Condition Monitoring Device For A Lightning Protection System Of A Wind Turbine Blade

Abstract

A condition monitoring device for a lightning protection system (LPS) of a wind turbine blade, wherein the condition monitoring device is mountable to a wind turbine. The device includes, a signal generation unit configured to generate and input probe signals into a protection unit of the LPS and/or to at least one tower conducting unit. The device includes a measurement unit configured to detect response signals, which are a system response of the probe signals via a wireless coupling between the LPS and the tower conducting unit. A control unit is configured to control the signal unit and the measurement unit and to process the response signals.

Claims

1. A condition monitoring device for a lightning protection system (LPS) of a wind turbine blade, wherein the condition monitoring device is mountable to a wind turbine, the condition monitoring device comprising: a signal generation unit configured to generate and input probe signals into a protection unit of a lightning protection system (LPS) of a wind turbine blade and/or to a tower conducting unit (30); measurement unit configured to detect response signals, which are a system response of the probe signals via a wireless coupling between the lightning protection system (LPS) of the wind turbine blade and the tower conducting unit; and a control unit configured to control the signal unit and the measurement unit and to process the response signals.

2. The condition monitoring device according to claim 1, wherein the wireless coupling comprises a capacitive coupling between the lightning protection system (LPS) of the blade and the tower conducting unit.

3. The condition monitoring device according to claim 1, wherein the protection unit of the lightning protection system (LPS) comprises a down conductor.

4. The condition monitoring device according to claim 1, wherein the tower conducting unit is formed at least sectionally by an exterior of a tower of the wind turbine.

5. The condition monitoring device according to claim 1, wherein the signal generation unit comprises a signal induction device configured to inductively input the probe signals into a system comprising the protection unit and/or into the tower conducting unit.

6. The condition monitoring device according to claim 1, wherein the signal generation unit comprises a waveguide coupler configured to input the probe signals into the protection unit and/or into the tower conducting unit, and wherein the waveguide coupler is configured to limit overvoltage across the condition monitoring device.

7. The condition monitoring device according to claim 1, wherein the signal generation unit is configured to be galvanically connected to the protection unit and/or the tower conducting unit by a hard-wired connection comprising at least one protection device.

8. The condition monitoring device according to claim 1, wherein the measurement unit comprises an inductive measurement device configured to inductively detect the response signals at the protection unit and/or at the at least one tower conducting unit.

9. The condition monitoring device according to claim 1, wherein the measurement unit is configured to be galvanically connected to the protection unit and/or to the tower conducting unit by a hard-wired connection comprising at least one protection device.

10. The condition monitoring device according to claim 1, wherein the probe signals which can be generated by the signal generation unit, are AC signals.

11. The condition monitoring device according to claim 1, wherein the probe signals, which can be generated by the signal generation unit, are high frequency signals.

12. The condition monitoring device according to claim 1, wherein the condition monitoring device is configured to measure a system response every time a respective wind turbine blade, comprising the lightning protection system (LPS), is aligned with a tower (30).

13. The condition monitoring device according to claim 1, wherein the control unit is configured to communicate with a data storage and analyzing device.

14. A condition monitoring system for operation monitoring of a wind turbine comprising a condition monitoring device, wherein the condition monitoring device comprises: a signal generation unit configured to generate and input probe signals into a system comprising a protection unit of a lightning protection system (LPS) of a wind turbine blade and/or a tower conducting unit; a measurement unit configured to detect response signals, which are a system response of the probe signals via a capacitive coupling between the lightning protection system (LPS) of the wind turbine blade and the tower conducting unit; a control unit configured to control the signal unit and the measurement unit and to process the response signals; and a data storage and analyzing device that is configured to communicate with the control unit of the condition monitoring device in order to receive and store the probe signals and the response signals.

15. A wind turbine comprising: a wind turbine blade; and a condition monitoring device comprising: a signal generation unit configured to generate and input probe signals into a protection unit of a lightning protection system (LPS) of the wind turbine blade and/or to a tower conducting unit; a measurement unit configured to detect response signals, which are a system response of the probe signals via a wireless coupling between the lightning protection system (LPS) of the wind turbine blade and the tower conducting unit; and a control unit configured to control the signal unit and the measurement unit and to process the response signals.

