Protection device for extra-high voltage flexible direct current power transmission system

Abstract

The utility model discloses a protection device for an extra-high voltage flexible direct current power transmission system, and solves the problem that in a protection device for a power transmission system, a resistor element is easily affected by external force and damaged, or stress is generated in the resistor element to affect the resistance value, so that the large current deformation resistance and the high voltage electric field of the resistor element are not uniform. The device comprises a resistor combination structure and an inter-stack connection pipeline, wherein the resistor combination structure comprises a plurality of resistor boxes; the plurality of resistor boxes comprise a plurality of in-box resistor modules, each in-box resistor module comprises a plurality of resistor units, a plurality of U-shaped metal resistor bodies are connected in series in each resistor unit to form a continuously bent strip, the through-flow section of the resistor is large, the through-flow capacity of large current is improved, meanwhile, the process of punching a resistor disc is abandoned, the utilization rate of a resistor material is improved, and the cost is reduced. The production cost is reduced, the competitiveness of the product is improved, and meanwhile, the insulators are arranged between the resistor units, so that the attraction effect between the resistor units can be prevented.

Description

Technical Field

[0001] This utility model relates to a protection device for power transmission systems, specifically a protection device for ultra-high voltage flexible DC transmission systems. Background Technology

[0002] With the ever-increasing demand for electricity in modern society, ultra-high voltage (UHV) flexible direct current (DC) transmission technology has developed steadily and rapidly. Meanwhile, the operational status of DC power lines is crucial to the safety and reliability of the entire power grid. In UHV flexible DC transmission systems, energy-consuming resistors must not only be able to withstand normal operating voltage and current, but also withstand the impact voltage and current caused by malfunctions in the energy-consuming valve triggering system, internal valve faults, faults in various parts of the flexible DC system, and AC system faults. Therefore, the following requirements must be met when designing the protection devices for the transmission system:

[0003] (1) The multiple resistor elements in the resistor module of the protection device are subjected to uniform force during the assembly process to avoid damage to the resistor elements and poor contact; (2) The energy-consuming resistor protection device will not generate stress in the resistor element due to deformation after being subjected to high-intensity external forces such as earthquakes and conductor tension, and high current stress; (3) The resistance of the energy-consuming resistor protection device will not exceed 550K under continuous operating voltage to avoid resistance exceeding the tolerance; (4) The resistor strip of the energy-consuming resistor protection device has the ability to withstand current of 4kA / 1.5s, and the fixed structure is safe and reliable; (5) The energy-consuming resistor protection device can meet the normal use when half of the resistor is short-circuited to ground.

[0004] In the current protection circuit of UHV flexible DC transmission system, the resistor element is easily damaged by external force or stress is generated in the resistor element, which affects the resistance value. This leads to the resistor element's ability to resist large current deformation and uneven high voltage electric field, which can cause adjacent resistors to be attracted together and cause a short circuit, resulting in an unsatisfactory protection effect on the transmission system.

[0005] Chinese patent CN 109300635 A discloses a starting resistor for high-voltage flexible DC transmission. It describes a layered arrangement of resistor boxes, with two or more resistor boxes in each layer, and each resistor box containing one resistor module. The resistor boxes in adjacent layers are connected and supported by post insulators. A sleeve is installed on the side wall of each resistor box, with the inside of the sleeve connected to the resistor module by a connecting piece, and the outside of the sleeve connected to a connecting tube or inlet / outlet terminal, forming a series structure. However, this patent only discloses the resistor modules within the resistor boxes, without specifying the composition of the resistor modules or the connection relationships between them. Under high-intensity external forces such as earthquakes or conductor tension, the resistors inside the resistor boxes may clump together, causing a short circuit. Utility Model Content

[0006] The purpose of this invention is to solve the technical problems in the protection circuit of current ultra-high voltage flexible DC transmission systems, where the resistive element is easily damaged by external forces or stress is generated inside the resistive element, affecting the resistance value, resulting in the resistive element's ability to resist large current deformation and uneven high voltage electric field, or adjacent resistors being attracted together, causing a short circuit. The invention provides a protection device for ultra-high voltage flexible DC transmission systems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A protection device for an ultra-high voltage flexible direct current transmission system includes n resistor combination structures and n-1 inter-stall connection pipelines, where n≥2. Each resistor combination structure includes m resistor boxes connected in series via inter-stall connection pipelines, and an inter-stall connection pipeline is connected in series between one resistor box of two adjacent resistor combination structures. Its special feature is that:

[0009] Each resistor box includes a box shell, and multiple internal resistor modules are installed inside the box shell in series.

