LU100169B1

LU100169B1 - Support structure for high voltage unit, system and method

Info

Publication number: LU100169B1
Application number: LU100169A
Authority: LU
Inventors: Axel Johansson
Original assignee: Abb Schweiz Ag
Priority date: 2017-04-10
Filing date: 2017-04-10
Publication date: 2018-05-25

Abstract

Support structure (14) for a high voltage unit (12), the support structure (14) comprising a plurality of post insulators (18) for supporting the high voltage unit (12) on a support surface (16); at least one elongated flexible element (28) arranged to be tensioned between at least two of the post insulators (18); and at least one damping device (34) arranged to damp movements (36) of an associated elongated flexible element (28) to reduce lateral sway (42) of the support structure (14). A high voltage system (10) comprising a high voltage unit (12) and a support structure (14) and a method of installing a high voltage system (10) comprising a high voltage unit (12) and a support structure (14) are also provided

Description

SUPPORT STRUCTURE FOR HIGH VOLTAGE UNIT, SYSTEM AND METHOD

Technical Field

The present disclosure generally relates to a support structure for a high voltage unit. In particular, a support structure for a high voltage unit comprising an elongated flexible element and a damping device, a high voltage system comprising a high voltage unit and a support structure and a method of installing a high voltage system comprising a high voltage unit and a support structure, are provided.

Background

High voltage equipment requires a large insulation distance to ground. When the equipment is placed standing on the ground, such as on the floor, long post insulators are required between the equipment and the ground. The equipment can be heavy, e.g. 20 to 30 metric tons. During a seismic event, the loads in these post insulators can be very high, especially the bending moment. The post insulators have a tendency to not be capable of handling these bending loads.

One type of known solution to handle these loads is to use stiff cross bracings. This may be done by attaching stiff insulators in a cross configuration between the, typically four, post insulators and seismic loads may be absorbed by tension and/or compression of the cross bracing insulators instead of bending moment in the post insulators. CN 104852603 A describes a multi-level voltage source current converter valve tower. The tower is supported by a support structure comprising a plurality of vertical insulators. Cross bracings are arranged between the vertical insulators. JP H06207479 A relates to a structure comprising horizontal beams and vertical flexible columns. Movements of the beams are transferred to a Hamper via a wire. JP H06207479 A is not suitable for supporting high voltage equipment.

Summary

By using insulators arranged as a cross bracing between the post insulators, very high loads are introduced to the cross bracing insulators and to the attachment points thereof. For high seismic levels, this solution is not applicable.

One object of the present disclosure is to provide a support structure for a high voltage unit capable of handling loads during a seismic event. A further object of the present disclosure is to provide a support structure for a high voltage unit capable of handling higher loads during a seismic event in comparison with prior art support structures. A still further object of the present disclosure is to provide a support structure for a high voltage unit that reduces the loads on the post insulators. A still further object of the present disclosure is to provide a support structure for a high voltage unit eliminating the need for cross bracings. A still further object of the present disclosure is to provide a support structure for a high voltage unit having a simple, cheap, reliable and/or compact design. A still further object of the present disclosure is to provide a support structure for a high voltage unit enabling a simple and/or effective installation and/or maintenance. A still further object of the present disclosure is to provide a high voltage system comprising a high voltage unit and a support structure for the high voltage unit solving at least one of the foregoing objects. A still further object of the present disclosure is to provide a method of installing a high voltage system comprising a high voltage unit and a support structure for the high voltage unit solving at least one of the foregoing objects.

According to one aspect, there is provided a support structure for a high voltage unit, the support structure comprising a plurality of post insulators for supporting the high voltage unit on a support surface; at least one elongated flexible element arranged to be tensioned between at least two of the post insulators; and at least one damping device arranged to damp movements of an associated elongated flexible element to reduce lateral sway of the support structure. The associated elongated flexible element may be one of the at least one elongated flexible element.

When the support structure sways laterally or swings, e.g. during a seismic event, the sway movements of the high voltage unit will be transferred via the at least one elongated flexible element to the at least one damping device. By introducing the at least one damping device to the support structure, a part of the energy of a seismic wave can be consumed by the damping device. The support structure according to this aspect is relatively flexible due to the energy absorption of the at least one damping device during a seismic event. In comparison with prior art solutions for high voltage units, the support structure can absorb higher seismic forces without mechanical failure.

