration sensor is arranged offset from the blade axis with an installation offset, such as a translational or rotational displacement, in particular with an angular offset, the acceleration sensor measures different accelerations. By precise positioning and orientation of the acceleration sensor on the blade axis, it can be ensured that the measured first acceleration and thus the first reference bending moment and / or the first reference axial force are not distorted by the installation offset. However, in practice, this may not always be possible and the actual installation direction of the sensor may deviate from the described optimal installation direction. It may therefore be necessary to identify the installation offset and take it into account when aligning the blade load measurement system in order to improve the accuracy of the alignment.

[0053] The strain sensor can be any suitable sensor, such as, for example, a piezoelectric strain gauge, a fiber Bragg grating pattern, in order to detect strain with or without temperature compensation. Depending on the application, it may be necessary to arrange the strain sensor at a specific position on the first rotor blade or the second rotor blade. Thus, the strain sensor can in principle be located at any arbitrary position on or in the first rotor blade or the second rotor blade.

[0054] In an advantageous embodiment, at least one strain sensor of the first blade load measurement system or the second blade load measurement system can be arranged on the first rotor blade or the second rotor blade in a radial region of at most 50%, preferably at most 30%, of the length of the rotor blade starting from the blade flange. As a result, the accuracy of the determination and thus the alignment of the measured first bending moment or the second bending moment and / or the measured first axial force or the second axial force can be further improved. In an advantageous embodiment, the alignment of the first blade load measurement system and / or the second blade load measurement system at the first rotor blade and / or the second rotor blade can be implemented on site by a computing device at the wind power facility and / or by a remote computing device. Depending on the application, it may be meaningful to align by a computing device at the wind power facility on site or by a remote computing device. The computing device at the wind power facility on site may be suitable for on-site alignment of the blade load measurement system in an offshore wind power facility, for example. A remote computing device may be desirable, for example, in order to calibrate the alignment method or monitor the alignment process. If the calibration is carried out by a remote computing device, a unit for storing the measurement data and for transmitting the measurement data wirelessly or by wire to the remote computing unit is particularly advantageous. The computing device can be part of the blade load measuring system. The computing device can be composed of one or more computing units. Furthermore, the calibration of the first blade load measuring system or the second blade load measuring system can be carried out by a common, i.e. the same, computing device or by different computing devices.

[0055] Furthermore, the object mentioned at the outset is achieved in particular by a device for calibrating a first blade load measuring system having at least one strain sensor in a first rotor blade of a wind turbine installation, the device having the following components:

[0056] a unit for measuring acceleration, the unit for measuring acceleration being designed to measure a first acceleration by means of a first acceleration sensor;

[0057] a unit for determining a bending moment and / or an axial force, the unit for determining a bending moment and / or an axial force being configured to determine a first reference bending moment and / or a first reference axial force based on the measured first acceleration and to determine the measured first bending moment and / or the measured first axial force based on measurement values ​​of at least one strain sensor of the first blade load measurement system and a first set of alignment parameters associated with the first blade load measurement system and having first initial alignment parameter values;

[0058] a unit for determining a deviation of a bending moment and an axial force, the unit for determining a deviation of a bending moment and an axial force being designed to determine a first deviation of a first reference bending moment and / or a first reference axial force from a measured first bending moment and / or a measured first axial force;

[0059] - a unit for adjusting the values ​​of tuning parameters of a tuning parameter set for a blade load measurement system, wherein the unit for adjusting the values ​​of tuning parameters of a tuning parameter set for a blade load measurement system is configured to adjust the values ​​of tuning parameters of a first tuning parameter set for a first blade load measurement system so that a first deviation is less than or equal to a threshold value.

[0060] The device described in this article can be used in particular for calibrating a first blade load measurement system having at least one strain sensor using the method described in this article, or the method can be implemented by the described device. In this regard, the variants and improvements described with respect to the method can also be applied with respect to the device.

