A structure of directly connecting the first and last ends of a GIL with a cable in a pipe gallery and a pressure test method thereof

Abstract

The embodiment of the application provides a GIL first-end and last-end direct connection structure with a cable in an underground pipe gallery and a withstand voltage test method thereof, the conductive assembly, the tee unit and the GIL three-phase separate-phase unit are arranged in the underground pipe gallery, the first feeding port and the second feeding port are arranged on the underground pipe gallery, the conductive assembly is connected with the tee unit, and the tee unit is connected with the GIL three-phase separate-phase unit. The GIL and the cable are installed in place at one time according to the embodiment of the application, the GIL main loop end terminal detachable conductor in the terminal shell can be removed without disassembling the cable terminal, an electrical isolation break is formed, a test interface reserved in the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL on-site withstand voltage test is realized, and the installation process cross waiting period of the GIL and the cable is effectively reduced.

Description

Technical Field

[0001] The embodiments of this application belong to the field of power technology, and in particular relate to a structure for direct connection between the head and end of a GIL and a cable in an underground utility tunnel and a method for withstand voltage testing thereof. It is mainly used to achieve on-site withstand voltage testing of the GIL without disassembling the cable terminal when the GIL and the cable are directly connected in an underground utility tunnel. Background Technology

[0002] Currently, common methods for connecting GIL to cables include indirect connection via conduit terminals and direct connection via cable terminals.

[0003] Among them, the indirect connection method of bushing terminal is mainly used in outdoor scenarios because the bushing needs to be placed outdoors before connecting the lead wire, and the outdoor environment is also convenient for carrying out on-site withstand voltage tests. However, it requires the construction of an outdoor terminal platform and occupies a certain area of ​​land. If this connection method is deployed in urban areas, the cost is high and it is not conducive to urban landscape and environmental safety. The direct connection method of cable terminal is applicable to both indoor and outdoor scenarios. However, in engineering applications, when the first and last ends of the GIL in the underground pipe gallery are directly connected to the cable, it is still the first application. In addition to fully considering the feasibility of the space for connecting GIL and cable, the space requirements for GIL on-site withstand voltage tests must also be considered.

[0004] 1. Current status of the GIL (Gas Injection Line) installation scheme where both ends are directly connected to cables within the underground utility tunnel in engineering applications.

[0005] When both ends of the GIL are directly connected to the cable, a compact three-dimensional space is used for vertical and lateral arrangement to meet the space size for personnel construction, maintenance, and testing. The branch outlets of the GIL are directly connected to the cable through cable terminals. During installation, the installation is carried out at a high position using a mobile installation platform. After installation, the installation platform is moved out of the feeding port, and the electrical connection is finally completed.

[0006] 2. Current status of GIL field withstand voltage scheme when both ends of the GIL are directly connected to the cable in the underground utility tunnel.

[0007] For GIL field withstand voltage testing, since GIL and cables have different withstand voltage standards, cables cannot be tested for insulation withstand voltage according to GIL standards. Therefore, GIL lines need to be tested for insulation withstand voltage separately in the field.

[0008] Note 1: GILs are divided into two types: three-phase separate enclosure GILs and three-phase shared enclosure GILs. In the three-phase separate enclosure GIL, each phase has an independent structure, and the withstand voltage test is also independent and unrelated for each phase. In the three-phase shared enclosure GIL, since the three phases are in the same enclosure, there is an electrical insulation relationship between the phases. All three phases must pass the insulation withstand voltage test for the GIL to be considered qualified.

[0009] Note 2: This section describes the withstand voltage technology solution for three-phase co-enclosure GIL and direct cable connection under complex working conditions.

[0010] When both ends of the GIL are directly connected to the cable in the underground utility tunnel, the GIL must be electrically disconnected from the cable terminals and cable sections during the on-site withstand voltage test.

