SENSOR ARRANGEMENT FOR A WIND TURBINE

Description

TECHNICAL AREA

[0001] The present invention relates to a sensor arrangement for use on a wind turbine, a wind turbine and a method for operating a wind turbine. STATE OF THE ART

[0002] Wind power is considered one of the cleanest, most environmentally friendly energy sources currently available. In this respect, wind turbines have garnered increasing attention. A wind turbine typically consists of a tower, at the top of which is a nacelle containing a rotor with a rotor hub and rotor blades, a generator, and a gearbox. The rotor blades capture the kinetic energy of the wind and transfer it, through rotational energy, to turn a shaft located in the nacelle that connects the rotor blades. This rotational energy is then transferred to a gearbox or, if no gearbox is used, directly to a generator. The generator then converts the mechanical energy into electrical energy, which can be fed into a power grid.

[0003] Wind turbines are controlled to maximize wind energy yield. If maximum (design) loads on components are exceeded, damage can occur, potentially leading to total failure. Since troubleshooting and repairs are extremely costly, especially for offshore installations, damage prevention and rapid analysis of component defects and damage to wind turbines are of paramount importance.

[0004] The condition of a rotor blade, including wear, material fatigue, and other changes that can occur due to aging or use, is the subject of condition monitoring for wind turbines. Knowing the condition allows for maintenance planning, an assessment of the current value of the turbine, and compliance with safety regulations and customer requirements.

[0005] A variety of sensors are used to monitor the operating conditions of wind turbines. For example, strain measurements can be taken to measure the bending of a rotor blade, acceleration measurements can be taken to measure the acceleration of a rotor blade, or other parameters can be measured.

[0006] From DE 10 2014 223 662 A1, a sensor arrangement for installation in a rotor blade of a wind turbine is known, in which sensor data acquired within a rotor blade are fused. The sensor arrangement comprises a pressure sensor and a multi-axis magnetic field sensor. The pressure sensor provides a pressure signal representing the internal pressure in the rotor blade. The multi-axis magnetic field sensor provides a magnetic field signal representing the direction of the Earth's magnetic field from the perspective of the rotor blade. The sensor arrangement is equipped with evaluation electronics for sensor data fusion from the sensors in the rotor blade.

[0007] The sensor arrangement mentioned above has the disadvantage, for example, that damage can only be detected inadequately or with a delay.

[0008] US 2013 / 0287567 A1 describes a wind turbine in which sensors are arranged on both the rotor blade and the tower. The sensor data are evaluated together to detect whether the rotor blade and the tower are bending in such a way that the rotor blade could come into contact with the tower. However, this technology does not provide damage detection for the wind turbine. US 2004 / 057828 A1 is another prior art document that discloses a sensor arrangement on a wind turbine.

[0009] In general, it is desirable to enable improvements in the monitoring of the sensors of a wind turbine and / or the wind turbine itself. SUMMARY OF THE INVENTION

[0010] The invention is based on the objective of providing a wind turbine or a method which enables improved damage detection or damage analysis.

[0011] The problem is solved by a wind turbine with the features of claim 1 or a method with the features of claim 7.

[0012] According to one embodiment, a wind turbine is provided with a sensor arrangement. The sensor arrangement for use on a wind turbine includes a rotor blade-related sensor, which is arranged in or on a rotor blade, and a non-rotor blade-related sensor. The sensor signals assigned to the rotor blade-related sensor are processed by fusion with the sensor signals assigned to the non-rotor blade-related sensor. The fusion of the sensor signals is performed depending on the operating state of the wind turbine's rotor blades. According to another embodiment, a method for operating a wind turbine is provided. The method includes acquiring the sensor data from the sensor arrangement and processing the sensor data. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Examples of implementation are shown in the drawings and explained in more detail in the following description. The drawings show: FIG. 1 a schematic representation of a wind turbine according to the embodiments described here; FIG. 2 a schematic representation of a part of a wind turbine with rotor blade-related and non-rotor blade-related sensors according to the embodiments described herein; FIG. 3 a block diagram of a sensor arrangement according to further embodiments described herein; and FIG. 4 A flowchart of a method for operating a wind turbine according to the embodiments described herein. WAYS TO IMPLEMENT THE INVENTION

[0014] The following section refers in detail to various embodiments of the invention, with one or more examples illustrated in the drawings.

