72.5kv single-tank type environmentally friendly gas insulated GIS structure for offshore wind power tower

Abstract

This invention discloses a 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers. It connects to the transformer on the wind turbine generator side at the top and to the submarine cables on both sides of the wind turbine tower at the bottom. A second chamber with a two-stage pressure differential enhances the gas pressure and insulation capacity within the insulation tank, solving the problem of insufficient mechanical lifespan of existing vacuum bubble corrugated pipe technology in 5-6 MPa high-pressure gas environments. The three-position switch adopts an innovative L-shaped direct-acting double-contact structure, fully utilizing the three-dimensional space. The insulation disc uses a dielectric constant functionally graded material to improve overall insulation performance. A shock-resistant base combining gas springs and hydraulic cylinders achieves vibration reduction and energy dissipation. The insulating gas is clean air, complying with carbon neutrality policies and representing the future development direction. Integrating all high-voltage switches into a single tank significantly reduces size, resulting in a compact structure, saving floor space, facilitating installation within offshore wind turbine towers, and minimizing the risk of gas and electrical leakage, thus offering a cost advantage.

Description

Technical Field

[0001] This invention relates to the field of power equipment, specifically to a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers. Background Technology

[0002] For large-capacity and long-distance offshore wind power transmission projects, the single-unit capacity of wind turbines is constantly increasing, and the voltage level of wind farm power collection systems is also rising accordingly. Currently, the maximum capacity is 12MW, and in the future, there may be 15MW or even 20MW offshore wind turbine units. To address the technological trend of future 10MW and above wind turbine units, the 72.5kV offshore wind power GIS (Gas Insulated Switchgear) power collection solution will become the mainstream. However, the mature solution for existing wind tower power collection switches is the 35kV ring main unit, which cannot meet the voltage requirements. On the other hand, the 72.5kV GIS layout method of onshore high voltage cannot meet the system wiring requirements of offshore wind turbine towers.

[0003] To address the above issues, Chinese Patent Publication No. CN215071312U discloses a three-phase common-enclosure GIS structure for wind turbine towers. This structure includes a control cabinet and, electrically connected to the control cabinet, a circuit breaker, a first isolating grounding switch, a second isolating grounding switch, a third isolating grounding switch, a first current transformer, and a voltage transformer. The first and second isolating grounding switches are vertically aligned, while the third isolating grounding switch is horizontally aligned. A first cable terminal is electrically connected to the lower part of the first isolating grounding switch; a second cable terminal is electrically connected to the lower part of the second isolating grounding switch; and a third cable terminal is electrically connected to the second current transformer. The first and second cable terminals are connected downwards, and the third cable terminal is connected upwards. This GIS structure reduces the space occupied by cable bends, has a compact structure, a small footprint, and is easy to install inside the wind turbine tower.

[0004] For example, Chinese Patent CN113970527A discloses a method for unmanned indoor inspection of GIS (Gas Infrared System) at an offshore wind farm substation, belonging to the field of unmanned substation inspection technology. This method utilizes an unmanned inspection robot, which is controlled to move to different locations to measure SF6 gas concentration and WIFI signal strength. Based on the received WIFI signal strength, the relative distance between each location is obtained, and the spatial coordinates of different locations are calculated, achieving spatial positioning of the inspection robot. After obtaining the gas concentration values ​​at different coordinates, the gas concentration at any location is estimated using gas diffusion theory. The residual between the measured and estimated values ​​is used to correct the gas diffusion model, obtaining accurate calculation data, and further generating an indoor gas concentration distribution map. The point of maximum concentration is identified as the gas leak point. This invention uses a simple device with low operating costs, enabling accurate monitoring of SF6 concentration at all locations within the GIS (Gas Infrared System) of an offshore substation through unmanned inspection, ensuring the safety and stability of the offshore substation's operation.