[0011] 1) After the initial installation of the GIL, it cannot be directly connected to the cable. Direct connection between the GIL and the cable can only be implemented after the GIL completes its field withstand voltage test. If one end of the GIL is the pressurized side, the cable terminal must not be connected initially. Insulation test fixtures and conductors, which connect to the main circuit at the GIL terminal, must be added inside the terminal housing and the GIL terminal air chamber sealed to achieve the final field insulation test. If the other end of the GIL is the non-pressurized side, the cable terminal can be either not connected initially or connected first. However, detachable conductors for electrical connections must not be installed inside the terminal housing. The main circuit at the GIL terminal is connected to the terminal shielding ball to achieve electrical disconnection. Electrical connections to the cable terminals at both ends of the GIL can only be made after each phase of the field insulation test has passed.

[0012] 2) If an insulation withstand voltage test is to be performed after emergency repair following a fault in the GIL during operation, either end of the GIL should be selected as the pressure-applying side. When connecting any phase of the pressure-applying GIL to the insulation test fixture, the originally connected cable and cable terminal of that phase must first be disassembled and pulled out from the GIL end. Then, the conductor of the GIL withstand voltage test fixture should be connected, and the air chamber at the GIL end should be sealed to ensure the independence of the GIL field insulation withstand voltage test for that phase. The other two phases of the pressure-applying GIL should be electrically disconnected, considering that each phase needs to withstand voltage. For testing purposes, it is possible to choose to disconnect the cable terminals in advance to achieve electrical disconnection, or not to disconnect the cable terminals temporarily. Only the detachable conductors for electrical connection inside the terminal housing need to be disconnected, and a terminal shielding ball is installed on the main circuit at the GIL terminal to achieve electrical disconnection. For the non-pressurized GIL, it is not necessary to disconnect the cable terminals. Only the detachable conductors for electrical connection inside the terminal housing of each phase need to be disconnected, and a terminal shielding ball is installed on the main circuit at the terminal of each phase of the GIL to achieve electrical disconnection. After the GIL has completed phase-by-phase withstand voltage testing, the cable terminals and cables need to be reconnected.

[0013] When the GIL (Gas Insulator) is directly connected to the cable at both ends in the underground utility tunnel, the existing technical solution does not directly reserve the withstand voltage test docking port. However, the GIL phase insulation withstand voltage test requires the corresponding test docking port. Therefore, it is necessary to repeatedly disassemble and install the cable and cable terminal to obtain the GIL phase withstand voltage test docking port.

[0014] 1) After the initial installation of GIL, test ports need to be reserved for the insulation withstand voltage test of each phase of GIL. The GIL withstand voltage test ports cannot be electrically directly connected to the cable and cable terminal. In addition, the non-withstand voltage test ports of GIL need to be electrically disconnected from the cable and cable terminal. If the cable and cable terminal have already been installed, the detachable conductors for electrical connection inside the terminal housing still need to be removed. The terminal shielding ball is installed in the main circuit of GIL terminal to achieve electrical disconnection. The connection between GIL and cable and cable terminal can only be implemented after all phases of GIL have completed the field withstand voltage test.

[0015] 2) If an insulation withstand voltage test is to be performed after emergency repairs following a fault in the GIL during operation, the electrical connection between the beginning and end of the GIL and the cable terminal must be disconnected. The cable and cable terminal that have been connected to either end of the GIL must be removed from the end of the GIL and then connected to the GIL withstand voltage test tooling conductor, etc., to achieve the independence of the GIL on-site insulation withstand voltage test. The connection between the GIL and the cable and cable terminal can only be implemented after all phases of the GIL have completed the on-site withstand voltage test.