16. The wind turbine according to claim 15, wherein the condition monitoring is arranged in the wind turbine blade of the wind turbine.

17. A method for an operation monitoring of a wind turbine by a condition monitoring device comprising: a signal generation unit configured to generate and input probe signals into a protection unit of a lightning protection system (LPS) of the wind turbine blade and/or to a tower conducting unit; a measurement unit configured to detect response signals, which are a system response of the probe signals via a wireless coupling between the lightning protection system (LPS) of the wind turbine blade and the tower conducting unit; and a control unit configured to control the signal unit and the measurement unit and to process the response signals, wherein the method comprises: generating a probe signal; inputting the probe signal into the protection unit of the lightning protection system (LPS) of the wind turbine blade and/or into the tower conducting unit; measuring a response signal which is a signal response of the probe signal via a wireless coupling between the lightning protection system (LPS) of the wind turbine blade and a tower.

18. The method according to claim 17, wherein the probe signal is an AC signal signals, in particular between 0 A and 5 A and/or 0 V and 50 V, and/or in a frequency range between 100 kHz to 10 GHz, preferably between 500 kHz to 5 GHz.

19. The method according to claim 17, further comprising storing and analyzing the probe signal and the response signal, wherein the analysis is preferably the wind turbine blade and/or the tower conducting unit.

20. The method according to claim 17, wherein the generating, the inputting, and the measuring are performed during operation of the wind turbine and/or wherein the inputting is performed every time the wind turbine blade is aligned with the tower.

21. A wind turbine comprising: a wind turbine blade; and a condition monitoring system comprising: a signal generation unit configured to generate and input probe signals into a system comprising a protection unit of a lightning protection system (LPS) of the wind turbine blade and/or a tower conducting unit; a measurement unit configured to detect response signals, which are a system response of the probe signals via a capacitive coupling between the lightning protection system (LPS) of the wind turbine blade and the tower conducting unit; a control unit configured to control the signal unit and the measurement unit and to process the response signals; and a data storage and analyzing device that is configured to communicate with the control unit of the condition monitoring device in order to receive and store the probe signals and the response signals.

Description

[0066] In the following, the invention is also described with respect to further details, features and advantages, which are explained in more detail with reference to the figures. The described features and combinations of features, as shown below in the figures and described with reference to the figures, are applicable not only in the respective combination indicated, but also in other combinations or in stand-alone manner, without thereby leaving the scope of the invention.

[0067] FIG. 1a shows a first example of an embodiment of a condition monitoring device according to the invention with hard-wired connections and a respective protection device;

[0068] FIG. 1b shows a second example of an embodiment of a condition monitoring device according to the invention comprising an inductive measurement device;

[0069] FIG. 1c shows a third example of an embodiment of a condition monitoring device according to the invention comprising a signal induction device;

[0070] FIG. 1d shows a fourth example of an embodiment of a condition monitoring device according to the invention comprising a signal induction device and an inductive measurement device;

[0071] FIG. 1e shows a fifth example of an embodiment of a condition monitoring device according to the invention comprising a waveguide coupler;

[0072] FIG. 2 shows an example of an embodiment of the waveguide coupler of FIG. 1e;

[0073] FIG. 3 an example a wind turbine blade comprising an example of a lightning protection system and an embodiment of a condition monitoring device according to the invention;

[0074] FIG. 4a a first example of a method for an operation monitoring of a wind turbine blade with condition monitoring device according to the invention, wherein the probe signal is injected into the lightning protection system of the blade;

[0075] FIG. 4b a second example of a method for an operation monitoring of a wind turbine blade with condition monitoring device according to the invention, wherein the probe signal is injected into the tower conducting unit;

[0076] FIG. 5 an example of an embodiment of a condition monitoring system for operation monitoring of a wind turbine according to the invention.

[0077] The figures are of a schematic nature only and are intended solely for the purpose of understanding the invention. Similar elements are provided with the same reference signs in the description of the examples of the embodiments.

[0078] In FIG. 1a to FIG. 1e examples of embodiments of a condition monitoring device 10 are shown. The condition monitoring device 10 according to FIG. 1a to FIG. 1e comprises a signal generation unit 11, a measurement unit 12 and a control unit 13.

