WIND FARM OFFSHORE COMMUNICATION SYSTEM

Abstract

A wind farm offshore communication system of a gas producing offshore wind farm, wherein the offshore wind farm includes a pipe to transfer gas produced at the offshore wind farm. The offshore communication system includes a communication unit configured to transmit and/or receive an electrical communication signal; and a coupling device coupled to the communication unit. The coupling device is configured to receive the electrical communication signal from the communication unit and to couple a corresponding electromagnetic wave into the pipe. A frequency of the electromagnetic wave is configured to allow the electromagnetic wave to propagate within the pipe. The coupling device may be configured to intercept an electromagnetic wave propagating within the pipe and to provide a corresponding electrical communication signal to the communication unit.

Claims

1. A wind farm offshore communication system of a gas producing offshore wind farm, the offshore wind farm comprising a pipe to transfer gas produced at the offshore wind farm, the offshore communication system comprising: a communication unit configured to transmit and/or receive an electrical communication signal; and a coupling device coupled to the communication unit; wherein the coupling device is configured to receive the electrical communication signal from the communication unit and to couple a corresponding electromagnetic wave into the pipe; wherein a frequency of the electromagnetic wave is configured to allow the electromagnetic wave to propagate within the pipe; and/or wherein the coupling device is configured to intercept an electromagnetic wave propagating within the pipe and to provide a corresponding electrical communication signal to the communication unit.

2. The wind farm offshore communication system according to claim 1, wherein the coupling device comprises at least one of an antenna and a resonator.

3. The wind farm offshore communication system according to claim 1, wherein the pipe comprises a manifold for collecting gas from wind turbines of the offshore wind farm, further wherein the coupling device is configured to be installed downstream of the manifold in a flow direction of the gas.

4. The wind farm offshore communication system according to claim 1, wherein the pipe attenuates an electromagnetic wave propagating within the pipe at one or more attenuating frequencies, the frequency of the electromagnetic wave coupled by the coupling device into the pipe being selected to avoid the one or more attenuating frequencies.

5. The wind farm offshore communication system according to claim 4, wherein the communication unit is configured to perform a frequency scan to determine the one or more attenuating frequencies and is further configured to select the frequency of the electrical communication signal to avoid the one or more attenuating frequencies.

6. The wind farm offshore communication system according to claim 1, wherein the frequency of the electromagnetic wave radiated by the coupling device comprises at least one first frequency, and wherein the communication unit is configured to receive a communication signal corresponding to the electromagnetic wave intercepted by the coupling device at at least one second frequency, wherein the at least one first frequency is equal to the at least one second frequency, or wherein the at least one first frequency is different from the at least one second frequency.

7. The wind farm offshore communication system according to claim 6, wherein the at least one first frequency comprises a plurality of frequencies in a first frequency band and wherein the at least one second frequency comprises a plurality of frequencies in a second frequency band, wherein the first frequency band is different from the second frequency band.

8. The wind farm offshore communication system according to claim 1, further comprising a communication connection between the communication unit and an offshore communication distribution unit of the offshore wind farm.

9. The wind farm offshore communication system according to claim 8, wherein the communication connection comprises a wireless communication device, wherein the communication unit is coupled to the wireless communication device, and wherein the wireless communication device is configured to communicate with a second wireless communication device at the communication distribution unit using wireless communication.

10. The wind farm offshore communication system according to claim 8, wherein the communication connection comprises a fiber communication device, wherein the communication unit is coupled to the fiber communication device, and wherein the fiber communication device is configured to communicate with a second fiber communication device at the communication distribution unit using optical fiber communication.

11. The wind farm offshore communication system according to claim 1, wherein the communication unit is mounted to the pipe, is provided in a floating device, is arranged at an offshore communication distribution unit of the offshore wind farm, or is arranged at a wind turbine of the offshore wind farm.

12. The wind farm offshore communication system according to claim 1, wherein the coupling device comprises: an enclosure mounted to the pipe and covering a wall portion of the pipe, the enclosure enclosing a cavity; an electrical feed-through between the cavity and an interior space of the pipe; an electrical connection leading through the feedthrough; and an antenna arranged in the interior space of the pipe and electrically connected by the electrical connection.

13. A wind farm onshore communication system of an onshore station, the onshore station being configured to receive gas produced at a gas producing wind farm via a pipe, wherein the onshore communication system comprises: a communication unit configured to transmit and/or receive an electrical communication signal; and a coupling device coupled to the communication unit, wherein the coupling device is configured to receive the electrical communication signal from the communication unit and to couple a corresponding electromagnetic wave into the pipe; wherein a frequency of the electromagnetic wave is configured to allow the electromagnetic wave to propagate within the pipe; and/or wherein the coupling device is configured to intercept an electromagnetic wave propagating within the pipe and to provide a corresponding electrical communication signal to the communication unit.

