Dry-type direct-current support capacitor for smart power grid

Abstract

The utility model discloses a dry-type DC support capacitor for an intelligent power grid, which comprises a shell, a core module, an electrical connection assembly, a wiring terminal assembly, filled resin, a pressure relief valve and a pressure switch, and is characterized in that the shell comprises a shell body, a shell bottom, a shell cover and a mounting bar; the mounting bar comprises a mounting bar body and a mounting nut, the core module comprises a core shell, an element, an element outgoing line copper foil and packaged resin, the core shell comprises a core shell body, a core shell side plate and a core shell bottom, and the electrical connection assembly comprises a confluence connection copper bar and an electrical connection outgoing line. The wiring terminal assembly comprises an insulator, a conducting rod, a round nut, an insulating washer, a sealing ring, a first insulating plate, a first electrode copper bar, a second insulating plate and a second electrode copper bar. The utility model has the advantages of simple structure and convenient installation and use, and can meet the requirements of long-term safe, stable and reliable operation of the direct current support capacitor under high voltage conditions.

Description

Technical Field

[0001] The utility model belongs to the technical field of capacitors, and particularly relates to a dry-type DC support capacitor for an intelligent power grid. Background Technique

[0002] The DC support capacitor is a key device for the converter valve of the intelligent power grid, and mainly plays roles such as stabilizing voltage and filtering. At present, in equipment such as high-power STATCOM and DC capacitors for flexible DC transmission projects, high-voltage and large-capacity DC support capacitors are required. The common features of such capacitors are dry structure, high voltage, large capacity, and large weight. The weight range of the DC support capacitor is between 100 and 210 kg, and the weight of the cast resin is between 20 and 50 kg.

[0003] There are relatively many such DC support capacitors in engineering applications, and the requirements for the reliability and consistency of their product performance are also relatively high. The owner has added a special test item of the partial discharge test between the terminal and the shell (pole shell) according to the actual use conditions. The current voltage levels of the DC support capacitors in use are mainly 2.2 kV DC and 2.8 kV DC. Requirements for the partial discharge test between the terminal and the shell: First, raise the voltage from the terminal to the shell to 5 kV ACrms Keep it for 10 s, record the partial discharge value (only for recording, not as a criterion for judgment), and lower the voltage to 3 kV ACrms Keep it for 60 s to measure the partial discharge amount, and the partial discharge amount is less than 10 pC. At present, the related products can basically reach 3 kV ACrms Keep the partial discharge amount for 60 s less than 10 Pc, but for 5 kV ACrms Keep the partial discharge amount for 10 s less than 50 Pc.

[0004] Document CN107275087B discloses a DC capacitor for an ultra-high-power three-level frequency converter. The capacitor is composed of a shell, a core, a wiring terminal, filled resin, and a pressure relief valve. This DC capacitor has the characteristics of small heat generation, good heat dissipation performance, high insulation withstand voltage strength, strong ability to withstand large current, low inductance, safe operation, dry type, oil-free and leak-free, etc.

[0005] Document CN209487322U discloses a power electronic capacitor for a flexible DC system, including a shell, a first core, and a second core. The first core includes a first element group, a first integral copper bar, and a second integral copper bar. The second core includes a second element group, a third integral copper bar, and a fourth integral copper bar. The integral copper bars adopt a low-inductance structure with tin-soldered leads and are welded at both ends of the element group. This capacitor realizes the goals of high voltage, large capacity, and large current of the capacitor, selects the integral copper bar welding method to reduce the inherent inductance, adopts the reverse parallel connection method, and uses the negative mutual inductance to reduce the equivalent inductance.

[0006] The capacitors with the above structure mainly consider the characteristics of heat dissipation, insulation, high current resistance, and low inductance, and all have a multi-core structure inside. Related products can basically reach 3 kV. ACrms It is required that the partial discharge amount within 60 s be less than 10 pC. In the above structures, the copper busbars are directly welded to the components. When the capacitor is subjected to a large electro-dynamic impact force, the copper busbars may directly pull or break the solder joints of the components, which may cause discharge at the solder joints and a decrease in capacitance.

[0007] With the development of the converter valve technology in the smart grid, relevant converter valve manufacturers have gradually adopted high-voltage IGBT devices to reduce the size of the converter valve. The voltage level of the DC support capacitor has become 4 kV DC, and the requirements for the partial discharge test between the terminal and the shell have also been increased. Requirements for the partial discharge test between the terminal and the shell: First, raise the voltage from the terminal to the shell to 7 kV. ACrms Maintain for 10 s, record the partial discharge value (only for recording, not as a criterion for judgment), and then reduce the voltage to 5 kV. ACrms Maintain for 60 s to measure the partial discharge amount, and the partial discharge amount should be less than 10 pC. It is very difficult for existing products to meet the corresponding requirements. Therefore, it is necessary to improve the structure and related production processes of the DC support capacitor to improve the partial discharge level of the DC support capacitor.

