Switchgear assembly

Technical Field

The invention relates to a switchgear assembly comprising an electric switchgear and a support structure supporting the electric switchgear, wherein the support structure comprises a plurality of damping devices configured for damping mechanical impacts of the electric switchgear, at least two of the plurality of damping devices are arranged on opposite sides on the support structure, and each damping device comprises a helical coil, an upper stabilizer attached to the support structure and a lower stabilizer configured for placing on an underground.

Background Art

Because of the needs for the offshore wind power, floating substations as well as floating wind turbines are developed and applied to offshore environment. In such case, a power grid equipment such as high voltage switchgear, typically called Plug And Switch System, PASS, located in the wind turbine will endure an offshore floating environment including long term vibration, shock, swing and tilting etc.

Without certain vibration and/or shock absorption solutions, large weight equipment can hardly endure in long term floating condition because physical and/or structure damage will occur. In addition to physical damage, the long-term floating environment will also cause the failure of a control box which is the weakest part on the switchgear. The failure of the control box will lead the failure of an insulating function of the switchgear.

Floating condition refers to a floating platform which utilizes a cable connected to an ocean bottom. Compared with offshore fixed platform, floating platforms have more severe requirements including 45 degrees tilting and 22.5 degrees swinging, shock and fixed frequency vibration. Thus, a need exists for a damping solution for high voltage switchgear, which not only has the advantages of vibration reduction and shock absorption, but also has suitable stiffness to protect from the large-scale tilting and swinging.

Summary of invention

It is an object of the present invention to provide an improved switchgear assembly for an offshore wind turbine and a damping device for an electric switchgear.

The object of the invention is solved by the features of the independent claims. Preferred implementations are detailed in the dependent claims.

Thus, the object is solved by a switchgear assembly comprising an electric switchgear and a support structure supporting the electric switchgear, wherein the support structure comprises a plurality of damping devices configured for damping mechanical impacts of the electric switchgear, at least two of the plurality of damping devices are arranged on opposite sides on the support structure, each damping device comprises a helical coil, an upper stabilizer attached to the support structure and a lower stabilizer configured for placing on an underground, the helical coil is hold by the upper stabilizer and the lower stabilizer in horizontally distant upper and lower positions and, of the at least two on opposite sides arranged damping devices, the upper positions are closer or further away from each other than the lower positions.

The proposed solution provides, compared to existing anti-vibration solutions which utilize wire-rope dampers, not only vibration reduction in three directions but also high stiffness which help to survive in 45° tilting and 22.5° swing condition. Moreover, due to a floating condition which includes random vibration and fixed frequency vibration, the proposed damping device protects from 90 minutes fixed frequency vibration endurance and 5g 11 ms shocks. The high stiffness provided by the proposed solution provides better support during required tilting and swinging test and a suitable damping ratio helps to control an amplification factor during a sweep frequency vibration. Moreover, compared to other types of dampers known from prior art such as rubber absorber and hydraulic damper, the proposed damping device is easy to be assembled and maintained, and is endurable in an offshore corrosion environment. Experimental tests have shown that the proposed damping device provides a better vibration reduction effect compared to other types of dampers.

The term that the upper positions are closer or further away from each other than the lower positions of the at least two on opposite sides arranged damping devices means preferably that, if the upper positions are closer than the lower positions, the on opposite sides arranged damping devices are inclined towards each other, thereby mitigating transversal vibrations. The same applies if the upper positions are further away from each other than the lower positions such that the opposite arranged damping devices are disinclined from each other. The term position shall be preferably be understood as the geographical point where the helical coil is hold by the upper stabilizer respectively the lower stabilizer. The term stabilizer should preferably be understood as means for holding the helical coil in the respective position. Preferably the stabilizer is provided as clamp. More preferably the stabilizer allows adjusting an inclination angle towards the helical spring, in order to adjust a stiffness of the damping.