[0016] It is evident that this will lead to laborious and cumbersome procedures such as dismantling and reinstalling cables in the limited space of underground utility tunnels. It will also increase a series of uncontrollable safety risks, such as failure of airtight connection and reduced insulation capacity during secondary connection after cable dismantling. Summary of the Invention

[0017] The purpose of this application is to provide a direct connection structure between the GIL (Gas Insulator) and cable in an underground utility tunnel and a method for its withstand voltage test. The GIL and cable are installed in one go. Without disassembling the cable terminal, the detachable conductor at the end of the GIL main circuit inside the terminal housing is removed to form an electrical isolation break. At the same time, the test interface reserved in the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL can be tested on-site independently. This effectively reduces the waiting period between the installation procedures of the GIL and the cable, thereby solving the problems in the background art.

[0018] To address the aforementioned technical problems, the technical solution provided in this application regarding the direct connection structure between the GIL (Gas Inlet and Outer Wall) and the cable within an underground utility tunnel, along with its withstand voltage test method, is as follows:

[0019] In a first aspect, embodiments of this application disclose a direct connection structure between the first and last ends of a GIL and a cable within an underground utility tunnel, comprising an underground utility tunnel, a first feeding port, a second feeding port, a conductive component, a three-way unit, and a GIL three-phase phase-splitting unit. The conductive component, the three-way unit, and the GIL three-phase phase-splitting unit are disposed within the underground utility tunnel. The first feeding port and the second feeding port are disposed on the underground utility tunnel. The conductive component is connected to the three-way unit, and the three-way unit is connected to the GIL three-phase phase-splitting unit.

[0020] In a preferred embodiment of any of the above solutions, the conductive component includes a cable, a cable terminal, and a terminal housing, wherein the cable is connected to the cable terminal, and the cable terminal is connected to the terminal housing.

[0021] In a preferred embodiment of any of the above solutions, the conductive component further includes a cable support connected to the cable, and the cable support is disposed on the mounting platform.

[0022] In a preferred embodiment of any of the above schemes, the direct connection structure between the GIL head and end and the cable in the underground utility tunnel further includes an inspection cover and a cable terminal inspection port. The cable terminal inspection port is disposed on the terminal housing, and the inspection cover is disposed on the cable terminal inspection port.

[0023] In a preferred embodiment of any of the above schemes, the three-way unit is connected to the GIL withstand pressure test interface, the GIL withstand pressure test interface is provided with a test interface cover plate, and the GIL withstand pressure test fixture is connected to the test interface cover plate.

[0024] In a preferred embodiment of any of the above schemes, the direct connection structure between the GIL head and end and the cable in the underground utility tunnel further includes a GIL pressure-resistant interface, which is connected to the tee unit, and a pressure-resistant cover is provided on the GIL pressure-resistant interface.

[0025] In a preferred embodiment of any of the above schemes, the GIL head and tail end structure directly connected to the cable in the underground utility tunnel further includes a shielding ball, which is disposed inside the terminal housing.

[0026] In a preferred embodiment of any of the above schemes, the conductive components are provided in multiple groups, and every two groups are connected to each other.

[0027] In a preferred embodiment of any of the above schemes, the cable support is provided in multiple ways.

[0028] Compared with the prior art, the GIL and cable are directly connected in the underground utility tunnel in the embodiment of this application. The GIL and cable are installed in one go. Without disassembling the cable terminal, the detachable conductor at the end of the GIL main circuit inside the terminal housing is removed to form an electrical isolation break. At the same time, the test interface reserved by the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL can be tested on site alone. This effectively reduces the waiting period between the installation procedures of GIL and cable.

[0029] Secondly, a method for a withstand voltage test of a GIL (Gas Insulator) head-to-end connection structure directly connected to a cable within an underground utility tunnel, the method comprising the following steps:

[0030] Step 1: Open the inspection cover at the first and second feed ports, pass through the cable terminal inspection port, remove the disassembly conductor inside the terminal housing, and install shielding balls on the GIL side terminal conductor of each phase main circuit to form an electrical break.

[0031] Step 2: Open the GIL withstand voltage cover plate reserved on the side of the tee unit at any end of the GIL as the pressure side, and install the insulation test fixture conductor through the GIL withstand voltage interface.

