CN215269334U

CN215269334U - External shield for high voltage equipment

Info

Publication number: CN215269334U
Application number: CN202120915468.9U
Authority: CN
Inventors: O·迪亚兹; L·阿雷瓦洛
Original assignee: Hitachi Energy Switzerland AG
Current assignee: Hitachi Energy Co ltd
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2021-12-21
Anticipated expiration: 2031-04-29

Abstract

The utility model relates to an external shield for high-voltage equipment. The structure (1) includes: a corner shielding element (2) configured as an L-shaped tube (9); and flat side shield elements (3), wherein the corner shield elements (2) and the side shield elements (3) are separate elements.

Description

External shield for high voltage equipment

Technical Field

The present disclosure relates to an external shielding structure for a high voltage device.

Background

In the design of air electrical insulation in High Voltage (HV) equipment several technical criteria have to be met, such as the switch surge withstand level (SIWL), the lightning surge withstand level (LIWL), long term stress, and creepage distances.

One important milestone in the design is that HV devices operate without corona discharge. This type of discharge starts with a high electric field concentration on the surface of a metal electrode insulated in atmospheric air, operating under HV. The onset of corona discharge is strongly dependent on electrode geometry and air properties such as temperature and humidity. Once corona discharges have been initiated, they may evolve into self-sustaining streamer discharges, then reach the lead-in phase, and finally bridge the complete air gap and reach full breakdown.

Metal rounded shields are commonly used in HV devices to form an electrostatic shield around sensitive parts of the protected equipment. These shields are located on the exterior portion of the device to avoid electric field concentrations on the protected device and on the shield itself. For example, large radius metal electrodes have been widely used to provide external electrostatic shielding for high and ultra-high voltage equipment. This use may also be extended to indoor equipment such as HVDC valve converters. This particular type of equipment requires electrical shielding from its internal laminar distribution towards its surroundings, mainly adjacent grounded structures and facility boundaries, such as floors, walls and ceilings.

Previous designs of electrostatic shielding structures provided large C-shaped corner shields. Other solutions, such as those shown for example in document WO 2019/219194 a1, provide specially designed structures for combining shielding and cooling functions. These solutions have good performance from an electrical point of view, but imply some additional challenges and drawbacks with respect to: flexible application to different systems, machine implementation and maintenance workloads.

There is a need to provide a shielding structure for HV devices that provides good performance from an electrical point of view while being flexibly applicable to different systems, is easy to implement at low cost and has a low maintenance effort.

SUMMERY OF THE UTILITY MODEL

According to an embodiment, a shielding structure for an HV device is implemented. The shielding structure comprises corner shielding elements configured as L-shaped tubes. The shielding structure includes flat side shielding elements. The corner shield elements and the side shield elements are separate elements. The L-shaped tubes of the corner shielding elements are oriented with their major dimension perpendicular to the height direction of the structure.

This shielding structure provides good performance from both electrical insulation and mechanical points of view. The proposed shielding structure achieves easy manufacturing and maintenance combined with low installation effort at the structure corners, using L-shaped tube corner shielding elements covering the structure corners, while not deviating from a good shielding behaviour. On the other structural side, flat side shield elements are used as small units, which also combine very good performance characteristics in terms of manufacturing, maintenance and installation effort with good electrical shielding properties.

This structure allows maintenance of the protected elements behind the shield without having to remove all or most of the structural shield elements as was the case with previous designs.

However, the proposed shielding structure is very compliant with the required conditions in terms of electrical shielding behavior in HV systems or devices by achieving the following effects:

-geometry, shape and dimensions prevent the initiation of a corona discharge on the surface of the shield;

it solves the mechanical challenges from previous designs, permitting a simpler mounting/dismounting process;

it has a low manufacturing cost.

According to a further embodiment of the shielding structure, the side shielding elements are configured without any tubes. This further eases the mounting/dismounting process and reduces the manufacturing costs.