[0061] In an advantageous embodiment, the device can be suitable for calibrating a second blade load measurement system having at least one strain sensor at a second rotor blade of a wind power plant, wherein

[0062] the unit for measuring acceleration is designed to determine a second acceleration based on the measured first acceleration and taking into account an angular offset between the first rotor blade and the second rotor blade;

[0063] - wherein the unit for determining a bending moment and / or an axial force is configured to determine a second reference bending moment and / or a second reference axial force based on a second acceleration and to determine a measured second bending moment and / or a measured second axial force based on a measurement value of at least one strain sensor of a second blade load measurement system and a second set of alignment parameters associated with the second blade load measurement system and having a second initial alignment parameter value;

[0064] wherein the unit for determining the deviation of the bending moment and the axial force is designed to determine a second deviation of a second reference bending moment and / or a second reference axial force from a measured second bending moment and / or a measured second axial force;

[0065] wherein the unit for adjusting the adjustment parameter values ​​of the adjustment parameter set for the blade load measuring system is configured to adjust the adjustment parameter values ​​of a second adjustment parameter set for the second blade load measuring system such that the second deviation is less than or equal to the threshold value.

[0066] In an advantageous embodiment, the device can also comprise a pitch angle use and / or setting unit in order to use the pitch angle and / or to set a defined pitch angle, in particular a different pitch angle.

[0067] In a preferred embodiment, the device may also include a unit for discarding acceleration, which is configured to compare the wind speed with a wind speed threshold and select the measured first acceleration when the wind speed is less than the wind speed threshold, and discard the measured first acceleration when the wind speed is greater than the wind speed threshold.

[0068] Furthermore, the object is achieved in particular by a wind power plant having a rotor with a hub and rotor blades which extend radially from the hub, wherein the number of rotor blades includes at least one first rotor blade, and the wind power plant is provided with a device as described above.

[0069] Similar or identical advantages result as have already been described in conjunction with the method described above.

[0070] Furthermore, the object is particularly achieved by a computer-readable storage medium, which contains instructions, which, when executed by at least one processor, prompt the at least one processor to implement the method as described above.

[0071] Similar or identical advantages result as have already been described in conjunction with the method described above.

[0072] Further embodiments are described in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The present invention is described in detail below based on the embodiments. Herein, it is shown:

[0074] Figure 1 shows a schematic side view of a wind power installation with a rotor blade according to one embodiment described herein;

[0075] Figure 2 shows a schematic side view of a rotor blade according to one embodiment described herein;

[0076] Figure 3 A flow chart is shown of a method for calibrating a first blade load measurement system having at least one strain sensor at a first rotor blade according to one embodiment described herein.

[0077] Figure 4 A flow chart of a method for calibrating a second blade load measurement system having at least one strain sensor at a second rotor blade according to one embodiment described herein is shown. DETAILED DESCRIPTION

[0078] The following describes an embodiment of the present invention. In the accompanying drawings, the same reference numerals represent the same or similar features of the corresponding embodiments.

[0079] Figure 1 A schematic side view of a wind power installation 100 according to an embodiment described herein is shown, the wind power installation having a first rotor blade 201, a second rotor blade 202 and a third rotor blade (not shown here). The wind power installation 100 comprises a tower 101 and a nacelle 102. A rotor is fastened to the nacelle 102. The rotor comprises a hub 103, to which rotor blades 201, 202 are fastened. According to a typical embodiment, the rotor has at least one, preferably two, more preferably three rotor blades. When the wind power installation is in operation, the rotor, i.e. the hub 103, rotates with the rotor blades mounted thereon about an axis 200, which corresponds to a central axis of the nacelle 102 passing through the center of the hub. Here, the nacelle 102 or its central axis 200 is tilted at an inclination angle α of eight degrees relative to its horizontal orientation with respect to a flat, horizontal ground surface, i.e. the horizontal central axis 203. The axis 211 extends along the longitudinal extension of each rotor blade 201, 202. The rotor blades 201 , 202 or their respective axes 211 are tilted away from the tower at a cone angle β of four degrees with respect to an axis 204 in the plane of rotation of the rotor or perpendicular to the central axis 200. In this case, the generator is driven to generate electric current.

[0080] As in Figure 1 As shown in FIG, at least one first acceleration sensor 310 is provided in the hub 103. The first acceleration sensor 310 is connected to an evaluation unit 330 via a signal line 300, which evaluates the measured signal. According to some embodiments, which can be combined with other embodiments, the first acceleration sensor 310 is a 6-DOF acceleration sensor, which measures acceleration and angular acceleration in three spatial directions, i.e. six degrees of freedom.