[0005] Currently, existing gas-insulated structures for offshore wind turbine towers have shortcomings: The first patented offshore wind power GIS solution uses a single-phase box-type structure for the third cable terminal, which includes three single-phase sub-cable terminals and multiple functional boxes spliced ​​together. Each additional splicing link introduces a risk of gas leakage and insulation failure, requires additional space, and incurs additional costs for splicing components. The second patented offshore wind power GIS solution uses SF6 gas as the insulating medium, which does not meet the environmental requirements for carbon neutrality, and the existing technology still needs improvement. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers, thereby solving the aforementioned problems.

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

[0008] A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers mainly comprises the following parts: a tank body, a first cable chamber, a second cable chamber, a third cable chamber, a first three-position mechanism chamber, a second three-position mechanism chamber, a third three-position mechanism chamber, a circuit breaker mechanism chamber, a control chamber, and a base. The tank body includes a first three-position switch, a second three-position switch, a third three-position switch, a circuit breaker switch, a first busbar, a second busbar, a third busbar, a first insulating cable outlet panel, a second insulating cable outlet panel, a third insulating cable outlet panel, a fourth insulating support panel, and a top cover. One end of the first three-position switch, the second three-position switch, and the third three-position switch is connected to the circuit breaker switch, and the other end is connected to the first insulating cable outlet panel, the second insulating cable outlet panel, and the third insulating cable outlet panel respectively via the first busbar, the second busbar, and the third busbar, forming a high-voltage primary main circuit section, installed within a single sealed tank body. The fourth insulating support panel is connected to the circuit breaker switch and serves as the main support for the circuit breaker switch.

[0009] Furthermore, the first insulating outlet panel, the second insulating outlet panel, the third insulating outlet panel, and the top cover are all equipped with sealing rings and are bolted to the tank body. The insulating cylinder, the outlet conductive seat, the end face of the vacuum interrupter shell, and the first bellows form an independent first cavity. A sealing ring is installed between the two connecting end faces to create an air seal. Clean air at a pressure of 2-3 MPa is filled to maintain a relatively low pressure to protect the vacuum bubbling end bellows.

[0010] Furthermore, the first three-position switch is composed of a first insulating support plate, a first disconnecting switch support base, a first grounding switch grounding base, and a first disconnecting switch moving contact. The first three-position switch adopts an L-shaped direct-acting double-contact structure, and the direct-acting double contact is driven by a single operating shaft.

[0011] Furthermore, the second and third position switches are composed of a second insulating support plate, a second disconnecting switch support base, a second grounding switch moving end, and a second disconnecting switch moving contact.

[0012] Furthermore, the third three-position switch is composed of a third insulating support plate, a third disconnecting switch support base, a third grounding switch moving end, and a third disconnecting switch moving contact.

[0013] Furthermore, the circuit breaker switch is composed of an insulating cylinder, a circuit breaker outlet socket, a circuit breaker vacuum interrupter chamber, and a switch stationary end support.

[0014] Furthermore, the insulating cylinder, the second corrugated pipe, and the tank top cover form a second cavity. The air pressure in the second cavity can be superimposed on the air pressure in the first cavity. The pressure difference between the cavities is less than the maximum withstand pressure of the second corrugated pipe, and the maximum pressure that can be filled with is 5 MPa of insulating gas.

[0015] Furthermore, the tank body is equipped with a first cable compartment, a second cable compartment, a third cable compartment, a circuit breaker mechanism compartment, a first three-station mechanism compartment, a second three-station mechanism compartment, a third three-station mechanism compartment, and a control room.

[0016] Furthermore, a base is installed below the tank body. The base has two layers. The top layer is a steel base welded from I-beams. Gas springs are installed at the four corners of the bottom of the steel frame. Multiple hydraulic cylinders are installed around the gas springs. The hydraulic rods are set in the vertical direction. Both the hydraulic cylinders and the gas springs can move up and down.

