Rotor blade with hub for wind turbines with measurement data and energy transmission arrangement and method for measurement data and energy transmission

Abstract

Rotor blade with hub (2) for wind turbines (3) with a measurement data and energy transmission arrangement (4), wherein: - at least one sensor unit (8) with at least one sensor (9) is fixed in the rotor blade (1), - at least one central unit (10) with at least one signal processing device (11) is arranged in the hub (2), - the central unit (10) and the sensor unit (8) are connected to each other via the measurement data and energy transmission arrangement (4), and - the measurement data and energy transmission arrangement (4) has at least one optical fiber (12), wherein the optical fiber (12) is arranged inside the rotor blade (1) and extends from the position (13) of the sensor unit (8) in the rotor blade (1) to the central unit (10) in the hub (2), characterized in that an energy converter (28) is provided in the sensor unit (8) to convert incoming light energy into electrical supply energy for the at least one sensor (9).

Description

The invention relates to a rotor blade with hub for wind turbines with a measurement data and energy transmission arrangement, and to a method for measurement data and energy transmission. A sensor unit with at least one sensor is fixed in the rotor blade, while a central unit with a signal processing device is arranged in the hub. The central unit and the sensor unit are connected via the measurement data and power transmission system. These sensors, located within the rotor blade, monitor wind turbines for damage, icing, cracks, and mechanical stresses. For example, the sensor can analyze natural vibrations and provide information about ice buildup, crack formation, and other damage such as delamination. The sensor inside the rotor blade is connected via an electrically conductive connection or a wireless link to a central unit located near the rotor hub. The central unit then transmits the signal, for example via Wi-Fi, to a nacelle, mast, or mast base of the wind turbine. However, the measurement data and power transmission systems used for the connection are particularly vulnerable to lightning strikes on wind turbines during thunderstorms due to the electrically conductive connections between the sensor unit and the central unit. This means that not only can damage occur to the turbine, rotor blades, and other components, but the sensors themselves, which are intended to quickly and reliably analyze any damage to the turbine, can also be affected. This is especially true because the strong electric and magnetic fields associated with lightning strikes and thunderstorms can couple into the sensor leads and destroy the sensor and / or the central unit. Even elaborate protective measures such as shielding do not offer complete protection against the unwanted coupling of such electric and magnetic fields.The installation of radio links from the transmitter unit to the central unit is also disadvantageous, since on the one hand an independent power supply is required for the sensor and on the other hand appropriate antennas must be provided for the radio link, which can also couple in electric and magnetic fields. Various optically operating sensors arranged in rotor blades are known from German patent applications DE 10 2005 017 716 A1, DE 10 2006 041 461 A1, and DE 10 2007 015 179 A1. According to patent application DE 10 2005 017 716 A1, the sensor has a free optical transmission path to detect the growth of deposits on the surface of the rotor blade. The other two patent applications use fiber-optic Bragg grating sensors, which can be used, for example, to perform strain and / or temperature measurements. In each case, a light emitter is arranged in the area of ​​the wind turbine hub, and the light it emits is guided to the sensor via an optical fiber in the blade. Light emitted by the sensor is also guided back to the hub via an optical fiber and evaluated there.Due to the purely optical operation of the sensors, the need for electrically conductive connections from the hub along the blade to the sensor is advantageously eliminated. However, purely optical sensors are only available for selected measurement applications. The object of the invention is to create a rotor blade with hub for wind turbines with a measurement data and energy transmission arrangement and to specify a method for measurement data and energy transmission, which also enables improved protection against electrical discharges from thunderclouds when using electrically operating sensors. The problem is solved by considering the subject matter of independent claims. Advantageous further developments arise from dependent claims. According to the invention, a rotor blade with a hub for wind turbines, including a measurement data and energy transmission arrangement, and a method for measurement data and energy transmission are provided. At least one sensor unit with at least one sensor is fixed in the rotor blade, while a central unit with a signal processing device is arranged in the hub. The central unit and the sensor unit are connected to each other via the measurement data and energy transmission arrangement. The measurement data and energy transmission arrangement includes at least one optical fiber, the optical fiber being arranged within the rotor blade and extending from the position of the sensor unit in the rotor blade to the central unit in the hub. An energy converter is provided in the sensor unit to convert incoming light energy into electrical supply energy for the at least one sensor. Since one or more optical fibers are provided