A high-voltage capacitor bank for extra-high voltage direct current transmission projects resistant to earthquakes

Abstract

The application provides an earthquake-resistant high-voltage capacitor bank for extra-high voltage direct current transmission engineering, which comprises a high-voltage tower and a low-voltage tower, the high-voltage tower and the low-voltage tower comprise a plurality of capacitor frame layers, each capacitor frame layer comprises a frame and a plurality of capacitor units, the frame comprises six load-bearing channel steels and four vertical steel pipes, the frame has a rectangular frame structure, the load-bearing channel steels form the main body of the rectangular frame structure, the steel pipes are arranged at four corners of the rectangular frame structure, and the capacitor units are installed on the load-bearing channel steels, the capacitor frame layers are connected through interlayer composite support insulators, and the interlayer composite support insulators are connected with the steel pipes of the capacitor frame layers above and below. The application solves the problem that the high-voltage capacitor bank in the prior art cannot reach a high tower layer number and a high earthquake level acceleration on the basis of a double-tower.

Description

Technical Field

[0001] This invention relates to the field of earthquake-resistant power transmission equipment technology, and more specifically to an earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects. Background Technology

[0002] Ultra-high voltage direct current (UHVDC) transmission refers to power transmission projects with voltage levels of ±800kV and above. UHVDC converter stations require a large number of high-voltage capacitor banks. AC high-voltage capacitor banks have rated voltages of 500kV and above, while DC high-voltage capacitor banks have rated voltages of ±800kV and above. The sending-end converter stations of UHVDC projects are typically built in remote areas such as Inner Mongolia and Xinjiang, which are also earthquake-prone regions. Because the capacitor banks have very large capacities, they can reach heights of over 10 meters and weigh over 40 tons. Currently, conventional earthquake-resistant technologies for capacitor banks are approaching their technological limits. Each UHVDC transmission project is a vital artery for national energy transmission and a key national project, requiring extremely high levels of equipment operational safety. Therefore, designing effective and reliable earthquake-resistant technologies for high-voltage capacitor banks has significant engineering value.

[0003] As the rated transmission power of ultra-high voltage direct current (UHVDC) transmission projects gradually increases from 8000MW to 12000MW, the required capacitive reactive power compensation capacity also gradually increases. However, the maximum capacity of a single capacitor remains at approximately 600kvar, inevitably leading to an increasing number of individual capacitors and consequently, an increasing number of layers required for capacitor banks. In the earthquake-prone Northwest region, the existing seismic-resistant structures of high-voltage capacitor banks used in UHVDC transmission projects face the following challenges: 1. While the horizontal acceleration resistance to earthquakes can reach 0.4g, the number of layers in a lateral double-tower configuration for a capacitor unit cannot reach 27; 2. While a lateral double-tower configuration for a capacitor unit can reach 27 layers, the horizontal acceleration resistance to earthquakes can only reach 0.317g; 3. Increasing the number of layers and improving the seismic resistance of high-voltage capacitor banks is mainly limited by the critical support component, the porcelain post insulator. Currently, the bending failure strength of mature porcelain post insulators is approximately 70MPa~80MPa, leaving little room for further strength improvement. Summary of the Invention

[0004] This invention provides an earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects, which solves the problem that existing high-voltage capacitor banks, based on double towers, cannot achieve a high number of tower stories and high earthquake resistance.

[0005] To address the aforementioned technical problems, this invention provides an earthquake-resistant high-voltage capacitor bank for ultra-high-voltage direct current (UHVDC) transmission projects, comprising a high-voltage tower and a low-voltage tower. Each high-voltage and low-voltage tower includes several capacitor frame layers. Each capacitor frame layer includes a frame and several capacitor units. The frame comprises six load-bearing channel steels and four vertical steel pipes, forming a rectangular frame structure. The load-bearing channel steels constitute the main body of the rectangular frame structure, and the steel pipes are located at the four corners of the rectangular frame structure. The capacitor units are mounted on the load-bearing channel steels. The invention also includes composite post insulators, comprising interlayer composite post insulators, high-voltage tower-to-ground composite post insulators, and low-voltage tower-to-ground composite post insulators. Each capacitor frame layer is connected to the others via interlayer composite post insulators. The interlayer composite post insulators are connected to the steel pipes of the upper and lower capacitor frame layers. The bottom of the high-voltage tower has three layers of high-voltage tower-to-ground composite post insulators, and the bottom of the low-voltage tower has one layer of low-voltage tower-to-ground composite post insulators. A connecting busbar connects the high-voltage tower and the low-voltage tower.