According to a further embodiment of the shielding structure, the side shielding elements each comprise a central section and an outer section, the central section terminating on both sides into said outer section, wherein the central section shows a C-shaped cross-section and wherein the outer sections provide rounded surfaces to round the central section towards the periphery on both sides. According to this embodiment, a mat-like shape of the side shielding element is achieved, which has an improved shielding function and still provides an easy mounting/dismounting of the element.

According to a further embodiment of the shielding structure, the corner shielding elements each comprise an outer end section into which the L-shaped tubes terminate at both ends, wherein the outer end sections provide a rounded surface to round the L-shaped tubes towards the outside. The rounded surface on each end is, for example, a hemisphere or hemispherical dome section. This embodiment further improves the electrical shielding function at the corners of the structure without departing from easy mounting/dismounting of elements and easy maintenance of components behind or inside the structure, in particular any HV device to be electrically shielded with respect to the periphery.

According to a further embodiment of the shielding structure, the corner shielding elements are arranged such that the L-shaped tubes cross a first plane by an L-shape, and wherein the side shielding elements are arranged such that their major dimension is parallel to a second plane, wherein the first plane is perpendicular to the second plane. In this embodiment, the shielding structure thus has a rectangular configuration, wherein the L-shaped tubes surround the corners of the structure inside the shield, and wherein the side shielding elements provide good area (area) shielding behavior along the sides of the inner structure.

According to a further embodiment of the shielding structure, each corner is arranged with a corner shielding element, respectively, the corner shielding elements being arranged one above the other in the height direction, and the L-shaped tubes being parallel to each other in the same orientation. This enables a flexible arrangement of the corner shielding elements in height direction and thus scalability to different systems, structures and applications to be shielded or protected by the shielding structure.

According to a further embodiment of the shielding structure, the side shielding elements are arranged on two opposite sides of the structure. In this embodiment, the two opposite sides may be the main sides of the structure, wherein on the other side the corner shielding elements are arranged to provide a respective shielding without any additional side shielding elements. Thus, the construction is still easy to implement, since the number of parts is kept as low as possible and scalability, flexibility and low maintenance effort are still provided.

According to a further embodiment of the shielding structure, each side shielding element is arranged with two corner shielding elements in the height direction of the structure, thereby defining a structural layer. Thus, in this embodiment, two relatively small corner shielding elements (in terms of the thickness of their tubes) are combined with one side shielding element. In this way, access to HV components surrounded by corner shielding elements at the corners of the shielding structure is easy and flexible, while at the same time good shielding performance on the sides may be maintained. Furthermore, any mechanical stress to the structural elements in the corner regions of the structure can be kept low.

Additionally, in this embodiment, these structures of corner shield elements and side shield elements may be organized in a layer type unit. This is for example suitable for application in valve converter structures used in High Voltage Direct Current (HVDC) systems. Such HVDC converter structures are often also constructed in layers. Thus, an easy mechanical construction and adaptation of the shielding structure to the internal converter structure may be achieved. Furthermore, easy and selective access of each respective layer to the parts of the internal transducer structure may be achieved without having to mount/dismount many parts of the shield.

According to a further embodiment of the shielding structure, a plurality of structural layers of the kind explained above are arranged one above the other in height direction. This enables a very good scalability to different systems having different heights.

According to a further embodiment, the shielding structure comprises a top shielding element and/or a bottom shielding element. This serves the purpose of good shielding performance in terms of the top and/or bottom side of the structure to be shielded.

Each feature described in relation to one of the above aspects is also disclosed herein in relation to the other aspects, even if the respective feature is not explicitly mentioned in the context of a particular aspect.

The accompanying drawings are included to provide a further understanding. In the drawings, elements having the same structure and/or function may be denoted by the same reference numerals. It will be understood that the embodiments shown in the drawings are diagrammatic representations and are not necessarily drawn to scale.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic front view of a shielding structure according to an embodiment;

fig. 2 is a schematic side view of the shielding structure according to fig. 1;

fig. 3 is a schematic plan view of a single layer of the shielding structure according to fig. 1 and 2.