[0017] Furthermore, the fourth insulating support plate is installed on the tank body, and a switch stationary end support is installed on the fourth insulating support plate. The upper end of the switch stationary end support is electrically connected to the stationary end of the circuit breaker vacuum interrupter, and the moving end of the circuit breaker vacuum interrupter is electrically connected to the circuit breaker outlet base. An insulating cylinder is installed on the circuit breaker outlet base, and the upper end of the insulating cylinder is clipped onto the end cover.

[0018] Compared to existing technologies, the advantages of this invention are as follows: A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers is connected to the transformer on the wind turbine generator side at the top and to the submarine cables on both sides of the wind turbine tower at the bottom. The second chamber, establishing a two-stage pressure differential, enhances the gas pressure and insulation capacity within the insulation tank, solving the problem of insufficient mechanical lifespan of existing vacuum bubble corrugated pipe technology in 5-6 MPa high-pressure gas environments; the three-position switch adopts an innovative L-shaped direct-acting double-contact structure, fully utilizing the three-dimensional space; the insulation disc uses functionally graded dielectric material (FGM) to improve overall insulation performance; an anti-vibration base combining gas springs and hydraulic cylinders achieves vibration reduction and energy dissipation; the insulating gas uses clean air, complying with carbon neutrality policies and representing the future development direction; all high-voltage switches are integrated into a single tank, significantly reducing size, resulting in a compact structure, saving floor space, facilitating placement within offshore wind turbine towers, and minimizing the risk of gas and electrical leakage, thus offering a cost advantage. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to the present invention;

[0020] Figure 2 This is an appearance diagram of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to the present invention;

[0021] Figure 3 This is a primary scheme diagram of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to the present invention;

[0022] Figure 4 This is a schematic diagram of the base structure of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to the present invention.

[0023] Figure 5 This is a schematic diagram of the dielectric constant gradient of the insulating cable tray of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to the present invention.

[0024] Figure 6 This invention provides a diagram of the first three-position switch of a 72.5kV single-tank environmentally friendly gas-insulated GIS structure L-shaped switch for offshore wind turbine towers.

[0025] Figure 7 This invention relates to a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure L-shaped first three-position switch connection map for offshore wind turbine towers;

[0026] Figure 8 This invention provides a closing diagram of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure L-shaped first three-position switch for offshore wind turbine towers.

[0027] Figure 9 This is a cross-sectional view of a 72.5kV single-tank type environmentally friendly gas-insulated GIS structure circuit breaker for offshore wind turbine towers according to the present invention; 104a-first cavity, 104b-second cavity, 104c-vacuum cavity, 1040-circuit breaker moving contact, 1041-insulating cylinder, 1045-first bellows, 1046-second bellows, 1047-outgoing conductor base, 1048-insulating tie rod, 1049-tank top cover. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] This invention provides a technical solution: a 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers, mainly comprising the following parts: tank body 1, first cable chamber 2, second cable chamber 3, third cable chamber 4, first three-position mechanism chamber 5, second three-position mechanism chamber 6, third three-position mechanism chamber 7, circuit breaker mechanism chamber 8, control room 9, and base 10. The tank body 1 includes a first three-position switch 101, a second three-position switch 102, a third three-position switch 103, a circuit breaker switch 104, a first busbar 105, a second busbar 106, and a third... Busbar 107, first insulated cable outlet panel 108, second insulated cable outlet panel 109, third insulated cable outlet panel 110, fourth insulated support panel 111, and top cover 112; one end of the first three-position switch 101, the second three-position switch 102, and the third three-position switch 103 are connected to the circuit breaker switch 104, and the other end is connected to the first insulated cable outlet panel 108, the second insulated cable outlet panel 109, and the third insulated cable outlet panel 110 respectively through the first busbar 105, the second busbar 106, and the third busbar 107, forming the high-voltage primary main circuit section, installed in a single sealed tank 1. The fourth insulated support panel 111 is connected to the circuit breaker switch 104, and the fourth insulated support panel is the main support for the circuit breaker switch.