[0006] The capacitor unit body is rectangular, and the small side of the capacitor unit is fitted to the load-bearing channel steel. Two rows of parallel capacitor units are installed on each frame, and the connection terminals of the two rows of capacitor units face back to back and towards the two sides respectively.

[0007] The capacitor unit is provided with a clamp structure on its small side, and the capacitor unit is connected to the load-bearing channel steel through the clamp structure and bolts.

[0008] The steel pipes of the frame are provided with flange supports on both the upper and lower sides.

[0009] An anti-dizziness ring is connected to the outside of the frame.

[0010] The beneficial effects of this invention are as follows: The earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects of this invention can withstand a horizontal acceleration of 0.4g when the capacitor units are installed on the side. At the same time, the total number of floors in the double tower can reach 27, which has strong overall earthquake resistance. The high number of floors allows for the installation of more capacitor units on the basis of the double tower, resulting in a very large overall capacity of the high-voltage capacitor bank. Attached Figure Description

[0011] Figure 1 This is a front view of an earthquake-resistant high-voltage capacitor bank for an ultra-high-voltage direct current transmission project according to an embodiment of the present invention.

[0012] Figure 2 This is a top view of an earthquake-resistant high-voltage capacitor bank for an ultra-high-voltage direct current transmission project according to an embodiment of the present invention.

[0013] Figure 3This is a top view of the capacitor frame layer according to an embodiment of the present invention;

[0014] Figure 4 This is a top view of the frame according to an embodiment of the present invention;

[0015] Figure 5 This is the front view of the frame according to an embodiment of the present invention;

[0016] Figure 6 This is a schematic diagram of a capacitor cell according to an embodiment of the present invention;

[0017] Figure 7 This is a schematic diagram of a load-bearing channel steel according to an embodiment of the present invention;

[0018] Figure 8 This is a schematic diagram of a steel pipe according to an embodiment of the present invention;

[0019] Figure 9 This is a cross-sectional view of a composite post insulator according to an embodiment of the present invention;

[0020] Figure 10 This is a finite element model diagram of a high-voltage capacitor bank according to an embodiment of the present invention;

[0021] Figure 11 This is a mode shape diagram of the high-voltage capacitor bank under modal analysis according to an embodiment of the present invention;

[0022] Figure 12 This is a displacement cloud diagram of the overall structure of the high-voltage capacitor bank according to an embodiment of the present invention;

[0023] Among them, 1-high voltage tower, 2-low voltage tower, 3-capacitor frame layer, 4-frame, 5-capacitor unit, 6-load-bearing channel steel, 7-steel pipe, 8-interlayer composite post insulator, 9-high voltage tower to ground composite post insulator, 10-low voltage tower to ground composite post insulator, 11-connecting busbar, 12-clamp structure, 13-flange support, 14-anti-corona ring. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] An earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects includes a high-voltage tower 1 and a low-voltage tower 2. The high-voltage tower 1 and the low-voltage tower 2 include several layers of capacitor frame layers 3. The capacitor frame layers 3 include frames 4 and several capacitor units 5.

[0026] The frame 4 comprises six load-bearing channel steels 6 and four vertical steel pipes 7. The frame 4 has a rectangular frame structure. The four load-bearing channel steels 6 form the four sides of the rectangular frame structure, and two additional load-bearing channel steels 6 are positioned within the rectangular frame structure, parallel to its long side. The steel pipes 7 are located at the four corners of the rectangular frame structure. The rectangular frame structure is 2700mm long and 1700mm wide. Flange supports 13 are provided on the upper and lower surfaces of the steel pipes 7 of the frame 4. A corona-resistant ring 14 is connected to the outside of the frame 4.

[0027] The capacitor unit 5 is mounted on the load-bearing channel steel 6. The main body of the capacitor unit 5 is rectangular, and its smaller side is fitted against the load-bearing channel steel 6; this installation method is called side-mounted installation. Two rows of parallel capacitor units 5 are mounted on each frame 4, with the connection terminals of the two rows of capacitor units 5 facing back-to-back towards both sides. The connection terminals of the capacitor units 5 are connected using multi-strand soft copper wire. A clamping structure 12 is provided on the smaller side of the capacitor unit 5, and the capacitor unit 5 is connected to the load-bearing channel steel 6 through the clamping structure 12 and bolts.