for the measurement data and energy transmission arrangement, additional elements are provided in both the sensor unit and the central unit in the hub to convert the measurement data, which is usually present as mechanical or electrical measured values, into optical signals and also to create an energy transfer from the rotor hub to the rotor blade and then to the sensor unit without a conductive connection. Cost-effective standard optoelectronic components can be used for this purpose. The non-metallic connection between the sensor unit and the central unit provides increased safety for both the sensor unit and the central unit, as no electromagnetic waves or interference can be coupled into the measurement data and power transmission system. Furthermore, the sensor system remains intact even after a lightning strike to a wind turbine, allowing the inventive arrangement to detect damage such as delamination or cracking that may occur on the rotor blade after a lightning strike. In one embodiment of the invention, the measurement data and energy transmission arrangement comprises two optical fibers. A first optical fiber supplies energy to the sensor unit in the rotor blade, while a second optical fiber transmits measurement data in the form of modulated light signals to the central unit. These optical fibers can be routed inside the rotor blade, with the fibers being arranged in a wave-like pattern to compensate for thermomechanical stresses on the inner surface of the rotor blade. They can be fixed in place using clips or adhesive. Alternatively, the optical fibers can be laminated into the rotor blade, allowing for the connection of both the sensor unit and the central unit in the hub via optical connectors at the ends protruding from the laminate.For reasons of reliability and measurement data acquisition, a sensor position within the rotor blade is provided in the area of ​​the middle third of the rotor blade length. Instead of two optical fibers, a single optical fiber can also be used to connect the sensor unit and the central unit, with beam splitters at the ends of the optical fiber ensuring that the beam is divided into a power transmission section and a measurement data transmission section. This can at least reduce the material costs for installation within the rotor blade. As mentioned above, the central processing unit (CPU) requires additional components to transmit light energy to the sensor via the optical fiber and to receive, evaluate, and process optical signals. For this purpose, the CPU includes an optical energy source that feeds energy from a light source into the optical fiber via an optical coupling unit. The CPU may also include a modulation unit if parameters are to be transmitted from the CPU to the sensor unit. Such a light source can be a laser diode or a light-emitting diode (LED). Furthermore, the CPU preferably includes a photodiode that receives the optical signals of the sensor unit's measurement data via the optical fiber and transmits them to the processing unit as electrical signals.The processing unit can transform the signals into measurement data and transform the measurement data into radio signals for a WLAN connection to a central processing and evaluation unit, for example in a control unit in the nacelle, or in the mast or at the base of the wind turbine. The sensor unit also includes additional components, such as a photodiode or photocell, which converts the light energy supplied via the optical fiber into electrical energy. Therefore, the sensor unit includes a photodiode or photocell in addition to the sensor itself. Furthermore, the mechanical or electrical measured values ​​from the sensor unit must first be converted into optical signals before they can be transmitted as optical signals to the central unit via an optical fiber. In a first embodiment of the measurement data and energy transmission arrangement, the sensor unit has a light source, which can be a laser diode or a light-emitting diode, and whose light is modulated by a corresponding modulation unit and then fed into the optical fiber via a coupling optic. In this embodiment of the invention, however, the light source must be supplied with energy, which can be omitted in subsequent embodiments of the invention. In a further embodiment of the invention, the sensor unit comprises a reflector, wherein a beam splitter directs the first part of the incoming light to the energy transfer point and reflects a second part of the incoming light at the reflector. The reflected light is then modulated by a modulation unit and passed on to the coupling optics and fed to the central unit via the optical waveguide. This reflector eliminates the need for an additional light source in the sensor unit, which saves costs and reduces the energy consumption of the sensor unit. In a further embodiment of the invention, the sensor unit has a semi-transparent reflector that transmits part of the incoming light for power supply and reflects a second part. The reflected light is modulated by the modulation unit and fed into the optical waveguide via the coupling optics and supplied to the central unit. This measurement data and power transmission arrangement of this embodiment of the invention has the advantage that a beam splitter at the input of the sensor unit is not required. A method for transmitting measurement data and energy between a rotor blade and the hub of a wind turbine comprises the following steps. First, a light energy source is provided in a central unit located in the rotor blade hub. The light from the energy source is then modulated, if necessary, and coupled into an optical fiber to supply energy to a sensor