[0032] Step 3: Next, introduce the GIL insulation withstand voltage test fixture from the ground into the underground pipe gallery and connect it to the GIL withstand voltage interface to achieve electrical connection with the GIL. After inflation, perform the GIL phase-by-phase insulation withstand voltage test.

[0033] Step 4: Set the phase numbers of the first and last phases of the GIL as phase A1 / phase A2, phase B1 / phase B2, and phase C1 / phase C2. After the GIL insulation withstand voltage test fixture is electrically connected to the phase A2 end, the cables inside the terminal housing of phases A1, B1 / B2, and C1 / C2 only need to be disassembled and shielding balls installed to form an electrical break. Then, the main circuit insulation withstand voltage test from the phase A2 end to the phase A1 end of the GIL can be carried out.

[0034] Compared with the prior art, the withstand voltage test method of the GIL and cable direct connection structure in the underground utility tunnel in this application embodiment allows the GIL and cable to be installed in one go. Without disassembling the cable terminal, the detachable conductor at the end of the GIL main circuit inside the terminal housing is removed to form an electrical isolation break. At the same time, the test interface reserved by the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL can be tested on-site independently. This effectively reduces the waiting period between the installation procedures of GIL and cable.

[0035] When the GIL fails, it is not necessary to disassemble the cable terminal. The operation of step 1 above can be repeated to carry out the GIL emergency repair and then conduct a separate on-site withstand voltage test. This perfectly avoids the time-consuming and laborious process of disassembling and reinstalling the cable side in the limited space of the underground pipe gallery, as well as a series of uncontrollable safety factors such as the failure of airtight connection and the reduction of insulation capacity during the secondary connection of the cable side, thus improving the quality of the installation and testing process. Attached Figure Description

[0036] The accompanying drawings, which are provided to further illustrate this application and constitute a component of it, are used to explain the application and do not constitute an undue limitation thereof. Some specific embodiments of the application will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings denote the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale.

[0037] Figure 1 This is a schematic diagram of the direct connection structure between the GIL and the cable in the underground utility tunnel according to an embodiment of this application.

[0038] Figure 2 This embodiment of the application shows a direct connection structure between the GIL (Gas Injection Line) and the cable within an underground utility tunnel. Figure 1 A top view from the M direction.

[0039] Figure 3 This is a schematic diagram of the pressure resistance of the direct connection structure between the GIL and the cable in the underground utility tunnel according to an embodiment of this application.

[0040] Figure 4 This embodiment of the application shows a direct connection structure between the GIL (Gas Injection Line) and the cable within an underground utility tunnel. Figure 3 The top view in the P direction.

[0041] Figure 5 This is a schematic diagram of the connection between any phase of the GIL pressurization side and the insulation test fixture in the direct connection structure between the first and last ends of the GIL and the cable in the underground utility tunnel, as described in this application embodiment.

[0042] Figure 6 This is a schematic diagram of the structure in which the GIL (Gas Injection Line) and the cable are directly connected in the underground utility tunnel, as described in this application embodiment. The GIL is electrically disconnected from the cable and the cable terminal, without disassembling the cable terminal.

[0043] Figure 7 This is a schematic diagram of the GIL withstand voltage interface structure reserved in the T-junction unit of the direct connection structure between the GIL head and end and the cable in the underground utility tunnel, as shown in the embodiment of this application.

[0044] Figure 8 In the embodiment of this application, the GIL (Gas Injection Line) and the cable are directly connected in the underground utility tunnel. Figure 7 Side view.

[0045] Figure 9 This is a schematic diagram of the structure in which the electrical connection between the GIL and the cable terminal is not disconnected in the direct connection structure between the GIL and the cable in the underground utility tunnel according to an embodiment of this application.

