Underground Layable Power Cable, In Particular, a Submarine Cable

Abstract

An underground layable power cable, in particular a submarine cable, having at least one phase conductor and at least one optical fiber conductor. The optical fiber conductor is integrated in the phase conductor. The optical fiber conductor may include at least one optical fiber. Further, the optical fiber may be surrounded by at least one protective layer, which may be formed from a plastic-gel combination. The gel may at least one of a silicone gel, a glass fiber material, or a carbon fiber material.

Claims

1. An underground layable power cable, wherein the power cable is a submarine cable, and wherein the power cable is a medium voltage cable or a high voltage cable, comprising at least one phase conductor, and at least one optical fiber conductor formed as a temperature sensor, wherein the optical fiber conductor is integrated in the phase conductor, wherein the optical fiber conductor comprises at least one optical fiber, wherein the optical fiber is surrounded by at least one protective layer, wherein the protective layer is formed from a plastic-gel combination, wherein the gel is a silicone gel, and/or a glass fiber material and/or a carbon fiber material.

2. The power cable according to claim 1, wherein the phase conductor comprises a substantially circular cross-section and the optical fiber conductor is arranged in the center of the phase conductor.

3. The power cable of claim 1, wherein the phase conductor is a phase conductor selected from the group consisting of: a segment manager with at least two segments, a stranded phase conductor, a pressed phase conductor, a profiled phase conductor, and a compressed phase conductor.

4. The power cable according to claim 1, wherein the optical fiber is surrounded by at least one protective layer in form of a protective tube.

5. The power cable according claim 1, wherein the protective layer is formed from a plastic-gel combination and the plastic material is high density polyethylene.

6. The power cable according to claim 1, wherein the diameter of the protective layer is between 0.5 mm and 5 mm.

7. The power cable according to claim 6, wherein the diameter of the protective layer is between 1 mm and 2.5 mm.

8. The power cable according to claim 1, wherein the power cable comprises three phase conductors and an optical fiber conductor is integrated in each of the three phase conductors.

9. A method for manufacturing a power cable according to claim 1, comprising: providing an optical fiber conductor, and enclosing the optical fiber conductor with at least two phase conductor elements of a phase conductor, such that a phase conductor with an integrated optical fiber conductor is manufactured.

10. An offshore wind energy system, comprising: a first offshore device and at least one further offshore device, wherein the first offshore device is electrically connected to the further offshore device by at least one power cable according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1 is a schematic view of a power cable according to the state of the art,

[0050] FIG. 2 is a schematic view of an embodiment of a power cable according to the present application,

[0051] FIG. 3 is a schematic view of a further embodiment of a power cable according to the present application,

[0052] FIG. 4 is a schematic view of a further embodiment of a power cable according to the present application,

[0053] FIG. 5 is a schematic view of a further embodiment of a power cable according to the present application,

[0054] FIG. 6 is a schematic view of a further embodiment of a power cable according to the present application,

[0055] FIG. 7 is a schematic view of a further embodiment of a power cable according to the present application,

[0056] FIG. 8 is a schematic view of a further embodiment of a power cable according to the present application,

[0057] FIG. 9 is a diagram of an embodiment of a method according to the present application, and

[0058] FIG. 10 is a schematic view of a further embodiment of a power cable according to the present application.

DETAILED DESCRIPTION

[0059] In the figures, the similar reference signs are used for same elements.

[0060] FIG. 2 shows a schematic view of an embodiment of a power cable 200 according to the present application. The illustrated underground layable power cable 200 may, in particular, be a submarine power cable 200. Preferably the power cable 200 is a medium voltage cable or a high voltage cable. For example, the submarine power cable 200 may be laid between a first (not shown) offshore device and a further (not shown) offshore device.

[0061] The power cable 200 comprises at least one phase conductor 202, which is formed by two phase conductor elements 214 in the form of two phase conductor segments 214.

[0062] As can be seen, an optical fiber conductor 210 is integrated in the phase conductor 202. The phase conductor 202 preferably has an essentially circular cross-section. The optical fiber conductor 210 is arranged, in particular, in the center of the phase conductor. In other words, the optical fiber conductor 210 in the phase conductor 202 runs through the middle or central axis of the phase conductor.

[0063] By means of a fiber optical temperature measurement, in particular, temperature changes in a power cable 200 can be determined via optical fiber conductor. One or more optical fiber(s) is/are used as sensors, which allow an exact local assignment of the temperature and reflect changes in temperature and pressure on the fiber. Due to the physical changes at the points where the temperature rises or the pressure on the fiber changes, reflections occur which contain components of different wavelengths in their backscattering. These scatterings can be roughly divided into Rayleigh scattering, Ramann scattering and Brillouin scattering. While Rayleigh scattering is not temperature dependent, Ramann and Brillouin scattering are temperature dependent scatterings which, unlike Rayleigh scattering, are spectrally shifted (so-called Stoke and Anti Stoke bands). Anti-Stoke bands are even more temperature dependent and are therefore preferably used for temperature measurements.

[0064] The at least one fiber optical conductor 210 installed in the power cable 200 can be led in a ring connection (or with open end) to a corresponding (not shown) temperature measuring facility.

[0065] By integrating at least one optical fiber 210 directly in the phase conductor 202, the actual temperature, i.e. in particular the maximum temperature of the power cable 200, can be measured. In particular, this can be done independently of the type of cable and/or ambient conditions. If necessary, it may be necessary to consider an optional protective coating when determining the actual cable temperature.