[0081] In addition, Figure 1 In the embodiment, a first blade load measuring system 410 comprising four strain sensors is arranged near the blade flange on the first rotor blade 201. Each strain sensor is designed as a fiber optic sensor. For the fiber optic strain sensors, the optical signal is transmitted to the evaluation unit 330 by means of an optical conductor 400, for example an optical fiber.

[0082] Figure 2 2 shows a schematic side view of a first rotor blade 201 according to an embodiment described herein. The length l of the rotor blade 201 extends from the blade flange 221 to the blade tip 231. Figure 2 Also shown in FIG. 1 is the center of gravity SP and its distance d from the blade flange of the rotor blade. sp .also, Figure 2 The first blade load measuring system 410 is shown at a distance d of 2% of the length of the rotor blade from the blade flange 221 . 410Positioning on the first rotor blade. The first blade load measuring system comprises four symmetrically arranged first planes e of the rotor blade cross section. 410 Due to the internal strain sensors, only the bending moment is required for adjustment.

[0083] Figure 3 A flow chart of a method 500 for aligning a first blade load measurement system 410 or its strain sensor according to the embodiments described herein is shown. When the rotor and thus the first rotor blade 201 rotate about the rotation axis 200, the first acceleration sensor 310 and the strain sensor of the first blade load measurement system 410 also undergo a corresponding rotational movement. Depending on the attitude of the first rotor blade 201, different accelerations, forces and moments act on the first rotor blade. For example, when the blade axis 211 of the first rotor blade 201 is oriented horizontally, i.e. orthogonally to the longitudinal axis of the tower 101, the first rotor blade is in a first attitude S1.

[0084] In a first step 501, the first acceleration sensor 310 measures a first acceleration in the first posture S1. The first acceleration sensor 310 is arranged in the rotating hub and is oriented so that the first acceleration sensor can measure the acceleration along the blade axis 211; optionally, the first acceleration sensor can measure the acceleration in three arbitrary, mutually orthogonal spatial directions, so that the acceleration in the blade axis direction 211 can be calculated; the acceleration is referred to below as the first acceleration measured in the z direction of the first rotor blade. The first acceleration sensor 310 can also measure two further accelerations orthogonal to the first acceleration measured in the z direction or can calculate it from acceleration measurements in multiple spatial directions; the acceleration is referred to below as the first acceleration measured in the y direction of the first rotor blade and the first acceleration measured in the x direction of the first rotor blade.

[0085] The gravity acceleration at the rotor blade is divided vectorially around the rotation axis 200 according to the cone angle, the tilt angle, the pitch angle and the rotor blade attitude. In the first attitude S1, the gravity acceleration in the z direction along the blade axis 211 is equal to zero and 9.81 m / s 2 The gravitational acceleration is divided into acceleration in the y direction and acceleration in the x direction only.

[0086] It is known from the production of the first, second and third rotor blades that the mass M of the rotor blade is 20,000 kg and that the centre of gravity SP is located at a distance d 20 m along the blade axis 211 of the rotor blade. sp Away from blade flange 221 .

[0087] In a second step 502, a first reference bending moment M of the first rotor blade 201 about the blade flange 221 as a load reference cross section is determined based on the measured first acceleration. B-1-加速度传感器 The first reference bending moment M of the first rotor blade B-1-加速度传感器 It is 3924kNm.

[0088] Likewise, the rotor blade is subjected to force and moment actions at a first plane of the rotor blade cross section in the first posture S1, which are detected by the strain sensors of the first blade load measurement system 410. In a third step 503, a measured first bending moment M of the first rotor blade 201 about the blade flange 221 as a load reference cross section is determined based on the measurements of the strain sensors and a first set of alignment parameters associated with the first blade load measurement system having a first initial alignment parameter value. B-1-应变传感器 In the present case, the measured first bending moment M for the first rotor blade B-1-应变传感器 Determined to be 3610kNm.

[0089] In the next step 504, the first reference bending moment M B-1-加速度传感器 The first bending moment M B-1-应变传感器 The comparison is performed in order to determine a first deviation A1. In the embodiment described, the first deviation A1 is 8%.