14. A wind farm communication system configured to provide communication for a gas producing offshore wind farm, the offshore wind farm comprising a pipe to transfer gas produced at the offshore wind farm, wherein the wind farm communication system comprises at least one offshore communication system according to claim 1 arranged at the offshore wind farm, and further comprises: an onshore communication system arranged at an onshore station, the offshore wind farm being coupled to the onshore station via the pipe, and/or a second offshore communication system arranged at a second offshore wind farm, wherein the offshore wind farm and the second offshore wind farm are coupled via the pipe.

15. A communication method for a gas producing offshore wind farm, the offshore wind farm comprising a pipe to transfer gas produced at the offshore wind farm, wherein an offshore communication system of the offshore wind farm comprise a communication unit configured to transmit and/or receive an electrical communication signal; and a coupling device coupled to the communication unit, wherein the method comprises: receiving, by the coupling device, the electrical communication signal from the communication unit and coupling a corresponding electromagnetic wave into the pipe, wherein a frequency of the electromagnetic wave is selected to allow the electromagnetic wave to propagate within the pipe, and/or intercepting, by the coupling device, an electromagnetic wave propagating within the pipe and providing a corresponding electrical communication signal to the communication unit.

Description

BRIEF DESCRIPTION

[0045] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0046] FIG. 1 is a schematic drawing showing a wind farm, an onshore station and a communication system according to an embodiment;

[0047] FIG. 2 is a schematic drawing showing an offshore communication system according to an embodiment;

[0048] FIG. 3 is a schematic drawing illustrating a time series of communication signals used in a communication system according to an embodiment;

[0049] FIG. 4 is a schematic drawing illustrating frequencies used in a communication system according to an embodiment;

[0050] FIG. 5 is a schematic drawing illustrating frequencies used in a communication system according to an embodiment;

[0051] FIG. 6 is a schematic drawing illustrating frequencies and transmission channels used in a communication system according to an embodiment;

[0052] FIG. 7 is a schematic drawing illustrating attenuating frequencies of a pipe used in a communication system according to an embodiment;

[0053] FIG. 8 is a schematic drawing illustrating the selection of frequencies for transmitting the communication signal in the pipe according to an embodiment;

[0054] FIG. 9 is a schematic drawing illustrating an exemplary implementation of a coupling device according to an embodiment;

[0055] FIG. 10 is a schematic drawing illustrating an exemplary implementation of a communication connection and a communication unit according to an embodiment; and

[0056] FIG. 11 is a flow diagram illustrating a communication method according to an embodiment.

DETAILED DESCRIPTION

[0057] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of the embodiments is given only for the purpose of illustration and is not to be taken in a limiting sense. It should be noted that the drawings are to be regarded as being schematic representations only, and elements in the drawings are not necessarily to scale with each other. Rather, the representation of the various elements is chosen such that their function and general purpose become apparent to a person skilled in the art. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted.

[0058] FIG. 1 schematically illustrates a wind farm 100 that includes plural wind turbines producing gas, in particular hydrogen gas. It further shows an onshore station 200 and a pipe 70, in particular a gas export pipe, that connects the wind farm 100 to the onshore station 200 to transport hydrogen produced at the offshore WF to the onshore station. As illustrated, the offshore WF 100 may include plural collection pipes that collect the gas from the different wind turbines and respective manifolds by which the pipes are aggregated into the single transport pipe 70. In operation, produced hydrogen is compressed to a pressure of between 30 and 200 bar and is transported via pipe 70 to onshore station 200. Pipe 70 may include a steel wall and may in particular have a configuration allowing the transport of hydrogen.

[0059] FIG. 1 further illustrates a communication system 10 according to an embodiment, which includes in the present example the wind farm offshore communication system 20 and the onshore communication system 50. Offshore communication system 20 includes a communication unit 22 and a coupling device 21 by means of which an electrical communication signal is coupled into the pipe 70 or received from pipe 70 for providing communication with the onshore station 200. It further includes a communication connection 40 between the communication unit 22 and an offshore communication distribution unit 43, which may be configured to distribute communication, such as control commands, to the wind turbines 110 of WF 100, and/or to receive monitoring signals from the wind turbines 110 of WF 100. Communication distribution unit 43 may in particular provide communication with the other wind turbines using for example a SCADA network, wherein such communication may occur via fiber-optic connections or by line-of-sight communication (using for example any known wireless communication standard). The offshore communication distribution unit 43 may be arranged at a wind turbine 110 of WF 100, or may be arranged on a dedicated offshore platform, for example a control platform, a hydrogen production and/or storage platform or the like. It should be clear that although the offshore WF 100 of FIG. 1 illustrates hydrogen production at each wind turbine 110, other topologies are conceivable, for example providing electrical energy produced at each wind turbine to a common hydrogen production platform.