in a sensor unit inside the rotor blade. Subsequently, the incoming light energy is converted into electrical energy in the sensor unit by means of an energy converter. Furthermore, electrical or mechanical measurement data from the sensor unit is transformed into optical signals, and a corresponding light source in the sensor unit is modulated by a modulation unit to transmit the measurement data as optical signals via the optical fiber to the central unit in the rotor hub.The optical signals are then received by the central unit and transformed into electrical signals using an energy converter such as a photodiode. Finally, the measurements are processed and the results are forwarded to a control unit located in a nacelle, mast, or mast base of the wind turbine. This method has the advantage that all measurement data and energy transmission between the sensor unit inside the rotor blade and the central unit in the hub area of ​​the rotor blade takes place via a fiber optic cable, so that electromagnetic interference cannot couple into the sensor unit and / or the central unit as well as into downstream control units, which allows the entire wind turbine to operate more reliably, especially since there is no longer any danger to the sensor unit or the central unit in the event of damage caused by lightning strikes and therefore any damage that occurs can be detected immediately and appropriate action can be taken to address it. Preferably, a photodiode or photocell is provided in the sensor unit, which can convert optical energy into electrical energy and thus power the sensor unit. The required light energy is coupled into the optical waveguide via a light source in the central unit and via a modulation unit and coupling optics, and received by the sensor unit. A laser diode or a light-emitting diode serves as the energy source, which is located in the central control unit. A laser diode or light-emitting diode is also used as a light source to transmit the measurement data from the sensor unit to the central unit. However, it is preferred that a portion of the light sent to the transmitter is coupled out by a beam splitter. The data can then be modulated back to the central unit using this portion of the light via a reflector and a modulation unit. A further improvement to the process is achieved by introducing a semi-transparent reflector, through which the energy transfer component is transmitted and a reflected component is modulated and supplied with measurement data via the optical fiber to the central unit. The invention will now be explained in more detail with reference to the accompanying figures. Fig. 1 shows a schematic view of a rotor blade with hub of a wind turbine with a measurement data and energy transmission arrangement according to a first embodiment of the invention; Fig. 2 shows a schematic diagram of a measurement data and energy transmission arrangement according to Fig. 1; Fig. 3 shows a schematic diagram of a measurement data and energy transmission arrangement according to a further embodiment of the invention; Fig. 4 shows a schematic diagram of a measurement data and energy transmission arrangement according to a further embodiment of the invention; Fig. 5 shows a schematic diagram of a measurement data and energy transmission arrangement according to a further embodiment of the invention. Fig. 1 shows a schematic view of a rotor blade 1 with hub 2 of a wind turbine 3 with a measurement data and energy transmission arrangement 4 according to a first embodiment of the invention. The rotor blade 1 is mechanically connected to the rotor hub 2 via a pitch angle adjustment mechanism 30. The hub 2 is held by a nacelle 27, the nacelle comprising at least one drive train, a generator, and a frequency converter. The nacelle 27 also includes a control and monitoring device 26. A sensor unit 8 is arranged inside the rotor blade 1 to monitor its functionality. The sensor unit 8 is preferably arranged in a position 13 in the middle third of the rotor length. A central unit 10 is arranged in the hub 2, which is connected to the drive train of the nacelle 27. The measurement data from the sensor unit are transmitted to the central unit via a measurement data and power transmission arrangement 4, which has optical fibers 12 as transmission lines. In this first embodiment of the invention, two optical fibers 12 are arranged inside the rotor blade 1, one of which supplies power to the sensor unit 8. The second optical fiber 12 optically transmits the measurement data from the sensor of the sensor unit 8 to the central unit 10 in the hub 2. Processed measurement data is then transmitted to the control and monitoring device 26 in the nacelle 27 via a WLAN connection 31. To protect the optical fibers from vibrations and thermal expansion of the rotor blade during operation, the optical fibers 12 are arranged in a wave-like pattern on the inside of the rotor blade 1.They can be clipped, glued, or even laminated into the rotor blade material. The corrugation protects the optical fibers from premature breakage under the tensile stress caused by vibrations and elongation of the rotor blade during operation. The control and monitoring device 26 can also be located in the mast 29 of the wind turbine 3 or in the mast base, which is not shown in detail here. Fig. 2 shows a detailed schematic diagram of a measurement data and energy transmission arrangement 4 according to Fig. 1. For the optical transmission of energy and measurement data, the central unit has additional components besides a signal processing unit 11, as does the sensor unit 8, which, in addition to the sensor 9, has further components for optical