[0008] In summary, this type of DC support capacitor needs to solve technical problems such as electro-dynamic force and partial discharge during the partial discharge test between the terminal and the shell, and at the same time improve the quality and lifespan of the capacitor. Summary of the Invention

[0009] In order to solve the existing technical problems of partial discharge and electro-dynamic force between the terminal and the shell of the DC support capacitor, the present utility model proposes a dry-type DC support capacitor for smart grid (hereinafter referred to as "capacitor").

[0010] The technical solution adopted by the present utility model is as follows.

[0011] The capacitor includes a housing, a core module, an electrical connection assembly, a terminal assembly, filled resin, a pressure relief valve, and a pressure switch. The housing includes a shell body, a shell bottom, a shell cover, and mounting lugs. The mounting lugs include a mounting lug body and a mounting nut. The core module includes a core housing, components, component lead-out copper foils, and encapsulated resin. The core housing includes a core housing body, core housing side plates, and a core housing bottom. The electrical connection assembly includes a bus connection copper bar and electrical connection lead-outs. The terminal assembly includes insulators, conductive rods, round nuts, insulating washers, sealing rings, a first insulating plate, a first electrode copper bar, a second insulating plate, and a second electrode copper bar. The component lead-out copper foils are welded to both end faces of the components. The encapsulated resin includes gaps between components, gaps between components and component lead-out copper foils, and gaps between components and the core housing. The component lead-out copper foils of the core module and the bus connection copper bars of the electrical connection assembly are soldered together, and the bus connection copper bars and the electrical connection lead-outs are soldered together. The lower end of the sealing ring is placed in the hole of the shell cover and sealed with sealant. The upper end of the sealing ring is placed in the convex groove at the bottom of the insulator. An insulating washer and a round nut are sequentially placed in the round groove at the upper end of the insulator. The lower end of the sealing ring is sequentially placed with a first insulating plate, a first electrode copper bar, a second insulating plate, and a second electrode copper bar. The upper end of the conductive rod passes upward through the inner holes of the second electrode copper bar, the second insulating plate, the first electrode copper bar, the first insulating plate, the sealing ring, the insulating washer, and the round nut in sequence. The bottom of the conductive rod is soldered to the first electrode copper bar and the second electrode copper bar respectively to serve as the two poles of the capacitor. The filled resin includes the resin filled in the gaps between core modules and the gaps between the core modules and the housing. The pressure relief valve and the pressure switch are installed on the capacitor shell cover.

[0012] The materials of the shell body, shell bottom, shell cover, and mounting lugs of the housing are SU304 stainless steel, and their thicknesses are all 3 mm.

[0013] The number of core modules is determined by the size and capacity of the capacitor. The core housing body is sealed with the core housing side plates and the core housing bottom with sealant in sequence. After the sealant cures, the components with the component lead-out copper foils welded are placed into the core housing, and the encapsulated resin is vacuum cast. After the encapsulated resin cures, the core module assembly begins. The upper ends of the component lead-out copper foils are bent, and the component lead-out copper foils of multiple core modules and the bus connection copper bars of the electrical connection assembly are soldered together.

[0014] The core housing body is folded into a "U" shape, its material is a PP board, and its thickness is 2 mm. The core housing side plates are rectangular, its material is a PP board, and its thickness is 2 mm. The core housing bottom is rectangular, its material is a PP board, and its thickness is 2 mm.

[0015] The encapsulated resin uses polyurethane, the mixing ratio of A and B materials is 20:100, and the density is 0.92 g / cm 3 , and the flame retardant grade is V0.

[0016] The component adopts a cylindrical shape. It is made by winding a metallized film around a mandrel and spraying gold layers at both ends, and has the performance of self-healing after local breakdown.

[0017] The copper foil material of the component lead-out is brass, with a thickness of 1 mm. The component lead-out copper foil includes multiple short wire strips, which are integrally stamped and the burr parts are polished, and the surface is tin-plated. The short wire strips are welded to the component. When the capacitor is impacted by a large electrodynamic force, the electrodynamic force is buffered by the short wire strips and then dispersed to the solder joints of each component, and the situation of the copper bus directly pulling or breaking the solder joints will not occur.

