An insulation test system and method for GIS and plug-in transformer free disassembly connection

Abstract

This invention provides an insulation testing system and method for GIS (Gas Insulated Switchgear) and plug-in transformers that does not require disassembly, relating to the field of high-voltage electrical equipment testing technology. It aims to solve the technical problems of traditional plug-in transformer insulation testing, which requires disassembling the high-voltage side plug-in connector, leading to complex operation, high cost, slow response, and safety hazards. This invention establishes a test channel by reconstructing the grounding circuit of the GIS equipment. The GIS side grounding switch is closed, the grounding connector of the transformer side grounding switch is removed, and its exposed leads are used as test access points. Combined with dedicated test wiring components and insulation testing instruments, a complete electrical circuit covering transformer insulation testing is constructed. This invention eliminates the need to disassemble the plug-in connector, saving disassembly time. The test data error rate compared to traditional disassembly tests is ≤1.8%, eliminating the risk of SF6 gas leakage caused by repeated disassembly and assembly. It is suitable for preventative testing and fault diagnosis of fully enclosed insulated transformers in power systems.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical equipment testing technology, and in particular to an insulation testing system and method for non-disassembly connection of GIS and plug-in transformer. Background Technology

[0002] Gas-insulated switchgear (GIS) uses SF6 gas as the insulating and arc-extinguishing medium to enclose high-voltage components such as circuit breakers, disconnectors, grounding switches, busbars, and instrument transformers within a grounded metal casing. It features a compact structure, strong insulation performance, and high safety and reliability, and is widely used in high-voltage and ultra-high-voltage power systems. With the upgrading of transformer manufacturing processes, cable-pluggable transformers, due to their fully enclosed insulation structure, effectively reduce the impact of environmental factors on equipment operation and have been widely used in power systems.

[0003] However, the fully enclosed insulation structure of this type of transformer leads to several significant drawbacks in traditional insulation performance testing methods. Specifically: Complex test preparation: Traditional testing requires first removing the plugs on the high-voltage side of the transformer, then installing dedicated test bushings and high-current terminals. This operation requires a specialized technical team, and a single disassembly can take 4-8 hours, resulting in extremely low efficiency in pre-test preparation. High economic costs: Each disassembly and reassembly operation involves high costs for specialized labor and equipment rental. Furthermore, equipment shutdown for testing causes power outages or production losses, resulting in high overall economic costs. Slow emergency response speed: When equipment malfunctions and urgent insulation testing is needed, the preparation work for removing the plugs causes significant delays in fault diagnosis. For example, in the accident at the No. 70 substation of a steel plant, delays in disassembly preparation led to a 6-hour delay in fault diagnosis, directly causing production losses of approximately 850,000 yuan. Significant safety hazards exist. Repeatedly disassembling and reassembling the plug can reduce its sealing performance and easily cause SF6 gas leakage. This not only affects the insulation performance of the equipment but also causes environmental hazards. At the same time, the electrical operations during the disassembly and reassembly process also increase the risk to personnel.

[0004] In the existing technology, some studies have attempted to simplify the test process by improving the structure of the test connector, but none of them have solved the fundamental problem that the plug and unplug head must be disassembled, and cannot avoid the above-mentioned defects at the root. Summary of the Invention

[0005] The purpose of this invention is to provide an insulation testing system and method for GIS and plug-in transformers that do not require disassembly. By modifying and reconstructing the test channel through the GIS grounding switch path, the insulation performance test of the plug-in connector can be achieved without disassembly, thus solving the technical drawbacks of traditional testing methods.

[0006] To achieve the above objectives, the present invention provides an insulation testing system for GIS and plug-in transformers that does not require disassembly. The system includes: GIS combined electrical appliance, plug-in transformer, test wiring assembly and insulation testing instrument;

[0007] The GIS combined electrical appliance includes an interconnected GIS disconnect switch and a grounding switch, wherein the grounding switch is connected to the high-voltage side plug-in head of the plug-in transformer;

[0008] The pluggable transformer is equipped with a grounding switch with a grounding connector. After the grounding connector is removed, the exposed lead-out terminals of the grounding switch are used as test access points.

[0009] The test wiring assembly is adapted to be installed at the test access point and is used to connect the insulation testing instrument to the test access point;

[0010] The insulation testing instrument is connected to the test access point through the test wiring assembly and is used to test the insulation performance of plug-in transformers, including winding DC resistance, dielectric loss factor, and leakage current.

[0011] Preferably, the test current loop constructed by the insulation testing instrument is as follows: insulation testing instrument → test access point → grounding switch → transformer winding → high voltage side plug-in connector → cable → GIS disconnect switch → grounding switch → test access point → insulation testing instrument.

[0012] Preferably, the test wiring assembly includes a test clamp, a test lead, and an insulating protective cover. The test clamp is a spring clamp with a current carrying capacity of 200A, and the contact surface of the test clamp is coated with conductive grease. The insulating protective cover has an IP54 protection rating and is adapted to be installed at the grounding switch after the grounding connector has been removed.