[0015] Wind turbines can be monitored and controlled by sensors in or on the rotor blades (blade-related) and / or in other parts (non-blade-related), for example, in or on the rotor hub, in or on the tower, and in or on the nacelle. Blade-related sensors can be used to implement one or more of the following applications or measure parameters: individual blade pitch of a rotor blade, lift optimization of a rotor blade, load control of a rotor blade or the wind turbine, load measurement on a rotor blade or the turbine.At the wind turbine, this includes the condition assessment of wind turbine components, for example, the condition of a rotor blade, ice detection, component lifetime estimation (e.g., of a rotor blade), control based on wind fields, control based on rotor wake effects, control of the wind turbine based on loads, control of the wind turbine in relation to neighboring wind turbines, predictive maintenance, and imbalance detection. Sensors not related to the rotor blades, for example, in the rotor hub, can be used to derive the gravitational and centripetal forces acting on the rotor blades.

[0016] Embodiments of the present invention relate to a sensor arrangement for a wind turbine, comprising a combination of rotor blade-related and non-rotor blade-related sensors. The invention further relates to the processing of the sensor data by fusion. By fusing or combining rotor blade-based sensor data with non-rotor blade-based sensor data, improved monitoring of the wind turbine can be achieved. Furthermore, the fusion of the sensor data can provide a more comprehensive picture of the condition and operation of the wind turbine.

[0017] Fusion, as used herein, involves processing rotor blade-based sensor data, taking into account disturbances such as the rotor blade's position relative to gravity or rotor oscillation when using a non-rotor blade-based sensor in the rotor hub. Furthermore, events such as natural disasters (lightning, icing, storms, hail, flooding, etc.), calm winds, or bird strikes can be detected. If the method detects an event either through an analysis of the rotor blade-based sensor data or through an analysis of the non-rotor blade-based sensor data, the sensor data from the rotor blade-based sensors can be processed and fused with the sensor data from the non-rotor blade-based sensors.If the system detects a change in the wind turbine, such as blade or drivetrain condition, the non-rotor blade-related sensors can be used to classify the event. This allows for a damage analysis that better assesses the size, type, and / or location of the malfunctions.

[0018] FIG. 1 Figure 1 shows a wind turbine 100. The wind turbine 100 comprises a tower 102 and a nacelle 104. The rotor is attached to the nacelle 104. The rotor includes a rotor hub 106 to which the rotor blades 108 are attached with a blade root 116. According to typical embodiments, the rotor has at least two rotor blades, and in particular three rotor blades. The rotor blade 100 has a blade axis 122 along its longitudinal extent. The length 124 of the rotor blade extends from the blade root 116 to the blade tip 118. During operation of the wind turbine 100, the rotor, i.e., the rotor hub 106 with the rotor blades 108, rotates about an axis. This drives a generator to produce electricity. Furthermore, the wind turbine 100 includes several sensors designed for optical, electrical, and / or magnetic generation of the sensor signals.The sensors can capture rotor blade-related and non-rotor blade-related parameters, such as pressure, temperature, acceleration, oscillation, vibration, strain, etc. Rotor blade-related sensor data, as used here, does not necessarily mean that it is generated within the rotor blade, as is the case, for example, with generator vibrations. It is also possible, for instance, to distinguish ice buildup from structural damage. As in... FIG. 1 As shown, rotor blade-related sensors are provided in or on a rotor blade 108 or in or on several rotor blades. The rotor blade comprises several sensors 120, which form a sensor group 110. Non-rotor blade-related sensors are provided in or on one or more of the following structures: rotor hub, tower, nacelle. The sensors are connected to an evaluation unit 112 via a signal line or signal lines. The evaluation unit provides a signal to a control unit 114 of the wind turbine.

[0019] According to some embodiments, which can be combined with other embodiments, the rotor blade-related sensors are fiber optic strain and fiber optic vibration sensors. For fiber optic sensors, an optical signal is transmitted to the evaluation unit 112 via a light guide, for example, an optical fiber. In a fiber optic sensor, the actual sensor element is typically provided within an optical fiber, for example, in the form of a fiber Bragg grating.