[0090] In the next step 505, the values ​​of the first tuning parameter set KP1 for the first blade load measurement system are adjusted based on the first deviation A1 so that the first deviation A1 is less than or equal to a threshold value. In the described embodiment, the threshold value S is 1%. B-l应变传感器 In this case, the first deviation A1 is 0.5% and thus smaller than the threshold value S, so that the tuning parameter values ​​of the tuning parameter set KP1 are selected to calibrate the first blade load measurement system or its strain sensor.

[0091] Figure 4 A flow chart of a method 600 for aligning a second blade load measurement system 420 according to an embodiment described herein is shown. A wind power plant has a second rotor blade 202, which is arranged at the hub at an angle offset W of 180° relative to the first rotor blade 201. In a first step 601, a second acceleration associated with the second rotor blade is determined based on a measured first acceleration 311 and an angular offset W between the first rotor blade and the second rotor blade. Thus, the measured first acceleration in the x-, y- and z-directions is converted into a second acceleration in the x-, y- and z-directions.

[0092] In a second step 602, a second reference bending moment M of the second rotor blade 202 is determined from the second acceleration.B-2-加速度传感器 The second reference bending moment M at the second rotor blade B-2-加速度传感器 The strain sensor of the second blade load measurement system 420 is located near the blade flange like the strain sensor of the first blade load measurement system 410 .

[0093] In a third step, a measured second bending moment M of the second rotor blade 202 about the load reference cross section, i.e. the blade flange 221 of the second rotor blade 202, is determined based on the measurements of the strain sensors of the second blade load measurement system 420 of the second rotor blade and a second set of alignment parameters associated with the second blade load measurement system 420 and having second initial alignment parameter values. B-2-应变传感器 .

[0094] In the present case, the second blade load measurement system determines a measured second bending moment M of the second rotor blade of −3010 kNm. B-2-应变传感器 .

[0095] In the next step 604, the second reference bending moment M of the second rotor blade is B-2-加速度传感器 The measured second bending moment M of the second rotor blade B-2-应变传感器 A comparison is made and a second deviation A2 is determined, which in the embodiment described is 23%.

[0096] In the next step 605, the values ​​of the tuning parameters of the second tuning parameter set KP2 for the second blade load measurement system 420 are adjusted based on the second deviation A2 so that the second deviation A2 is less than or equal to a threshold value of 1%. B-2-应变传感器 In the case of , the second deviation A2 is 0.9% and thus smaller than the threshold value S, so the tuning parameter values ​​of the second tuning parameter set KP2 are selected to calibrate the second blade load measurement system or its strain sensor at the second rotor blade.

[0097] Reference numerals list

[0098] 100 Wind power facilities

[0099] 101 Tower

[0100] 102 Pod

[0101] 103 Hub

[0102] 200 Rotor axis of rotation

[0103] 201 / 202 1st rotor blade / 2nd rotor blade

[0104] 203 Horizontal center axis of the pod

[0105] 204 Axis of the rotor in the plane of rotation

[0106] W is the angle between the rotor blades about the axis of rotation.

[0107] 211 Blade axis

[0108] 221 Blade flange

[0109] 231 Leaf Tip

[0110] l The length of the rotor blade from the blade flange to the blade tip

[0111] M is the mass of the rotor blades

[0112] SP Center of gravity of the rotor blade

[0113] d SP Distance of the center of gravity from the blade flange of the rotor blade

[0114] e 410 First plane of the rotor blade cross section of the first rotor blade

[0115] d 410 The distance between the first blade load measurement system 410 on the first rotor blade and the blade flange

[0116] S1 First attitude of the first rotor blade

[0117] 300 signal lines

[0118] 310 First acceleration sensor

[0119] 330 evaluation units

[0120] 400 Photoconductor

[0121] 410 First blade load measurement system with four strain sensors for a first rotor blade

[0122] 420 a second blade load measurement system having four strain sensors for a second rotor blade,

[0123] M B-1-加速度传感器 A first reference bending moment due to acceleration at the first rotor blade M B-2-加速度传感器 Second reference bending moment due to acceleration at the second rotor blade M B-1-应变传感器 A measured first bending moment based on a measurement value of at least one strain sensor of the first blade load measurement system and a first set of alignment parameters associated with the first blade load measurement system and having a first initial alignment parameter value

