OFFSHORE SUBMARINE CABLE FOR OFFSHORE WIND FARM

Abstract

An offshore submarine cable for an offshore wind farm. The offshore submarine cable has a power capacity between 3 MW and 2.5 GW, at least one weighting element having a density of at least 5 g/cm.sup.3 at 20° C., and at least one armor package.

Claims

1) Offshore submarine cable for an offshore wind farm, comprising: a power capacity between 3 MW and 2.5 GW, at least one weighting element having a density of at least 5 g/cm.sup.3 at 20° C., and at least one armor package, wherein the at least one weighting element is formed by the at least one armor package having at least one layer made of a material with a density of at least 7.5 g/cm.sup.3 at 20° C., wherein the armor package is formed by three layers, wherein each of the armor layers comprises a plurality of ropes made of steel, wherein at least two of the three layers have counter lay direction and wherein at least two of the three layers have different lay lengths, and wherein each of the armor layers has a thickness between 3 and 5 mm.

2. Offshore submarine cable according to claim 1, wherein the weighting element is formed by at least one conductor of the offshore submarine cable, wherein the conductor is made of copper.

3. Offshore submarine cable according to claim 1, wherein the weighting element is formed by at least one shielding of the offshore submarine cable, wherein the shielding is made of copper or lead.

4. Offshore submarine cable according to claim 1, wherein a first layer of the armor package has a short lay length, a second layer of the armor package has a long lay length and a third layer of the armor package has a short lay length, wherein the long lay length is between 2 and 3 m, and wherein the short lay length is between 1.2 and 2 m.

5. Offshore submarine cable according to claim 1, wherein a first layer of the armor package has a first lay direction, a second layer of the armor package has a second lay direction opposite to the first lay direction and a third layer of the armor package has a third lay direction opposite to the second lay direction, which is in particular identical with the first lay direction.

6. Offshore wind farm, comprising: at least two offshore devices electrically connected to each other by at least one offshore submarine cable according to claim 1, and/or one offshore device and one onshore device electrically connected to each other by at least one offshore submarine cable according to one of the preceding claims.

7. Use of an offshore submarine cable according to claim 1 for electrically connecting at least one offshore device with at least one of a further offshore device or an onshore device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] These and other aspects of the present patent application become apparent from and will be elucidated with reference to the following figures. The features of the present application and of its exemplary embodiments as presented above are understood to be disclosed also in all possible combinations with each other.

[0038] In the figures show:

[0039] FIG. 1 a schematic view, in particular, a sectional view, of an embodiment of an offshore submarine cable according to the present application,

[0040] FIG. 2 a schematic view, in particular, a sectional view, of a further embodiment of an offshore submarine cable according to the present application,

[0041] FIG. 3 a schematic view, in particular, a sectional view, of a further embodiment of an offshore submarine cable according to the present application, and

[0042] FIG. 4 a schematic view of an embodiment of an offshore wind farm according to the present application.

[0043] Like reference numerals in different figures indicate like elements.

DETAILED DESCRIPTION OF THE INVENTION

[0044] FIG. 1 shows a schematic view, in particular, a sectional view, of an embodiment of an offshore submarine cable 100 according to the present application. The offshore submarine cable 100 is configured to be used in offshore wind farms (see FIG. 4). The offshore submarine cable 100 has a power capacity between 3 MW and 2.5 GW. In particular, cable may be a MV (medium voltage) offshore submarine cable comprising a power capacity between 3 MW and 70 MW, preferably between 9 MW and 60 MW, or a HV (high voltage) offshore submarine cable comprising a power capacity between 70 MW and 2.5 GW, preferably between 360 MW and 1500 MW. Preferably, the offshore submarine cable 100 is a medium voltage cable or a high voltage cable. For example, the offshore submarine cable 100 may be laid between a first offshore device (not shown) and another offshore device (not shown).

[0045] In the present example, the offshore submarine cable 100 comprises an electrical conductor 102 in form of a single phase conductor 102. It shall be understood that a phase conductor can be formed by a single conductor element (as shown in FIG. 1) or by two or more conductor elements (not shown) (e.g. a segmented conductor, compacted conductor etc.).

[0046] Furthermore, the depicted offshore submarine cable 100 has an (electrical) insulation layer 104 surrounding the conductor 102. As can be further seen from FIG. 1, the offshore submarine cable 100 comprises at least one shielding 106 in form of a shield layer 106 surrounding the electrical insulation layer 104.

[0047] In addition, an armor package 108 in form of a single armor layer 108 surrounds the shielding 106. It shall be understood that a further (not shown) isolation layer can be provided between shielding 106 and the armor package 108. The armor package 108 is formed by a plurality of robes 112 and cables, respectively. Further, the armor package 108 is presently surrounded by an outer shell 110.

[0048] Furthermore, filling material (not shown), in particular, with a high density (e.g. at least 5 g/cm.sup.3 at 20° C.) may be provided in order to eliminate any imperfections of the offshore submarine cable 100 and in order to weight the offshore submarine cable 100.

