WO2011031198A1

WO2011031198A1 - A switchgear

Info

Publication number: WO2011031198A1
Application number: PCT/SE2009/051014
Authority: WO
Inventors: Erik Lejerskog; Tobias Johansson; Daniel BJÖRKLÖF
Original assignee: Seabased Ab
Priority date: 2009-09-11
Filing date: 2009-09-11
Publication date: 2011-03-17

Abstract

The invention relates to a switchgear having electric components (2, 3) enclosed by a housing (1). According to the invention the switchgear has a frame structure (6). At least one electric component (2) is mounted on a cooling element (7). Clamping means (8) is mounted on the frame structure (6) and presses the cooling element against an inner surface of the housing wall (41). The invention also relates to a method for manufacturing such a switch- gear.

Description

A SWITCH GEAR

Field of Invention

The present invention in a first aspect relates to a switchgear including electric components and a housing enclosing the electric components.

The invention also relates to a wave power plant including such a switch- gear and to an electric network connected to such a wave power plant.

In a second aspect, the invention relates to a use of the invented switch- gear.

In a third aspect, the invention relates to a method for manufacturing such a switchgear.

Background of invention

The electric components in a switchgear generates heat. It is therefore necessary to provide for cooling of these components in some way. In many cases the required cooling can be transferred through the walls of the switchgear housing, provided that the heat can be transferred away from the exterior of the housing. A direct conduction of the heat from the components is normally the most effective way to lead away the heat, and that requires that the components contacts the housing wall directly or indirectly via a heat conductive material. The components thereby could be mounted on the wall. However, this leads to complications from a manufacturing point of view. Maintenance and repair of the components are also difficult.

The object of the present invention is to arrange conductive cooling of electric components in a switchgear in a way that simplifies a rational manufacturing, maintenance and repair of the switchgear and simultaneously assures an effective cooling.

Summary of invention

The object of the invention in achieved according to the first aspect thereof in that a switchgear of the kind initially specified includes the specific features that the switchgear includes a frame structure, that at least one cooling element is mounted on the frame structure, that at least one electric component is mounted on the at least one cooling element and that clamping means is mounted on the frame structure, which clamping means is arranged to press the at least one cooling element against an inner surface of the housing wall.

By mounting the components on a frame structure the flexibility at manufacturing, maintenance and repair is much better than if the components were mounted directly on the wall of the housing. The clamping means and the cooling elements allow that the electric components can be mounted on the frame structure before this structure is brought in place in the switchgear. When mounting the components accordingly, one is thus not hindered by the narrow space within the switchgear which makes this procedure simple and convenient. After the compo- nents and the cooling elements have been mounted, the frame structure is brought into place in the housing, and the cooling elements with the components mounted thereon are clamped against the wall of the housing. Also when components require maintenance, repair or exchange it is merely to release the clamping means and remove the housing or part thereof, and the operation can be made without the surrounding housing wall as an obstacle.

The cooling element of course should be of a material with good heat conduction properties. Metals, such as e.g. aluminium therefore are appropriate materials.

According to a preferred embodiment of the invented switchgear the cool- ing element is a cooling plate having an outer surface abutting said inner surface of the wall and having a mounting surface on the opposite side on which mounting surface said at least one electric component is mounted.

Having the cooling element in the shape of a plate results in a relatively short conduction distance. This shape also is geometrically advantageous to opti- mize the use of the available space within the housing.

According to a further preferred embodiment a plurality of electric components is mounted on the cooling plate and at least some of the electric components are mounted in a common box, which is mounted on the plate.

By mounting a plurality of components on each cooling plate the required number of cooling plates can be relatively low. By gathering a plurality of the components in a common box the mounting operations will be still further facilitated since the components could be pre-mounted in the box before attaching it to the cooling plate. Also a logical and well-arranged localization of the components thereby can be attained. According to a further preferred embodiment the clamping means includes spring means.

By the spring means the cooling plates can be strong and securely pressed against the wall of the housing in a very simple way.

According to a further preferred embodiment the frame structure is provided with actuating means arranged to activate or deactivate the clamping means.

This facilitates to arrange the frame structure with the cooling plates and the components in the housing as well as releasing it from the housing wall.

According to a further preferred embodiment the clamping means includes an individual clamping device for each cooling plate and the actuating means includes an actuating device for each clamping device.

This simplifies the general construction of the frame structure and its components.

According to a further preferred embodiment the actuating device includes at least one pneumatic or hydraulic cylinder.

Using such cylinders normally is the most efficient way to achieve a high actuation force. Preferably the actuating device has more than one cylinder, e.g. four cylinders.