[0030] The first insulating outlet panel 108, the second insulating outlet panel 109, the third insulating outlet panel 110, and the top cover 112 are all equipped with sealing rings and bolted to the tank body 1, forming a sealed first cavity. The first cavity is filled with clean air at 5-6 MPa as an insulating gas. The insulating outlet panels are made of advanced functionally graded dielectric (FGM) materials. FGM refers to a structure in which fillers (SiO, Al2O3, TiO, SrTiO3) with different dielectric strengths are distributed in different parts of the insulating substrate (usually epoxy resin) to achieve a gradient arrangement of the dielectric constant of the insulating components. Currently, the manufacturing methods of FGM insulators include lamination, centrifugation, 3D printing, and flexible casting. According to the application scenario of the basin insulator, the electric field is strongest near the electrode 300. By using FGM to increase the relative dielectric constant of the insulating surface near the electrode 300 (ε=10) and then decreasing it along the surface (ε=4), the surface discharge can be reduced, and the size of the basin insulator can be reduced. Generally speaking, the size of the disc insulator determines the size of the GIS gas chamber. Therefore, reducing the size of disc insulators will also reduce the size of GIS air chambers.

[0031] The circuit breaker switch 104 consists of an insulating cylinder 1041, a circuit breaker outlet seat 1042, a circuit breaker vacuum interrupter 1043, and a switch stationary end support 1044. In this invention, the insulating cylinder 1041, the outlet conductive seat 1047, the end face of the circuit breaker vacuum interrupter 1043, and the first bellows 1045 form an independent first cavity 104a. A sealing ring is installed between the two connecting end faces for gas sealing, and clean air at a pressure of 2-3 MPa is filled to maintain a relatively low pressure to protect the moving end bellows of the vacuum breaker, thus solving the problem that existing vacuum breaker bellows technology cannot meet mechanical life requirements in a high-pressure gas environment of 5-6 MPa. The second bellows 1046, the insulating cylinder 1041, and the tank top cover 1049 form a second cavity 104b. The air pressure in the second cavity 104b can be superimposed on the air pressure of the first cavity 104a, and the pressure difference between the cavities is less than the maximum withstand pressure of the second bellows 1046. It can be filled with insulating gas up to 5 MPa. By increasing the insulating gas pressure, the insulation performance per unit distance within the cavity is improved, thereby shortening the net distance between conductors and the creepage distance on the surface of the insulating components. This allows for a reduction in the overall size of the insulating components (insulating rods / insulating cylinders), enabling the miniaturization of the circuit breaker's insulating structure.

[0032] The first cable compartment 2 is equipped with a first cable terminal 201, the second cable compartment 3 is equipped with a second cable terminal 301, and the third cable compartment 4 is equipped with a third cable terminal 401. Optional installations include a through-type current transformer 202 and a rear-mounted surge arrester 302. The cable compartment shell serves as structural support and protects against marine environmental pollution.

[0033] The first three-position mechanism chamber 5, the second three-position mechanism chamber 6, the third three-position mechanism chamber 7, and the circuit breaker mechanism chamber 8 are equipped with their respective switch operating mechanisms. The shell of the mechanism chamber serves as structural support and prevents marine environmental pollution.

[0034] The control room 9 is equipped with electrical control components, relay protection, metering elements, etc., and is used to control the circuit breaker, the first three-position switch 101, the second three-position switch 102, and the third three-position switch 103 via electrical signals. The control room shell serves as structural support and protects against marine environmental pollution.