[0010] Each box-mounted resistor module includes multiple resistor units connected in series.

[0011] Each resistor unit includes a left fixed plate, a right fixed plate, a row of upper mica screws, at least a row of lower mica screws, and multiple U-shaped metal resistors. The upper and lower mica screws are fixedly connected between the left and right fixed plates, respectively. The multiple U-shaped metal resistors are connected in series, with their ends connected in series with the corresponding ends of the U-shaped metal resistors in adjacent resistor units, and are arranged between a row of upper and lower mica screws, or between two adjacent rows of lower mica screws.

[0012] In the resistor unit, multiple U-shaped metal resistors are connected in series to form a continuously bent strip. The resistor has a large current-carrying cross section, which improves the ability to carry large currents. At the same time, the process of stamping resistor sheets is eliminated, which improves the utilization rate of resistor materials, reduces production costs, and enhances the competitiveness of the product.

[0013] Multiple resistor units within each box resistor module are arranged vertically in sequence, with multiple insulators evenly distributed between adjacent resistor units; the bottom resistor unit connects to multiple box resistor module support insulators. The insulators separate adjacent resistor units, preventing them from closing together due to vibration or external force.

[0014] Furthermore, multiple internal resistor modules within each resistor box are arranged vertically in sequence, and these modules are connected in series. This vertical arrangement reduces the space required.

[0015] Furthermore, each resistor box is fixedly connected to a box inlet pipe and a box outlet pipe. One end of the box inlet pipe is connected to the internal resistor module at one end, and one end of the box outlet pipe is connected to the internal resistor module at the other end. The other ends of the box inlet pipe and the other ends of the box outlet pipe are respectively connected to the inter-box connection pipeline or the inter-stack connection pipeline. A second equalizing ring is fitted on both the box inlet pipe and the box outlet pipe. The inter-box connection pipeline or the inter-stack connection pipeline connected to the box inlet pipe and the box outlet pipe is connected inside the second equalizing ring.

[0016] Furthermore, a first equalizing ring is fitted onto the upper and lower ends of the outer wall of each resistor box.

[0017] Furthermore, each resistor combination structure contains m resistor boxes arranged vertically, with a second insulator group between two adjacent resistor boxes, and the bottom surface of the bottom resistor box is connected to the first insulator group.

[0018] The first insulator group is connected between the bottom surface of the bottom resistor box and the ground, while the second insulator group is connected between two adjacent resistor boxes. The insulator torque, rod diameter, and number of insulators for both groups are calculated based on environmental seismic requirements. This eliminates stress on the box caused by deformation of the entire resistor system due to earthquakes, conductor tension, or other external forces, enhancing the stress safety and reliability of the energy-consuming resistors. The specifications of the first and second insulator groups are selected based on the lightning and creepage ratio requirements between the resistor terminals, calculated and evenly distributed to each insulator. Simultaneously, the uneven voltage distribution characteristics of the entire system must be considered, and the calculated withstand value for each insulator group needs to be multiplied by a non-uniform voltage distribution coefficient of 1.05.

[0019] Furthermore, the series connection pipeline between two adjacent resistor combination structures is specifically as follows:

[0020] In two adjacent resistor combination structures, the tail resistor box of one resistor combination structure is connected in series with the head resistor box of the other resistor combination structure through an inter-stall connection pipeline, and the tail resistor box of the other resistor combination structure is connected in series with the head resistor box of the next resistor combination structure through an inter-stall connection pipeline.

