DE102006025832A1 - Offshore installation structure for wind turbine, has tubular pile stretched above waterline during low tide, and structural part with smaller cross section connected above tubular pile in water column - Google Patents

Abstract

The installation structure has a carrying structure with a tubular pile (1) flushed by highest occurring waves. A predominant part of a used space enclosed by the installation structure is provided in the tubular pile. The tubular pile is anchored in a sea floor (2), where the tubular pile is stretched above a waterline during low tide. A structural part (4) with smaller cross section is connected above the tubular pile in a water column. An inlet (5) is provided at a side wall of the structural part. An independent claim is also included for a method for constructing an offshore installation structure.

Description

State of the art

Known Support structures for Offshore structures are single-pipe structures, usually executed as so-called monopile with a steel pipe rammed into the seabed, as tripods, in which a central tube is supported laterally, or as truss structures. These constructions can i.a. with piles, Concrete weights (gravitational foundations) or suction piles (suction buckets) founded on the seabed become.

By The wave attack will be considerable personnel exercised on buildings in the sea.

in the Wave attack area above the calm water level is therefore a small cross section particularly advantageous, sometimes he will rejuvenated across from the cross section within the water column. The actual utility rooms are located then above the wave attack area. They often collar over the actual support structure and are often referred to as a platform, also as "topside".

Examples for offshore substations are from the Institute for Wind Energy of the TU Delft (Hrsgb.) in OPTI-OWECS Final Report Volume 4; A typical design solution for offshore Wind Energy Conversion System, Aug. 1998 and on the website http://seas-nve.dk/Upload/gfx/nystedvindmollepark.jpg (May 2006).

Also Floating platforms are located below the water level usually only subordinate systems such as tanks and buoyancy bodies.

installations on the seabed have the disadvantage of poorer accessibility.

inventive idea

The Invention takes advantage of the fact that in construction with only a supporting pipe in the water column this usually a considerable Diameter, often between 3 and 7 meters. A sufficient diameter is required to transfer moment loads into the seabed while he rather harms in the wave attack area. If it succeeds, much of the required volume to accommodate in this tube can on a separate platform above the wave attack area be waived. An arrangement of the largest possible parts of the volume below The water table is advantageous because there the particle velocities the water in the swell are smaller and thus the wave forces relatively are less than something above. If one platform is lost then the support structure as a whole for much lower loads Because no comprehensive power transmission between the platform and the lower part of the supporting structure is required in originally medium altitude range the structural dimensions and thus the absorption of wave forces in be reduced in this area.

One Access for maintenance purposes takes place offshore only if limited Swell. For one dry access therefore suffices an access opening which is above the influence of smaller waves is located. When the access port is overflowed by extreme waves, is that for the accessibility not decisive. The cross section of the structure may be in the range be reduced if the building part has no or less loads must be transferred from upper parts of the structure. At a smaller cross-section also results in fewer refractions of the waves, the accessibility So less is the impact of the waves against the structure with special needs. There is little interaction especially if that Building part with a larger cross-section Completely a good deal covered by water will, if necessary, only at high tide. It can also be cheap when the incoming waves first partly rejected by the pipe or the lower part of the structure, which finally over this lower part of the structure protruding wave crests then, so to speak, into the void run, and then splash the waves less against the slimmer "tower" of the structure.

If the building area with the access or the entire building at very big Waves are washed over (can), the wave loads are further limited. Compared to an underwater construction in the narrower sense, in which cavities are constantly under water and at no time dry access is possible, however, are the Requirements for waterproofness limited. Possibly. can be minor leaks in areas that are only briefly under water, accepted become.

Preferred application

A Particularly advantageous utilization of this principle results in an offshore substation. Substations are referred to as substations with high-voltage transformers (depending on Voltage level also referred to as high voltage transformers) in conjunction with switchgear. Offshore substations in existing offshore wind farms are used to convert electrical power from medium to high voltage.