[0124] MB-2-应变传感器 A measured second bending moment based on a measurement value of at least one strain sensor of a second blade load measurement system and a second set of alignment parameters associated with the second blade load measurement system and having a second initial alignment parameter value

[0125] A1 / A2 First Deviation / Second Deviation

[0126] S Threshold

[0127] KP1 / KP2 First calibration parameter set / second calibration parameter set for the first blade load measurement system / second blade load measurement system for the first rotor blade / second rotor blade 500 Method for calibrating a first blade load measurement system having at least one strain sensor

[0128] 501 Measuring a first acceleration with the aid of a first acceleration sensor 502 Determine a first reference bending moment based on a measured first acceleration of a first rotor blade

[0129] 503 Determine a measured first bending moment based on a measurement value of at least one strain sensor of the first blade load measurement system and a first alignment parameter set associated with the first blade load measurement system and having a first initial alignment parameter value.

[0130] 504 Determine a first deviation between a first reference bending moment and a measured first bending moment 505 Adjust the tuning parameter value of the first tuning parameter set for the first blade load measurement system so that the first deviation is less than or equal to the threshold value

[0131] 600 Method for calibrating a second blade load measurement system having at least one strain sensor

[0132] 601 Determine a second acceleration associated with the second rotor blade based on the measured first acceleration and the angular offset between the first rotor blade and the second rotor blade 602 Determine a second reference bending moment based on a second acceleration of a second rotor blade 603 Determine a measured second bending moment based on a measurement value of at least one strain sensor of a second blade load measurement system and a second alignment parameter set associated with the second blade load measurement system and having second initial alignment parameters.

[0133] 604 Determine a second deviation between the second reference bending moment and the measured second bending moment 605 Adjust the calibration parameter value of the second calibration parameter set for the second blade load measurement system so that the second deviation is less than or equal to the threshold value

Claims

1. A computer-implemented method for calibrating a first blade load measurement system having at least one strain sensor at a first rotor blade of a wind power plant, the method comprising the following steps: a) measuring a first acceleration by means of a first acceleration sensor; b) determining a first reference bending moment and / or a first reference axial force based on the measured first acceleration; c) determining a measured first bending moment and / or a measured first axial force based on measurement values ​​of at least one strain sensor of the first blade load measurement system and a first set of alignment parameters associated with the first blade load measurement system and having first initial alignment parameter values; d) determining a first deviation of the first reference bending moment and / or the first reference axial force from the measured first bending moment and / or the measured first axial force; e) adjusting the values ​​of the first tuning parameter set for the first blade load measurement system so that the first deviation is less than or equal to a threshold value.

2. The computer-implemented method of claim 1, It is characterized in that The method comprises calibrating a second blade load measurement system having at least one strain sensor at a second rotor blade, the method comprising the following steps: a) determining a second acceleration associated with the second rotor blade based on the measured first acceleration taking into account an angular offset between the first rotor blade and the second rotor blade; b) determining a second reference bending moment and / or a second reference axial force based on the second acceleration; c) determining a measured second bending moment and / or a measured second axial force based on measurement values ​​of at least one strain sensor of the second blade load measurement system and a second set of alignment parameters associated with the second blade load measurement system and having second initial alignment parameters; d) determining a second deviation of the second reference bending moment and / or the second reference axial force from the measured second bending moment and / or the measured second axial force; e) adjusting the values ​​of the second tuning parameter set for the second blade load measurement system so that the second deviation is less than or equal to a threshold value.

3. A computer-implemented method according to claim 1 or 2, It is characterized in that Steps a) to d) are repeatedly performed, in particular at least 50 times, more particularly at least 100 times, more particularly at least 1000 times, more particularly at least 10000 times, and alternatively step e) the tuning parameter value is adjusted so that the first deviation or the second deviation detected in step d) is less than or equal to a threshold value, wherein a different pitch angle and / or a different acceleration is detected in each repetition.

4. A computer-implemented method according to any one of the preceding claims, It is characterized in that Prior to step a), a pitch angle is used and / or a defined pitch angle, in particular a different pitch angle, is set.

