Dry-mate wet-design branch joint and method for realizing a subsea distribution of electric power for wet cables

Abstract

Termination assembly for three-phase high voltage submarine cable(s) (1a-c), has an open enclosure (10) with at least two cable lead-in (3a-c) located at one end (16) of the enclosure, at least six termination units (21-29) within the enclosure for receiving three phase conductors per cable, respectively.

Claims

1. A termination assembly for three-phase high voltage submarine cable(s), comprising: an open enclosure with at least two cable lead-ins located at one end of the enclosure, and at least three termination units within said enclosure for connecting three phase conductors per cable.

2. The assembly according to claim 1, wherein the enclosure comprises at least one aperture to facilitate flooding.

3. The assembly according to claim 1, comprising: lifting means located on the enclosure at an opposite end in relation to said lead-in(s).

4. The assembly according to claim 1, wherein said termination units are T-connectors.

5. The assembly according to claim 4, wherein said T-connectors are oriented within said enclosure with their central legs extending substantially in a direction between said one and opposite ends.

6. The assembly according to claim 5, wherein the dimensions of said enclosure are largest in said direction.

7. The assembly according to claim 1 for a branching connection of cables, wherein three cable lead-ins are provided within said enclosure.

8. The assembly according to claim 4, wherein three T-connectors for one phase conductor are mounted directly interconnected on a common supporting bracket.

9. A method of subsea distribution of electric power from a plurality of wind turbines to one or more consumers, comprising: connecting the plurality of wind turbines to a cable that is connected to a termination assembly for three-phase high voltage submarine cables, the termination assembly comprising: an open enclosure with two cable lead-in means for entry of each cable into the enclosure, and at least six termination units within said enclosure for receiving three phase conductors per cable, respectively, connecting at least another cable to said termination assembly, the at least another cable forming at least part of a main cable for supplying produced electric energy from the plurality of wind turbines to one or more consumers.

10. The method according to claim 9, wherein the enclosure comprises at least one aperture to facilitate flooding.

11. The method according to claim 9, further comprising a step of lowering the termination assembly under water where the enclosure is flooded with water.

12. The method according to claim 9, wherein the termination assembly comprises lifting means located on the enclosure at an opposite end in relation to said lead-in means.

13. The method according to claim 9, wherein said termination units are T-connectors.

14. The method according to claim 13, wherein three T-connectors for one phase conductor are mounted directly interconnected on a common supporting bracket.

15. The method according to claim 9, wherein the wind turbines are offshore floating wind turbines or types of floating or ground mounted platforms or wind turbines.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In the following description this invention will be further explained by way of exemplary embodiments shown in the drawings:

[0055] FIG. 1 is a cross-sectional and perspective view of a termination assembly according to the invention.

[0056] FIG. 2 is an enlarged cross-sectional view of three T-connectors assembled within an enclosure, corresponding to parts of FIG. 1.

[0057] FIG. 3 is a still more enlarged and detailed cross-section of a T-connector for use in a specific embodiment of this invention.

[0058] FIG. 4a is a front side view, a lateral view and a perspective view of the open terminal assembly.

[0059] FIG. 4b is a front side view, a lateral view and a perspective view of the closed terminal assembly.

[0060] FIG. 5a is an enlarged cross-sectional view of two T-connectors assembled for use in a specific embodiment of this invention.

[0061] FIG. 5b is an enlarged cross-sectional view of three T-connectors assembled for use in a specific embodiment of this invention.

[0062] FIG. 5c is an enlarged cross-sectional view of four T-connectors assembled for use in a specific embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0063] The embodiment of FIG. 1 discloses interconnecting three submarine power cables 1a, 1b and 1c. Thus, cables 1a and 1c, may belong to a main cable for supplying produced electric energy from a number of wind turbines to consumers on-shore. Cable 1b may be connected to a wind turbine in the system. What is done at this point in the system is to electrically connect each phase of the three-phase cable 1b to each corresponding phase of cable(s) 1a and 1c. This takes place inside an enclosure 10 shown in FIG. 1 (and FIGS. 2, 4a and 4b). The enclosure 10 may advantageously comprise at least one aperture 50 in order to ease the flooding of the enclosure 10. The at least one aperture 50 may be a hole or a slit. The enclosure 10 will be flooded when placed under the sea level. Before entering enclosure 10, the cables 1a-c are each surrounded by a bend stiffener or a bend restrictor 2a-c, respectively, according to known methods. Moreover, lead-in means 3a-c for entry of each cable into the enclosure are provided, also as known per se. Preferably, the lead-ins are not sealed in a water-tight manner to the enclosure, such that water may easily enter the enclosure when submerged in water.