The electric switchgear may be a high voltage switchgear, i.e. , a switchgear with a rating voltage above 52 kV to 420 kV with breaking current capability ranging from 31.5 to 63 kA. The electric switchgear may be a gas-filled switchgear. The switchgear may be configured for a wind turbine, such as an offshore wind turbine, for example. The switchgear may be provided as a power grid equipment such as high voltage switchgear, typically called “PASS”, and/or may include electrical disconnect switches, fuses and/or circuit breakers used to control, protect and isolate electrical equipment, such as the wind turbine.

The support structure can be understood as a frame on which the electric switchgear is placed, thereby carrying the entire weight of the switchgear, preferably made of metal. The support structure may comprise two on opposite sides and distant arranged metal rods. The damping devices are preferably arranged at opposite sides of the support structure, for example at the metal rods. The damping devices may also be arranged respectively associated to comers of the support structure. The support structure may comprise a rectangle like shape. The helical coil is elastically deformable and dampens mechanical impacts. The helical coil may be designed such that it dampens mechanical impacts both from vertical, transversal and longitudinal directions. Accordingly, the helical coil can be sufficiently elastically deformable in all three directions. The helical coil can be made from stainless steel, for example.

As an example, the damping device comprises four helical coils located at four corners of the support structure. The helical coil may be positioned such that a longitudinal axis extends parallel to a mounting surface of the support structure. This orientation of the helical coil ensures that the weight of the switchgear can be taken up and sufficient damping in all three directions can be ensured. The geometry of the coil, such as outer dimension and pitch, can be optimized according to the weight and mass distribution of the switchgear and the required damping in the spatial directions. The upper stabilizer may be attached to the support structure by welding or by a bolted connection. The lower stabilizer is preferably also configured for connecting by means of a bold to the underground, such for example a floor.

The damping device may be configured for damping mechanical impacts due to intermittent or constant vibrations of mechanical parts of the wind turbine during operation. As an example, such mechanical parts may be motors which may be used for operation of a circuit breaker. As a further example, such mechanical parts may be rotors of the wind turbine, which may lead to a constant vibration during their rotation.

According to a preferred implementation the helical coil is led through the upper stabilizer and the lower stabilizer and/or the helical coil comprises a wire-rope. The upper stabilizer and/or the lower stabilizer may have the shape of bar. The upper stabilizer and/or the lower stabilizer may enclose a defined angular section of the coil, thereby holding the coil in a defined position. A longitudinal axis of the helical coil preferably extends parallel to a mounting surface of the support structure.

In another preferred implementation a line drawn between the upper and lower positions is inclined by 22,5°, by 30°, by 45°, by 60° or by 90°, in particular in respect to the underground. In our words, the upper and lower positions are not vertically above each other, but are rather inclined. In respect to two on opposite sides arranged damping the rises this means that the opposite upper and lower positions are preferably both inclined respectively both disinclined towards each other.

According to a preferred implementation the switchgear assembly comprises an upper connector attached to and arranged between the upper stabilizer and the support structure and a lower connector attached the lower stabilizer and configured for placing on the underground, whereby, in axial direction of the coil, the upper connector and the lower connector comprise a triangular shape. Such wise the line drawn between the upper and lower positions can be realized inclined by 22,5°, by 30°, by 45° or by 60°, in particular in respect to the underground. In other words, due to the triangle shape, in particular in side, the horizontal displacement between the upper and lower positions can be achieved. Specifically, the upper connector and/or the lower connector can be provided as 45° oriented converter plates. Thereby, one side of the upper connector can be attached to the support structure, while the other 45° oriented side can be attached to the upper stabilizer. In an analogous manger, one side of the upper connector can be attached to the upper stabilizer, while the other 45° oriented side can be attached to the underground, for example by screws.

In another preferred implementation the switchgear assembly comprises at least three damping devices of which two damping devices are arranged on a same side of the support structure, wherein the upper position of one of the same side damping devices is arranged horizontally distant to the upper position of the other one of the same side damping devices and the lower position of the same side damping devices is arranged horizontally distant to the lower position of the one of the same side damping devices. In other words, two of the damping devices arranged on the same side are oriented opposite to each other i.e. inclined towards each other. Such wise transversal vibrations can be mitigated even more effective. The 45° orientation can obtain an optimized stiffness and/or damping ratio at tilting and swinging condition, in particular according to vibration/ti Iting/swing test method for electrical installations in ships as per GB_T 2423.101-2008 or GB_T 7094-2016, such that a stiffness of the helical coil is different in three directions x, y, z.