While outdoor substations on land are usually the largest in a substation, the transformer transformer occupies the largest volume in an offshore substation with SF ₆ switches. A transformer is regularly in a closed, oil-filled container, the regular maintenance is limited to monitoring the oil filling. An arrangement according to the invention below the water level allows direct cooling by seawater on the outside of the transformer or the building. In contrast to the usual horizontal installation of transformers, it would preferably be arranged vertically in the tube. Compared to a transformer on a higher platform, vertical cable runs can also be saved.

design

in the Basically there is a risk of intrusion of (spray) water. That's why it makes sense to have more sensitive equipment the substation like switches and controls in one up to arrange the closed area above the access.

In order to would even with possible short circuits in a switching device a low risk of fire in the transformer below. Introductions of cables and terminals could if necessary in medium altitude between transformer and switching devices are arranged to cable routes limit and in case of a possible fire of the switchgear also not to be affected.

Even for the Case of ingress of water at the level of access would be the upper one Area - too with overflow of very high waves - before water access protected. The effect that the water with its pressure caged there Air can compress something, and thus a rise in the water level over the Top edge of the opening also allows is reduced, if in the upper part as little open air volume is available.

Conceivable would be too a special lock construction, in which the access opening in leads a room, the trough-like and open only upwards. Then would be at Leak in the door or at the entrance opened Door no water in cavities below the front door be able to walk. The opening The lock area could also be up by a second Door or one Cover to be closed.

In an advantageous construction could the part of the support structure that has the larger diameter and the transformer absorbs, approximately at the level of the calm water level end. Upwards would follow a slimmer part. Below the access could this slimmer part e.g. Tanks or other closed or insensitive Pick up components.

Of the The upper part of the structure is prefabricated on land. Preferably would the preassembled unit also include the transformer, the is inserted in the lower part of the structure for final assembly, and would also include a cover of the lower part.

Possibly. can the weight of the upper part of the structure and the transformer in conjunction with a rubber-mounted and sealed bedding on the circumference of the rammed pipe pile a sufficient connection produce.

In addition to the access openings on the side could the upper part has a removable upper side or an access to the Have top, are possible through the further loading and unloading and also bulkier or only with a crane to be moved plant parts can be assembled or disassembled. This opening can even before startup for used the assembly of finished switching groups ashore in the supporting structure become.

in the Trap of a transformer in the lower part of the building can be caused by the waste heat of the building Transformers basically A drying of water can be expected, located in the lower part of the accessible Area is located. But there is an increased danger that it will be in the precipitates the highest part of the enclosed space. This especially at low outside air temperatures. That's why it would be beneficial a round of transformer oil or a special cooling and heating fluid to provide in this upper part of the structure to there with increased air temperatures to prevent condensation of moisture on switching devices or their housings. An air conditioning and desalination / dehumidification of the indoor air remains independently of it makes sense.

One Another advantage is the lower vertical load on the foundation as a result the buoyancy corresponding to that of the transformer or the other internals displaced Water.

It would not contradict the idea of the invention, if the structure is kept particularly narrow in the low waves area, and above the access area or above the attack area low waves re-expansion of the structure takes place to provide additional useful volume above the water table. This could limit especially the fatigue loads by the continuous wave attack become.

Conceivable would be too a construction with uniform or less changed Diameter, which ends a few meters above the water level and of very large ones Waves is washed over. That would Above all, the extreme loads are limited by very large waves out. It should be remembered that the particle velocities very big Waves in the upper part of the wave crest are the largest, also a larger lever arm exercise to the seabed, so that just a "submersion" of these wave crests themselves very beneficial. Therefore, it is less disadvantageous when a part of the structure itself with large cross section above the Calm level is, as long as he is not too far up extends.

Also possible is a construction, in which up above the extreme wave range reaching Structure with relatively low building volume connects. there could it is u.a. around a landing area for helicopters, an area for abseiling people from the helicopter, a recording for lighting and protections or act around a measuring tower. A truss structure could be particularly useful here, because a truss structure has less cross-sectional area, and because in sufficient Height slimmer Rod constructions possible could be as always in the Water-exposed area, where especially the risk of vortex vibrations consists. The outer dimensions the truss structure could quite possibly have the dimensions of the tube in the water column.