[0021] Alternatively, in two adjacent resistor combination structures, the first resistor box of one resistor combination structure is connected in series with the last resistor box of the other resistor combination structure through an inter-stall connection pipeline, and the first resistor box of the other resistor combination structure is connected in series with the last resistor box of the next resistor combination structure through an inter-stall connection pipeline.

[0022] Furthermore, the upper part of the enclosure has a louvered structure, and the protection level meets the IP23 requirement;

[0023] The bottom of the outer shell is made of stainless steel mesh with 10×10mm holes.

[0024] Furthermore, the first insulator group includes an even number of supporting insulators, which are evenly connected to the bottom surface of the resistor box;

[0025] The second insulator group consists of an even number of supporting insulators, which are evenly connected between the two resistor boxes.

[0026] Furthermore, m ≤ 3.

[0027] The beneficial effects of this utility model are:

[0028] 1. This utility model relates to a protection device for an ultra-high voltage flexible DC transmission system. The resistor unit uses multiple U-shaped metal resistors connected in series to form a continuously bent strip. The resistor has a large current-carrying cross section, which improves the current-carrying capacity of large currents. At the same time, it eliminates the process of stamping resistor sheets, improves the utilization rate of resistor materials, reduces production costs, and enhances the competitiveness of the product.

[0029] 2. This utility model provides a protection device for an ultra-high voltage flexible DC transmission system. Multiple insulators are evenly arranged between two adjacent resistor units, which can prevent short circuits caused by the attraction between resistor units and improve the stress safety and reliability of the protection device.

[0030] 3. This utility model provides a protection device for an ultra-high voltage flexible DC transmission system. A first insulator group is set between the resistor box and the ground, and a second insulator group is set between multiple resistor boxes. At the same time, insulators supporting the resistor modules inside the resistor box are set between the resistor modules inside the resistor box. This can eliminate the stress on the resistor element caused by the deformation of the energy-consuming resistor due to high-intensity external forces such as earthquakes and conductor tension.

[0031] 4. This utility model provides a protection device for an ultra-high voltage flexible DC transmission system. The resistor combination structure and the number of resistor boxes are determined according to actual needs, and can meet the normal use when half of the resistors are short-circuited to ground.

[0032] 5. This utility model provides a protection device for an ultra-high voltage flexible DC transmission system. The upper part of the outer shell of the resistor box is a louvered structure, and the bottom is a stainless steel mesh with 10×10mm holes to ensure smooth heat dissipation and meet the requirement that the temperature rise of the resistor element under a short-time current of 4kA is no more than 550K. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of a protection device for an ultra-high voltage flexible DC transmission system according to the present invention;

[0034] Figure 2 This is a schematic diagram of the structure inside the resistor box in an embodiment of a protection device for an ultra-high voltage flexible DC transmission system according to this utility model;

[0035] Figure 3 This is a schematic diagram of the structure of a resistor unit in an embodiment of a protection device for an ultra-high voltage flexible DC transmission system according to the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of the inlet pipe of the enclosure and the second equalizing ring in an embodiment of a protection device for an ultra-high voltage flexible DC transmission system according to the present invention.

[0037] In the diagram, 1-resistor assembly structure; 11-first insulator group; 12-resistor box; 121-box shell; 122-resistor module inside the box; 1221-left fixing plate; 1222-right fixing plate; 1223-upper mica screw; 1224-lower mica screw; 1225-U-shaped metal resistor body; 123-resistor module support insulator inside the box; 124-box inlet pipe; 125-box outlet pipe; 13-second insulator group; 14-first equalizing ring; 15-inter-box connection pipeline; 16-second equalizing ring; 2-inter-stall connection pipeline. Detailed Implementation