[0049] Between the phase conductor 102 and the insulating layer 104, an inner (not shown) semiconductor layer may be arranged. In addition, an outer semiconductor layer (not shown) may be disposed between the insulating layer 104 and the shielding layer 106.

[0050] The present offshore submarine cable 100 is characterized in that it comprises an armor package 108 and one or more weighting element(s) 102, 106, 108 (and 112, respectively) each having a density of at least 5 g/cm.sup.3 at 20° C. In the present example, the conductor 102 is made of copper, the shielding 106 is made of copper and the ropes 112 are made of steel. In other words, three weighting elements 102, 106, 108 (and 112, respectively) are provided wherein each of said weighting elements 102, 106, 108 (and 112, respectively) has a density of at least 7.5 g/cm.sup.3 at 20° C.

[0051] In order to avoid the necessity to use a CPS system, the present offshore submarine cable 100 comprises an armor package 108 configured to mitigate mechanical stress and strain. More particularly, the offshore submarine cable 100 has a single armor layer 108 with a plurality (e.g. between 5 to 20) of steel ropes 112, wherein the layer 108 (i.e. the steel ropes 112) has a long lay length (e.g. between 2 and 3 m). It shall be understood that according to other variants of the application an armor layer may have a short lay length (e.g. between 1.2 and 2 m).

[0052] FIG. 2 shows a schematic view, in particular, a sectional view, of a further embodiment of an offshore submarine cable 200 according to the present application. In order to avoid repetitions, in the following the differences between the embodiment of FIG. 1 and the embodiment of FIG. 2 are essentially described. With regard to the other components of the offshore submarine cable 200, it is referred to the above example.

[0053] The depicted offshore submarine cable 200 comprises an electrical shielding 206. In the present case, the electrical shielding 206 is made of lead. Lead has the advantage of a higher density than copper. In addition, lead is also capable to provide assurance regarding water ingress.

[0054] Furthermore, the armor package 208, 214 includes two armor layers 208, 214. Each of the armor layers 208, 214 comprises a plurality of ropes 210, 216 made of steel. Preferably the first layer 208 may have a short lay length and the second layer 214 may have a long lay length.

[0055] Furthermore, in order to provide two modes of stress relief, the two layers 208, 214 may have same lay directions and different lay angles.

[0056] It shall be understood that according to other variants of the present application, the two layers may have same lay directions and same lay angles or opposite lay directions and same or different lay angles.

[0057] FIG. 3 shows a schematic view, in particular, a sectional view, of a further embodiment of an offshore submarine cable 300 according to the present application. In order to avoid repetitions, in the following the differences between the embodiment of FIG. 3 and the embodiments of FIGS. 1 and 2 are essentially described. With regard to the other components of the offshore submarine cable 300, it is referred to the above examples.

[0058] As can be seen from FIG. 3, the armor package 308, 314, 318 of the offshore submarine cable 300 comprises three armor layers 308, 314, 318. Each of the armor layers 308, 314, 318 comprises a plurality of ropes 312, 316, 320 made of steel. Preferably, the first layer 308 may have a short lay length, the second layer 314 may have a long lay length and the third layer may have a short lay length.

[0059] The three layers 308, 314, 318 may have counter lay directions in order to optimize the mitigation of mechanical stress and strain imposed on the offshore submarine cable 300 during installation and/or operation.

[0060] For instance, the first layer 308 may have a first lay direction, the second layer 314 may have a second lay direction opposite to the first lay direction and the third layer 318 may have a third lay direction opposite to the second lay direction (and identical with the first lay direction). It shall be understood that the lay angles may be the same or different.

[0061] It shall be further understood that according to other variants of the present application, an offshore submarine cable may comprise four or more armor layers which can be configured as described hereinbefore.

[0062] FIG. 4 shows a schematic view of an embodiment of an offshore wind farm 430 according to the present application. The offshore wind farm 430 comprises a plurality of offshore devices 432, 434. The offshore wind farm 430 comprises, in particular, at least one offshore substation 432 with at least one transformer 438 and a plurality of wind turbines 434. All wind turbines 434 can be designed substantially the same. A wind turbine 434 may include a generator (not shown) that converts the kinetic energy of the wind into electrical energy.

[0063] The wind turbines 434 may preferably be arranged in the form of at least one string. A string comprises two or more wind turbines 434 that are electrically connected in series. Preferably, a plurality of strings may be provided. One end of a string may be electrically coupled to the offshore substation 432 via at least one offshore submarine cable 400.1.

[0064] The other end of a string (not shown) may have an electrical connection to one end of another string. In normal operation of the wind farm, so in the event that there is no network fault, this electrical connection can be opened or disconnected. If a network fault occurs in one of the two strings, the electrical connection (also called a loop connection) can be closed so that electrical power can be transmitted via this connection (e.g. formed by an offshore submarine cable).

[0065] The offshore substation 432 is electrically connected to an onshore substation 436 by at least one further offshore submarine cable 400.2. The onshore substation 436 is configured to feed the electrical power into a (public) grid 440.

[0066] The offshore submarine cables 400.1, 400.2 are formed similar to the previously described offshore submarine cables 100, 200 or 300.

[0067] 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.

[0068] 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.

[0069] 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.