[0028] Capacitor unit 5 serves to filter system harmonics, compensate for inductive reactive power, and improve the power factor. The materials used to manufacture capacitor unit 5 include polypropylene film, benzyl toluene, aluminum foil, stainless steel plate, and tubing.

[0029] It also includes composite post insulators, which include interlayer composite post insulators 8, high-voltage tower-to-ground composite post insulators 9, and low-voltage tower-to-ground composite post insulators 10. Each layer of the capacitor frame 3 is connected by four interlayer composite post insulators 8, and the interlayer composite post insulators 8 are connected to the flange supports 13 of the upper and lower capacitor frame layers 3. The bottom of the high-voltage tower 1 is provided with three layers of high-voltage tower-to-ground composite post insulators 9, with eight high-voltage tower-to-ground composite post insulators 9 in each layer located at the four corners. The bottom of the low-voltage tower 2 is provided with one layer of low-voltage tower-to-ground composite post insulators 10, with a total of eight high-voltage tower-to-ground composite post insulators 9 located at the four corners. A connecting busbar 11 connects the high-voltage tower 1 and the low-voltage tower 2.

[0030] The weight of a single capacitor unit 5 is between 60kg and 120kg. 12 to 24 capacitor units 5 are installed on each layer of frame 4, and each layer of frame 4 needs to bear a weight between 1400kg and 3000kg.

[0031] Specifically, in this embodiment, the high-voltage tower 1 includes a 13-layer capacitor frame layer 3, and the low-voltage tower 2 includes a 14-layer capacitor frame layer 3, for a total of 27 layers. The high-voltage tower 1 has a total weight of 58 tons and a height of 18.5m, while the low-voltage tower 2 has a total weight of 59 tons and a height of 17m. The load-bearing channel steel 6 of this invention has a height h, a leg width b, an inner diameter D1 and an outer diameter D2 of the steel pipe 7, and a rod diameter d of the composite support insulator. By controlling the matching of these parameters, the displacement of the top of the capacitor bank tower of this invention can be effectively controlled. The moment of inertia of the steel pipe is calculated according to... Calculate, where The moment of inertia of the steel pipe is given. The inner diameter D1 of steel pipe 7 ranges from 140mm to 360mm, and the outer diameter D2 of steel pipe 7 ranges from 160mm to 380mm. The moment of inertia of the load-bearing channel steel 6 is calculated according to... Calculate, where The moment of inertia of the load-bearing channel steel 6 is given. The height h of the load-bearing channel steel 6 ranges from 80mm to 180mm. The width of the load-bearing channel steel 6 is given. The range is 50mm~100mm. The moment of inertia of the composite post insulator section is based on... Calculate, where For the moment of inertia of the composite post insulator, It refers to the rod diameter of the insulator, specifically the rod diameter of the interlayer composite post insulator. The diameter of the low-voltage tower-to-ground composite support insulator ranges from 70mm to 280mm. The diameter of the composite support insulator for high-voltage towers ranges from 140mm to 320mm. The range is 140mm~360mm. It refers to the height of the composite post insulator, and the interlayer composite post insulator. Low-voltage tower to ground composite post insulator with a range of 500mm~1050mm Composite post insulators for high-voltage towers with a thickness ranging from 1200mm to 2000mm. The range is 1800mm~5200mm.

[0032] This invention utilizes ANSYS software to establish a finite element model of the capacitor bank, as shown in the model below. Figure 10 As shown, seismic simulation calculations of stress and displacement were performed based on a seismic intensity of 9 degrees, a horizontal acceleration of 0.4g, and a vertical acceleration of 0.32g. The fundamental dynamic equations under seismic action were calculated according to... In the formula, M is the mass matrix, C is the damping matrix, and K is the stiffness matrix. For ground motion acceleration, These represent the nodal displacement, velocity, and acceleration vectors, respectively. The above equation is decoupled using modal decomposition, becoming n independent differential equations. The seismic response of the structure is then obtained using the response spectrum method. Modal decomposition response spectrum method is a method used to calculate the seismic action of multi-degree-of-freedom systems. This method utilizes the acceleration design response spectrum of single-degree-of-freedom systems and the principle of modal decomposition to solve for the equivalent seismic action corresponding to each mode. Then, according to certain combination principles, the seismic action effects of each mode are combined to obtain the seismic action effect of the multi-degree-of-freedom system. The modal decomposition response spectrum method first calculates the natural vibration modes of the structure, selects several modes to calculate the horizontal seismic action of each mode, applies the horizontal seismic action of each mode to the structure, and calculates its internal forces. Finally, the internal forces of each mode are combined to obtain the internal forces and deformation of the structure under seismic action. Its basic principle is to use the "code" response spectrum to first obtain the corresponding "maximum" seismic force of each mode, and then combine them to obtain the combined seismic action of the structure. The allowable breaking stress of the load-bearing channel steel 6 and steel pipe 7 is 355 MPa, and the combined seismic force of the load-bearing channel steel 6 and steel pipe 7 must be less than 355 MPa. The allowable breaking stress of the composite post insulator is (150~250) MPa, determined by the rod diameter and structure, and the combined seismic force of the composite post insulator must be less than... MPa. The mode shapes of the structure under modal analysis of the capacitor bank are as follows: Figure 11 The displacement cloud diagram of the overall structure of the capacitor bank is as follows: Figure 12 .