[0064] The enclosure 10 may be a in the shape of a splitable box, such as a square box or a cylindrical box, for ease of access for installation of power cables.

[0065] Inside the enclosure 10 there are three groups of T-connectors 21-23, 24-26 and 27-29, respectively, supported by a bracket 19. T-connectors 21-23 are shown more detailed in FIG. 2, i.e. for one (corresponding) phase 11a, 11b and 11c from respective cables 1a-c. The similar arrangements are provided for connecting the other two cable phases by means of groups 24-26 and 27-29, respectively, of T-connectors.

[0066] As will be seen from FIG. 2, T-connectors 21, 22 and 23 are directly attached to one another by plugging together at their upper or transverse legs with a through-running electrically conductive path comprising conducting elements 34 and 35. In this manner conductors 31, 32 and 33 belonging to cable phases 11a, 11band 11c, respectively, are connected together. Looking again at FIG. 1, there is shown one phase 13a from cable 1a, being extended to T-connector 27 in the third or rear group of T-connectors.

[0067] The central or main leg 45 is indicated for T-connector 21, with all other T-connectors having the same kind of central leg, all such central legs being oriented vertically as shown in the drawings. The T-connectors can also rotate so as to be opposed to each other 180 degrees along the “34 axis”, as illustrated in FIGS. 5a-c. This of course does not mean that in actual service this orientation is normal. It is to be noted also that in the embodiment shown in FIG. 1, the axial direction of power of cables 1a-c, as well as the bend stiffeners or bend restrictors 2a-c is generally the same as for the above central or main legs 45. In actual practice this is a very advantage arrangement, facilitating the assembling operations as well as any repair or changes to be made during the lifetime of the termination assembly.

[0068] Lead-ins 3a-c are provided at one end or side wall 16 of enclosure 10. The opposite end or side wall is denoted 17. At the end 17 there is provided lifting means in the form of an eye structure 100 making possible deployment as well as retrieval of the whole assembly with power cables 1a-c connected thereto. It will be understood that depending on water depth at the site of installation, there may be a quite considerable weight to be carried by lifting eye 100 during such operations. In many cases it may be considered advantageous to have the dimensions of enclosure 10 to be largest in a direction between the end or side walls 16 and 17, and also to have the central legs 45 of the T-connectors mounted to extend substantially in the longitudinal direction of the enclosure, i.e. more or less in parallel to the direction of cables 1a-c when entering the enclosure through bend the stiffeners or bend restrictors 2a-c and lead-ins 3a-c.

[0069] Although FIG. 1 illustrates the important case of three electric power cables 1a-c interconnected within enclosure 10, alternatives with at least two three-phase high voltage submarine cables, especially alternatives with two to ten three-phase high voltage submarine cables fall within the scope of the invention.

[0070] An embodiment of the invention with two termination units 20, such as T-connectors is illustrated in FIG. 5a, an embodiment of the invention with three termination units 20, such as T-connectors is illustrated in FIG. 5b and an embodiment of the invention with four termination units 20, such as T-connectors is illustrated in FIG. 5c.

[0071] A still more simplified arrangement is illustrated in FIG. 3, where a single phase of cable 1x is connected to T-connector 20 with a similar kind of central leg 45 as in the above embodiment, and with two transverse legs 26 and 27, to serve only as a termination and insulation of cable 1x. Thus, a common cylindrical housing 41 of insulating material and insulating plugs 42 as well as rubber caps 43 provide for the required insulation and termination. This is particularly useful for testing purposes, which may be a quite important operation during installation of submarine cables. For this purpose, it may be sufficient to have just one cable lead-in and three termination units or T-connectors for testing of a three-phase high voltage submarine cable.

[0072] FIGS. 4a and 4b show different views of the open (FIG. 4a) and closed (FIG. 4b) terminal assembly. In particular these figures show an embodiment of the at least one aperture 50 exemplified here by a series of holes and slits on the side walls of the housing 10. These apertures 50 will advantageously help with flooding the housing 10 when the housing 10 is put under the water level.