[0038] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0039] This embodiment describes a protection device for an ultra-high voltage flexible DC transmission system, such as... Figure 1 As shown, the device includes four resistor combination structures 1. Each resistor combination structure 1 comprises six first insulator groups 11 set on the ground, with the upper end of each first insulator group 11 connected to a resistor box 12. In this embodiment, each resistor combination structure 1 includes three resistor boxes 12, and six second insulator groups 13 are arranged between two adjacent resistor boxes 12. The three resistor boxes 12 are vertically arranged, and the upper and lower outer walls of each resistor box 12 are connected to first equalizing rings 14. Two adjacent resistor boxes 12 are connected in series through inter-box connecting pipelines 15, and one resistor box 12 of two adjacent resistor combination structures is connected in series through inter-stall connecting pipelines 2. By setting the first insulator groups 11 between the resistor boxes 12 and the ground, and designing the second insulator groups 13 between multiple resistor boxes 12, the positions of adjacent resistor boxes 12 are relatively fixed, preventing the problem of resistor band pull-in causing short circuits. This eliminates the stress on the resistive element caused by deformation of the energy-consuming resistor due to high-intensity external forces such as earthquakes and conductor tension, enhancing the stress safety and reliability of the energy-consuming resistor device.

[0040] The size of the 15-gauge connecting pipeline is determined based on the current of the resistor.

[0041] In this embodiment, a series connection line 2 is connected between two adjacent resistor combination structures 1 and one resistor box 12. The position of the series-connected resistor boxes 12 is determined according to the actual lightning strike between the resistor terminals; the specific connection is as follows:

[0042] In two adjacent resistor combination structures 1, the tail resistor box 12 of one resistor combination structure 1 is connected in series with the head resistor box 12 of the other resistor combination structure 1 through the inter-stacking connection pipeline 2, and the tail resistor box 12 of the other resistor combination structure 1 is connected in series with the head resistor box 12 of the next resistor combination structure 1 through the inter-stacking connection pipeline 2.

[0043] Alternatively, in two adjacent resistor combination structures 1, the first resistor box 12 of one resistor combination structure 1 is connected in series with the last resistor box 12 of the other resistor combination structure 1 through the inter-stacking connection pipeline 2, and the first resistor box 12 of the other resistor combination structure 1 is connected in series with the last resistor box 12 of the next resistor combination structure 1 through the inter-stacking connection pipeline 2.

[0044] In this embodiment, a first equalizing ring 14 is connected to the outer wall of the upper and lower ends of the resistor box 12. The upper edge and four corners of the resistor box 12 are set inside the first equalizing ring 14, which can prevent corona generation.

[0045] In this embodiment, as Figure 2 As shown, the resistor box 12 includes a box shell 121, six internal resistor modules 122, twenty-four internal resistor module support insulators 123, a box inlet pipe 124, and a box outlet pipe 125. Each internal resistor module 122 has four internal resistor module support insulators 123 at its bottom. The internal resistor module support insulators 123 support the internal resistor module 122 and eliminate the stress on the resistor element caused by deformation of the energy-consuming resistor due to high-intensity external forces such as earthquakes and wire tension, thereby enhancing the stress safety and reliability of the energy-consuming resistor device.

[0046] Two adjacent box-type resistor modules 122 are connected in series by wires. One end box-type resistor module 122 is connected in series with the box body inlet pipe 124, and the other end box-type resistor module 122 is connected in series with the box body outlet pipe 125. The box body inlet pipe 124 and the box body outlet pipe 125 are both connected to the outer wall of the box body shell 121. They are used to connect to the box body inlet pipe 124 or the box body outlet pipe 125 of another resistor box 12 through the inter-box connection pipe 15, or to connect to the box body inlet pipe 124 or the box body outlet pipe 125 on another resistor combination structure 1 through the stack connection pipe 2.

[0047] In this embodiment, the end box-mounted resistor module 122 is used to be connected through the box inlet pipe 124 or the box outlet pipe 125, and the internal box-mounted resistor module 122 is used in series to meet the requirements of different resistors.

[0048] like Figure 2 As shown, each box-type resistor module 122 includes multiple resistor units, and four insulators are set between two resistor units to prevent the resistor units from engaging. Multiple resistor units are connected in series with wires, and the resistor units at the ends are connected in series with the resistor units of adjacent box-type resistor modules 122. The specifications of the insulators are determined by the inter-terminal lightning protection of the entire resistor.