When the elongated flexible element is tensioned between the at least two of the post insulators, there will be a significant movement of the associated damping device for a certain deflection of the support structure, due to, for example, a seismic event. The damping of the support structure by the at least one damping device via at least one elongated flexible element can eliminate the need for cross bracings. One further advantage associated with this is that broken components can be replaced easily.

The post insulators may be oriented substantially vertically, or inclined, such as at least 50, such as at least io°, with respect to a vertical axis. A post insulator according to the present disclosure may alternatively be referred to as an insulated rod, insulated bar, insulated column or insulated strut. The post insulators have an elongated appearance and may be substantially straight. The support structure according to the present disclosure may be constituted by a standing support structure.

The high voltage unit according to the present disclosure may for example be constituted by a high voltage direct current (HVDC) semiconductor valve structure. Further examples of high voltage units are capacitor and breaker applications. A high voltage within the present disclosure may be a voltage of at least 100 kV. Thus, a high voltage system according to the present disclosure may have a system voltage of at least loo kV.

The support surface may be constituted by a valve hall floor. However, in case the high voltage system is arranged in a valve hall, the support surface may or may not be constituted by a valve hall floor. The support surface may for example be constituted by a part of a valve carrying scaffold. The support surface may be planar. In addition, the support surface may be horizontal or substantially horizontal.

According to one variant, the support structure comprises four post insulators, four elongated flexible elements and four damping devices. Each damping device may be arranged to damp movements of one of the elongated flexible elements. Moreover, each elongated flexible element may be tensioned between two outer post insulators.

The at least one elongated flexible element may however be arranged in various alternative ways relative to the post insulators and the one or more damping devices. According to two further variants, the support structure comprises four post insulators, two elongated flexible elements and two damping devices. Each damping device may be arranged to damp movements of one of the elongated flexible elements. In the first variant, each elongated flexible element may be tensioned diagonally between two post insulators. In the second variant, each elongated flexible element may be tensioned between two outer post insulators, e.g. one elongated flexible element may extend in a first horizontal direction and one elongated flexible element may extend in a second horizontal direction, substantially perpendicular to the first horizontal direction.

According to a still further variant, the support structure comprises four post insulators, only one elongated flexible element and only one damping device arranged to damp movements of the elongated flexible element. In this variant, the elongated flexible element may be tensioned between any two of the four post insulators.

Throughout the present disclosure, the at least one elongated flexible element may comprise, or may be constituted by, a wire rope, cable or chain. The at least one damping device may be attached to a stationary structure, e.g. to the ground.

The at least one damping device may comprise, or may be constituted by, a viscous damper. The viscous damper may be a linear viscous damper arranged substantially parallel with a portion of the at least one elongated flexible element. A linear viscous damper comprises one or more members moving linearly to and from one or more chambers. The linear viscous damper may be substantially horizontally arranged.

The at least one damping device may be arranged adjacent to the support surface. This solution facilitates maintenance of the damping device. Moreover, this solution enables a large insulation distance between the at least one elongated flexible element and the high voltage unit, e.g. by means of tension insulators. For example, the at least one damping device may be arranged within one meter, such as within 0.5 meters, such as within 0.3 meters, from the support surface.

The support structure may further comprise two tension insulators associated with one of the at least one elongated flexible element and connected to a respective end of the elongated flexible element for insulating the elongated flexible element from the high voltage unit. The length of the tension insulators may be adjusted to provide a necessary insulation distance to the elongated flexible element. Each tension insulator may be fixedly attached, or rotationally coupled, to one of the post insulators.

The tension insulators may be of the same type as the post insulators, or of a different type, to insulate the elongated flexible element from the high voltage unit. The name tension insulators is used to distinguish these insulators from the post insulators of the support structure, which are mainly compression insulators. When the tension insulators are connected to a respective end of the elongated flexible element, the tension insulators are pulled (tensioned) by the elongated flexible element as the support structure sways laterally. Throughout the present disclosure, the post insulators may alternatively be referred to as primary insulators and the tension insulators may alternatively be referred to as secondary insulators.