[0018] The material of the busbar connecting copper bus is brass, with a thickness of 1 mm, and the surface is tin-plated.

[0019] The electrical connection lead-out adopts a multi-strand copper braided wire, with an electrical cross-sectional area of 36 mm2, and the surface is tin-plated.

[0020] The material of the insulator is SMC composite material, with a groove at the top, a convex groove at the bottom, and an inner hole in the middle.

[0021] The material of the conductive rod is brass, with an external thread at the upper end, a smooth rod in the middle part, a square at the bottom, and the outer surface is tin-plated.

[0022] The material of the round nut is brass, with an inner hole in the middle, an internal thread, and the outer surface is nickel-plated.

[0023] The material of the insulating washer is electrical cardboard.

[0024] The material of the sealing ring is silicone rubber, with a Shore hardness of 40 - 45 degrees.

[0025] The first insulating board is made of 2 mm thick epoxy board, with 8 square holes with a length of 17 mm, and the four corners are chamfered.

[0026] The material of the first electrode copper bus is brass, with a thickness of 1 mm, the surface is tin-plated, there are 4 square holes with a length of 17 mm, 4 round holes with a diameter of 50 mm, and 1 folded edge with a length of 10 mm.

[0027] The second insulating board is made of 2 mm thick epoxy board, with 8 square holes with a length of 17 mm, and the four corners are chamfered.

[0028] The material of the second electrode copper bus is brass, with a thickness of 1 mm, the surface is tin-plated, there are 4 square holes with a length of 17 mm, 4 round holes with a diameter of 50 mm, and 1 folded edge with a length of 10 mm.

[0029] The filled resin is polyurethane, the mixing ratio of A and B materials is 20:100, and the density is 0.92 g / cm 3 , and the flame retardant grade is V0.

[0030] Furthermore, the filled resin and the encapsulated resin are made of the same material.

[0031] Furthermore, the size of the first insulating plate is larger than that of the first electrode copper bar, the second insulating plate, and the second electrode copper bar. The length of the second insulating plate is longer than that of the first electrode copper bar and the second electrode copper bar, and the width of the second insulating plate is shorter than that of the first electrode copper bar and the second electrode copper bar.

[0032] Furthermore, the electrical connection outgoing wire is welded to the first electrode copper bar at the folded edge, and the electrical connection outgoing wire is welded to the second electrode copper bar at the folded edge.

[0033] The beneficial effects of the present utility model are as follows: The capacitor has the characteristics of electrical soft connection, secondary casting, safe and stable operation, high reliability, etc., solves the problem of reducing the impact on components during large electrodynamic shocks, and realizes a partial discharge amount of less than 3 pC when maintaining 5 kV for 60 s and at the same time a partial discharge amount of less than 10 pC when maintaining 7 kV for 10 s, improving the quality and lifespan of the capacitor. ACrms Maintain a partial discharge amount of less than 3 pC for 60 s and at the same time maintain a partial discharge amount of less than 10 pC for 10 s when at 7 kV ACrms Improve the quality and lifespan of the capacitor.

[0034] The structure of the present utility model is simple, convenient for installation and use, and can meet the requirements of long-term safe, stable, and reliable operation of the DC support capacitor under high voltage conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the implementation of the present utility model;

[0036] Figure 2 is Figure 1 the left view of;

[0037] Figure 3 is Figure 1 the top view of;

[0038] Figure 4 is Figure 1 the front vertical sectional structure schematic diagram of;

[0039] Figure 5 is Figure 1 the reverse vertical sectional structure schematic diagram of;

[0040] Figure 6 is Figure 1 the enlarged vertical sectional structure schematic diagram of part A in;

[0041] Figure 7 is the structure schematic diagram of the core module;

[0042] Figure 8 is the schematic diagram of part of the terminal block assembly;

[0043] In the figure, 1 - outer shell; 2 - core module; 3 - electrical connection component; 4 - terminal block component; 5 - filled resin; 6 - pressure relief valve; 7 - pressure switch;

[0044] 11 - housing; 12 - bottom of the housing; 13 - cover of the housing; 14 - mounting bracket;

[0045] 21 - core housing; 22 - component; 23 - copper foil for component lead-out; 24 - encapsulated resin;

[0046] 31 - busbar connection copper bar; 22 - electrical connection lead-out;

[0047] 41 - insulator; 42 - conductive rod; 43 - round nut; 44 - insulating washer; 45 - sealing ring; 46 - first insulating plate; 47 - first electrode copper bar; 48 - second insulating plate; 49 - second electrode copper bar;

[0048] 141 - mounting bracket body; 142 - mounting nut;

[0049] 211 - core housing body; 212 - core housing side plate; 213 - core housing bottom. Detailed implementation mode

[0050] The following further describes the present utility model in conjunction with the accompanying drawings and specific embodiments.