[0049] like Figure 3 As shown, in this embodiment, the resistor unit includes a left fixed plate 1221, a right fixed plate 1222, an upper mica wire rod 1223, a lower mica wire rod 1224, and multiple U-shaped metal resistors 1225. A row of upper mica wire rods 1223 and at least one row of lower mica wire rods 1224 are fixedly connected between the left fixed plate 1221 and the right fixed plate 1222, respectively. Multiple U-shaped metal resistors 1225 are connected in series and positioned between the upper mica wire rods 1223 and the lower mica wire rods 1224. Both the upper mica wire rods 1223 and the lower mica wire rods 1224 are constructed by covering metal wire rods with insulating material. The use of multiple U-shaped metal resistors 1225 connected in series to form a continuously bent strip results in a large current-carrying cross-section, improving the ability to carry large currents. Simultaneously, it eliminates the need for stamping resistor sheets, increasing the utilization rate of the resistor material, reducing production costs, and enhancing the product's competitiveness. The corresponding ends of the U-shaped metal resistors 1225 in the adjacent resistor units are connected in series and are arranged between a row of upper mica wire rods 1223 and lower mica wire rods 1224, or between two adjacent rows of lower mica wire rods 1224.

[0050] like Figure 4 As shown, in this embodiment, a second equalizing ring 16 is sleeved on both the box inlet pipe 124 and the box outlet pipe 125. The box-to-box connection line 15 or the stack-to-stack connection line 2 connected to the box inlet pipe 124 and the box outlet pipe 125 are all connected inside the second equalizing ring 16 to prevent corona generation.

[0051] In this embodiment, the first insulator group 11 is connected between the bottom surface of the bottom resistor box 12 and the ground, and the second insulator group 13 is connected between two adjacent resistor boxes 12. The insulator torque, insulator rod diameter, and number of insulators used for the first insulator group 11 and the second insulator group 13 are calculated according to the environmental seismic level requirements. This can eliminate the stress on the box body caused by the deformation of the entire resistor due to external forces such as earthquakes and conductor tension, and enhance the stress safety and reliability of the energy dissipating resistor. The specifications of the first insulator group 11 and the second insulator group 13 are selected based on the lightning and creepage distance requirements between the resistor terminals, and are evenly distributed to each insulator through calculation. At the same time, the uneven voltage distribution characteristics of the entire system need to be considered, and the calculated withstand value of each insulator needs to be multiplied by 1.05 times the uneven voltage distribution coefficient.

[0052] In this embodiment, the upper end of the outer shell 121 of the resistor box 12 is a louver structure, and the bottom is a stainless steel mesh with 10×10mm holes to ensure smooth heat dissipation and meet the requirement that the temperature rise of the resistor element under a short-term current of 4kA is no more than 550K.

[0053] The resistor modules 122 inside the resistor box 12 are arranged in a symmetrical structure, which can eliminate the stress on the resistor element caused by the deformation of the energy-consuming resistor due to high-intensity external forces such as earthquakes and wire tension, and enhance the stress safety and reliability of the energy-consuming resistor.

[0054] In this embodiment, the U-shaped metal resistor 1225 is made of nickel-chromium alloy strip.

[0055] Both the first equalizing ring 14 and the second equalizing ring 16 are made of aluminum alloy.