According to a preferred implementation the support structure comprises two the opposite sides, a first plurality of damping devices, preferably four damping devices, is arranged on one side and a second plurality of damping devices preferably four damping devices, is arranged one the other side. Such implementation has been proven very reliable for effectively mitigating transversal vibrations. Thereby preferably all of the first plurality of damping devices and all of the second plurality of damping devices are inclined towards each other. Preferably each two damping devices are arranged opposite and inclined towards each other.

In another preferred implementation the support structure comprises a third side orthogonal to the two opposite sides, whereby a third plurality of damping devices preferably four damping devices, is arranged on the third side. The third side preferably is arranged in-between a longitudinal extension of the two opposite sides, for example around a middle or one third of the longitudinal extension. The third plurality of damping devices can all be inclined in the same direction or in different directions. Such third side of damping devices allows to solving an uneven distribution of center of mass of the electric switchgear.

According to a further preferred implementation the damping device is configured for damping vibrations in a frequency range between 10 Hz and 200 Hz, preferably between 10 Hz and 100 Hz. The vibration caused during normal operation of the wind turbine may be characterized by one or more specific frequencies and/or amplitudes. As an example, a specific frequency may be in the range of 1 to 200 Hz. More specifically, such frequencies may be in the range of 40 Hz and 200 Hz or in the range of 40 Hz to 80 Hz. Generally, the frequencies of vibrations during normal operation may be larger than frequencies caused by inadvertent and/or extreme outer impacts such as earthquakes or inadvertent shocks during transport or installation of the device. The amplitudes of vibrations caused during normal operation may be generally smaller than the amplitudes caused by earthquakes or inadvertent shocks during transport or installation of the electric switchgear.

In another preferred implementation the support structure comprises an upper rigid support and a lower rigid support, whereby the upper rigid support supports the electric switchgear and is attached to all upper stabilizers and/or all upper connectors and the lower rigid support is configured for placing on the underground and is attached to all lower stabilizers and/or lower connectors. The switchgear may be directly fixed to the upper rigid support. The support structure and/or the lower rigid support may comprise a mounting surface for mounting the switchgear assembly on a floor as underground at an installation site. The floor and/or underground may be a floor of a wind turbine tower, for example. The support structure may also serve to securely fix the switchgear assembly to the floor. The support structure may be thereby be fixed to the floor by bolts. The damping device may be located between the upper rigid support and the lower rigid support.

According to a preferred implementation the at least two of the damping devices comprise different damping characteristics. For example, one of the at least two of the damping devices may most effectively mitigate vibrations in the range of 1 to 200 Hz, while another one of the at least two of the damping devices may most effectively mitigate vibrations in the range of 40 Hz to 80 Hz. Such wise a more efficient damping can be achieved.

In another preferred implementation one of the damping devices is configured for damping vibrations of a lower frequency than another one of the damping devices. For example, one of the at least two of the damping devices may most effectively mitigate vibrations in the range of 1 to 100 Hz, while another one of the at least two of the damping devices may most effectively mitigate vibrations in the range of 100 Hz to 200 Hz. Such wise a more efficient damping can be achieved.

According to a preferred implementation the switchgear assembly as described before is configured for a wind turbine, whereby the plurality of damping devices are configured for damping mechanical impacts due to vibrations during operation of mechanical parts of the wind turbine, preferably of an off-shore wind turbine. The wind turbine may comprise mechanical parts such as motors which may be used for operation of a circuit breaker. As a further example, such mechanical parts may be rotors of the wind turbine, which may lead to a constant vibration during their rotation. In this respect the underground can a floor of the wind turbine.

The object is further solved by a wind turbine comprising the switchgear assembly as described before. The switchgear assembly may be installed in a section of a wind turbine tower, whereby the section may be a bottom section of the tower, where the switchgear assembly is installed on a floor thereof as underground.