The two tension insulators may be non-parallel. For example, the two tension insulators may be arranged in an X-configuration between two of the post insulators. For example, the at least one elongated flexible element and the two associated tension insulators may be arranged in a single plane, e.g. substantially parallel with the vertical direction or inclined with respect to the vertical direction. Furthermore, the at least one elongated flexible element, alone or together with the two associated tension insulators, may be arranged in a loop configuration. The two tension insulators may be arranged above the at least one damping device.

The support structure may further comprise at least one elastic element configured to bias or force the support structure into a neutral position, e.g. an upright position. In this manner, a mechanical spring effect may be created. During lateral sway of the support structure, the at least one elastic element deforms elastically and provides a restoring counter force, proportional to the deformation of the elastic element, forcing the support structure towards the neutral position.

The properties of the at least one elastic element and the damping constant of each of the at least one damping device may be tuned to optimize the structural response of the support structure. In case no such elastic elements are provided, higher mechanical demands are put on the post insulators.

According to one variant, the support structure comprises one elastic element associated with each post insulator. According to a further variant, the support structure comprises one elastic element associated with several, or all, of the post insulators. In any case, the at least one elastic element may be arranged below, e.g. at the bottom of, each post insulator.

The at least one elastic element may be arranged functionally in parallel with the at least one damping device. If a post insulator is connected to the support surface both via the elastic element and via the elongated flexible element and the at least one damping device, the elastic element is arranged functionally in parallel with the at least one damping device.

The at least one elastic element may be constituted by a plate arranged between the support surface and an associated post insulator and connected to the support surface and to the associated post insulator. One plate may be associated with each post insulator of the support structure, e.g. the support structure may comprise four post insulators and four plates. Each plate may be made of steel. As an alternative to plates, each of the at least one elastic element may be constituted by a matrix of mechanical coil springs.

The support structure may further comprise at least one joint associated with each post insulator such that the post insulators are arranged to support the high voltage unit via the at least one joint. This is beneficial since the high voltage unit and the post insulators may be sensitive for large bending moments. The post insulators may for example be made of porcelain or epoxy. For example, a high voltage unit comprising a light valve and epoxy beams is sensitive to large bending moments. One joint may be arranged on top of each post insulator.

The at least one joint may be a universal joint, e.g. a joint comprising two or more substantially perpendicular rotational axes. As an alternative example, the at least one joint may be a ball joint. When one or more of the post insulators are arranged to support the high voltage unit via a universal joint (or ball joint), relative tilting forces of the high voltage unit are not transmitted to the post insulator.

The support structure may further comprise at least one wheel or pulley associated with the at least one elongated flexible element and the at least one elongated flexible element may be wound around the at least one pulley. A pulley support for rotationally supporting the pulley may be fixedly connected, directly or indirectly, to an associated post insulator or to the support surface.

According to one variant, the support structure comprises two pulleys associated with the at least one elongated flexible element and the at least one elongated flexible element is wound around the two pulleys. The two pulleys may be arranged substantially aligned with the lower attachment point of a respective post insulator. The at least one elongated flexible element may thereby comprise a relatively long portion extending between the two lower attachment points of the two post insulators. This allows for an efficient performance of the damping device. Moreover, this solution allows for a compact design of the support structure.

The support structure may further comprise a carrier fixedly connected to the at least one elongated flexible element and fixedly connected to the at least one damping device. The carrier may be guided in a slot in the support surface.

According to a further aspect, there is provided a high voltage system comprising a high voltage unit and a support structure according to the present disclosure for supporting the high voltage unit on a support surface.

According to a further aspect, there is provided a method of installing a high voltage system comprising a high voltage unit and a support structure according to the present disclosure, the method comprises determining the Eigen frequency of the high voltage system; determining a required stiffness of at least one elastic element to match the Eigen frequency of the high voltage system; providing the at least one elastic element; and arranging the at least one elastic element to bias the support structure into a neutral position. The step of providing the at least one elastic element may comprise providing at least one elastic element constituted by a plate having a thickness corresponding to a stiffness closest to the required stiffness.