The in the water column can also be a square tube or a kinked, have oval or conical shape. It can be additionally exhausted or be held laterally.

The Pipe forming the lower part of the structure may be interrupted. It may in particular consist of a lower part, which in the Ground is rammed, and from an upper part whose wall would be too thin to the To absorb ramming impacts,

Of the upper part of the structure could et al with the help of an apron, the slightly larger diameter has as the lower part of the building to be stuck on this (claim 16).

Of the Gap between apron and rammed pile could then with high-strength concrete (grouting material) or another pressure-resistant filling material filled become.

Outside at the apron could Thermowells for Cable led to the seabed be cut down below either straight or a funnel-shaped recording have (I-tubes) or the cables arcuate in their horizontal laying direction follow in the seabed (J-tubes).

The apron could also a different rounding than the pile or the lower part of the structure have, so that in cross-section sections with a wider Gap between pile and apron result. In these sections could then protective tubes between apron and pile are guided, which take the cables to the seabed or from the seabed. Then will either the entire remaining area between apron and Stake frictionally concreted, or the sections without protective tubes, where apron and Pile close together, take over the entire power transmission between apron and stake. cable guides on the inside of an apron with an overall smooth surface have the advantage of less wave attack.

At the reverse case, inserting a mounting unit with the upper part of the structure in the rammed Stake, would also the transition area filled with concrete. This has the advantage that the waves hit directly on the pile, thus less forces be transferred between the building parts.

After this due to manufacturing tolerances and as a result of pile driving no exact Dimensional accuracy of Stake is reached, it is also not possible there with a fixed transformer housing insert exactly the right dimensions. However, the presence of Salt water between the transformer and the surrounding steel pipe ruled out comes a flexible serving (for example, as a strong film) with which this water is used pour in of transformer oil outward repressed is (claim 19). This would additionally a further protection against oil losses form. After a flexible wrapping basically the Risk of damage when installing, could it may be more advantageous to provide this only in addition to a fixed enclosure and to design the plant in such a way that, if necessary, a company despite damage the flexible cladding possible would.

A circular shape of the pile is to be preferred as a rule for limiting the shaft loads and for production reasons. Also, the upper, slimmer part will preferably be circular. However, an eccentric arrangement can be advantageous, on the one hand to get access farther away from the outer edge of the lower part, on the other hand, to lines on the outer wall of the slimmer part vertically down to the outside wall of the lower part to lead.

Of the upper part can also be arranged so eccentric that he in places over the survives lower part, so that lines from the inside of the upper part of the building perpendicular to the outside the lower part of the building or to be mounted there protective tubes are performed can.

at a rammed steel pipe produces considerable shocks, which is a transformer damage would if he already during of ramming would be associated with it. In rammed construction would The transformer therefore subsequently with its own wrapping in inserted this pipe be set or above. In a low-vibration Installation in or on the seabed could be against the transformer already installed on land in the pipe and the structure if necessary in one piece be installed. The supporting tube could then both the outer wall and the oil tank of the Form transformers.

The Dimensions of a substation according to the invention could e.g. 4 to 6 meters in diameter of the lower structural part, the at low tide protrudes about a meter from the sea - that corresponds about the gauge of railways, with which many transformers be transported - and around 2-3 Meter diameter of the upper part of the structure of the switchgear where necessary would record in several levels. The access could e.g. 2 to 4 feet above the average water level and the building as a whole about 6 meters above sticking out, but still lying below the level of large ocean waves. The substation could e.g. with the help of a tubular Apron over one rammed mono pile are plugged, which is around 10 meters below the waterline ends. A limitation of the length The pile has the advantage that the danger of buckling is less and the rest Part of the building no longer for the loads during ramming must be interpreted.

A inventive construction can also be achieved by using an existing construction, the maybe before as a wind measuring tower was used later is reused. This could be the existing construction will be cut to the desired height, and the new structure inserted in the old or attached with a transition piece become. Possibly. can be below the water surface for receiving the transformer an enlargement of the Cross section may be required. This would then respect the total attacking loads are compensated by the cross-sectional area in the vicinity or above the water level is reduced, so that the lower Part of the support structure remains sufficiently sized.