According to a further preferred embodiment, the clamping device includes a plurality of mechanical pressure springs.

By using mechanical pressure springs to press the cooling plates against the wall, a strong a reliable clamping force is attained by very simple means. By employing a plurality of springs the clamping force can be well distributed over the surface of the cooling plate such that the cooling plate can abut the wall with similar pressure over a large area, thereby increasing the heat conduction. Normally four springs are sufficient.

According to a further preferred embodiment the frame structure includes a plurality of cooling plates arranged such that the forces on the clamping devices balance each other partly or completely.

Having a plurality of cooling plates provides a higher degree of flexibility and increases the cooling capacity. Further, the available space can be optimally utilized. Balancing the clamping force partly or completely reduces or eliminates, respectively, the force that has to be taken up by the frame structure, thereby it will be lower demands for a robust mounting of the frame structure.

According to a further preferred embodiment the outer surface of the cooling plate has a shape that corresponds to the shape of the inner surface of the part of the wall of the housing against which part the cooling plate abuts.

When these surfaces correspond to each other, the cooling plate will abut the housing wall with its entire surface which is advantageous for achieving a high heat conduction to the wall.

According to a further preferred embodiment a cooling paste is arranged between said outer surface of the cooling plate and the surface of said part of the wall.

The cooling paste will further increase the heat conduction to the wall since it will compensate for any irregularity between the matching surfaces that might create areas without direct contact between the two surfaces. The cooling paste fills up these voids and cerate heat conduction also at these areas.

According to a further preferred embodiment, the housing has a main section and a bottom section attached to the main section, the main section having a cylindric barrel wall and a top wall, the at least one cooling plate being arranged to abut the inner surface of the barrel wall, and the frame structure is supported by the bottom section.

Dividing the housing into these two sections simplifies the mounting of the frame structure in the switchgear. The frame structure can easily be mounted on the bottom section, and then the main section can be attached on the bottom section such that it surrounds the frame structure, whereafter the cooling plates are clamped against the barrel wall.

Preferably the cylindrical barrel wall has a circular cylindrical shape. Preferably the bottom section mainly consists of a bottom wall and possibly a short upwardly directed part for attachment to the main section. The main section thus forms almost the entire vertical walls of the housing.

Preferably the bottom section and the top wall of the main section are cup- shaped.

According to a further preferred embodiment, the housing is water tight and is arranged to be submerged. An important application of the invented switchgear is for submerged wave power driven generators, in which case it is appropriate that also the switchgear is submerged. This embodiment makes the switchgear particularly suitable for such applications. The surrounding sea water provides for an effective cooling of the housing.

The above specified preferred embodiments of the invented switchgear are set out in the dependent claims. It is to be understood that further preferred embodiments of course can be realized by any possible combination of preferred embodiments mentioned above.

A wave power plant according to the present invention including the invented switchgear, in particular according to any of the preferred embodiments thereof.

An electric network according to the present invention is connected to the invented switchgear, in particular to any of the preferred embodiments thereof.

A use according to the present invention includes that the switchgear is used for supplying energy to an electric network.

The method according to the present invention for manufacturing a switchgear having electric components and a housing enclosing the electric components includes the following specific measures;

- mounting at least one cooling element on a frame structure

mounting at least one electric component on the cooling element mounting clamping means on the structure arranged for clamping the at least one cooling element against an inner surface of the housing wall

- mounting actuating means on the structure, arranged to activate or deactivate the clamping means

providing a bottom section of the housing

mounting the frame structure on the bottom section,

mounting a main section of the housing to the bottom section such that the frame structure becomes enclosed, whereby the actuating means during this step keeps the clamping means deactivated affecting the actuating means to activate the clamping means after the mounting of the main section on the bottom section. According to preferred embodiments of the invented method it is performed for manufacturing a switchgear according to the present invention, in particular to any of the preferred embodiments thereof.

The invented wave power unit, the invented network, the invented use and the invented method have advantages of similar kind as those of the invented switchgear and the preferred embodiments thereof, and which have been described above.

The invention will be further explained through the following detailed de- scription of examples thereof and with reference to the accompanying drawings.

Brief description of the drawings

Fig. 1 is a schematic section through a switchgear according to the invention. Fig. 2 is a section along line II - II of fig. 1 .

Fig. 3 is a perspective view of a switchgear of a similar kind as that of fig. 1 . Fig. 4 is a perspective view of a detail of a switchgear according to the invention. Fig. 5 is a perspective view of a detail of fig. 4.

Fig. 6 is a schematic representation of a wave power plant according to the

invention.