[0035] The first three-position switch 101 consists of a first insulating support plate 1011, a first disconnecting switch support base 1012, a first grounding switch grounding base 1013, and a first disconnecting switch moving contact 1014. The first three-position switch 101 adopts an L-shaped direct-acting double-contact structure. The direct-acting double contacts are driven by a single operating shaft, enabling mutually exclusive interlocking of the positions in a direct-acting single-contact three-position switch scheme, preventing the simultaneous closing of two switches. The main gear 206 is mounted on the main shaft of the mechanism. The main gear 206 is an incomplete spur gear with clearance slots, symmetrically arranged on both sides of the driven gear. The grounding driven gear 207 and the disconnecting driven gear / 205 mesh with the spur gear. The grounding synchronizing gear 203 is arranged inside the main gear 206, and the disconnecting synchronizing gear 204 is arranged outside and inside the main gear 206. The grounding synchronous gear 203 and the grounding driven gear 207 rotate synchronously and mesh with the grounding switch rack 202; the isolation synchronous gear 204 and the isolation driven gear 205 rotate synchronously and mesh with the isolation switch rack 201. The grounding switch rack 202 is rigidly connected to the grounding switch moving contact 1015, and the isolation switch rack 201 is rigidly connected to the first isolation switch moving contact 1014. The grounding switch moving contact 1015 and the first isolation switch moving contact 1014 are fitted inside the first isolation switch support 1012.

[0036] Figure 6 With the first three-position switch 101 in the closed state, the main shaft of the mechanism drives the main gear 206 to rotate clockwise by a certain angle (65°), which in turn drives the grounding driven gear 207. The grounding switch gear rack group drives the grounding switch moving contact 1015 to insert into the first grounding switch grounding seat 1013, completing the grounding closing. At the same time, the main gear 206's clearance groove allows the isolation driven gear 205 to pass, and the first isolating switch moving contact 1014 does not move, remaining in the isolated position. The main gear 206 rotates in the opposite direction by the same angle, and the grounding switch opens. The main shaft of the mechanism drives the main gear 206 to rotate counterclockwise by a certain angle (65°), which in turn drives the isolation driven gear 205. The isolating switch gear rack group drives the first isolating switch moving contact 1014 to insert into the isolating switch closing seat 1016, completing the isolation closing. At the same time, the main gear 206's clearance groove allows the grounding driven gear 207 to pass, and the grounding switch moving contact 1015 does not move, remaining in the connected position. The main gear 206 rotates in the opposite direction by the same angle, causing the disconnect switch to open. The connection diagram and closing diagram for the L-type first three-position switch 101 are shown below. Figure 7 and Figure 8 .

[0037] The traditional GIS uses a direct-acting single-contact three-position switch scheme, which requires a long space in the contact movement direction (X direction). The L-type direct-acting double-contact three-position switch of the present invention only occupies half of the space in the X direction, and the other half is turned to the Y direction. This structure is more conducive to the compact arrangement of GIS structures with multiple switches in a common box.

[0038] The second three-position switch 102 is composed of a second insulating support plate 1021, a second disconnecting switch support base 1022, a second grounding switch moving end 1023, and a second disconnecting switch moving contact 1024.

[0039] The third three-position switch 103 consists of a third insulating support plate 1031, a third disconnecting switch support base 1032, a third grounding switch moving end 1033, and a third disconnecting switch moving contact 1034.

[0040] The three-position switch is functionally divided into a disconnector and a grounding switch. The disconnector adopts a direct-acting structure, which has better field strength than the knife switch structure. The moving contact moves directly out of the disconnector support and into the closing seat, closing the disconnector; when the moving contact moves directly and fully into the disconnector support, the disconnector opens. The first disconnector closing seat 1016 is integrated on the circuit breaker outgoing terminal seat 1042, while the second and third disconnector closing seats are integrated on the circuit breaker switch stationary support.

[0041] The grounding switch of the first three-position switch 101 is a slow direct-acting structure. The moving end is on the high-voltage side. The circuit is closed when the grounding moving contact is fully connected to the grounding base 1013 of the first grounding switch, and the circuit is opened when the grounding moving contact is fully entered into the disconnecting switch support base 1012.

[0042] The grounding switches of the second and third position switches 102 and the third and third position switches 103 are fast direct-acting structures with short-circuit current switching capability. When the moving end of the switch is on the ground potential side, the switch is closed when the grounding moving contact is fully connected to the second disconnector support 1022 and the third disconnector support 1032. When the grounding moving contact is pulled to a safe insulation distance by the mechanism, the switch is opened.