Detailed Description

Fig. 1 illustrates a front view of a shielding structure 1. The shielding structure 1 is configured to electrically shield the HV device surrounded by the shielding structure 1. For example, the shielding structure 1 serves the purpose of not allowing the initiation of a corona discharge. The HV device is e.g. a HVDC converter valve having a plurality of layers of stacked modules connected by one or more bus bars (not shown in the figure).

The shielding structure 1 comprises a top shielding element 5 and a bottom shielding element 6, which serve the purpose of shielding HV or HVDC equipment or systems towards the top and bottom periphery. Furthermore, the shielding structure 1 comprises a multitude of corner shielding elements 2 and side shielding elements 3.

The corner shielding elements 2 are each constructed from an L-shaped tube. In fig. 1, only one leg of the corresponding L-shaped tube of each corner shielding element 2 is illustrated, due to the perspective of the front view. The corner shielding elements 2 are arranged such that they are bent or curved such that their L-shaped tubes surround the corners of the shielding structure 1. The corner shielding elements 2 thus provide very good shielding performance at the corners of the structure 1. At the same time, the corner shielding element 2 has advantageous properties in terms of ease of installation and low effort for mounting/dismounting parts of the structure. Furthermore, any mechanical stress to the structural elements in the corner regions of the structure 1 (the corner shielding elements 2 themselves or other structural components) can be kept at a low level.

The side shield elements 3 are configured as flat elements and each provide some flat surface for shielding the HV or HVDC device or system towards the periphery. In this respect, the side shielding elements 3 are distributed along the sides (front) of the shielding structure 1 in order to provide an overall shielding on the surface of the HV or HVDC device or system surrounded by the shielding structure 1.

In the embodiment according to fig. 1, the shielding structure provides a spatial extension having a width in a first direction x and a height in a second direction z perpendicular to the first direction x. According to the detailed embodiment in fig. 1, there are corner shielding elements 2 at each corner and three side shielding elements 3 between the corners, i.e. three columns of side shielding elements 3, in the width direction x. At each side shield element 3, two

corner shield elements

2a, 2b are arranged at each corner in the height direction z of the structure 1. The arrangement thus defines a structural layer 4. Between the top shield element 5 and the bottom shield element 6, there are ten rows of such layers 4 in the height direction z.

The shielding structure 1 provides good maintenance of the HV or HVDC equipment or system surrounded by the shielding structure 1, since only separate corner shielding elements 2 or side shielding elements 3 have to be mounted/dismounted in order to access parts or components of the HV or HVDC equipment or system. Furthermore, with the concept of stacked/layered "tiles" of corner shielding elements 2 and side shielding elements 3, the construction of the shielding structure 1 is still easy to implement by keeping the number of parts as low as possible and still providing scalability, flexibility and low maintenance effort. Additionally, the shielding structure 1 has good performance in terms of electrical shielding behavior.

In the embodiment of the shielding structure 1 according to fig. 1, for example, five-layer HVDC converter valves using the proposed side shielding configuration may be shielded, which are represented as five pairs of shielding layers 4 (five structural layers).

Fig. 2 illustrates a side view of the shielding structure 1 according to fig. 1 with a spatial extension having a depth in a third direction y and the above-mentioned height in a second direction z perpendicular to the third direction y. Fig. 2 illustrates the respective other leg of the L-shaped tube of the corner shielding element 2 (see explanation above). Furthermore, in fig. 2, the mat-like configuration of the flat side shielding elements 3 is visible (located "behind" the respective two L-shaped tubes of the corner shielding elements 2). Here, it is also clearly visible that each single side shield element 3 is arranged with two corner shield elements 2 in the height direction z. As can be further seen from fig. 2, in the depth direction y of the shielding structure 1, without additional side shielding elements 3 in the y-direction, shielding is maintained only by corner shielding elements 2 located opposite each other at the respective corners.

Fig. 3 illustrates a plan view of one single shield layer 4 when "cut through" the shield structure 1 according to fig. 1 and 2 in the x-y plane. Each such layer 4 shows four corner shielding elements 2 arranged at respective corners 12a to 12 d. Each corner shielding element 2 has an L-shaped tube 9 and

outer end sections

10a, 10b, into which

outer end sections

10a, 10b the L-shaped tube 9 ends at both ends. The

outer end sections

10a, 10b provide rounded surfaces to round the L-shaped tube 9 outwards and provide good electric field shielding properties. The rounded surface is, for example, a hemisphere or hemispherical dome section.

