Offshore Structure

Abstract

An offshore structure includes an electrical device with a housing filled with an insulating liquid, and it includes an expansion vessel system, the inner volume of which has a region containing insulating liquid as well as a gas cushion. The housing, a pipe and the expansion vessel system form a pressure-tight, hermetically sealed unit. The offshore structure is particularly easy to build due to the fact that the gas cushion is at least in part arranged below sea level.

Claims

1-14. (canceled)

15. An offshore structure, comprising: an electrical device having a housing filled with an insulating liquid; an expansion vessel system with an inner volume forming a gas cushion, wherein at least a part of said gas cushion is arranged below sea level; and a pipeline disposed to connect said housing to said expansion vessel system, wherein said housing, said pipeline and said expansion vessel system are connected to form a pressure-tight, hermetically sealed unit.

16. The offshore structure according to claim 15, wherein an entire said expansion vessel system is arranged below the sea level.

17. The offshore structure according to claim 15, wherein said expansion vessel system comprises: an expansion vessel containing a region with insulating liquid, wherein the pipeline is filled with liquid and is connected to said region with the insulating liquid in said expansion vessel; a compression chamber connected via a gas-filled pipeline to the part of the gas cushion that is contained in said expansion vessel, wherein said compression chamber is arranged below the sea level.

18. The offshore structure according to claim 17, further comprising at least one second electrical device having a second housing filled with an insulating liquid, and wherein: said expansion vessel system comprises a second expansion vessel; said second housing is connected via a second liquid-filled pipeline to said second expansion vessel, which contains a second region with insulating liquid; and the part of the gas cushion that is contained in said second expansion vessel is connected to said compression chamber via a second gas-filled pipeline.

19. The offshore structure according to claim 15, wherein said pipeline is filled with gas.

20. The offshore structure according to claim 19, further comprising at least one second electrical device having a second housing filled with an insulating liquid and a gas-filled pipeline connecting said second housing to said expansion vessel system.

21. The offshore structure according to claim 15, wherein said expansion vessel system comprises a plurality of interconnected expansion vessels and/or compression chambers.

22. The offshore structure according to claim 15, wherein that part of the gas cushion that is arranged below the sea level is formed in a hollow structural element of a foundation structure of the offshore structure.

23. The offshore structure according to claim 22, wherein said hollow structural element at least partially forms a wall enclosing the gas cushion.

24. The offshore structure according to claim 22, wherein a space remaining between said compression chamber and said hollow structural element is filled with water.

25. The offshore structure according to claim 17, wherein said expansion vessel comprises a diaphragm separating the gas cushion from the insulating liquid.

26. The offshore structure according to claim 17, wherein said liquid-filled pipeline has a Buchholz relay.

27. The offshore structure according to claim 15, wherein said electrical device is a transformer.

28. The offshore structure according to claim 15, comprising a wind power installation.

Description

[0028] Exemplary embodiments of the invention will be discussed in more detail on the basis of drawings, in which:

[0029] FIG. 1 shows an offshore wind power installation having a transformer with an expansion vessel in the foundation structure,

[0030] FIG. 2 shows an offshore substation having a transformer and compression chambers in the foundation structure,

[0031] FIG. 3 shows a further offshore substation having a transformer and compression chambers in the foundation structure,

[0032] FIG. 4 shows an offshore wind power installation having two transformers, each with one expansion vessel, and a compression chamber in the foundation structure,

[0033] FIG. 5 shows a further offshore wind power installation having two transformers, each with one expansion vessel, and a compression chamber in the foundation structure, and

[0034] FIG. 6 shows a further offshore wind power installation having a transformer, with an incorporated expansion space, and a compression chamber in the foundation structure.

[0035] Identical parts are provided with the same reference signs in all the drawings.

[0036] FIG. 1 shows an exemplary embodiment for a substation 6, arranged on the foundation structure 9 of an offshore wind power installation 7, for an offshore wind farm. The substation 6 has a transformer 1 with a hermetically sealed housing 1.1 which is filled with an insulating liquid 1.5, and further has a cooling system 1.8. The foundation structure 9 fixes the wind power installation 7, with its tower 7.1, the nacelle 7.6 and the rotor 7.7 fastened thereon, in the seabed 12.

[0037] The thermally induced variations in volume of the insulating liquid 1.5 result in the flow of the latter into a compression chamber 2.2, which is embedded in a hollow structural element 8 of the foundation structure 9, via a pipeline 5 which is equipped with a Buchholz relay 1.6. The compression chamber 2.2 is dimensioned such that, above the changing level of the insulating liquid 3, space is formed for a gas cushion 4 which accommodates the variations in volume of the fluid. The pipeline 5 to the compression chamber 2.2 leads to the bottom thereof, and so, independent of the fill level, it is ensured that the connecting line to the transformer is filled with insulating liquid 1.5, 3 at all times.

[0038] The compression chamber 2.2 is arranged in a hollow structural element 8 of the foundation structure such that it is substantially situated below the sea level 11. The hollow structural element 8 is filled with fresh water 15. The gas cushion 4 then substantially absorbs the temperature of the surrounding seawater 14. For example, in large parts of the North Sea, the water temperature varies only between 4 C. and 18 C. It is thus possible for the hermetically sealed transformer 1 to work with a drastically reduced pressure range. The compression chambers can be reduced in size significantly.