[0079] The condition monitoring device 10 according to FIG. 1a to FIG. 1e comprises a housing, wherein the signal generation unit 11, the measurement unit 12 and the control unit 13 are arranged. Preferably, the housing (or the condition monitoring device per se) is roughly not larger than 20 cm20 cm20 cm, more preferably not larger than 10 cm10 cm10 cm.

[0080] The signal generation unit 11 is configured to generate and input (inject) probe signals S.sub.1 into a protection unit 23 of the lightning protection system LPS of the wind turbine blade 20 and/or into at least one tower conducting unit 30.

[0081] The measurement unit 12 is configured to detect response signals S.sub.2, which is the system response (impedance or reflection) by introducing the probe signals S.sub.1 in the path consisting of the lightning protection system LPS (or parts thereof) and/or the blade 20, the tower conducting unit 30 and the capacitive coupling between these components. Alternatively, the coupling could be realized by means of one or more antennas (e.g. in the blade) and one or more corresponding receivers (e.g. in the tower).

[0082] The control unit 13 is configured to control the signal generation unit 11 and the measurement unit 12. For example, the control unit 13 is configured to trigger the signal generation unit 11 in order to generate and output a probe signal S.sub.1 and/or to feed signal characteristics for the definition of a probe signal S.sub.1 to the signal generation unit 11.

[0083] Moreover, the control unit 13 is configured to process the response signals S.sub.2. In a possible embodiment, the response signals S.sub.2 may be processed (analyzed) directly in the control unit 13. Preferably, the control unit 13 is configured to communicate with a data storage device in order to submit the received response signals S.sub.2 to the data storage and analyzing device, where the response signals are stored and analyzed. Alternatively or additionally, the control unit 13 is configured to perform a pre-processing, in particular to filter out, e.g., erroneous response signals according to certain criteria (like amplitude, noise, etc.), in order to suppress processing of these signals.

[0084] For details of a corresponding lightning protection system LPS reference is made to FIG. 4 and for details on the coupling between the lightning protection system LPS and the tower conducting unit 30 reference is made to FIGS. 5a and 5b which are described later.

[0085] In FIG. 1a a first example of an embodiment of a condition monitoring device 10 is shown. According to FIG. 1a, the signal generation unit 11 and the measurement unit 12 are connected (or connectable) to a protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30 by a hard wired connection.

[0086] The condition monitoring device 10 comprises a protection unit 14 to protect the condition monitoring device 10 from a destructive current impulse generated, for example, during a lightning strike. In a possible embodiment, the protection unit 14 comprises at least one surge protection device.

[0087] FIG. 1b shows a second example of an embodiment of a condition monitoring device 10. In this embodiment, the measurement unit 12 comprises an inductive measurement device 12a configured to inductively detect the response signals S.sub.2 at the protection unit 23 and/or at least one tower conducting unit 30. With the inductive measurement device 12a a physical (hard wired) connection between the measurement unit 12 and the protection unit 23 of the lightning protection system LPS and/or the at least one tower conducting unit 30 is avoided, in order to protect the measurement unit 12 from a destructive current pulse generated, for example, during a lightning strike.

[0088] The signal generation unit 11 is connected or connectable to the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30 by a hard wired connection. For the connection of the signal generation unit 11 the condition monitoring device 10 comprises a protection unit 14, in particular at least one surge protection device (as in example of FIG. 1a).

[0089] In an alternative approach as shown in FIG. 1c, the condition monitoring device 10 comprises a signal induction device 11a.

[0090] With the signal induction device 11a, a physical (hard wired) connection between the signal generation unit 11 and the protection unit 23 of the lightning protection system LPS and/or the at least one tower conducting unit 30 is avoided, in order to protect the signal generation unit 11 from a destructive current pulse generated, for example, during a lightning strike.

[0091] According to the example shown in FIG. 1d, the condition monitoring device 10 comprises both, a signal induction device 11a and an inductive measurement device 12b. In this embodiment, the entire circuitry of the condition monitoring device 10 is not directly connected hard wired to the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30, so that a particularly high level of protection against destructive current pulses is provided.