[0020] FIG. 2 Figure 1 shows a section of a wind turbine 100, depicting sections of three rotor blades 108. Each rotor blade 108 is equipped with an arrangement of a first strain sensor 202, a second strain sensor 204, and a third strain sensor 206. Furthermore, according to the embodiments described herein, a first vibration sensor 208 and a second vibration sensor 210 are provided. These numerical values ​​are only examples. Suitable other numbers, such as four strain sensors or three vibration sensors, can also be used. The sensor signals are made available to the evaluation unit 112, for example, via signal lines.

[0021] Strain gauges are used to determine the blade loads. They can be mounted at the blade root 116 of the rotor blade 108. The vibration sensors 208, 210 can be mounted at a position approximately halfway along the length 124 of the rotor blade 108. According to some embodiments, the strain gauges 202, 204, 206 can be mounted at an axial distance (i.e., along the blade axis 122) from the blade root 116 of approximately 5 m or less. According to further embodiments, which can be combined with other embodiments described herein, the vibration sensors 208, 210 can be mounted within a range of ±5 m in the axial direction (along the blade axis 122) from the center of the rotor blade 108. According to further embodiments, the vibration sensors 208, 210 can be installed in an area that lies in a region extending from the center of the rotor blade 108 to the blade tip 118.

[0022] The blade loads on a wind turbine can be derived from the blade bending moments. The blade bending moment acting on rotor blade 108 can be calculated from the signals of strain sensors 202, 204, and 206. Blade bending moments generally represent an indirect measurement quantity in metrology. For blade load measurement, the blade loads are determined indirectly by measuring the blade strains. The measured strains represent the direct measurement quantity. The transfer function of the blade bending moments to the strain signals can be determined by calibrating the measuring system. By forming an inverse function, the blade bending moments can then be deduced from the measured strain signals.

[0023] The ratio of the bending moment to the deflection of the rotor blade is proportional to the stiffness of the rotor blade 108. The stiffness of the rotor blade material 108 can be considered a measure of the condition or strength of the rotor material. Strength decreases when individual fibers in a fiber-reinforced composite material break or the fiber bond delaminates. Therefore, in-situ measurement of the blade condition can be performed using the described setups and methods. This in-situ measurement allows for improved detection of aging, material fatigue, or similar conditions.

[0024] The use of three strain sensors 202, 204, and 206 provides redundancy and thus increased reliability against failures. Furthermore, temperature-compensated strain sensors, particularly temperature-compensated fiber optic strain sensors, can be used in the embodiments described here. Using temperature-compensated strain sensors minimizes the influence of temperature on the determination of blade bending moments. Fiber optic strain sensors also exhibit high peak and continuous load strength, enabling highly reliable blade bending moment determination.

[0025] According to the embodiments described here, a first vibration sensor 208 and a second vibration sensor 210 are located in the axial region (along the blade axis 122). Vibration sensors in the rotor blade 108 allow for the determination of blade vibrations and enable applications such as blade condition monitoring or ice detection. Alternatively, the vibration sensors 208 and 210 can also be arranged on the rotor blade 108 without being integrated into it. The use of fiber optic sensors enables reliable measurement of blade vibration without interference from electromagnetic fields or high electrical currents, such as those caused by lightning strikes. Fiber optic sensors can be provided without electrical components. This prevents a lightning strike from directly affecting electronic components and / or cables or signal cables for electronic components.

[0026] Sensor group 110 (in FIG. 1 The rotor blade-related sensors (as shown) comprising a first strain sensor 202, a second strain sensor 204, a third strain sensor 206, a first vibration sensor 208, and a second vibration sensor 210 are each provided in or on a rotor blade 108. The non-rotor blade-related sensors are provided in or on one or more parts of the wind turbine, such as the tower 212, rotor hub 214, or nacelle 216. In embodiments, the non-rotor blade-related sensors are provided on parts of the wind turbine that are different from the rotor blades 108. The signals from the rotor blade-related and non-rotor blade-related sensors are provided to the evaluation unit 112, for example, via signal lines. The evaluation unit delivers the sensor signals to a controller 114 (in FIG. 1 (shown) of the wind turbine.