Further, as can be seen from fig. 3, on two

opposite sides

11a, 11b there are six complementary side shielding elements 3, three such elements on each

side

11a and 11 b. The side screen elements 3 each comprise a central section 7 and

outer sections

8a, 8b, the central section 7 terminating on both sides into said

outer sections

8a, 8 b. The central section 7 is configured so as to show a C-shaped cross-section (when cut through the central section 7 and viewed in the y-z plane). The

outer sections

8a, 8b provide rounded surfaces to round the central section 7 outwards on both sides. Therefore, the side shield element 3 is configured with a pad-like shape to provide good shielding performance.

The presented design is one of different possible solutions for a hierarchically organized shield of HV devices. The proposed shielding structure 1 is very compliant with the required conditions in terms of electrical shielding behaviour in HV systems or devices by the following steps: geometry, shape and size to achieve prevention of initiation of corona discharge on the surface of the shield; solving mechanical challenges known from previous designs; and permits a simpler mounting/dismounting process, which, incidentally, has a low manufacturing cost.

While the disclosure is susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.

List of reference numerals

1 Shielding Structure

2 corner shield element

3 side shield element

4 structural layer

5 Top Shielding element

6 bottom shield element

7 center section

8a, 8b outer section

9L-shaped tube

10a, 10b end section

11a and 11b sides

12a, 12b, 12c, 12 d.

Claims

1. A shielding structure (1) for a high voltage device, characterized in that the shielding structure (1) comprises:

-a corner shielding element (2) configured as an L-shaped tube (9), and

-a flat side shielding element (3),

wherein the corner shield element (2) and the side shield element (3) are separate elements, and

wherein the L-shaped tubes of the corner shielding elements (2) are oriented with their main dimension perpendicular to the height direction (z) of the structure (1).

2. Shielding structure (1) according to claim 1,

wherein the side shield element (3) is configured without any tube.

3. Shielding structure (1) according to claim 1 or 2, wherein the side shield elements (3) each comprise a central section (7) and an outer section (8a, 8b), the central section (7) terminating on both sides into the outer sections (8a, 8b),

wherein the central section (7) shows a C-shaped cross-section and wherein the outer sections (8a, 8b) provide rounded surfaces to round the central section (7) outwards on both sides.

4. Shielding structure (1) according to one of claims 1 to 2, wherein said corner shielding elements (2) each comprise an outer end section (10a, 10b), said L-shaped tubes (9) terminating at both ends into said outer end sections (10a, 10b),

wherein the outer end sections (10a, 10b) provide rounded surfaces to round the L-shaped tube (9) outwards.

5. Shielding structure (1) according to one of claims 1 to 2, wherein the corner shielding elements (2) are arranged such that the L-shaped tubes (9) span a first plane, and wherein the side shielding elements (3) are arranged such that their main dimension is parallel to a second plane,

wherein the first plane is perpendicular to the second plane.

6. Shielding structure (1) according to any one of claims 1 to 2, characterized in that each corner (12a, 12b, 12c, 12d) is arranged with a corner shielding element (2), respectively, the corner shielding elements (2) being arranged one above the other in the height direction (z), and the L-shaped tubes (9) being parallel to each other in the same orientation.

7. Shielding structure (1) according to any one of claims 1 to 2, characterized in that said side shielding elements (3) are arranged on two opposite sides (11a, 11b) of said structure (1).

8. Shielding structure (1) according to any one of claims 1 to 2, characterized in that in the height direction (z) of the structure (1) two corner shielding elements (2) are arranged per side shielding element (3), thereby defining a structural layer (4).

9. Shielding structure (1) according to claim 8, wherein a plurality of structural layers (4) are arranged one above the other in the height direction (z).

10. Shielding structure (1) according to any one of claims 1 to 2 and 9, characterized in that the shielding structure (1) comprises a top shielding element (5) and/or a bottom shielding element (6).