[0056] The above description is merely a specific embodiment of this utility model and a comparison of the effects of the specific embodiments with relevant comparative examples. However, the protection scope of this utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A protection device for an ultra-high voltage flexible direct current transmission system, comprising n resistor combination structures (1) and n-1 inter-unit connection pipelines (2), wherein n≥2, each resistor combination structure (1) includes m resistor boxes (12) connected in series via inter-unit connection pipelines (15), and an inter-unit connection pipeline (2) is connected in series between one resistor box (12) of two adjacent resistor combination structures (1); characterized in that: Each of the resistor boxes (12) includes a box shell (121), and a plurality of internal resistor modules (122) are arranged in series inside the box shell (121); Each of the in-box resistor modules (122) includes a plurality of resistor units connected in series; Each of the resistor units includes a left fixed plate (1221), a right fixed plate (1222), a row of upper mica screws (1223), at least one row of lower mica screws (1224), and a plurality of U-shaped metal resistors (1225). The upper mica screws (1223) and lower mica screws (1224) are respectively fixedly connected between the left fixed plate (1221) and the right fixed plate (1222). The plurality of U-shaped metal resistors (1225) are connected in series, and the ends are connected in series with the corresponding ends of the U-shaped metal resistors (1225) in the adjacent resistor unit. They are arranged between a row of upper mica screws (1223) and lower mica screws (1224), or between two adjacent rows of lower mica screws (1224).

2. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: Multiple resistor units within each of the box-in-the-box resistor modules (122) are arranged vertically in sequence, and multiple insulators are evenly arranged between two adjacent resistor units; the bottom resistor unit is connected to multiple box-in-the-box resistor module support insulators (123).

3. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: Multiple internal resistor modules (122) are arranged vertically in sequence within each resistor box (12), and the multiple internal resistor modules (122) are connected in series.

4. The protection device for an ultra-high voltage flexible DC transmission system according to claim 3, characterized in that: Each of the resistor boxes (12) is fixedly connected to a box inlet pipe (124) and a box outlet pipe (125). One end of the box inlet pipe (124) is connected to a box-in resistor module (122) at one end, and one end of the box outlet pipe (125) is connected to a box-in resistor module (122) at the other end. The other end of the box inlet pipe (124) and the other end of the box outlet pipe (125) are respectively connected to an inter-box connection pipeline (15) or an inter-stack connection pipeline (2). A second equalizing ring (16) is sleeved on both the box inlet pipe (124) and the box outlet pipe (125). The inter-box connection pipeline (15) or the inter-stack connection pipeline (2) connected to the box inlet pipe (124) and the box outlet pipe (125) are all connected inside the second equalizing ring (16).

5. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: Each of the resistor boxes (12) has a first equalizing ring (14) fitted onto the upper and lower ends of its outer wall.

6. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: Each resistor combination structure (1) has m resistor boxes (12) arranged vertically, and a second insulator group (13) is arranged between two adjacent resistor boxes (12). The bottom surface of the bottom resistor box (12) is connected to the first insulator group (11).

7. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: The series connection pipeline (2) between one resistor box (12) of the two adjacent resistor combination structures (1) is specifically as follows: In two adjacent resistor combination structures (1), the tail resistor box (12) of one resistor combination structure (1) is connected in series with the head resistor box (12) of the other resistor combination structure (1) through the inter-stacking connection pipeline (2), and the tail resistor box (12) of the other resistor combination structure (1) is connected in series with the head resistor box (12) of the next resistor combination structure (1) through the inter-stacking connection pipeline (2). Alternatively, in two adjacent resistor combination structures (1), the first resistor box (12) of one resistor combination structure (1) is connected in series with the last resistor box (12) of the other resistor combination structure (1) through the inter-stacking connection pipeline (2), and the first resistor box (12) of the other resistor combination structure (1) is connected in series with the last resistor box (12) of the next resistor combination structure (1) through the inter-stacking connection pipeline (2).

8. The protection device for an ultra-high voltage flexible DC transmission system according to claim 1, characterized in that: The upper part of the enclosure (121) is a louver structure, and the protection level meets the IP23 requirement; The bottom of the outer shell (121) of the box is a stainless steel mesh with 10×10mm holes.

9. The protection device for an ultra-high voltage flexible DC transmission system according to claim 6, wherein the first insulator group (11) comprises an even number of supporting insulators, which are uniformly connected to the bottom surface of the resistor box (12); The second insulator group (13) comprises an even number of supporting insulators, which are evenly connected between the two resistor boxes (12).

10. The protection device for an ultra-high voltage flexible DC transmission system according to claim 6, wherein m ≤ 3.

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