[0027] The non-rotor blade-related sensors can be, for example, acceleration, acoustic emission, temperature, and / or vibration sensors.

[0028] It is possible to retrofit an existing wind turbine. For example, sensors already installed on an existing wind turbine can be used, and only the evaluation unit needs to be retrofitted.

[0029] By combining or fusing rotor blade-based sensor data with non-rotor blade-based sensor data, improved monitoring of the wind turbine can be achieved. Furthermore, fusing the sensor data can provide a better understanding of the condition and operation of the wind turbine, potentially leading to further applications.

[0030] FIG. 3 Figure 300 shows a block diagram of a sensor arrangement 200 according to an embodiment of the present invention. The sensor arrangement 200 can be used in conjunction with the [unclear text] in [unclear text]. FIG. 1 The illustrated wind turbine 100 is used. According to the present invention, the sensor arrangement 200 comprises rotor blade-related sensors 302 and non-rotor blade-related sensors 304. The rotor blade-related sensors 302 and the non-rotor blade-related sensors 304 are connected to the evaluation unit 112. The evaluation unit 112 is configured to process the sensor data by fusion. The rotor blade-related sensors 302 are arranged in a common sensor group 306. The non-rotor blade-related sensors 304 are arranged in another common sensor group 308.

[0031] According to the invention, the sensor group of rotor blade-related sensors comprises strain and vibration sensors. Monitoring a wind turbine includes measuring vibrations with two vibration sensors in two different spatial directions (in a Cartesian coordinate system) and measuring strains or blade bending moments in at least two, for example, three different spatial directions. In particular, the vibration measurement can include measuring frequency shifts of vibrations. Furthermore, the vibration measurement can be designed such that no measurement of absolute accelerations or measurements in frequency ranges takes place for the signals relevant for control and / or status determination. For control and / or status determination of the wind turbine, only a frequency shift is determined based on the vibration sensors.According to the embodiments described here, the signals are used for monitoring or control, in particular for one of the applications mentioned above. Typically, the strain is measured in three spatial directions (in a Cartesian coordinate system), so that a strain with any orientation in the plane of the leaf root can also be determined.

[0032] The non-rotor blade-related sensors 304, such as accelerometers in the rotor hub, can determine the gravitational force and the centripetal force acting on the hub or rotor blades.

[0033] According to some embodiments, which can be combined with other embodiments, the evaluation unit 112 includes a signal converter that generates a digital signal. The digital signal is then converted into an optical signal and transmitted. The digitized transmission directly after signal evaluation has the advantage that the digital optical signal is less susceptible to distortion effects, particularly during optical transmission and / or conversion, than, for example, an analog signal. Thus, higher measurement accuracy can be achieved.

[0034] FIG. 4Figure 400 shows a flowchart of a method 400 for operating a wind turbine according to embodiments of the present invention. The method 400 can utilize the sensor arrangement 200 and the wind turbine 100 according to the embodiments described herein. The method 400 comprises, in step 402, acquiring the sensor data determined by the sensor arrangement, and in step 404, processing the sensor data. In step 404 of the processing, the rotor blade-related sensor is calibrated. During the calibration of the measuring system (e.g., condition monitoring system or drive train), disturbances caused by the position of the rotor blade relative to gravity or by vibration of the entire rotor when using the non-rotor blade-related sensor in the rotor hub can be taken into account. Furthermore, in step 404 of the processing, an event such as natural forces (lightning strike, icing, storm, hail, flood, etc.) can be taken into account.The system can detect events such as calm winds or bird strikes. It can also detect very weak events, such as leading edge delamination (delamination at the rotor blade's leading edge). If the system detects an event based on either an analysis of rotor blade-based or non-rotor blade-based sensor data, the sensor data from the rotor blade-based sensors can be processed and fused with the sensor data from the non-rotor blade-based sensors. This allows the non-rotor blade-based sensor data to be used to validate the results of the analysis of the rotor blade-based sensor data. If the system detects a change in the wind turbine, such as a change in blade or drivetrain condition, the non-rotor blade-related sensors can be used to classify the event.If the method detects an event from an analysis or evaluation of the rotor blade-based sensor data, and the analysis or evaluation of the non-rotor blade-based sensor data does not detect the event, then the non-rotor blade-based sensor data can be used to validate the results from the analysis or evaluation of the rotor blade-based sensor data. This allows for a damage analysis in which the size, type, and / or location of the malfunctions can be better assessed.