transmission. In this first embodiment of the invention, two optical waveguides 12 and 12' are provided between the central unit 10, which is arranged in the hub, and the sensor unit 8, which is arranged in the rotor blade and contains the sensor 9. The first optical waveguide 12 serves for power transmission, while the second optical waveguide 12' serves for measurement signal transmission. For power transmission, the central unit 10 has a light energy source 25, which here is implemented by a light-emitting diode 14, although it could also be a laser diode. The light from the LED 14 is fed into the optical waveguide 12 via a modulation unit 15 and a coupling optic. At the transition between the hub and the rotor blade, as shown in Fig. 1 with the pitch angle adjustment mechanism 30, a connector 16 is arranged in the area of ​​the optical waveguide 12 and another connector 17 in the area of ​​the optical waveguide 12'. These connectors 16 and 17 facilitate the mounting of the typically three rotor blades to the hub by providing a corresponding number of optical connectors on the central unit. Furthermore, the central unit has a photoreceiver in the form of a photodiode 19, which transforms optical signals coming from the sensor unit 8 via the optical waveguide 12' into electrical signals for the signal processing unit 11. The sensor unit 8 includes, as further components of the measurement data and energy transmission arrangement 4, a photodiode 20 or a photocell as an energy converter 28, which converts the light energy into electrical supply energy for the sensor 9. In addition, a light source 18 is provided in the sensor unit 8, which is implemented here by a light-emitting diode 21. The light from this light-emitting diode is modulated into optical signals by a modulation unit connected to the sensor 9, which are transmitted via the optical fiber 12' and via the optical connector 17 of the receiving photodiode 19. While this first embodiment uses two optical waveguides 12 and 12', the following figures use only a single optical waveguide 12 for transmitting the measurement data and the energy. Components with the same functions as in the preceding Figures 1 and 2 are designated with the same reference numerals in Figures 3, 4 to 5 and are not discussed separately. Fig. 3 shows a schematic diagram of a measurement data and energy transmission arrangement 5 of a further embodiment of the invention. The difference from the embodiment shown in Fig. 2 is that the measurement data and energy transmission arrangement 5 has only one optical fiber 12, which connects the sensor unit 8 inside the rotor to the central unit 10 inside the hub via an optical connector in the form of an optical fiber plug 16. For this purpose, a beam splitter 23 is additionally provided for both the sensor unit 8 and the central unit 10. This beam splitter 23 divides the light transferred in the optical fiber, or the light information contained therein, into an energy transmission component and a measurement data transmission component. The additional components, as already discussed for Fig. 2, remain unchanged in this second embodiment of the invention. Fig. 4 shows a schematic diagram of a measurement data and energy transmission arrangement 6 according to a further embodiment of the invention. This differs from the previous measurement data and energy transmission arrangement in that, instead of the light source in the sensor unit 8, only a reflector 22 is provided, which reflects the portion of the beam for measurement data transmission and modulates it via the modulation unit 15 and couples corresponding measurement data into the optical waveguide 12 via the coupling optics and the beam splitter 23. In this embodiment of the invention, an additional light source for supplying the measurement data modulation unit 15 is omitted. Fig. 5 shows a schematic diagram of a measurement data and energy transfer arrangement 7 according to a further embodiment of the invention. This differs from the previous embodiments in that the sensor unit 8 does not contain a beam splitter, but rather a partially transparent or semi-transparent reflector 24 that transmits the light energy for energy transfer and reflects a smaller portion of the light. This reflected portion is then modulated by the modulation unit 15 to modulate the sensor's measurement data and coupled into the optical waveguide 12 as optical signals. The central unit 10 has the same structure as shown in the preceding Figs. 3 and 4. Reference symbol list 1 Rotor blade 2 Hub 3 Wind turbine 4 Measurement data and energy transmission arrangement 5 Measurement data and energy transmission arrangement 6 Measurement data and energy transmission arrangement 7 Measurement data and energy transmission arrangement 8 Sensor unit 9 Sensor 10 Central processing unit 11 Signal processing unit 12 Fiber optic cable 13 Position of the sensor unit 14 Light-emitting diode or laser diode as energy source 15 Modulation unit (for measurement data) 16 Fiber optic connector 17 Fiber optic connector 18 Light source (sensor) 19 Photodiode (central processing unit) 20 Photodiode 21 Light-emitting diode (sensor) 22 Reflector 23 Beam splitter 24 Semi-transparent reflector 25 Energy source (central processing unit) 26 Control unit (nabulb) 27 Nabulb 28 Energy converter 29 Mast 30 Pitch angle adjustment mechanism 31 WLAN connection

Claims