Fig. 1 is a schematic vertical section through a switchgear according to the invention and fig. 2 is a section along line II - II of fig. 1 . The switchgear has electrical components 2, 3, such as rectifiers, filters, capacitors, semiconductors, IGBT:s, transformers, etc., of which some 2 generate heat and has to be cooled and others 3 do not need any substantial cooling.

The switchgear has an enclosing housing 1 , which is water-tight for submerged use. The housing consists of a main part 4 and a bottom part 5. The main part 4 is formed by a barrel wall 41 extending practically along the complete height of the switchgear and a top wall 42 made in one piece together with the barrel wall 41 . The main part 4 is mounted on the bottom part 5 by means of flanges 43, 53. The bottom part 5 is supported by feet 51 which rest on the sea bottom or a base plate. The housing has a diameter of 2 - 2,5 m.

Within the housing 1 there is a frame structure 6 of U-beams of steel. The frame structure has three vertical beams 61 attached to and supported by the bot- torn section 5. The vertical beams 61 are connected by three upper horizontal beams 62, and three lower horizontal beams 63.

The frame structure also has upper support beams 64 and lower support beams 65 supporting a clamping device. Each support beam 64 extends between two of the vertical beams 61 and consists of two identical sections forming an angle of 120° with each other. Each set of support beams 64, 65 thus form a regular hexagon as is best seen in fig. 2.

The electrical components 2 that require cooling are mounted on cooling plates 7 of aluminium which are pressed against the barrel wall 41 of the housing 1 by a clamping device, including springs 8, which are supported by the frame structure 6. Hydraulic cylinders 9 are mounted on the frame structure 6 by which cylinders 9 the cooling plates 7 can be withdrawn from their positions abutting the barrel wall 41 . In the view of fig. 1 each spring 8 is located behind a respective cylinder 9, and should be visible behind it. For clarity reason only the cylinder is illus- trated at three of the locations and on the fourth only the spring is illustrated and the cylinder 9 left out.

As can be seen in fig. 2 each cooling plate 7 has a segmental cross section with a planar inner mounting surface 71 and an outer surface 72 corresponding to the shape of the barrel wall 41 . The cooling plate and its related device is il- lustrated only on one of the six sides of the hexagon, and it is to be understood that there is a cooling plate on each of the other five sides as well and which are arranged in the same way.

Each cooling plate 7 is pressed by four springs acting close to each corner thereof. The springs 8 are supported by the support beams 64, 65 of the frame structure 6. One pair of springs 8 is attached to each side of the hexagon formed by the upper support beams 64. Springs 8 are correspondingly attached to the lower support beams 65. Also the hydraulic cylinders are correspondingly pairwise arranged to each side of the hexagons formed by the upper 64 and lower 65 support beams. The piston rod 91 of each cylinder is attached to a respective attach- ment flange 73 on the cooling plate 7.

When manufacturing the switchgear the frame structure is used to attach the components. The electrical components 2 that require cooling are mounted on the inner side 71 of each cooling plate 7. Then each cooling plate 7 is mounted to the frame structure 6 such that it is connected thereto by the two pairs of springs 8 and the two pair of hydraulic cylinders 9. The frame structure 6 is then attached to the bottom section 5 of the housing by attaching the lower end of each vertical beam 61 thereto. Alternatively the attachment of the frame structure 6 to the bottom section 5 can be done before the above described assembly or when only some of the assembly steps have been made.

When the frame structure 6 is secured to the bottom section 5 of the housing 1 , those electric components 3 that do not require cooling can be mounted inside the frame structure.

When the assembly work is completed the main section 4 is brought in place on the bottom section and secured thereto by bolts through the flanges 43, 53 on the lower end of the main section 4 and the upper end of the bottom section 5, respectively.

The main section 5 of the housing 1 now encloses the frame structure 6 and all its components. When putting the main section 5 in place the hydraulic cyl- inders 9 are pressurized in which state the piston rod 91 of the respective cylinder 9 is in the retracted position whereby the cooling plates 7 are pulled towards the frame structure 6 against the action of the springs 8. In that position the cooling plates 7 thus are withdrawn from is normal operation positions and leaves a free space so that the main section 4 easily can be brought in place.

After the two sections 4 and 5 are attached to each other the pressure in the hydraulic cylinders is released whereby the springs 8 will press the cooling plates against the inner surface of the barrel wall 41 of the main section 4. Should the switchgear need to be demounted, e.g. for service or repair, the hydraulic cylinders are pressurized and the cooling plates 7 are withdrawn from contact with the barrel wall 41 .