As used herein, a substantially perpendicular/parallel relationship includes a perfectly perpendicular/parallel relationship as well as deviations from a perfectly perpendicular/parallel relationship with up to 5 %, such as up to 2 %. Furthermore, a vertical direction as used herein refers to a direction aligned with the direction of the force of gravity and a horizontal direction refers to a direction perpendicular to the vertical direction.

Brief Description of the Drawings

Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:

Fig. 1: schematically represents a perspective view of one example of a high voltage system comprising a high voltage unit and a support structure;

Fig. 2: schematically represents a front view of the high voltage system in

Fig. 1;

Fig. 3: shows simulations of bending moments in post insulators during a seismic event with and without a damping device; and

Fig. 4: shows simulations of deflections of a support structure during the seismic event with and without the damping device.

Detailed Description

In the following, a support structure for a high voltage unit comprising an elongated flexible element and a damping device, a high voltage system comprising a high voltage unit and a support structure and a method of installing a high voltage system comprising a high voltage unit and a support structure, will be described. The same reference numerals will be used to denote the same or similar structural features.

Fig. l schematically represents a perspective view of one example of a high voltage system io in a neutral position. The high voltage system io comprises a high voltage unit 12 and a support structure 14.

The high voltage system 10 of this example is arranged in a hall having a support surface 16 constituted by a horizontal and planar hall floor. Fig. 1 further denotes a vertical axis Z, a first horizontal axis X and a second horizontal axis Y, perpendicular to the first horizontal axis X.

The support structure 14 comprises a plurality of post insulators 18, four in Fig. 1, arranged to support the high voltage unit 12 on the support surface 16. The support structure 14 in Fig. 1 is a standing support structure such that the entire gravity load of the high voltage unit 12 is transferred to the support surface 16 by the post insulators 18 when no lateral forces are present.

The high voltage unit 12 may be a HVDC semiconductor valve structure. The high voltage unit 12 of this example comprises several valve layers, each comprising two valve modules 20. An electric shield structure comprising a plurality of electric shields, such as corona shields, may be arranged around the valve layers of the high voltage unit 12 in order to lower the electrical fields to minimize the risk for partial discharge and/or flashover.

The high voltage unit 12 of this example further comprises a plurality of module supports 22, columns 24 and column supports 26. Each module support 22 supports two valve modules 20. The module supports 22 are stacked on each other by means of the columns 24. The module supports 22 are supported on the columns 24 via the column supports 26.

The high voltage unit 12 has a rectangular cross section and one post insulator 18 is associated with each corner of the high voltage unit 12. However, the high voltage unit 12 may have alternative shapes. The high voltage unit 12 maybe subjected to hundreds of kilovolts.

Each post insulator 18 of this example is approximately five meters long. The post insulators 18 are made of an electrically insulating material, for example porcelain or epoxy. Both porcelain and epoxy are brittle and therefore sensitive to bending moments. The post insulators 18 establish an insulating distance for the high voltage unit 12 to ground, i.e. to the support surface 16. The post insulators 18 may for example be of the model 16SM510471 by Shemar.

The support structure 14 further comprises at least one elongated flexible element 28. In the example of Fig. 1, the elongated flexible element 28 is constituted by a wire rope which may have a diameter of approximately 15 mm. The elongated flexible element 28 is tensioned, for example by means of one or more stretching screws (not shown).

The support structure 14 of this example further comprises two tension insulators 30. The tension insulators 30 functions to insulate the elongated flexible element 28 from the high voltage unit 12. The tension insulators 30 of this example are stiff, but flexible tension insulators 30 could alternatively be used.

Each tension insulator 30 is attached, directly or indirectly, to an end of the elongated flexible element 28. Moreover, each tension insulator 30 is coupled to one of the post insulators 18. As shown in Fig. 1, the two tension insulators 30 are arranged in an X-configuration between the two post insulators 18. As can also be seen in Fig. 1, the support structure 14 does not comprise any cross bracings.