Rotor blade with hub (2) for wind turbines (3) with a measurement data and energy transmission arrangement (4), wherein: - at least one sensor unit (8) with at least one sensor (9) is fixed in the rotor blade (1), - at least one central unit (10) with at least one signal processing device (11) is arranged in the hub (2), - the central unit (10) and the sensor unit (8) are connected to each other via the measurement data and energy transmission arrangement (4), and - the measurement data and energy transmission arrangement (4) has at least one optical fiber (12), wherein the optical fiber (12) is arranged inside the rotor blade (1) and extends from the position (13) of the sensor unit (8) in the rotor blade (1) to the central unit (10) in the hub (2), characterized in that an energy converter (28) is provided in the sensor unit (8) to convert incoming light energy into electrical supply energy for the at least one sensor (9). Rotor blade according to claim 1, characterized in that the measurement data and energy transmission arrangement (4) has two optical waveguides (12), wherein the sensor unit (8) in the rotor blade (1) is supplied with energy via a first optical waveguide (12) and measurement data in the form of light signals are transmitted via the second optical waveguide (12). Rotor blade according to claim 1 or claim 2, characterized in that the central unit (10) has a semiconductor laser or a light-emitting diode (14) as an energy source for the sensor unit (8). Rotor blade according to one of the preceding claims, characterized in that the central unit (10) has a modulation unit (15) and a coupling unit with an optical fiber connector (16) which feeds the energy of the light source (18) into the first optical fiber (12). Rotor blade according to one of the preceding claims, characterized in that the central unit (10) has a photodiode (1) or photocell which receives measurement data from the sensor unit (8) via the second optical fiber (12) and via an optical fiber connector (17) and transmits it to a signal processing unit (11). Rotor blade according to one of the preceding claims, characterized in that the sensor unit (8) has, in addition to a sensor (9), a photodiode (20) or a photocell which converts optical energy into electrical energy and supplies the sensor (9) of the sensor unit (8). Rotor blade according to one of the preceding claims, characterized in that the sensor unit (8) has, in addition to a sensor (9), a laser diode or a light-emitting diode (21) which feeds measurement data into the second optical waveguide (12) via a modulation unit (15) and a coupling optic. Rotor blade according to one of claims 1 or 3 to 7 characterized in that the measurement data and energy transmission arrangement (4) for energy transmission and measurement data transmission has a single optical waveguide (12) which is operated in multiplexing. Rotor blade according to claim 8 characterized in that the sensor unit (8) has a reflector (22) and a beam splitter (23), wherein the beam splitter (23) supplies a first part of the incoming light to the energy transfer and reflects a second part of the incoming light at the reflector (22) and supplies the reflected and modulated light via the single optical waveguide (12) to the central unit (10). Rotor blade according to one of the preceding claims, characterized in that the sensor unit (8) has a semi-transparent reflector (24) which allows part of the incoming light to pass through for energy supply and reflects a second part and supplies the reflected and modulated light by the modulation unit (15) to the central unit (10) via an optical fiber (12). A method for transmitting measurement data and energy between a rotor blade (1) and a hub (2) of a wind turbine (3), comprising the following process steps: - Providing an energy source (25) in a central unit (10) in the hub (2) of the rotor blade (1); - Coupling the light from the energy source (25) into an optical fiber (12) to supply energy to a sensor (9) in a sensor unit (8) inside the rotor blade (1); - Converting the incoming light energy into electrical energy in the sensor unit (8) by means of an energy converter (28); - Transforming electrical or mechanical measurement data from the sensor unit (8) into optical signals from a light source (18) by means of a modulation unit (15) of the sensor unit (8); - Sending the measurement data from the sensor (9) as optical signals via an optical fiber (12) to the central unit (10) in the rotor hub (2);- Receiving the optical signals in the central unit (10) and transforming them into electrical signals by means of an optoelectronic signal converter; - Processing the measurements and forwarding the results to a control unit (26) in a nacelle (27), a mast (29) or a mast base of the wind turbine (3).; Method according to claim 11, characterized in that the energy for supplying the sensor (9) is transmitted via a first optical waveguide (12) and the measurement data of the sensor (9) are transmitted via a second optical waveguide (12). Method according to claim 11 or 12, characterized in that the energy transmission and the measurement data transmission are transmitted via a single optical waveguide (12). Method according to one of claims 11 to 13, characterized in that a part of the light is transferred to a reflector (22) in the sensor unit (8) for energy transfer by means of a beam splitter (23) and this part of the light is modulated for the transmission of the measurement data and is transmitted to the central unit (10) via an optical waveguide (12). Method according to one of claims 11 to 13, characterized in that in the sensor unit (8) a semi-transparent reflector (24) allows a first part of the incoming light to pass through for energy supply and reflects a second part and modulates the reflected light with the measurement data and supplies it to the central unit (10) via an optical waveguide (12).

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