[0046] Numbered in the diagram: Underground utility tunnel 1, First feeding port 11, Second feeding port 12, Cable 2, Cable support 21, Cable terminal 3, Terminal housing 31, Inspection cover 32, Cable terminal inspection port 33, GIL withstand voltage test interface 34, Test interface cover 35, T-junction unit 4, GIL three-phase phase separation unit 5, GIL withstand voltage test interface 6, Installation platform 7, Shielding ball 8, Detachable conductor 9. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely embodiments of one component of the present application, and not embodiments of the entire application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort should fall within the scope of protection of the present application.

[0048] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0049] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0051] The following embodiments of this application use a GIL (Gas Insulator) head-end and cable direct connection structure in an underground utility tunnel and its withstand voltage test method with front and rear wheels as an example to illustrate the solution of this application. However, this embodiment does not limit the scope of protection of this application.

[0052] In this application, the terms are defined as follows: GIL: A rigid gas-insulated transmission line with a rigid metal casing, filled with insulating gas, and featuring a central conductive rod and epoxy supports. Cable termination: A device installed at the end of a cable to ensure electrical connection to the rest of the system and maintain insulation up to the termination point.

[0053] Example

[0054] like Figures 1 to 3 As shown, this application provides a direct connection structure between the first and last ends of a GIL and a cable within an underground utility tunnel. In a first aspect, this application discloses a direct connection structure between the first and last ends of a GIL and a cable within an underground utility tunnel, comprising an underground utility tunnel 1, a first feed port 11, a second feed port 12, a conductive component, a three-way unit 4, and a GIL three-phase phase-splitting unit 5. The conductive component, the three-way unit 4, and the GIL three-phase phase-splitting unit 5 are disposed within the underground utility tunnel 1. The first feed port 11 and the second feed port 12 are disposed on the underground utility tunnel 1. The conductive component is connected to the three-way unit 4, and the three-way unit 4 is connected to the GIL three-phase phase-splitting unit 5.

[0055] like Figures 1 to 4 As shown, the conductive component includes a cable 2, a cable terminal 3, and a terminal housing 31. The cable 2 is connected to the cable terminal 3, and the cable terminal 3 is connected to the terminal housing 31. The conductive component also includes a cable support 21, which is connected to the cable 2. The cable support 21 is disposed on the mounting platform 7. The conductive component is provided in multiple sets, and every two sets are connected to each other. There are multiple cable supports 21.

[0056] like Figures 1 to 4 As shown, the GIL head and tail and the cable are directly connected in the underground pipe gallery. The structure also includes a maintenance cover plate 32 and a cable terminal maintenance port 33. The cable terminal maintenance port 33 is provided on the terminal housing 31, and the maintenance cover plate 32 covers the cable terminal maintenance port 33. The tee unit 4 is connected to the GIL withstand voltage test interface 34. The GIL withstand voltage test interface 34 is provided with a test interface cover plate 35. The GIL withstand voltage test fixture is connected to the test interface cover plate 35. The structure also includes a GIL withstand voltage interface 6, which is connected to the tee unit 4. The GIL withstand voltage interface 6 is provided with a withstand voltage cover plate. The structure also includes a shielding ball 8, which is provided inside the terminal housing 31.

[0057] Compared with the prior art, the GIL and cable are directly connected in the underground utility tunnel in the embodiment of this application. The GIL and cable are installed in one go. Without disassembling the cable terminal, the detachable conductor at the end of the GIL main circuit inside the terminal housing is removed to form an electrical isolation break. At the same time, the test interface reserved by the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL can be tested on site alone. This effectively reduces the waiting period between the installation procedures of GIL and cable.

[0058] To enable on-site withstand voltage testing of GIL without disassembling the cable terminal when the GIL is directly connected to the cable at both ends in the underground utility tunnel, the technical solution of this invention is described in detail below.

[0059] In the engineering application of this invention, the GIL is arranged so that both ends are directly connected to the cable in the underground utility tunnel.