[0013] Preferably, the insulation testing instruments include a DC resistance tester, a dielectric loss tester, and a leakage current tester, used to perform insulation performance tests on winding DC resistance, dielectric loss factor, and leakage current.

[0014] Preferably, it also includes a safety protection component, which includes Class III insulating protective equipment.

[0015] Compared with the prior art, the insulation test system for GIS and plug-in transformer without disassembly provided by the present invention has the following beneficial effects: The present invention constructs the test access point by reusing the existing GIS and plug-in transformer structure, and can complete the insulation test without disassembling the high-voltage plug-in head, which greatly simplifies the operation, shortens the test time, eliminates the sealing and leakage hazards caused by disassembly and assembly, reduces the test cost, and at the same time ensures the integrity and reliability of the test circuit, and has good practicality and safety.

[0016] This invention also provides an insulation test method for non-disassembly connection of GIS and plug-in transformer, the method comprising the following steps:

[0017] Step S1: Confirm that the GIS grounding switch is in the open state, disconnect the power supply to the corresponding bay of the substation, and set a safety warning.

[0018] Step S2: Close the grounding switch on the GIS side, remove the grounding connector of the grounding switch on the transformer side, install an insulating protective cover at the grounding switch after removing the grounding connector, use the exposed lead-out terminals of the grounding switch as the test access point, and install the test wiring assembly on the test access point so that the test wiring assembly connects the insulation testing instrument to the test access point.

[0019] Step S3: Detect the loop impedance of the entire test circuit. After passing the test, proceed to the test stage.

[0020] Step S4: Test the insulation performance of the plug-in transformer by using an insulation testing instrument to measure the winding DC resistance, dielectric loss factor, and leakage current.

[0021] Preferably, step S1 further includes: detecting the SF6 gas density of the GIS equipment, wherein an SF6 gas density greater than or equal to 0.4 MPa is considered qualified, and activating an arc flash protection system with an action time of less than or equal to 5 ms.

[0022] Preferably, in step S2, before closing the GIS side grounding switch, the initial state of the switch is confirmed by both the mechanical position indicator and the electrical signal. The switch is closed using an insulated operating rod. After closing, the contact resistance of the grounding switch is measured to be less than or equal to 500μΩ to be considered qualified. During the operation, the operator wears Class III insulated protective equipment.

[0023] Preferably, in step S2, before removing the grounding connector, it is verified that there is no voltage, and the insulation resistance of the exposed terminal to ground after removal is greater than or equal to 100MΩ to be considered qualified.

[0024] Preferably, the test wiring assembly includes a test clamp, a test lead, and an insulating protective cover. The test clamp is a spring clamp with a current carrying capacity of 200A, and the contact surface of the test clamp is coated with conductive grease. The insulating protective cover has an IP54 protection rating.

[0025] Compared with the prior art, the insulation test method for non-disassembly connection of GIS and plug-in transformer provided by the present invention has the same beneficial effects as the insulation test system for non-disassembly connection of GIS and plug-in transformer provided by the above technical solution, and will not be repeated here.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The following is a timing diagram illustrating the operation flow of the insulation testing method provided in an embodiment of the present invention;

[0029] Figure 2 A schematic flowchart of the insulation test method provided in an embodiment of the present invention is shown;

[0030] Figure 3 A wiring diagram of the improved testing method provided in this embodiment of the invention is shown;

[0031] Figure 4 A schematic diagram of the actual test points after the improved test method provided in the embodiment of the present invention is shown. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In this embodiment, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations, intended to present related concepts in a specific manner, and should not be construed as superior or more advantageous than other embodiments or designs.

[0034] This invention provides an insulation testing system for GIS and plug-in transformers that allows for non-disassembly connection. The system includes: GIS combined electrical appliances, plug-in transformers, test wiring assemblies, and insulation testing instruments.

[0035] The GIS switchgear includes an interconnected GIS disconnector and a grounding switch ES. The grounding switch ES is connected to the high-voltage side plug-in of the pluggable transformer via a cable, providing a GIS-side path for the test current circuit. Specifically, the GIS switchgear includes a 35kV GIS disconnector and a grounding switch ES, which are mechanically and electrically connected.

[0036] The plug-in transformer is equipped with a grounding switch with a grounding connector. After removing the grounding connector, the exposed leads of the grounding switch serve as the test connection point P, replacing the traditional plug-in connection point, thus achieving test connection without disassembly. Specifically, the plug-in transformer can be a 35kV fully enclosed insulation type.

[0037] The test wiring assembly is adapted and installed at test access point P to connect the insulation testing instrument to test access point P. The test wiring assembly includes a dedicated test clamp, test leads, and an IP54-rated insulating protective cover. The test clamp can be a spring-loaded clamp with a 200A current-carrying capacity, and the contact surface is coated with conductive paste containing ≥60% silver to ensure the stability and conductivity of the electrical connection. The test leads can be 35kV high-voltage test leads. The insulating protective cover is installed at the grounding switch after the grounding connector has been removed to prevent safety accidents caused by exposed terminals.