[0060] For effecting communication with the communication unit 22, the communication connection 40 may comprise a further communication unit 41 establishing a data link 42 with the unit 43. For example, communication unit 41 may be implemented as a wireless transmitter/receiver and establish a wireless communication link with the unit 43, each of the units 41, 43 comprising a respective antenna. Such link may for example work according to any of the known WLAN or other wireless standards. In another example, communication unit 41 may be implemented as a fiber communication unit and data link 42 may include an optical fiber connection, wherein a further fiber communication unit is implemented in unit 43. Other implementations are conceivable. Communication units 22 and 41 may be separate units and may connected via a cable; however, it is desirable that both units are implemented in the same device. For example, they may be provided on a floating platform. A cable connection, such as a coaxial cable, may be used to connect the communication unit 22 to coupling device 21.

[0061] This is illustrated in more detail in the implementation of FIG. 2, which shows coupling device 21 being connected by coaxial cable 31 to communication unit 22. The coupling device 21 includes a feed-through 27 to lead the electrical connection into the pipe 70 and an antenna 23 arranged inside the pipe. As mentioned above, resonators or other devices capable of receiving and transmitting electromagnetic radiation, in particular in the radio-frequency range, may be used in place of antenna 23. Further, absorbers and/or reflectors may be provided behind antenna 23 (i.e. the direction opposite to the direction in which the coupling device 51 of the other communication system 50 is located).

[0062] Turning back to FIG. 1, the wind farm onshore communication system 50 likewise includes a coupling device 51 and a communication unit 52, which is for example connected to a SCADA communication link or controller 55 via a communication connection 80. Communication connection 80 can be configured similarly to communication connection 40; however, since the communication unit 52 is generally located onshore, a simple cable connection may be desirable, or communication unit 52 may directly be integrated in the SCADA system 55.

[0063] Onshore communication system 50 may be configured similarly to offshore communication system 20. In particular, the coupling device 51 may include an antenna 53 and an electrical feed-through 28, as shown in FIG. 2. The above outlined other possible implementations of coupling device 21 also apply to the coupling device 51. It may likewise be connected by a coaxial cable 61 to the communication unit 52. Communication units 22, 52 may each include a transmitter and a receiver, or a transceiver. Accordingly, the transceiver or transmitter can generate a respective electrical communication signal at a desired frequency (or range of frequencies), which is provided to coupling device 21, 51, which couples the communication signal into pipe 70, and in particular converts the electrical signal to electromagnetic radiation that propagates within the pipe 70.

[0064] A flow diagram of a respective communication method is illustrated in FIG. 11. In step S10, at a first coupling device (e.g. 21), an electrical communication signal is received from the first communication unit 22, in particular via cable 31. In step S11, the coupling device 21 couples an electromagnetic wave (i.e. electromagnetic radiation) corresponding to the received electrical signal into pipe 70. The electromagnetic wave propagates within pipe 70 and is intercepted (or received) by the second coupling device 51 (step S12). By reception, it is transformed into an electrical signal that is, via cable 61, received at the second communication unit 52 (step S13). The communication system may likewise work the other way round, i.e. transmission of the radiation by coupling device 51 and reception by coupling device 21.

[0065] Without requiring an additional physical communication connection, for example via an optical fiber or electrical cable, communication between the offshore communication system 20 and the onshore communication system 50 is thus enabled. In particular, the onshore SCADA system 55 can communicate with the SCADA network connected to distribution unit 43 via the pipe 70, so respective monitoring and control data can be exchanged. In view of the robustness of pipe 70, such communication system provides improved robustness and is furthermore relatively simple and cost-efficient to implement. In particular, no subsea cable needs to be laid over several tens or even more than hundred kilometers.

[0066] FIGS. 1 and 2 exemplarily illustrate the communication between an offshore WF 100 and an onshore station 200. It should however be clear that the respective communication may also be carried out between two offshore communication systems 20, for example between two offshore WFs coupled by a respective pipe. Plural WFs 100 may for example be connected in a start connection via pipes 70 and connected to one or more onshore stations 200. In such topology, each WF 100 may communicate with each of the other WFs 100 and with the onshore station 200 via the respective communication system 10, in particular by providing an offshore communication system 20 at each WF 100 and an onshore communication system 50 at each onshore station 200. Communication is likewise possible if several wind farms feed into the same pipe (corresponding to a serial connection of wind farms), wherein the wind farms may communicate directly with each other if the range of the electromagnetic radiation is long enough, or an intermediate wind farm may relay the communication.