[0060] When both ends of the GIL are directly connected to cable 2, a compact, vertically arranged, three-dimensional space is adopted to meet the space requirements for personnel construction, maintenance, and testing. The branch outlets of the GIL are connected to the tee unit 4 (with an insulation withstand voltage test interface), and then directly connected to cable 2 and cable terminal 3. During installation, a mobile installation platform 7 is used for high-level installation. After installation, the installation platform 7 is moved out of the first feeding port 11 or the second feeding port 12, finally completing the electrical connection. Figures 1 to 4 As shown, this invention provides a field pressure withstand technology solution for GILs where both ends of the GIL are directly connected to the cable in an underground utility tunnel.

[0061] When the GIL is first installed and tested for withstand voltage, the detachable conductor 9 inside the terminal housing 31 at the beginning and end of the GIL is removed. Then, the shielding ball 8 is installed to form an electrical break. The GIL insulation withstand voltage test fixture is introduced from the ground into the underground pipe gallery 1. The electrical connection with the GIL is achieved through the GIL withstand voltage interface 6 reserved on the side of the tee unit 4 at any end of the GIL as the pressurized side. After inflation, the GIL phase-by-phase insulation withstand voltage test is performed. The technical solution of this invention mainly describes the technical solution for the GIL standalone withstand voltage test. For the withstand voltage test of the cable, it is set to pressurize from the far end of the cable connection terminal (not the beginning and end of the GIL).

[0062] When a fault occurs during GIL operation, if an insulation withstand voltage test is performed after emergency repair, first remove the detachable conductor 9 inside the terminal housing 31 at the beginning and end of the GIL, then install the shielding ball 8 to form an electrical break, and then introduce the GIL insulation withstand voltage test fixture from the ground into the underground pipe gallery. Through the GIL withstand voltage interface reserved on the side of the tee unit at any end of the GIL as the pressurized side, the electrical connection with the GIL is achieved. After inflation is completed, the GIL phase-by-phase insulation withstand voltage test is performed. The operation process is the same as the insulation withstand voltage mode during the initial installation. It is not necessary to remove the cable terminal 3. The operation is safe and convenient, and can greatly save emergency repair time.

[0063] After all phases of the GIL have completed the field withstand voltage test, install the detachable conductor 9 between the GIL main circuit terminal conductor and the cable terminal to restore the electrical connection between the GIL, the cable, and the cable terminal. Figure 9 (As shown).

[0064] Therefore, in this embodiment of the invention, when the GIL and cable are directly connected in the underground pipe gallery 1, the GIL and cable 2 are installed in place at once. Without disassembling the cable terminal 3, a three-way unit 4 (with a reserved interface for the insulation GIL withstand voltage test) is added to obtain the insulation GIL withstand voltage test interface 34. This eliminates the cumbersome process of obtaining the insulation GIL withstand voltage test interface 34 by disassembling the cable terminal 3, avoids the safety factors caused by repeatedly disassembling the cable and cable terminal, and ultimately achieves the independent on-site withstand voltage test of the GIL. It also eliminates the need to disassemble the cable terminal to achieve the independent on-site withstand voltage test of the GIL after emergency repair.

[0065] Secondly, such as Figures 5 to 9 As shown, a withstand voltage test method for a GIL (Gas Insulator) with a direct connection between its start and end points and a cable in an underground utility tunnel is described. When both the start and end points of the GIL are directly connected to the cable, the outlets of each phase branch of the GIL are connected to a three-way unit 4 (with an insulation withstand voltage test docking interface), and then directly connected to the cable 2 and the cable terminal 3. During the GIL insulation withstand voltage test, without disassembling the cable terminal 3, the detachable conductor 9 at the end of the GIL main circuit inside the terminal housing 31 is removed to form an electrical isolation break. At the same time, the GIL withstand voltage test docking interface 34 reserved in the transition three-way unit between the GIL and the cable terminal 3 is used to connect the GIL withstand voltage test equipment, thus realizing the independent on-site withstand voltage test of the GIL. In addition, during this withstand voltage operation, the waiting period for the installation procedures of the GIL and the cable is effectively reduced.