[0039] FIG. 2 shows an offshore substation 6 which is arranged on a platform whose foundation structure 9 is formed from a multi-part pipe structure. In the exemplary embodiment in FIG. 2, the expansion vessel system is formed by multiple separated expansion vessels 2.1, 2.2. The expansion vessel 2.1 is connected via a pipeline 5.5 to further compression chambers 2.2 for the gas cushion 4, which chambers are arranged such that the gas cushion 4 is thermally decoupled from the temperature of the insulating liquid 1.5 in the transformer 1. In the exemplary embodiment, both the expansion vessel 2.1 and the compression chambers 2.2 which are thermally decoupled from the transformer 1 are formed by sheet-metal cylinders.

[0040] FIG. 3 shows an offshore substation 6 which is situated on a platform. Said platform is anchored in the seabed 12 via pipe-shaped hollow structural elements 8. In the exemplary embodiment, use is made of said hollow structural elements 8 for accommodating the expansion vessel system formed from an expansion vessel 2.1 and a compression chamber 2.2. In the exemplary embodiment, a segment of the foundation structure 9 forms the compression chamber 2.2. The casing surface of the hollow structural element 8 forms a part of the housing of the compression chamber 2.2. In this specific exemplary embodiment, the gas cushion 4 is separated from the insulating liquid 3 by a diaphragm 2.5 which is arranged inside the expansion vessel 2.1 for the insulating liquid 3. As a result of this separation, the dissolving of the gas of the gas cushion 4 in the insulating liquid 3 is substantially avoided.

[0041] FIG. 4 finally shows an exemplary embodiment in which an offshore substation 6 is integrated in the hollow structure which accommodates the tower 7.1 of a wind power installation 7. In the exemplary embodiment, the substation 6 has multiple fluid-filled components (transformers 1 and throttles) which each have their own expansion vessel 2.1 for the insulating liquid 3. The expansion vessels 2.1 are each connected on the gas side to a common compression chamber 2.2 via pipelines 5.5. In order to accommodate the compression gas 4, multiple transformers 1 accordingly use a common compression chamber 2.2 below the sea level 11, with the separation of the insulating liquids 1.5, 3 being maintained.

[0042] The use of a common compression volume allows a reduction in the total volume to be realized since not all the components have the same operating temperature. Furthermore, in this way, part of the installations may operate in overload mode without a corresponding dimensioning of the individual compression chambers being necessary.

[0043] FIG. 5 likewise shows an exemplary embodiment in which multiple transformers 1 are arranged in the tower 7.1 or the foundation structure 9 of a wind power installation 7. The transformers 1 each have their own expansion vessel 2.1. The expansion vessels 2.1 are connected via pipelines 5.5 to a compression chamber 2.2 which is used jointly by multiple transformers 1.

[0044] Furthermore, in the exemplary embodiment, both the transformers 1 and the expansion vessel system with the compression chamber 2.2 are arranged inside the foundation structure 9 or the tower 7.1 of a wind power installation 7. The cooling of the transformer 1 may be realized both via oil-water coolers and air coolers or radiators and is not represented in the exemplary embodiment.

[0045] In the exemplary embodiment, the wall of the foundation structure 9 at least partially represents the housing of the expansion vessel system or of the compression chamber 2.2.

[0046] FIG. 6 shows an exemplary embodiment in which the expansion space for accommodating the temperature-induced variations in volume of the insulating liquid 1.5 is arranged inside the transformer housing 1.1. The space not taken up by the insulating liquid, and the pipeline 5.5 and the compression chamber 2.2 of the expansion vessel system are filled with a gas cushion 4. With rising temperature, the insulating liquid 1.5, 3 expands and displaces the gas into the compression chamber 2.2 of the expansion vessel system through the pipeline 5.5. Since the largest part of the gas is then situated inside the compression chamber 2.2 and the latter scarcely has variations in temperature due to the thermal coupling to the water temperature, the volume expansion coefficient of the gas can be effective only to a small extent and has only a small influence on the inner pressure of the transformer 1 and the expansion vessel system thereof.

[0047] No fixing of the foundation structure 9 to the seabed 12 is shown in FIGS. 5 and 6 since the foundation structure 9 may also be designed as a floating foundation.

LIST OF REFERENCE SIGNS

[0048] 1 Transformer [0049] 1.1 Housing [0050] 1.5 Insulating liquid [0051] 1.6 Buchholz relay [0052] 1.8 Cooling system [0053] 2.1 Expansion vessel [0054] 2.2 Compression chamber [0055] 2.5 Diaphragm [0056] 3 Insulating liquid [0057] 4 Gas cushion [0058] 5, 5.1, [0059] 5.5 Pipeline [0060] 6 Offshore substation [0061] 7 Wind power installation [0062] 7.1 Tower [0063] 7.6 Nacelle [0064] 7.7 Rotor [0065] 8 Hollow structural element [0066] 9 Foundation structure [0067] 11 Sea level [0068] 12 Seabed [0069] 14 Seawater [0070] 15 Fresh water