[0092] A further embodiment of a condition monitoring device 10 is shown in FIG. 1e. The condition monitoring device 10 according to FIG. 1e comprises an inductive measurement device 12a as described above. However, in this embodiment, the condition monitoring device 10 comprises a waveguide coupler 11b. The signal generation unit 11 is configured to inject the probe pulses S1 to the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30 via this waveguide coupler 11b.

[0093] In the examples according to FIG. 1a to FIG. 1e, the signal generation unit 11, the measurement unit 12 and the control unit 13 are arranged in a common housing of the condition monitoring device 10. However, alternatively, the condition monitoring device 10 may comprise modular units. For example, the signal generation unit 11, the measurement unit 12 and the control device 13 may be separate modules of the condition monitoring device 10.

[0094] In addition, in the examples according to FIG. 1a to FIG. 1e, the protection unit 23 (e.g., the down conductor 23) is always connected on the left hand side and the tower conducting unit 30 always on the right hand side of the condition monitoring device 10. However a vice versa configuration is of course also possible, i.e. to connect the protection unit 23 (e.g., the down conductor 23) to the left hand side and the tower conducting unit 30 to the right hand side of the condition monitoring device 10.

[0095] An embodiment of the waveguide coupler 11b and its functional features are described in the following with reference to FIG. 2.

[0096] FIG. 2 shows a schematic cross section of a waveguide coupler 11b (as used in the condition monitoring device 10 of FIG. 1e).

[0097] The waveguide coupler 11b is used to convert probe signals S.sub.1 to the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30.

[0098] For this embodiment the probe signals are assumed to be radio frequency signals.

[0099] On the left of FIG. 2 the probe signal S1 is injected into the waveguide coupler 11b via a RF connector 61, e.g., via a coaxial cable. The shielding of the coaxial cable may be connected to a chassis 60 of the waveguide coupler 11b. The signal core of the coaxial cable may be connected to RF transition elements 62 arranged inside the waveguide coupler 11b. From a DC perspective the core and shield are connected together to the chassis 60 and ultimately to the chassis ground 65.

[0100] From an RF/Impulse perspective the transition elements 62 launch a transverse electromagnetic wave along the waveguide coupler 11b.

[0101] On the right hand side of the diagram, the transverse electromagnetic wave corresponding to the probe signal S.sub.1 hits the second transition elements 62 which convert the probe signal S.sub.1 back to an output cable 23,30, which may be the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30. Preferably, there is an insulator 63 provided between the waveguide coupler 11b and the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30.

[0102] Specific dimensions and geometry of the waveguide coupler 11b and of transitions elements 62 are dependent on the specific frequency of the input signal.

[0103] Because the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30 cable is directly connected to the second transition 62 on the right of the waveguide coupler 11b, an incoming destructive lightning current L is dumped into the waveguide chassis 60 which is in turn directly connected to the system chassis ground 65.

[0104] In a possible embodiment, the tower conducting unit 30 is connected downstream the system chassis ground 65.

[0105] The waveguide coupler 11b ensures that the lighting current path L is controlled and prevents potentially destructive current flow and subsequent voltage transients from adversely affecting the condition monitoring device 10.

[0106] In summary, this embodiment of the condition monitoring device 10 comprising the waveguide coupler 11b, provides an injection of the probe signal S.sub.1 in the protection unit 23 of the lightning protection system LPS and/or to at least one tower conducting unit 30 whilst providing protection to the injection circuit from the destructive lighting impulse current L.

[0107] In FIG. 3 an example of a wind turbine blade 20 comprising a lightning protection system LPS and a condition monitoring device 10 according to the invention is shown.

[0108] The condition monitoring device 10 is located inside the wind turbine blade 20 preferably close to the root-end of the blade and more preferably in proximity to the protection unit 23.

[0109] The lightning protection system LPS of the wind turbine blade 20 comprise protection units embedded in the structure of the blade 20. These protection units are routed inside the blade 20 and/or are integrated in the shell 21 of the blade 20. The lightning protection system LPS can be designed with several in parallel routed protection units. Furthermore, in case the blade is constructed with conductive Carbon Fiber Reinforced Polymers (CFRP) 22, these elements are also typically integrated into the LPS.