Fig. 3 illustrates the switchgear in a perspective view before mounting the main section thereto and with some parts thereof left out for clarity reasons. Thus the two cooling plates on the front is left out and also the hydraulic cylinders,

Fig. 4 is a perspective view of one of the cooling plates 7 and its connec- tion to the frame structure. The cooling plate 7 is illustrated in its withdrawn position, when the hydraulic cylinders 9 are pressurized, retracting the piston rods 91 , whereby the springs 8 are compressed. The electric components are located in two boxes 21 attached to the cooling plate. Fig. 5 in a perspective view illustrates a part of the cooling plate 7 in fig. 4. The outer surface 72 thereof is coated with a cooling paste 74, i.e. a gel having good heat conduction properties.

Fig. 6 illustrates a wave power plant consisting of five wave power units with generators 102a - 102e connected to a common switchgear 100 through a respective connection 101 a-101 e. The switchgear 100 supplies the energy to an electric network 104.

Claims

1 . A switchgear including electric components (2, 3) and a housing (1 ) enclosing the electric components (2, 3) characterized in that the switchgear further includes a frame structure (6), in that at least one cooling element (7) is mounted on the frame structure (6), in that at least one electric component (2) is mounted on the at least one cooling element (7) and in that clamping (8) is mounted on the frame structure (6), which clamping means is arranged to press the at least one cooling element (7) against an inner surface of the housing wall (41 ).

2. A switchgear according to claim 1 characterized in that the cooling element (7) is a cooling plate (7) having an outer surface (72) abutting said inner surface of the wall (41 ) and having a mounting surface (71 ) on the opposite side on which mounting surface (71 ) sad at least one electric component (2) is mounted.

3. A switchgear according to claim 2 characterized in that a plurality of electric components (2) is mounted on the cooling plate (7) and in that at least some of the electric components are mounted in a common box (21 ), which is mounted on the plate (7).

4. A switchgear according to claim 2 or 3 characterized in that the clamping means (8) includes spring means (8).

5. A switchgear according to any of claims 2 - 4 characterized in that the frame structure (6) is provided with actuating means (9) arranged to activate or deactivate the clamping means (8).

6. A switchgear according to claim 5 characterized in that the clamping means includes an individual clamping device (8) for each cooling plate (7) and the actuating means (9) includes an actuating device (9) for each clamping device.

7. A switchgear according to claim 6 characterized in that the actuating device (9) includes at least one pneumatic or hydraulic cylinder (9).

8. A switchgear according to claim 6 characterized in that the clamping device (9) includes a plurality of mechanical pressure springs (8).

9. A switchgear according to claim 7 or 8 characterized in that the frame structure includes a plurality of cooling plates (7) arranged such that the forces from the clamping devices (8) on the frame structure (6) balance each other partly or completely.

10. A switchgear according to claim 2 characterized in that the outer surface (72) of the cooling plate has a shape that corresponds to the shape of the inner surface of the part of the wall (41 ) of the housing (1 ) against which part the cooling plate (7) abuts.

1 1 . A switchgear according to claim 10 characterized in that the a cooling paste (74) is arranged between said outer surface (72) of the cooling plate (7) and the surface of said part of the wall (41 ).

12. A switchgear according to claim 2 characterized in that the housing (1 ) has a main section (4) and a bottom section (5) attached to the main section (1 ), the main section (1 ) having a cylindric barrel wall (41 ) and a top wall (42), the at least one cooling plate (7) being arranged to abut the inner surface of the barrel wall (41 ), and in that the frame structure (6) is supported by the bottom section (5).

13. A switchgear according to claim 2 characterized in that the housing (1 ) is water tight and being arranged to be submerged.

14. A wave power plant characterized in that the plant includes a switchgear (100) according to claim 13 and a plurality of wave power driven generators (102a) connected to the switchgear (100).

15. An electric network (104) characterized in that the network is connected to a switchgear (100) according to claim 14.

16. A method for manufacturing a switchgear, which switchgear includes electric components and a housing enclosing the components, characterized in that the method includes the steps of

- mounting at least one cooling element on a frame structure

- mounting at least one electric component on the cooling element

- mounting clamping means on the frame structure arranged for clamping the at least one cooling element against an inner surface of the housing wall

- mounting actuating means on the frame structure, arranged to activate or deactivate the clamping means

- providing a bottom section of the housing

- mounting the frame structure on the bottom section

- mounting a main section of the housing to the bottom section such that the frame structure becomes enclosed, whereby the actuating means during this step keeps the clamping means deactivated

- affecting the actuating means to activate the clamping means after the mounting of the main section on the bottom section.

17. A method according to claim 16 characterized in that the method is performed for mounting a switchgear as specified in any of claims 1 - 14.