[0051] From Figures 1 - 8 It can be seen that:

[0052] The capacitor includes a housing (1), a core module (2), an electrical connection assembly (3), a terminal assembly (4), filled resin (5), a pressure relief valve (6), and a pressure switch (7); the housing (1) includes a housing body (11), a housing bottom (12), a housing cover (13), and mounting lugs (14); the mounting lugs (14) include a mounting lug body (141) and a mounting nut (142); the core module (2) includes a core housing (21), components (22), component lead copper foils (23), and encapsulated resin (24); the core housing (21) includes a core housing body (211), core housing side plates (212), and a core housing bottom (213); the electrical connection assembly (3) includes a bus connection copper bar (31) and electrical connection leads (32); the terminal assembly (4) includes insulators (41), conductive rods (42), round nuts (43), insulating washers (44), sealing rings (45), a first insulating plate (46), a first electrode copper bar (47), a second insulating plate (48), and a second electrode copper bar (49); the component lead copper foils (23) are welded to both end faces of the components (22), and the encapsulated resin (24) includes gaps between the components (22), gaps between the components (22) and the component lead copper foils (23), and gaps between the components (22) and the core housing (21); the component lead copper foils (23) of the core module (2) and the bus connection copper bar (31) of the electrical connection assembly (3) are soldered together, and the bus connection copper bar (31) and the electrical connection leads (32) are soldered together; the lower end of the sealing ring (45) is placed in the hole of the housing cover (13) and sealed with sealant, the upper end of the sealing ring (45) is placed in the convex groove at the bottom of the insulator (41), the insulating washer (44) and the round nut (43) are sequentially placed in the round groove at the upper end of the insulator (41), the lower end of the sealing ring (45) is sequentially placed with the first insulating plate (46), the first electrode copper bar (47), the second insulating plate (48), and the second electrode copper bar (49), the upper end of the conductive rod (42) sequentially passes upward through the inner holes of the second electrode copper bar (49), the second insulating plate (48), the first electrode copper bar (47), the first insulating plate (46), the sealing ring (45), the insulating washer (44), and the round nut (43), and the bottom of the conductive rod (42) is soldered to the first electrode copper bar (47) and the second electrode copper bar (46) respectively to serve as the positive and negative poles of the capacitor; the filled resin (5) includes resin filled in the gaps between the core modules (2) and the gaps between the core module (2) and the housing (1); the pressure relief valve (6) and the pressure switch (7) are installed on the capacitor housing cover (13).

[0053] The number of the core modules (2) is determined by the size and capacity of the capacitor; the core housing body (211) is sealed with sealant successively between the core housing side plates (212) and the core housing bottom (213); after the sealant is cured, the components (22) welded with the component lead-out copper foils (23) are put into the core housing (21), and then the resin (24) for vacuum casting encapsulation is started; after the encapsulated resin (24) is cured, the assembly of the core modules (2) is started. The upper ends of the component lead-out copper foils (23) are bent, and the component lead-out copper foils (23) of multiple core modules (2) and the busbar connection copper bars (31) of the electrical connection assembly (3) are welded.

[0054] The materials of the housing (11), the housing bottom (12), the housing cover (13) and the mounting bracket (14) are SU304 stainless steel, and the thickness of each is 3 mm.

[0055] The core housing body (211) is folded into a "U" shape, and its material is PP board with a thickness of 2 mm; the core housing side plates (212) are rectangular, and their materials are PP boards with a thickness of 2 mm; the core housing bottom (213) is rectangular, and its material is PP board with a thickness of 2 mm.

[0056] The encapsulated resin (24) is polyurethane, and the mixing ratio of A and B materials is 20:100, with a density of 0.92 g / cm 3 , and the flame retardant grade is V0.

[0057] The components (22) are cylindrical in shape, made by winding metallized film on a mandrel and spraying gold layers at both ends, and have the performance of self-healing after local breakdown.

[0058] The material of the component lead-out copper foil (23) is brass, with a thickness of 1 mm; the component lead-out copper foil (23) includes multiple short wire strips, which are integrally stamped, and each burr part is polished and the surface is tin-plated; the short wire strips are welded to the components. When the capacitor is impacted by large electrodynamic force, the electrodynamic force is buffered by the short wire strips and then dispersed to the solder joints of each component, and the situation that the copper bar directly pulls or breaks the solder joint will not occur.