[0043] The first three-position switch 101 is arranged at the top and is connected to the upper conductor circuit breaker outlet base 1042 of the circuit breaker switch 104. The other end is plugged into the first busbar 105. The first busbar 105 is fixed to the first insulating outlet panel 108 with bolts. The first cable terminal 201 is installed on the first insulating outlet panel 108 and connected to the wind turbine transformer cable.

[0044] The second and third position switches 102 and 103 are arranged at the bottom, symmetrically distributed on the left and right sides of the circuit breaker switch 104, and connected to the stationary end support 1044 of the lower conductor switch of the circuit breaker. The other end is respectively connected to the second busbar 106 and the third busbar 107. The second busbar 106 and the third busbar 107 are fixed to the second insulating cable outlet panel 109 and the third insulating cable outlet panel 110 with bolts. The second cable terminal 301 and the third cable terminal 401 are installed on the second insulating cable outlet panel 109 and the third insulating cable outlet panel 110 and connected to the submarine cable ring network on both sides of the wind tower.

[0045] The first disconnector support base 1012 is bolted to the first insulating support plate 1011, the second disconnector support base 1022 is bolted to the second insulating support plate 1021, and the third disconnector support base 1032 is bolted to the third insulating support plate 1031. The first insulating support plate 1011, the second insulating support plate 1021, and the third insulating support plate 1031 are bolted to the tank body. The first insulating support plate 1011, the second insulating support plate 1021, the third insulating support plate 1031, and the fourth insulating support plate 111 serve two purposes: first, to support the disconnector support bases; and second, to provide insulation between the disconnector support bases and the tank body.

[0046] The fourth insulating support plate 111 is installed on the tank body, and a switch stationary end support 1044 is installed on the plate, serving as support and insulation. The upper end of the switch stationary end support 1044 is electrically connected to the stationary end of the circuit breaker vacuum interrupter 1043, and the moving end of the circuit breaker vacuum interrupter 1043 is electrically connected to the circuit breaker outlet seat 1042. An insulating cylinder 1041 is installed on the circuit breaker outlet seat 1042. The upper end of the insulating cylinder 1041 is clamped onto the end cover, fixing it radially. The insulating cylinder 1041 contains a mechanism cam, a contact spring, and an insulating pull rod, which is bolted to the moving end of the vacuum interrupter. The mechanism cam is externally connected to the circuit breaker mechanism, driving the circuit breaker to open and close.