5. A computer-implemented method according to any one of the preceding claims, It is characterized in that When the wind speed exceeds the wind speed threshold, the first acceleration measured is discarded.

6. A computer-implemented method according to any one of the preceding claims, It is characterized in that The first acceleration sensor measures acceleration in at least one, in particular two, more particularly three spatial directions and / or is formed by an inertial measurement unit and / or an acceleration sensor, preferably two, more particularly three acceleration sensors, are arranged in the hub of the wind power plant.

7. A computer-implemented method according to any one of the preceding claims, It is characterized in that At least one strain sensor of the first or second blade load measuring system is arranged on the first or second rotor blade in a radial region of at most 50%, preferably at most 30%, of the length of the rotor blade starting from the blade flange.

8. A computer-implemented method according to any one of the preceding claims, It is characterized in that The calibration of the first blade load measurement system and / or the second blade load measurement system at the first rotor blade and / or the second rotor blade is carried out on site by a computing device at the wind power plant and / or by a remote computing device.

9. A device for calibrating a first blade load measuring system having at least one strain sensor at a first rotor blade of a wind power plant, the device comprising the following components: a unit for measuring acceleration, the unit for measuring acceleration being designed to measure a first acceleration by means of a first acceleration sensor; a unit for determining a bending moment and / or an axial force, the unit for determining a bending moment and / or an axial force being configured to determine a first reference bending moment and / or a first reference axial force based on a measured first acceleration and to determine a measured first bending moment and / or a measured first axial force based on a measurement value of at least one strain sensor of the first blade load measurement system and a first set of alignment parameters associated with the first blade load measurement system and having a first initial alignment parameter value; a unit for determining a deviation of a bending moment and an axial force, wherein the unit for determining a deviation of a bending moment and an axial force is designed to determine a first deviation of the first reference bending moment and / or the first reference axial force from the measured first bending moment and / or the measured first axial force; - A unit for adjusting the values ​​of tuning parameters of a tuning parameter set for a blade load measurement system, wherein the unit for adjusting the values ​​of tuning parameters of a tuning parameter set for a blade load measurement system is configured to adjust the values ​​of tuning parameters of the first tuning parameter set for the first blade load measurement system so that the first deviation is less than or equal to a threshold value.

10. The device according to claim 9, It is characterized in that The device is suitable for calibrating a second blade load measurement system having at least one strain sensor at a second rotor blade of a wind power plant, wherein the unit for measuring acceleration is designed to determine a second acceleration based on the measured first acceleration and taking into account an angular offset between the first rotor blade and the second rotor blade; - wherein the unit for determining a bending moment and / or an axial force is configured to determine a second reference bending moment and / or a second reference axial force based on the second acceleration and to determine a measured second bending moment and / or a measured second axial force based on measurement values ​​of at least one strain sensor of the second blade load measurement system and a second set of alignment parameters associated with the second blade load measurement system and having second initial alignment parameter values; - wherein the unit for determining the deviation of the bending moment and the axial force is configured to determine a second deviation of the second reference bending moment and / or the second reference axial force from the measured second bending moment and / or the measured second axial force; The unit for adjusting the values ​​of the tuning parameters of the tuning parameter set for the blade load measurement system is configured to adjust the values ​​of the tuning parameters of the second tuning parameter set for the second blade load measurement system such that the second deviation is smaller than or equal to a threshold value. 11 . The device according to claim 9 , further comprising a pitch angle utilization and / or setting unit in order to utilize the pitch angle and / or to set a defined pitch angle, in particular a different pitch angle.

12. The device according to any one of claims 9 to 11, further comprising a unit for discarding acceleration, wherein the unit for discarding acceleration is configured to compare the wind speed with a wind speed threshold, and when the wind speed is less than the wind speed threshold, select the measured first acceleration, and when the wind speed is greater than the wind speed threshold, discard the measured first acceleration.

13. A wind power facility, It is characterized in that A rotor is provided with a hub and rotor blades which extend radially from the hub, wherein the number of rotor blades includes at least one first rotor blade, and the wind power plant is provided with an apparatus according to any one of claims 9 to 12.

14. A computer-readable storage medium, the computer-readable storage medium comprising instructions, which, when executed by at least one processor, prompt the at least one processor to implement the method according to any one of claims 1 to 8.

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