[0059] The material of the busbar connection copper bar (31) is brass, with a thickness of 1 mm, and the surface is tin-plated.

[0060] The electrical connection lead-out (32) uses multi-strand copper braided wire, with an electrical cross-sectional area of 36 mm2, and the surface is tin-plated.

[0061] The material of the insulator (41) is SMC composite material, with a groove at the top, a convex groove at the bottom, and an inner hole in the middle.

[0062] The material of the conductive rod (42) is brass, with an external thread at the upper end, a smooth rod in the middle part, a square at the bottom, and the outer surface is tin-plated.

[0063] The material of the round nut (43) is brass, with an inner hole in the middle, an internal thread, and its outer surface is nickel-plated.

[0064] The material of the insulating washer (44) is electrical cardboard.

[0065] The material of the sealing ring (45) is silicone rubber, with a Shore hardness of 40 - 45 degrees.

[0066] The first insulating board (46) is made of 2 mm thick epoxy board, with 8 square holes of 17 mm in length, and the four corners are chamfered.

[0067] The material of the first electrode copper bar (47) is brass, with a thickness of 1 mm, its surface is tin-plated, it has 4 square holes of 17 mm in length, 4 round holes of 50 mm in diameter, and a 10 mm long hem.

[0068] The second insulating board (48) is made of 2 mm thick epoxy board, with 8 square holes of 17 mm in length, and the four corners are chamfered.

[0069] The material of the second electrode copper bar (49) is brass, with a thickness of 1 mm, its surface is tin-plated, it has 4 square holes of 17 mm in length, 4 round holes of 50 mm in diameter, and a 10 mm long hem.

[0070] The filled resin (5) uses polyurethane, the mixing ratio of A and B materials is 20:100, and the density is 0.92 g / cm 3 , and the flame retardant grade is V0.

[0071] Furthermore, the filled resin (5) and the encapsulated resin (24) use the same material.

[0072] Furthermore, the size of the first insulating board (46) is larger than that of the first electrode copper bar (47), the second insulating board (48), and the second electrode copper bar (49); the length of the second insulating board (48) is longer than that of the first electrode copper bar (47) and the second electrode copper bar (49); the width of the second insulating board (48) is shorter than that of the first electrode copper bar (47) and the second electrode copper bar (49).

[0073] Furthermore, the electrical connection outgoing line (32) is welded to the first electrode copper bar (47) at the hem; the electrical connection outgoing line (32) is welded to the second electrode copper bar (49) at the hem.

[0074] As described above, it is only the preferred specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present utility model should be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims

1. A dry-type DC support capacitor for smart grid, characterized by: The dry-type DC support capacitor for smart grid includes a shell, a core module, an electrical connection assembly, a terminal assembly, a filling resin, a pressure release valve and a pressure switch. The shell includes a shell body, a shell bottom, a shell cover and a mounting bracket. The mounting bracket includes a mounting bracket body and a mounting nut. The core module includes a core shell, a component, a component outlet copper foil and a packaging resin. The core shell includes a core shell body, a core shell side plate and a core shell bottom. The electrical connection assembly includes a busbar and an electrical connection outlet. The terminal assembly includes an insulator, a conductive rod, a round nut, an insulating washer, a sealing ring, a first insulating plate, a first electrode copper bar, a second insulating plate and a second electrode copper bar. The component lead-out copper foil is welded to both end surfaces of the component. The encapsulated resin includes gaps between components, gaps between components and component lead-out copper foils, and gaps between components and the core shell. The component lead-out copper foil of the core module and the busbar connection copper bar of the electrical connection assembly are connected by soldering. The busbar connection copper bar and the electrical connection lead are connected by soldering. The lower end of the sealing ring is placed in the hole of the shell cover and sealed with a sealant. The upper end of the sealing ring is placed in the convex groove at the bottom of the insulator. The circular groove at the upper end of the insulator is sequentially placed with an insulating washer and a round nut, the lower end of the sealing ring is sequentially placed with a first insulating plate, a first electrode copper bar, a second insulating plate and a second electrode copper bar, the upper end of the conductive rod passes upward through the inner holes of the second electrode copper bar, the second insulating plate, the first electrode copper bar, the first insulating plate, the sealing ring, the insulating washer and the round nut, the bottom of the conductive rod is respectively connected to the first electrode copper bar and the second electrode copper bar by soldering as the two poles of the capacitor, the filled resin includes the resin filling the gap between the core modules and the gap between the core module and the shell, and the pressure release valve and the pressure switch are installed on the capacitor shell cover.

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