[0047] The base 10 consists of two layers. The top layer is a steel base 1001 welded from I-beams, used to connect the tank. Gas springs 1002 are installed at the four corners of the bottom of the steel frame. Multiple hydraulic cylinders 1003 are mounted around the gas springs 1002, with hydraulic rods arranged vertically. The hydraulic rods of the multiple hydraulic cylinders 1003 support the entire machine. Both the hydraulic cylinders 1003 and the gas springs 1002 can move up and down. The hydraulic cylinder 1003 has a steep pressure-stroke curve; if used alone for vibration resistance, the equipment would sway significantly, which is detrimental to the stability of the cable interface. Therefore, the hydraulic cylinder 1003 primarily serves a supporting function. The gas spring 1002 has a shallow pressure-stroke curve, a gentle amplitude, and strong impact resistance. However, if the gas spring deflates, it lacks rigid support and requires the support of the hydraulic cylinders 1003. This combined structure has a low natural frequency, effectively resisting vibration and swaying. The base 10 supports the tank 1 and the cable compartment bracket.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers, characterized in that, It comprises the following parts: tank body (1), first cable chamber (2), second cable chamber (3), third cable chamber (4), first three-station mechanism chamber (5), second three-station mechanism chamber (6), third three-station mechanism chamber (7), circuit breaker mechanism chamber (8), control room (9), and base (10). The tank body (1) includes a first three-station switch (101), a second three-station switch (102), a third three-station switch (103), and a circuit breaker switch (104). The system comprises a first busbar (105), a second busbar (106), a third busbar (107), a first insulating cable outlet panel (108), a second insulating cable outlet panel (109), a third insulating cable outlet panel (110), a fourth insulating support panel (111), and a top cover (112). One end of the first three-position switch (101), the second three-position switch (102), and the third three-position switch (103) is connected to a circuit breaker switch (104), and the other end is connected to the first busbar (105). The second busbar (106) and the third busbar (107) are connected to the first insulating outlet panel (108), the second insulating outlet panel (109), and the third insulating outlet panel (110), forming the high-voltage primary main circuit. This circuit is installed inside a single sealed tank (1). The fourth insulating support panel (111) is connected to the circuit breaker switch (104). The circuit breaker switch (104) consists of an insulating cylinder (1041), a circuit breaker outlet base (1042), and a circuit breaker vacuum interrupter (1043). 043) The switch stationary end support (1044) is composed of the fourth insulating support plate (111) installed on the tank body (1), the switch stationary end support (1044) is installed on the fourth insulating support plate (111), the upper end of the switch stationary end support (1044) is electrically connected to the stationary end of the circuit breaker vacuum interrupter (1043), the moving end of the circuit breaker vacuum interrupter (1043) is electrically connected to the circuit breaker outlet seat (1042), and the circuit breaker outlet seat (1042) is equipped with an insulating cylinder (1041).

2. The 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 1, characterized in that: The insulating cylinder (1041), the outgoing conductor seat (1047), the end face of the circuit breaker vacuum interrupter chamber (1043) and the first bellows (1045) form an independent first cavity (104a). A sealing ring is installed between the two connecting end faces to form an air seal. Clean air at a pressure of 2-3 MPa is filled to maintain a relatively low pressure to protect the vacuum interrupter end bellows.

3. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 2, characterized in that: The second bellows (1046), the insulating cylinder (1041), and the tank top cover (1049) form an independent second cavity (104b). The air pressure in the second cavity (104b) can be superimposed on the air pressure in the first cavity (104a). The pressure difference between the cavities is less than the maximum withstand pressure of the second bellows (1046).

4. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 3, characterized in that: The first three-position switch (101) is composed of a first insulating support plate (1011), a first disconnecting switch support base (1012), a first grounding switch grounding base (1013), and a first disconnecting switch moving contact (1014). The first three-position switch (101) adopts an L-shaped direct-acting double-contact structure, and the direct-acting double-contact is driven by a single operating shaft.

5. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 4, characterized in that: The second three-position switch (102) is composed of a second insulating support plate (1021), a second disconnecting switch support base (1022), a second grounding switch moving end (1023), and a second disconnecting switch moving contact (1024).

6. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 5, characterized in that: The third three-position switch (103) is composed of a third insulating support plate (1031), a third disconnecting switch support base (1032), a third grounding switch moving end (1033), and a third disconnecting switch moving contact (1034).

7. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 6, characterized in that: The tank body (1) is equipped with a first cable chamber (2), a second cable chamber (3), a third cable chamber (4), a first three-station mechanism chamber (5), a second three-station mechanism chamber (6), a third three-station mechanism chamber (7), a circuit breaker mechanism chamber (8), and a control room (9).

8. A 72.5kV single-tank environmentally friendly gas-insulated GIS structure for offshore wind turbine towers according to claim 7, characterized in that: The tank body (1) is equipped with a base (10) below it. The base (10) is divided into two layers. The top layer is a steel base (1001) welded from I-beams. Gas springs (1002) are installed at the four corners of the bottom of the steel frame. Multiple hydraulic cylinders (1003) are installed around the gas springs (1002). The hydraulic rods are set in the vertical direction. Both the hydraulic cylinders (1003) and the gas springs (1002) can move up and down.

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