[0066] like Figures 5 to 9 As shown, a withstand voltage test method is provided for a GIL (Gas Insulator) head and tail section directly connected to a cable in an underground utility tunnel. The method includes the following steps:

[0067] Step 1: Open the inspection cover 32 at the first and second feeding ports, pass through the cable terminal inspection port 33, first remove the detachable conductor 9 inside the terminal housing 31 at the beginning and end of the GIL, and then install the shielding ball 8 to form an electrical break.

[0068] Step 2: Open the GIL withstand pressure cover plate reserved on the side of the tee unit 4 at any end of the GIL as the pressure side, and install the insulation test fixture conductor through the GIL withstand pressure interface 6.

[0069] Step 3: Then, introduce the GIL insulation withstand voltage test fixture from the ground into the underground pipe gallery 1 and connect it to the GIL withstand voltage interface 6 to achieve electrical connection with the GIL. After inflation, perform the GIL phase-by-phase insulation withstand voltage test.

[0070] Step 4: Set the phase numbers of the first and last phases of the GIL as phase A1 / phase A2, phase B1 / phase B2, and phase C1 / phase C2. After the GIL insulation withstand voltage test fixture is electrically connected to the phase A2 end, the cable 2 inside the terminal housing 31 of phase A1, phase B1 / B2, and phase C1 / C2 ends only needs to be disassembled and the shielding ball 8 installed to form an electrical break. Then, the main circuit insulation withstand voltage test from the phase A2 end to the phase A1 end of the GIL can be carried out.

[0071] And so on:

[0072] After the electrical connection of the GIL insulation withstand voltage test fixture is completed on the B2 side, the removable conductor 9 in the terminal housing of the B1, A1 / A2, and C1 / C2 sides can be removed and the shielding ball 8 installed to form an electrical break. Then, the GIL main circuit insulation withstand voltage test from the B2 side to the B1 side can be carried out.

[0073] After the electrical connection of the GIL insulation withstand voltage test fixture is completed on the C2 end side, the removable conductor 9 inside the terminal housing 31 of the C1, B1 / B2, and A1 / A2 ends can be removed and the shielding ball 8 installed to form an electrical break. Then, the GIL main circuit insulation withstand voltage test from the C2 end to the C1 end can be carried out.

[0074] After all phases of the GIL have completed the field withstand voltage test, install the detachable conductor 9 between the GIL main circuit end conductor and the cable terminal 3 to restore the electrical connection between the GIL, cable 2, and cable terminal 3.

[0075] When a fault occurs during GIL operation, if an insulation withstand voltage test is performed after emergency repair, it is not necessary to disassemble cable terminal 3. The operation of step 1 above can be repeated to achieve another independent on-site withstand voltage test after GIL emergency repair. The operation process is the same as the insulation withstand voltage mode during the initial installation. It is not necessary to remove the cable terminal. The operation is safe and convenient, which can greatly save emergency repair time, effectively reduce the cumbersome procedures, and improve the quality of installation and testing.

[0076] Compared with the prior art, the withstand voltage test method of the GIL and cable direct connection structure in the underground utility tunnel in this application embodiment allows the GIL and cable to be installed in one go. Without disassembling the cable terminal, the detachable conductor at the end of the GIL main circuit inside the terminal housing is removed to form an electrical isolation break. At the same time, the test interface reserved by the transition tee unit between the GIL and the cable terminal is used to connect the GIL withstand voltage equipment, and finally the GIL can be tested on-site independently. This effectively reduces the waiting period between the installation procedures of GIL and cable.