[0067] The coupling device 21 of the offshore communication system 20 is placed downstream (in the direction of gas flow) of the last manifold of wind farm 100, which may result in an improved quality of the transmitted signal, as the number of junctions it has to pass is reduced.

[0068] Turning back to FIG. 2, the communication unit 22 of the offshore communication system 20 may be arranged directly at a wind turbine 110 or a control/communication platform of the offshore WF 100, so that the coaxial cable 31 may extend to such wind turbine or control platform. In other implementations, unit 22 may be arranged on a floating platform, e.g. together with communication unit 41, or it may be mounted in a housing connected to pipe 70.

[0069] For effecting the communication explained above with respect to FIGS. 2 and 11, communication unit 22 (and 52) may use the same frequency or frequencies for transmission and reception. Accordingly, as only one of the communication units 22, 52 can transmit at any time, a time division multiplexing scheme, as illustrated in FIG. 3, may be employed. Offshore communication unit 20 may transmit in time slots 1 and onshore communication unit 50 may transmit in time slots 2. Half duplex communication may thereby be enabled.

[0070] In another example, the offshore communication unit 20 may transmit at a first frequency f.sub.1 and receive at a second frequency f.sub.2 different from f.sub.1. The onshore communication unit 50 may then transmit at frequency f.sub.2 and receive at frequency f.sub.1, as illustrated in FIG. 4. Using different frequencies for communication, a full duplex communication may be achieved in which both, onshore and offshore communication units may transmit and receive at the same time.

[0071] Another possible implementation is illustrated in FIG. 5, wherein the transmitter Tx1 at the WF offshore communication system 20 transmits at plural frequencies within a first frequency range 91 and the transmitter Tx2 at the onshore communication system 50 transmits at plural frequencies within a second frequency range 92. As shown in FIG. 6, the receiver of the respective communication system 20, 50 may then receive in the respective other frequency range. Receiver Rx1 of offshore communication system 20 receives in the second frequency range 92 whereas the receiver Rx2 at the onshore communication system 50 receives in the first frequency range 91. By using frequency ranges, multiple communication channels may thus be established, and the communication bandwidth may be increased. Furthermore, communication over extended ranges may be possible, since a smearing out of the frequencies when communicating over longer ranges may have only a reduced effect on the quality of communication (for example when using two or more frequencies for transmitting the same communication signal).

[0072] Although two frequency ranges 91, 92 are illustrated in FIGS. 5 and 6, it should be clear that further frequency ranges may be employed, and that they may be narrower or wider, for example by using plural narrow frequency ranges alternatingly by the first and the second communication system 20, 50. It should be clear that the transmitter or transceiver at the respective communication unit 22, 52 generates a respective electrical communication signal, which is then converted into electromagnetic radiation at the respective frequency by the respective coupling device 21, 51. Further, although the description above and further below refers to an onshore communication system 50, it should be clear that two offshore communication systems 20 may communicate in a similar fashion. Furthermore, if more than two communication systems 20, 50 communicate, further frequency ranges may be employed to allow communication between each of these systems at the same time. A particular advantage is that the pipe 70 is a closed system, which essentially corresponds to a Faraday cage, so that electromagnetic radiation does hardly penetrate through the walls of the pipe. Accordingly, the frequency ranges can be chosen quite freely for communication, since the communication will not be in conflict with the existing standards for radio-communication.

[0073] Pipe 70 may attenuate a propagating electromagnetic wave at certain frequencies, which is illustrated in FIG. 7. These attenuating frequencies 94, at which the propagating wave is damped more than at other frequencies, may depend on the geometry of the pipe and the particular configuration. The attenuating frequencies 94 further depend on the distance between the receiver and the transmitter (i.e. the length of the pipe therebetween). The frequencies 94 at which such higher attenuation occurs may be determined upfront, for example in a calibration procedure. In other implementations, one or more communication units 22, 52 may be configured to perform a frequency sweep (i.e. changing the transmitting frequency over a predetermined frequency range) to determine the transmission characteristic of the pipe 70 and in particular the location of attenuating frequencies 94. The respective other communication unit may for example measure the signal strength in dependence on the received frequency.