The support structure 14 of this example further comprises two pulleys 32. The pulleys 32 are rotationally arranged on pulley supports (not shown) fixed to the support surface 16. The elongated flexible element 28 extends between the two tension insulators 30 and around the two pulleys 32.

As can be seen in Fig. 1, the elongated flexible element 28 and the two tension insulators 30 form a loop. However, the elongated flexible element 28 may alternatively form a loop alone, e.g. if the two tension insulators 30 are somewhat shortened.

The support structure 14 further comprises a damping device 34. The damping device 34 of this example is constituted by a linear viscous damper arranged horizontally and substantially parallel with the portion of the elongated flexible element 28 between the two pulleys 32. The damping device 34 provides a force proportional to the movement speed in a movement direction 36 of the damping device 34 and of the horizontal portion of the elongated flexible element 28. The working region of the damping device 34 along the movement direction 36 may be ± 0.25 m from the illustrated central, neutral position.

The damping device 34 may be a commercially available damping device. The damping device 34 may have a fixed damping constant, e.g. set by the manufacturer, or an adjustable damping constant for on site adjustments. The damping constant may be, for example, 10 kNs/m.

The support structure 14 of this example further comprises a carrier 38. The carrier 38 fixedly connects the elongated flexible element 28 to the damping device 34. The carrier 38 is guided back and fourth in the movement directions 36 by means of a slit (not shown), or similar, provided in the support surface 16. The carrier 38 may comprise engaging members, such as claws, to engage the slit. The carrier 38 may be substantially centered between two post insulators 18 in the illustrated neutral state of the support structure 14.

The support structure 14 of this example further comprises four joints 40. Each joint 40 is arranged on top of one of the respective post insulators 18 and is connected to an associated column support 26. In Fig. 1, the joints 40 are illustrated as ball joints. However, alternative joints, such as universal joints, may be employed. If the post insulators 18 would be made flexible, the joints 40 could be omitted.

In case of a seismic event, the high voltage system 10 is caused to sway laterally, as indicated by arrow 42. Due to the joints 40, the high voltage unit 12 can be maintained substantially vertically oriented and relative tilting forces between the high voltage unit 12 and the post insulators 18 are not transmitted via the joints 40.

As the high voltage system 10 sways laterally in one direction, one of the tension insulators 30 is pushed by an associated post insulator 18 and one of the tension insulators 30 is pulled by an associated post insulator 18. As a consequence, the elongated flexible element 28 is pulled around the pulleys 32 and also pulls one of the tension insulators 30. The movement of the elongated flexible element 28 is damped by the damping device 34. Thereby, also the support structure 14 is damped by the damping device 34.

Although not fully illustrated in Fig. 1, the arrangement of the elongated flexible element 28, the tension insulators 30, the pulleys 32 and the damping device 34 as described above is provided on all four sides of the support structure 14.

The support structure 14 in Fig. 1 further comprises a plurality of elastic elements, here implemented as plates 44, configured to bias the support structure 14 back to the neutral position. The plates 44 are described in more detail in connection with Fig. 2.

Fig. 2 schematically represents a front view of the high voltage system 10 in Fig. l. As can be seen in Fig. 2, the elongated flexible element 28 comprises a relatively long horizontal region between the two pulleys 32.

The support structure 14 comprises a plurality of bolts 46 to connect the plates 44 to the support surface 16. The plates 44 are raised from the support surface 16, e.g. approximately 30 mm, by means of the bolts 46.

The plates 44 may be made of metal, e.g. steel. One type of a steel suitable for the plates 44 is a high tensile steel having a tensile strength of at least 800 MPa. In this example, the plates 44 have a square profile of 1*1 meters and a thickness of approximately 20 mm. Simulations by the applicant have proven that the plates 44 may be designed to only deform elastically.

The plates 44 on which the post insulators 18 are mounted act as mechanical springs, deforming elastically and pushing the support structure 14 back to the neutral, straight-up position. Each plate 44 may be substantially flat in the neutral state of the support structure 14. When the downward force from one post insulator 18 is increased, the associated plate 44 is made concave, or made more concave. The properties of the plates 44 and the damping constant of the damping device 34 may be tuned to optimize the structural response of the support structure 14. For example, the geometry, thickness and material of the plates 44 may be adjusted for this tuning purpose.