[0077] When the GIL fails, it is not necessary to disassemble the cable terminal. The operation of step 1 above can be repeated to carry out the GIL emergency repair and then conduct a separate on-site withstand voltage test. This perfectly avoids the time-consuming and laborious process of disassembling and reinstalling the cable side in the limited space of the underground pipe gallery, as well as a series of uncontrollable safety factors such as the failure of airtight connection and the reduction of insulation capacity during the secondary connection of the cable side, thus improving the quality of the installation and testing process.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to the component or whole component technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A structure for direct connection between the head and tail of a GIL (Gas Infrared Utility Tunnel) and a cable within an underground utility tunnel, characterized in that, The system includes an underground pipe gallery, a first feeding port, a second feeding port, conductive components, a three-way unit, and a GIL three-phase phase separation unit. The conductive components, three-way unit, and GIL three-phase phase separation unit are located within the underground pipe gallery. The first and second feeding ports are located on the underground pipe gallery. The conductive components are connected to the three-way unit, and the three-way unit is connected to the GIL three-phase phase separation unit. When both ends of the GIL are directly connected to the cable, each phase branch outlet of the GIL is connected to the three-way unit. The three-way unit has an insulation withstand voltage test interface, which is then connected to the cable. This allows the GIL insulation withstand voltage test fixture to be introduced from the ground into the underground pipe gallery. During the GIL insulation withstand voltage test, the GIL withstand voltage test fixture is connected through the GIL withstand voltage test interface reserved in the transition three-way unit between the GIL and the cable terminal, enabling a separate on-site withstand voltage test of the GIL.

2. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 1, characterized in that, The conductive component includes a cable, a cable terminal, and a terminal housing, wherein the cable is connected to the cable terminal, and the cable terminal is connected to the terminal housing.

3. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 1, characterized in that, The conductive component also includes a cable support connected to the cable and disposed on the mounting platform.

4. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 3, characterized in that, It also includes an inspection cover and a cable terminal inspection port, wherein the cable terminal inspection port is disposed on the terminal housing and the inspection cover is disposed on the cable terminal inspection port.

5. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 4, characterized in that, The GIL withstand pressure test interface is equipped with a test interface cover plate, and the GIL withstand pressure test fixture is connected to the test interface cover plate.

6. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 5, characterized in that, It also includes a shielding ball, which is disposed inside the terminal housing.

7. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel as described in claim 6, characterized in that, The conductive components are provided in multiple sets, and every two sets are connected to each other.

8. The direct connection structure between the GIL head and end and the cable in the underground utility tunnel according to claim 7, characterized in that, The cable supports are provided in multiple locations.

9. A withstand voltage test method for a direct connection structure between the GIL (Gas Inlet and Outer Wall) and the cable in an underground utility tunnel as described in claim 8, characterized in that, The method includes the following steps: Open the inspection cover at the first and second feed ports, pass through the cable terminal inspection port, remove the detachable conductor inside the terminal housing, and install shielding balls on the GIL side terminal conductor of the main circuit at each phase terminal to form an electrical break. Open the GIL withstand voltage cover plate reserved on the side of the tee unit at either end of the GIL as the pressure side, and install the insulation test fixture conductor through the GIL withstand voltage interface. The GIL insulation withstand voltage test fixture is then introduced from the ground into the underground pipe gallery and connected to the GIL withstand voltage interface to achieve electrical connection with the GIL. After inflation, the GIL phase-by-phase insulation withstand voltage test is performed. If the phases at the beginning and end of the GIL are numbered as phase A1 / phase A2, phase B1 / phase B2, and phase C1 / phase C2, then after the GIL insulation withstand voltage test fixture is electrically connected to the phase A2 end, the cables inside the terminal housing of phases A1, B1 / B2, and C1 / C2 only need to be disassembled and shielding balls installed to form an electrical break. Then, the main circuit insulation withstand voltage test from the phase A2 end to the phase A1 end of the GIL can be carried out.

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