Of the Volume requirements in the upper part of the system can be reduced if preferably many plant components are transferred to other structures, e.g. certain switchgear on the first wind turbine one in the substation beginning strand.

The Arrangement of access in an occasionally reached by waves altitude is also transferable to buildings, their used volume predominantly located above the water level, and may u.a. wave loads on access platforms.

A Arrangement of the transformer in the tower base in the area of the waterline, possibly also floating, is also with (medium voltage) transformers for the Power output of individual wind turbines possible. For offshore wind turbines could the Turminnenbereich also as a container for the event of leaks of Transformer oil or of the transmission oil be used.

Of the tilted by 90 °, upright installation of the transformer in a pipe section also allows a structural summary of the substation with a wind turbine. An arrangement of the transformer near the waterline may be one above, avoid any required expansion of the tower diameter and mitigates effects of the extra Mass on the oscillatory behavior of the tower.

Further manifestations The invention will become apparent from the claims.

pictures

1 shows a construction according to the invention, in which a tubular pile 1 in the Meresboden 2 is anchored, crosses the water column and in the situation shown with low swell slightly above the water surface 3 enough. On top is another building part 4 , shown here as a vertical and centrally located pipe, on whose side wall an access 5 located. Stairs and pedestals are neglected in this presentation.

2 shows a similar structure, in which the upper part of the building 6 However, it is arranged laterally offset.

3 shows a section through such a structure that receives a substation. In the interior of the tubular building part is located, hatched indicated, the vast majority 7 of the used space of this building, the Auf the transformer is used. The transformer or housing receiving it is within the tubular pile 1 hooked. The upper part of the structure 6 takes switchgear 8th on. He is in 2 and 3 placed so eccentrically to the lower part of the structure that it is on the left side over the tubular pile 1 survives. There are cables on this side 9 and their protective tubes 10 to the outside of the tubular pile 1 and become the seabed there 2 guided. Other cables for connecting the switching devices to the transformer are not shown.

In the area of the access opening 5 is a tub-like protection against water ingress 11 shown. In the water filled interior 12 If necessary, a water exchange or a water treatment can take place in the pile below the space used.

4 shows a variant in which the rammed pipe pile 13 a few meters below the sea surface ends and the other parts of the building were placed on top. The area with the transformer 14 has a slightly larger diameter than the tubular pile. He has a cylindrical apron 15 on that the pipe post 13 encloses, and after filling the gap with concrete or filling compound is non-positively connected to the tubular pile. On the outside of the apron are protective tubes 10 attached for the cables. At the height of the transformer 14 However, these protective tubes were drawn into the interior of the cylindrical sheath of the transformer to provide less wave attack.

5 shows a horizontal cross section through the variant of 4 with the pipe post 13 and a circular apron 15 , on the outside of which protective tubes for cables 10 are located.

6 shows a cross section in which the skirt is divided into three sections 16 . 17 and 18 the circumference of the circular tubular pile 13 snuggles and there allows a direct power transmission, but otherwise maintains some distance in the protective tubes 19 are arranged.

7 shows another variant, in which now the apron 20 circular shaped, is the pole 21 but flattened on two sides and thus oval, and now in two places protective tubes 22 between the pole and the apron. Thus, the protective tubes are no longer exposed as separate objects to the wave attack.

8th shows an offshore wind turbine with the gondola 23 on a tube tower 24 in which a transformer 25 floating within the pipe and cooled by the surrounding water installed and associated with switchgear 26 connected is.