[0074] As illustrated in FIG. 8, the one or more frequencies used for communication by the communication system 20, 50 may be adjusted so as to avoid the attenuating frequencies 94, in particular so as to lie at frequencies different from the attenuating frequencies 94. The left-hand part of FIG. 8 illustrates a situation in which the first frequency f.sub.1 lies in a range experiencing normal attenuation, whereas frequency f.sub.2 lies at or close to an attenuating frequency. The communication unit 22, 52 is configured to adjust the frequency used for transmission such that it is shifted away from the attenuating frequency 94, i.e. such that is lies within a frequency range at which the radiation experiences normal attenuation in the pipe. The frequency may in particular be moved such that attenuation is minimal and that the amplitude at which the transmitted signal is received is maximized. The respective frequency tuning may occur in cooperation between the communication units 22, 52. Communication between the offshore communication system 20 and the onshore communication system 50 can thus be tuned and fine-tuned to achieve optimal signal transmission and bandwidth (or correspondingly, of two offshore communication systems 20).

[0075] Although FIG. 8 illustrates representative frequencies f.sub.1, f.sub.2, it should be clear that each of these may refer to a frequency band including plural transmission frequencies. The used frequency bands can thus efficiently be shifted out of the notches in the transmission spectrum at which high attenuation exists.

[0076] FIG. 9 schematically illustrates a further possible implementation of the coupling device 21. A housing 24, such as a subsea enclosure, is provided and attached to the pipe 70 and provides an inner cavity 25. The electrical connection to the communication unit 22 is fed into the cavity 25 via the electrical through connection 29. In cavity 25, it is connected to antenna 23. The electrical feed-through 27 has an antenna 26 connected at one side inside cavity 25 and a second antenna 28 connected inside pipe 70. In cavity 25, electromagnetic coupling takes place between antenna 23 and antenna 26, as illustrated by the arrow. The communication signal is then coupled into pipe 70 via antenna 28. Should a leakage exist via the electrical feed-through 27, the leaked gas will be collected in cavity 25. Increased safety may thus be achieved, for example in hazardous environments. In other implementations, an electrical connection may be provided between the electrical feed-through 27 and the electrical through connection 29 (i.e. antennas 23 and 26 may not be present). Such configurations likewise achieves an increase in safety, whereas the configuration of FIG. 9 additionally avoids that gas creeps through insulation of such electrical connection.

[0077] The electrical feed-through 27 of FIGS. 2 and 9 may for example be implemented as a penetrator that is capable of withstanding a predefined pressure difference which may exist between the inside of pipe 70 and the outside, e.g. surrounding seawater or cavity 25.

[0078] FIG. 10 illustrates a particular example in which the communication connection 40 employs optical fiber communication via the optical fiber 48. Optical fiber 48 may be used to transmit both, data communication and optical power. The communication unit 41 of the communication link 40 may for example include a fiber communication device 44. An optical transmitter/receiver 45 receives and/or transmits an optical communication signal via optical fiber 48 and provides a corresponding electrical communication signal to the communication unit 22. Furthermore, light at one or more wavelengths provided to supply power may be taken out of the optical fiber 48 and may be supplied to a photo cell 46, as illustrated in FIG. 10. Photo cell 46 provides respective electrical power for powering the communication unit 22. A converter 47 may be provided for converting the electrical power generated by photo cell 46 to the required voltage level. The optical communication unit 44 and the communication unit 22 may for example be provided on the same floating platform 35.

[0079] It is again noted that other configurations are conceivable, for example providing a wireless communication unit instead of optical communication unit 45 and providing an electrical power cable or solar panel for powering such wireless communication unit and the communication unit 22.

[0080] It should further be clear that each coupling device 21, 51 may include plural antennas, for example different receiving and transmitting antennas adapted to the respective frequency or frequency range. For transmission through pipe 70, a lower cutoff frequency generally exits. In an embodiment, the transmission mode is chosen that has the lowest cutoff frequency. This may for example be the TE11 mode. The frequency of transmission may for example lie within a range of 10 kHz to 5 GHz, desirably between 1 MHz and 2 GHz. For example, for a pipe of radius 0.5 m, the cutoff frequency for the TE11 mode may lie at about 176 MHz. Accordingly, a frequency above this cutoff frequency may be chosen. As indicated above, the frequency may be chosen so as to avoid the attenuating frequencies 94. In particular, the frequency may also be chosen such that only single mode propagation exists in the pipe within the respective frequency range. For the TE11 mode, single mode propagation may for example be achieved if the frequency is chosen such that the wavelength of the electromagnetic wave lies within a range of 2.6 a<λ<3.4a, wherein a designates the pipe radius. The pipe may generally have a radius between about 0.3 m and 2 m.

[0081] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0082] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.