[0035] Fusion is performed on a case-by-case basis. It depends on the operating conditions, such as rotor speed, temperature, ice accumulation, rotor blade pitch angle, etc. An upper threshold suitable for the procedure is defined. This upper threshold is a defined upper limit for the rotor speed, above which safe operation of the wind turbine is no longer permissible or possible. Fusion cannot be performed after this threshold is exceeded.

[0036] Although the present invention has been described above using typical embodiments, it is not limited to these but can be modified in many ways. Furthermore, the invention is not limited to the applications mentioned.

Claims

1. A wind turbine (100), comprising a sensor arrangement (200), comprising: a sensor group (110, 306) of rotor blade-related sensors (202, 204, 206, 208, 210, 302) which are arranged in or on a rotor blade and comprise strain and vibration sensors; and at least one not rotor blade-related sensor (212, 214, 216), wherein the sensor signals associated with the rotor blade-related sensors (202, 204, 206, 208, 210, 302) are processed through fusion with the sensor signals associated with the not rotor blade-related sensor (212, 214, 216), wherein the fusion of the sensor signals associated with the rotor blade-related sensors (202, 204, 206, 208, 210, 302) with the sensor signals associated with the not rotor blade-related sensor (212, 214, 216) is performed depending on the operating state of the rotor blades of the wind turbine (100), and characterised in that the fusion of the sensor signals associated with the rotor blade-related sensors (202, 204, 206, 208, 210, 302) with the sensor signals associated with the not rotor blade-related sensor (212, 214, 216) is not performed if the rotor speed exceeds an upper threshold value.

2. The wind turbine (100) according to claim 1, wherein the rotor blade-related sensor (202, 204, 206, 208, 210) and / or the not rotor blade-related sensor (212, 214, 216) are configured for optical, electric and / or magnetic generation of the sensor signals.

3. The wind turbine (100) according to any one of the preceding claims, wherein the rotor blade-related sensor (202, 204, 206, 208, 210) and / or the not rotor blade-related sensor (212, 214, 216) each provide a pressure, acceleration, temperature, oscillation, strain, ice quantity or noise emission signal.

4. The wind turbine (100) according to any one of the preceding claims, wherein the not rotor blade-related sensor is arranged in or on one or more of the following structures of the wind turbine (100): rotor hub, tower, nacelle.

5. The wind turbine (100) according to any one of the preceding claims, wherein the operating state of the rotor blades of the wind turbine (100) is the rotor speed, the temperature, the ice accumulation or the angle of attack of the rotor blades.

6. The wind turbine (100) according to any one of the preceding claims, having a control (114) for collecting and processing the sensor data determined by the sensor arrangement (200).

7. A method (400) for operating a wind turbine (100) according to any one of the claims 1 to 6, the method (400) comprising the following steps: collecting (402) the sensor data determined by the sensor arrangement; and processing (404) the sensor data.

8. The method (400) according to claim 7, where, in the step of processing (404), the rotor blade-related sensor is calibrated, wherein the not rotor blade-related sensor is taken into consideration for the calibration.

9. The method (400) according to claim 7 or 8, where, in the step of processing (404), an event, typically a lightning strike, is recognised.

10. The method (400) according to any one of claims 7 to 9, where, in the step of processing (404), the sensor data of the rotor blade-related sensor is processed with the sensor data of the not rotor blade-related sensor through fusion.

11. The method (400) according to any one of claims 7 to 10, where, in the step of processing (404), the sensor data of the rotor blade-related sensor is validated with the sensor data of the not rotor blade-related sensor.

12. The method (400) according to any one of claims 7 to 11, where, in the step of processing (404), the event is classified.