[0066] As an example, the power cable 200 has an (electrical) insulation layer 204 around the phase conductor 202, a shielding layer 206 (e.g. of copper) and an outer cable sheath 208. Furthermore, (not shown) filling material may be provided to compensate unevenness if necessary. Between the phase conductor 202 and the insulating layer 204 an inner (not shown) semiconductor layer may be provided. In addition, an outer (not shown) semiconductor layer may be arranged between the insulating layer 204 and the shielding layer 206. The outer sheath 208 may contain steel wires that can absorb the tensile forces during installation and/or operation. In this way the submarine cable 200 can be protected from damages.

[0067] It shall be understood that according to other variants of a power cable according to the application, other layer orders may be provided as long as the at least one optical fiber conductor is integrated in the at least one phase conductor.

[0068] FIGS. 3 to 7 show schematic views of various embodiments of power cables with different (exemplary) types of phase conductors 302 to 702, but it should be noted that for a better overview only the phase conductors are shown. It goes without saying that a power cable as shown in FIGS. 3 to 7 may have further layers, such as insulating layer, shielding layer, inner and outer semi-conducting layer, outer sheath, filling material etc., in accordance with the explanations in FIG. 2

[0069] FIG. 3 shows a stranded phase conductor 302. The optical fiber conductor 310 arranged in the central axis of the phase conductor 302 is surrounded, and in particular, wrapped, by a large number of phase conductor elements 314 in the form of stranded conductors 314.

[0070] In addition, FIG. 4 shows a pressed and compressed, respectively, phase conductor 402 (also called compressed round conductor). A plurality of phase conductor elements 414 can surround the at least one optical fiber conductor 410 in a compressed form.

[0071] FIG. 5 shows a profiled phase conductor 502 (also called profiled conductor), in which a large number of profiled phase conductor elements 514 are wound around at least one optical fiber conductor 510.

[0072] As can be seen in FIG. 6, a phase conductor 602 can be formed as a segment conductor 602 (also called a segmented conductor). Such a segmented conductor 602 can comprise at least two phase conductor elements 614 in the form of segments 614. Six segments 614 are provided, which surround the at least one optical fiber conductor 610.

[0073] FIG. 7 shows a compacted conductor 702 with a plurality of phase conductor elements 714 surrounding at least one optical fiber conductor 710.

[0074] It shall be understood that a phase conductor may be formed differently according to other variants of the application.

[0075] FIG. 8 shows a schematic view of a further embodiment of a power cable 800 according to the present application. In order to avoid repetition, only the differences to the embodiments according to the previous FIGS. 2 to 7 are essentially described below. For the other components of the power cable 800 we refer in particular to the above explanations.

[0076] The optical fiber conductor 810 shown in FIG. 8 comprises at least one optical fiber 820 (e.g. a single mode fiber or a multimode fiber), in particular, a plurality of optical fibers 820, and at least one protective layer 822. The optical fiber conductor may be configured for temperature measurement and, in particular, for information transmission.

[0077] The protective layer 822 can surround the at least one optical fiber 820 and can be formed as protective tube 822, for example. Preferably, the protective layer 822 can be formed from a plastic-gel combination. In other variants of the application, the protective layer 822 can be used as a protective tube formed from glass fiber, carbon fiber or the phase conductor material (e.g. copper or aluminum).

[0078] The optical fiber 810 can have a diameter 824 between 0.5 mm and 5 mm, preferably between 1 mm and 2.5 mm.

[0079] FIG. 9 shows an exemplary diagram of a method for manufacturing a power cable according to the present application. In particular, the method described can be used to manufacture a power cable according to an embodiment shown in FIGS. 2 to 8.

[0080] First, in step 901, at least one optical fiber can be provided (e.g. produced) for the production of an optical fiber conductor in accordance with the application.

[0081] The optical fiber can be provided with a protective layer in step 902. For example, the optical fiber can be inserted into a (plastic) tube and/or be coated with a protective layer.

[0082] In step 903, the manufactured optical fiber conductor can be provided for further processing. Then, in step 904, the provided optical fiber conductor can be enclosed (sheathed) with at least two phase conductor elements of a phase conductor in such a way that a phase conductor with an integrated optical fiber conductor is manufactured. In particular, in this step the phase conductor elements (e.g. cable cores) can be wound around the correspondingly provided optical fiber conductor.

[0083] In a simple way, a power cable that can be laid underground in accordance with the application, in particular, a submarine cable, can be manufactured.

[0084] FIG. 10 shows a schematic view of an embodiment of a power cable 1000 according to the present application. The illustrated underground layable power cable 1000 may, in particular, be a submarine power cable 1000. Preferably, the power cable 1000 is a medium voltage cable or a high voltage cable. In order to avoid repetition, only the differences to the embodiments according to the previous FIGS. 2 to 8 are described below. For the other components of the power cable 1000, we refer in particular to the above explanations.

[0085] The power cable 1000 shown here comprises three phase conductors 1002, each with a plurality of phase conductor segments 1014. In particular, the outer sheath 1008 encloses the three phase conductors 1002.

[0086] An optical fiber conductor 1010 is integrated in each of the phase conductors 1002. This allows the temperature of each phase conductor of the power cable 1000 to be monitored.

[0087] It should be noted that for a better overview only phase conductors 1002 are shown. It goes without saying that the power cable as shown in FIG. 10 can have other layers, such as insulating layers, shielding layers, inner and outer semiconductor layers, filling material, etc., in accordance with the explanations in FIG. 2.

[0088] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0089] The use of the terms a and an and the and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. 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. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0090] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.