Claims (22)

Structural work for offshore installations, characterized in that the supporting structure, at least in the upper part of the water column and below the level of calm water at low tide, mainly from only one tubular building part ( 1 ), which is at least flooded by the highest occurring waves, and that is located in this tubular part of the structure of the major part of the used, enclosed by the building space. Structure according to claim 1, characterized in that the tubular building part (1) named in claim 1 ( 1 ) reaches at least at low tide to above the waterline. Building according to claim 1 or 2, characterized in that the tubular building part (1) named in claim 1 ( 1 ) is flooded regularly at high tide. Building according to one of the preceding claims, characterized characterized that it is predominantly or completely from the highest waves are washed over at the location. Building according to one of the preceding claims, characterized characterized in that above the tubular structure part in the wave attack area only connect building parts with much less wave attack, especially those with a smaller cross-section. Building according to one of the preceding claims, characterized in that above the tubular structural part ( 1 ) in the water column another, mainly upright oriented building part ( 4 ) connects with a smaller cross-section, on whose side wall an access ( 5 ), which is at least at low Tidestand and low swell in the dry. Structure according to claim 6, characterized that the upper part of the structure opposite the lower so far horizontally offset is that it overhangs the lower one side, and that this supernatant is used to lines from the inside of the upper part of the building to the outside to lead the lower part of the building. Building according to one of the preceding claims, characterized in that above the access is a used space, which by a closed upper envelope surface before the rise protected from water in this area. Building according to claim 8, characterized in that in the upper area of the enclosed space predominantly body ( 8th ) with airtight enclosing enclosures, while the area at height just above the access to a greater extent to the building interior contains open volumes of air, so that even when larger quantities of water with strong external pressure, a rise in the water level is counteracted in the upper area. Building according to one of the preceding claims, characterized in that behind an entrance opening from an only upwardly open enclosure ( 11 ) is delimited area in which possibly entering through the inlet opening water accumulate and, if necessary, can flow back through the inlet opening, so that a further penetration of water is counteracted. Building for Offshore installations, characterized that there is one Substation or at least one high or high voltage transformer takes up, and that the high or extra high voltage transformer inside the tubular Structural part of a load-bearing structure is located, and at least partially located below the calm water level at low tide. Structure according to one of the preceding claims, characterized in that the transformer ( 25 ) in the volume of water ( 12 ) is floating within the tubular structure part. Building according to one of the preceding claims, characterized in that it accommodates a substation, and that the transformer and substations of substation in the same tubular Building part are located. Building according to one of claims 1 to 12, characterized in that it receives a substation, and that the transformer predominantly below the waterline in a tubular building part ( 1 ) and the switchgear is predominantly in another building part ( 4 ) above the waterline. Method of constructing a building according to a the previous claims, characterized, that first a pipe in the ground is rammed, and then a unit already prefabricated on land is connected with it, With - in to insert the rammed pipe Plant parts, A transitional part to the Pipe, - one top cover of this pipe and - protruding beyond this tube Building parts together with installations installed there Building according to one of the preceding claims, characterized characterized in that a lower tubular structural part partially is introduced as a pile in the ground and an upper part of the structure with the help of a slightly larger apron that in the transition area encloses the lower part of the building, is put on this. Building according to claim 16, characterized that apron at certain portions of the circumference a greater distance from the lower Complies with the construction part, and that there in the space protection tubes for receiving cables or led lines become. Building according to one of the preceding claims, characterized characterized in that the interior of the tube with distilled or low-salt water becomes. Building according to one of the preceding claims, characterized in that a transformer in the rammed pile is introduced, and the transformer during assembly of a flexible cladding is enclosed during filling of transformer liquid against the outer wall presses and thereby displaces the water previously present there. Offshore wind turbine with tube tower, characterized in that the transformer ( 25 ) in the volume of water ( 12 ) is floating within the tower. Offshore wind turbine with tubular tower, at the partially overlap two pipe sections of the tower and by pouring the Splits a non-positive Connection between the pipe sections is made by characterized in that the upper tube section in the overlap region has the larger diameter has and a cable from the inside of the upper tube section through the Gap to the outside of the lower pipe section becomes. Building with a tubular tower for offshore installations, characterized in that it receives or carries an offshore wind turbine and in a lower pipe section, at least partially below the waterline, a high or maximum chip tion transformer is installed with upright longitudinal extent.