[0110] In the embodiment according to FIG. 3, the protection unit 23 of the lightning protection system LPS is configured as a down conductor 23.

[0111] The example of the lightning protection system LPS of the blade 20 as shown in FIG. 3 further comprises (but is not limited to) a tip receptor 25, two side receptors 26, two CFRP structural elements 22 and a plurality of respective electrical conductors 24 to the down conductor 23 as respective protection units.

[0112] In the shown example, the signal generation unit 11 and the measurement unit 12 of the condition monitoring device 10 are connected to the down conductor 23 of the lightning protection system LPS of the blade. A respective connection of condition monitoring device 10 to the down conductor 23 can relate to one of the embodiments as described with respect to FIGS. 1a to 1e.

[0113] The operation of the condition monitoring device 10 for monitoring a condition of the lightning protection system LPS of blade 20 as shown in FIG. 3 is described below with respect to FIG. 4a.

[0114] In the embodiment as shown in FIG. 4a, the condition monitoring device 10 is arranged inside a blade 20 as shown in FIG. 3. The wind turbine comprising said blade 20 comprises a tower 31.

[0115] The probe signal S.sub.1 is generated by the signal generation unit 11 and is injected into the down conductor 23 of the lightning protection system LPS of the blade 20.

[0116] Preferably high frequency AC pulses and/or repetitive signals with specific rise-times and in specific frequency ranges are injected as probe signals S.sub.1 into the down conductor 23 of the blade 20.

[0117] When the blade 20 is aligned with the tower 31, a capacitive coupling cc between lightning protection system LPS of the blade 20 and tower conducting unit 30 is a system response of the probe signals S.sub.1. Thereby a return-path for response signals S.sub.2 inside the blade is enabled, e.g. by resonance or reflectance of the probe signals S.sub.1 inside the lightning protection system LPS.

[0118] Preferably, the tower conducting unit 30 is formed at least sectionally by the exterior of the tower 31 of the wind turbine. In a possible embodiment, the exterior of the tower 31 comprises metal (in particular steel) and/or reinforced concrete, in order to enable a conduction of high frequency signals.

[0119] In a possible embodiment, the condition monitoring device 10 is configured to measure the system response every time the respective wind turbine blade 20, comprising the lightning protection system LPS, is aligned with the tower 31, providing a wireless (capacitive) coupling between the LPS (or parts of it) and tower conducting unit 30 and thereby enabling a return-path for the signal.

[0120] In an alternative possible embodiment, the probe signals S.sub.1 are injected continuously and a respective measurement of the response signal is (only) triggered when the respective blade is aligned with the tower.

[0121] The alignment of the tower and the blade may be determined by the response signals itself or by at least one accelerometer.

[0122] Depending on the impedance characteristics of the blade 20, the response signal S.sub.2 of the probe signal S.sub.1 will be recorded by the measurement unit 12.

[0123] Subsequently an analysis of the response signal S.sub.2 of the blade 20 is performed, and thereby the condition of the lightning protection system LPS of the blade is determined.

[0124] A corresponding signal processing of the response signals S.sub.2 (carried out by the control unit 13 and/or a data storage and analyzing device 50see FIG. 5) can rely on travelling wave and reflection theory, as well as resonance points.

[0125] Faults of the lightning protection system LPS to be detected therewith include, but are not limited to, complete disconnected conductors such as a disconnected down conductor 23, disconnection of lightning receptors 5,6 or expanded metal foil, change of impedance inside the blade, such as in specific conductors or equipotential bonding. Algorithms are designed to analyze the response signals S.sub.2 which provide the information where and when the fault occurred.

[0126] Furthermore, the response signal S.sub.2 may identify or predict a potential fault of the lightning protection system LPS of the blade 20 to occur in the future, based on slow changes in the impedance matrix of the lightning protection system LPS of the blade 20, which will cause the measurement responses (system response) to change.

[0127] Various algorithms are used to detect faults in the lightning protection system LPS and to locate a potential fault or a slowly degrading connection.