The object is further solved by a use of a damping device for supporting an electric switchgear in a wind turbine as described before and damping mechanical impacts due to vibrations during operation of mechanical parts of the wind turbine.

The object is further solved by a method of manufacturing a switchgear assembly, the method comprising the steps of: providing an electric switchgear, and providing a support structure for supporting the electric switchgear, wherein the support structure comprises a plurality of damping devices configured for damping mechanical impacts of the electric switchgear, at least two of the plurality of damping devices are arranged on opposite sides on the support structure, each damping device comprises a helical coil, an upper stabilizer attached to the support structure and a lower stabilizer configured for placing on an underground, the helical coil is hold by the upper stabilizer and the lower stabilizer in horizontally distant upper and lower positions and, of the at least two on opposite sides arranged damping devices, the upper positions are closer or further away from each other than the lower positions.

In a preferred implementation the method comprises the step of: determining one or more frequencies and/or amplitudes of vibrations during normal operation of a wind turbine, wherein the plurality of damping devices are configured for damping mechanical impacts of the determined frequencies and/or amplitudes.

Such way the damping devices may be optimized for damping the determined frequencies and/or amplitudes and may have a minor damping functionality for other frequencies and/or amplitudes, thereby in sum resulting in a more efficient damping.

Further implementations and advantages of the method are directly and unambiguously derived by the person skilled in the art from the assembly as described before.

Brief description of drawings

These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.

In the drawings:

Fig. 1 shows a schematic, partially sectional view of a part of a wind turbine tower comprising a switchgear assembly according to a preferred implementation,

Fig. 2 shows a perspective view of the switchgear assembly comprising a support structure of Fig. 1 according to the preferred implementation,

Fig. 3 shows a perspective view of the support structure of Fig. 2 comprising a plurality of damping devices according to the preferred implementation, and

Fig. 4 shows a perspective view of a single damping device 12 of Fig. 3 according to the preferred implementation.

Description of implementations Fig. 1 schematically shows a switchgear assembly 1 in a section 2 of a wind turbine tower 3 according to a preferred implementation.

The section 2 is a bottom section of the tower 3. The switchgear assembly 1 is positioned and fixed on a floor as underground 4 inside the tower 3. A nominal height of such an offshore wind turbine tower 3 is more than 150 m and such wind turbine has a capacity of at least 5 MW. Therefore, the tower 3 cannot be transported in a single piece but in several sections. The individual sections are pre-assembled with auxiliary equipment, such as a switchgear, control panel, trans former and other equipment. The sections are individually transported to a final site by sea and/or road transport.

Fig. 2 shows the switchgear assembly 1 of Fig. 1 in a more detailed schematic view comprising an electric switchgear 5 and a support structure 6 supporting the electric switchgear 5. The electric switchgear 5 comprises a variety of circuit breakers, fuses etc. not discussed in more detail, operating on voltages from 72.5 to 420 kV with breaking current capability ranging from 31 .5 to 63 kA. The electric switchgear 5 is firmly fixed onto the metal support structure 6 having a rectangle like form by means of bolts.

Fig. 3 shows the support structure 6 in more detail without the electric switchgear 5 installed thereon. The support structure 6 comprises a plurality of damping devices 12, namely twelve damping devices 12 each configured for damping mechanical impacts of the electric switchgear 5.