By selecting thicker plates 44, e.g. having 25 mm thickness, the support structure 14 can be made stiffer. By selecting thinner plates 44, e.g. having 15 mm thickness, the support structure 14 can be made softer. In this way, the stiffness of the support structure 14 can easily be trimmed to match the Eigen frequency of the high voltage system 10.

As shown in Fig. 2, the damping device 34 comprises a cylinder 48, a piston rod 50 and a piston rod attachment 52. The cylinder 48 is fixed to a stationary structure 54, e.g. to ground. The piston rod 50 is arranged to move back and fourth along in the movement directions 36 and into and out from the cylinder 48. The piston rod attachment 52, which is here implemented as an eyebolt, is fixedly attached to the carrier 38.

Fig. 3 shows simulations of bending moments in post insulators 18 during a seismic event with and without a damping device 34 and Fig. 4 shows simulations of deflections of a support structure 14 during the seismic event with and without the damping device 34. As can be seen, the provision of at least one damping device 34 according to the present disclosure significantly reduces the bending moments in the post insulators 18 and also reduces the deflections of the support structure 14 during seismic events.

While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.

Claims

A support structure (14) for a high voltage unit (12), the support structure (14) comprising: a plurality of support insulators (18) for supporting the high voltage unit (12) on a support surface (16), at least one elongate flexible element (28 ) arranged to be tensioned between at least two of the support insulators (18) and at least one damping device (34) arranged to dampen movements (36) of an associated elongated flexible element (28) to a lateral one To reduce swaying (42) of the support structure (14).

2. Support structure (14) according to claim 1, wherein the at least one damping device (34) comprises a viscous damper or is formed by this.

The support structure (14) of claim 2, wherein the viscous damper is a linear viscous damper disposed substantially parallel to a portion of the at least one elongated flexible member (28).

4. supporting structure (14) according to any one of the preceding claims, wherein the at least one damping device (34) adjacent to the support surface (16) is arranged.

A support structure (14) according to any one of the preceding claims, further comprising two guy insulators (30) associated with one of the at least one elongated flexible member (28) and connected to a corresponding end of the elongate flexible member (28) about the elongate one insulating element (28) from the high voltage unit (12).

6. support structure (14) according to claim 5, wherein the two guy insulators (30) between two of the support insulators (18) are arranged in the form of an X.

A support structure (14) according to any one of the preceding claims, further comprising at least W-110 an elastic member configured to bias the support structure (14) to a neutral position.

8. The support structure (14) according to claim 7, wherein the at least one elastic element is formed by a plate (44) disposed between the support surface (16) and an associated column insulator (18) and connected to the support surface (16) and the associated Column insulator (18) is connected.

A support structure (14) according to any one of the preceding claims, further comprising at least one hinge (40) connected to each column insulator (18) such that the column insulators (18) are arranged to connect the high voltage unit (12) by at least to wear a joint (40).

The support structure (14) of claim 9, wherein the at least one hinge (40) is a universal joint.

The support structure (14) of any one of the preceding claims, further comprising at least one diverting pulley (32) associated with the at least one elongated flexible member (28), and wherein the at least one elongated flexible member (28) about the at least one diverting pulley (32) is wound.

A support structure (14) according to any one of the preceding claims, further comprising a support (38) fixedly connected to the at least one elongate flexible member (28) and fixedly connected to the at least one damping device (34).

A high voltage system (10) comprising a high voltage unit (12) and a support structure (14) according to any preceding claim for supporting the high voltage unit (12) on a support surface (16).

A method of constructing a high voltage system (10) comprising a high voltage unit (12) and a support structure (14) according to any one of claims 1 to 12, the method comprising: determining the natural frequency of the high voltage system (10), determining a required Stiffness of at least one elastic element to correspond to the natural frequency of the high voltage system (10), providing the at least one elastic element and disposing the at least one elastic element to bias the support structure (14) to a neutral position.

15. The method of claim 14, wherein the step of providing the at least one elastic member comprises providing at least one elastic member formed by a plate (44) having a thickness which corresponds to the stiffness required next to the closest stiffness ,