[0128] In addition, it is possible to generate a fingerprint signal for a specific blade and apply machine learning & artificial intelligence analysis methods to track significant changes in the response signals S.sub.2 and thereby mapping the changes in the conductive system of the blade 20. A fingerprint signal may e.g. refer to an initial signal measured at an initial installation. Significant changes from the original signature of the fingerprint signal (during a short time instance or during a long time change) can indicate different failure modes in the blade.

[0129] In FIG. 4b an alternative embodiment for an arrangement of the condition monitoring device 10 is shown.

[0130] In the embodiment as shown in FIG. 4b, one (single) condition monitoring device 10 is arranged inside the nacelle 32 of the wind turbine.

[0131] The probe signal S.sub.1 is generated by the signal generation unit 11 and is injected into the tower conducting unit 30.

[0132] Preferably, the tower conducting unit 30 is formed at least sectionally by the exterior of the tower 31 of the wind turbine. In a possible embodiment, the exterior of the tower 31 comprises metal (in particular steel) and/or reinforced concrete, in order to enable a conduction of high frequency signals.

[0133] Alternatively or additionally, the tower conducting unit 30 comprises a conductor such as a straight conductive element or a coaxial cable which is arranged at the exterior or inside the tower 31.

[0134] This enables to realize essentially the same features and properties regarding a status monitoring of the lightning protection system LPS as described in connection with FIG. 4a, except that here the signal path is directed in the opposite direction. Apart from the signal direction and the arrangement of the condition monitoring device 10 in the nacelle 32, the explanations described for FIG. 4a also apply to this embodiment according to FIG. 4b. The benefit being that we can have only one measurement system looking at three blades in turn.

[0135] In FIG. 5, a wind turbine comprising a condition monitoring system for operation monitoring is shown.

[0136] The condition monitoring system comprises in this example three condition monitoring devices 10, where each device 10 is arranged in a respective blade 20 of the wind turbine.

[0137] Each blade 20 comprises a lightning protection system LPS and the arrangement of the condition monitoring device 10 identical or similar to the one described with respect to FIG. 3.

[0138] Further, condition monitoring system comprises a remote data storage and analyzing device 50. The system is configured that the respective control units 13 of the condition monitoring devices 10 may communicate (exchange data) with the remote data storage and analyzing device 50.

[0139] Preferably the communication with the remote data storage and analyzing device 50 is a wireless communication.

[0140] In a possible embodiment, the data storage and analyzing device 50 is configured as a computer system or as part of a cloud computing system.

[0141] The data storage and analyzing device 50 is configured to perform a signal processing of the received response signals S.sub.2 as described in connection with respect to FIG. 4a.

[0142] It is also possible, that the data storage and analyzing device 50 is connected to a plurality of wind turbines (or their respective condition monitoring devices 10). Thus, the quantitative assessment of the condition of wind turbines with respective condition monitoring devices can be compared across a fleet of similar wind turbines, e.g., to provide OEMs a better understanding of the failure mechanisms.

[0143] In case of an occurring defect at the lightning protection system LPS of a wind turbine an operator can be informed immediately by the data storage and analyzing device 50, e.g. with the help of a sms, a corresponding app or the like.

[0144] In an alternative embodiment of the system described with respect to FIG. 5, the wind turbine comprises a single condition monitoring devices 10 in the nacelle 32 as described with respect to FIG. 4b.

REFERENCE SIGNS

[0145] 10 condition monitoring device [0146] 11 signal generation unit [0147] 11a signal induction device [0148] 11b waveguide coupler [0149] 12 measurement unit [0150] 13 control unit [0151] 20 blade [0152] 21 blade shell [0153] 22 CFRP structural elements connected to the protection unit [0154] 23 protection unit (down conductor) [0155] 24 electrical conductors [0156] 25 protection unit (tip receptor) [0157] 26 protection unit (side receptor) [0158] 30 tower conducting unit [0159] 31 tower [0160] 32 nacelle [0161] 50 (remote) data storage and analyzing device [0162] 60 waveguide chassis [0163] 61 RF connector [0164] 62 transition elements [0165] 63 insulator [0166] 65 chassis ground [0167] L destructive lighting impulse current [0168] S.sub.1 probe signal [0169] S.sub.2 response signal [0170] LPS lightning protection system [0171] cc capacitive coupling