[0033] The strength verification of bolts is also a key aspect of this invention. Bolt stress is calculated using flange connections, and bolts subjected to tension, bending moment, and shear force must meet certain requirements. In the formula N t The maximum tensile force of the bolt is N. t b For tensile bearing capacity, N v The maximum tensile force of the bolt is N. v b For shear bearing capacity.

[0034] In summary, the earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects of the present invention can withstand a horizontal acceleration of 0.4g when the capacitor units are installed horizontally on the side. At the same time, the total number of floors in the double tower can reach 27, which has strong overall earthquake resistance. The high number of floors allows for the installation of more capacitor units on the basis of the double tower, resulting in a very large overall capacity of the high-voltage capacitor bank.

[0035] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A high-voltage capacitor bank resistant to earthquakes for use in an extra-high voltage direct current transmission project, characterized in that: The system includes a high-voltage tower (1) and a low-voltage tower (2). Each high-voltage tower (1) and low-voltage tower (2) includes several capacitor frame layers (3). Each capacitor frame layer (3) includes a frame (4) and several capacitor units (5). The frame (4) includes six load-bearing channel steels (6) and four vertical steel pipes (7). The frame (4) has a rectangular frame structure. The load-bearing channel steels (6) form the main body of the rectangular frame structure. The steel pipes (7) are located at the four corners of the rectangular frame structure. The capacitor units (5) are installed on the load-bearing channel steels (6). The system also includes composite post insulators, which include... Interlayer composite post insulator (8), high-voltage tower to ground composite post insulator (9), low-voltage tower to ground composite post insulator (10), each layer of the capacitor frame layer (3) is connected by the interlayer composite post insulator (8), the interlayer composite post insulator (8) is connected to the steel pipe (7) of the upper and lower capacitor frame layers (3), the bottom of the high-voltage tower (1) is provided with three layers of high-voltage tower to ground composite post insulator (9), the bottom of the low-voltage tower (2) is provided with one layer of low-voltage tower to ground composite post insulator (10), the high-voltage tower (1) and the low-voltage tower (2) are connected by a connecting pipe busbar (11); The high-voltage tower (1) includes a 13-layer capacitor frame layer (3), and the low-voltage tower (2) includes a 14-layer capacitor frame layer (3), with a total of 27 layers in the two towers; the high-voltage tower (1) has a total weight of 58 tons and a height of 18.5m, and the low-voltage tower (2) has a total weight of 59 tons and a height of 17m.

2. The high-voltage capacitor bank resistant to earthquakes for extra-high voltage direct current transmission projects according to claim 1, characterized in that, The capacitor unit (5) has a rectangular body. The small side of the capacitor unit (5) is fitted to the load-bearing channel steel (6). Two rows of parallel capacitor units (5) are installed on each frame (4). The connection terminals of the two rows of capacitor units (5) face back to back and towards the two sides respectively.

3. The high-voltage capacitor bank resistant to earthquakes for extra-high voltage direct current transmission projects according to claim 2, characterized in that, The capacitor unit (5) is provided with a clamp structure (12) on its small side, and the capacitor unit (5) is connected to the load-bearing channel steel (6) through the clamp structure (12) and bolts.

4. The earthquake-resistant high-voltage capacitor bank for ultra-high voltage direct current transmission projects as described in claim 1, characterized in that, Flange supports (13) are provided on the upper and lower sides of the steel pipe (7) of the frame (4).

5. The high-voltage capacitor bank resistant to earthquakes for extra-high voltage direct current transmission projects according to claim 1, characterized in that, An anti-dizziness ring (14) is connected to the outside of the frame (4).

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