Fig. 4 shows a single damping device 12 in more detail. Each damping device 12 comprises a helical coil 14, an upper stabilizer 16 and a lower stabilizer 17. The helical coil 14 provided as a wire-rope is led on opposite sides through the upper stabilizer 16 and the lower stabilizer 17 at respective upper and lower positions 18, 19. Such wise the upper stabilizer 16 and the lower stabilizer 17 respectively the upper and lower positions 18, 19 a hold distant from each other. Further, the upper stabilizer 16 respectively the upper position 18 is arranged horizontally displaced the from the lower stabilizer 17 respectively the lower position 19. Such wise a line drawn between the upper and lower positions 18, 19 is inclined. In order to achieve said horizontal displaced position, each damping device 12 further comprises an upper connector 20 and a lower connector 21 , each provided as metal comprising a triangular shape in axial direction of the helical coil 14. The upper connector 20 is firmly attached to the upper stabilizer 16, while the lower connector 21 is firmly attached to the lower stabilizer 17. Such wise the upper and lower positions 18, 19 are displaced by 45° respectively the line drawn between the upper and lower positions 18, 19 is inclined by 45°. Beside that, other angles such as for example 22,5°, 30° or 60° are possible as well. The upper connector 20 and the lower connector 21 thereby surround the upper stabilizer 16, the helical coil 14 and the lower stabilizer 17. The upper stabilizer 16 and the lower stabilizer 17 are each provided two-part as flat metal rods, wherein the helical coil 14 is fixed between the two parts connected together.

Turning back to Fig. 4, the support structure 6 comprises twelve damping devices 12, whereas each four damping devices 12 are arranged opposite to each other and in a row along a longitudinal edge of the support structure 6. Specifically, the support structure 6 comprises an upper rigid support 10 and a lower rigid support 11 each made of parallel and distantly arranged metal rods and defining a rectangular support for the electric switchgear 5. The upper connector 20 is firmly attached by screws to the upper rigid support 10 such wise arranged on the upper connector 20, whereby the upper connector 20 is firmly attached by screws to the lower rigid support 11 , which is configured for placing on the underground 4, where it is fixed to the underground 4 by screws as well. While each two on opposite sides damping devices 12 are arranged close to longitudinal ends of the support structure 6, two other opposite arranged damping devices 12 are arranged side by side around in the middle between the longitudinal ends of the support structure 6. Thereby each one damping device 12 is arranged opposite to one other damping device 12.

For these opposite arranged damping devices 12, the upper positions 18 are closer than the lower positions 19. In other words, the damping devices 12 arranged along the longitudinal sides are all inclined towards the respective opposite arranged damping device 12. The damping devices 12 are configured for damping vibrations in a frequency range between 10 Hz and 200 Hz, preferably between 10 Hz and 100 Hz. Thereby at least one pair of opposite arranged damping devices 12 comprise different damping characteristics i.e. damp different frequency ranges.

As explained, the opposite arranged damping devices 12 of the implementation shown in Fig. 3 are each inclined towards the opposite arranged damping device 12. While not shown, in another implementation one of two damping devices 12 arranged on a same longitudinal side can be arranged horizontally distant to the upper position 18 of the other one of the damping devices 12 arranged on the same longitudinal side, while the lower position 19 of the damping devices 12 arranged on the same longitudinal side is arranged horizontally distant to the lower position of the one of the same side damping devices 12. In other words, along the longitudinal side one damping device 12 can be inclined inwards, while one other damping device 12 can be inclined outwards in another direction.

As can be further seem from Fig. 3, the support structure 6 respective the upper rigid support 10 and the lower rigid support 11 each comprise a third metal rod orthogonally extending between the before described longitudinal rods at a third side 22. The four remaining damping devices 12 are arranged at these two distant third metal rod of the upper rigid support 10 and the lower rigid support 11. These four remaining damping devices 12 are all inclined in the same direction.

In a respective method of manufacturing such switchgear assembly 1 , first one or more frequencies and/or amplitudes of vibrations during normal operation of the wind turbine can be determining. In a second the plurality of damping devices 12 can be manufactured respectively configured for damping mechanical impacts of the determined frequencies and/or amplitudes. In other words the plurality of damping devices 12 can be manufactured so as to most effectively damp vibrations at the determined frequencies and/or amplitudes.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed implementations. Other variations to be disclosed implementations can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.

Reference signs list

1 switchgear assembly

2 section

3 tower

4 floor

5 electric switchgear

6 support structure

10 upper rigid support

11 lower rigid support

12 damping device

14 helical coil

16 upper stabilizer

17 lower stabilizer

18 upper position

19 lower position

20 upper connector

21 lower connector

22 third side