[0038] The insulation testing instrument is connected to the test access point P via a test wiring assembly and is used to test the insulation performance of plug-in transformers, including winding DC resistance, dielectric loss factor, and leakage current. Specifically, the insulation testing instrument includes a DC resistance tester, a dielectric loss tester, and a leakage current tester, which are connected to the test access point P via test leads to perform insulation performance tests on transformer winding DC resistance, dielectric loss factor, and leakage current.

[0039] Furthermore, the test current loop constructed by this invention completely covers the key parts of transformer insulation testing. The specific test current loop is as follows: insulation testing instrument → test access point P → grounding switch → transformer winding → high voltage side plug-in connector → cable → GIS disconnect switch → grounding switch ES → test access point P → insulation testing instrument.

[0040] Furthermore, the insulation testing system for the GIS and plug-in transformer, which allows for seamless connection without disassembly, also includes safety protection components. These components encompass personnel protection, parameter detection, equipment protection, and emergency response parts. Specifically, they include Class III insulation protection equipment, a 35kV withstand voltage insulation mat, a 10kV voltage detector, a 100A micro-ohmmeter, a 2500V megohmmeter, a pressure sensor, an SF6 gas density detector, an arc flash protection system (action time less than or equal to 5ms), a five-proof interlocking system, a 35kV insulation tie rod, a fire blanket, and a sandbox, comprehensively mitigating various safety risks during the testing process.

[0041] Compared with the prior art, the insulation test system for GIS and plug-in transformer without disassembly provided by the embodiments of the present invention has the following beneficial effects: The present invention constructs the test access point by reusing the existing GIS and plug-in transformer structure, and can complete the insulation test without disassembling the high-voltage plug-in head, which greatly simplifies the operation, shortens the test time, eliminates the sealing and leakage hazards caused by disassembly and assembly, reduces the test cost, and at the same time ensures the integrity and reliability of the test circuit, and has good practicality and safety.

[0042] This invention also provides an insulation test method for the non-disassembly connection of GIS and plug-in transformer. Figure 1 The following is a timing diagram illustrating the operation flow of the insulation testing method provided in an embodiment of the present invention. Figure 2 A schematic flowchart of the insulation test method provided in an embodiment of the present invention is shown; Figure 3 A wiring diagram of the improved testing method provided in this embodiment of the invention is shown; Figure 4 A schematic diagram of actual test points after implementing the improved testing method provided in this embodiment of the invention is shown. Figures 1-4 As shown, the method includes the following steps:

[0043] Step S1: Confirm that the GIS grounding switch ES is in the open state, disconnect the power supply to the corresponding bay of the substation, and set a safety warning.

[0044] It should be noted that during the test preparation phase, the grounding switch ES of the GIS switchgear was confirmed to be in the open state, the power supply to the corresponding bay of the substation was disconnected, and a "Do Not Close" safety warning sign was hung; the SF6 gas density detector was used to test the SF6 gas density on site to ensure that the density was ≥0.4MPa; and the effectiveness of the mechanical + electrical double lock of the five-proof interlocking system was verified to prevent misoperation.

[0045] Step S2: Close the GIS side grounding switch ES, remove the grounding connector of the transformer side grounding switch, install an insulating protective cover at the grounding switch after removing the grounding connector, use the exposed lead-out terminal of the grounding switch as the test access point P, and install the test wiring assembly on the test access point P, so that the test wiring assembly connects the insulation testing instrument to the test access point P.

[0046] It should be noted that step S2 is the test point modification stage, which specifically includes:

[0047] Step S2.1: Close the grounding switch ES: Use a dedicated insulated operating rod to switch the GIS-side grounding switch ES from the open to the closed state, and confirm the closed state through both the mechanical position indicator and electrical signals. Measure its contact resistance using a 100A micro-ohmmeter to ensure that the contact resistance is ≤500μΩ;

[0048] Step S2.2: Remove the grounding connector: After verifying that there is no voltage on the transformer-side grounding switch using a 10kV detector, remove the grounding connector using an M16 insulated socket wrench; immediately after removal, install an IP54 protection level insulating cover, and check the withstand voltage between the exposed terminals and ground potential to ensure that the withstand voltage is ≥10kV / 1min.

[0049] Use a 2500V megohmmeter to measure the insulation resistance at the removal location, ensuring the insulation resistance is ≥100MΩ. Insulate the removed grounding connector to prevent short circuits or electric shocks.

[0050] Step S2.3: Install the test wiring assembly: Lay a 35kV withstand voltage insulating pad at the test connection point P, and install the special test clamp coated with conductive paste containing ≥60% silver at the test connection point P. Use a pressure sensor to measure the contact pressure of the clamp, ensuring it is 70±5N, and use a 100A micro-ohmmeter to measure the contact resistance, ensuring it is ≤50μΩ; perform windproof and wire-fixing treatment on the test clamp, and connect the test clamp to the insulation testing instrument through the test lead.

[0051] Throughout this process, operators must wear Class III insulating protective equipment. Before the operation is performed, a triple confirmation mechanism for the operation ticket must be implemented (confirmation by the operator, supervisor, and person in charge in sequence).

[0052] Step S3: Detect the loop impedance of the overall test circuit. After passing the test, proceed to the test stage.

[0053] It should be noted that during the circuit testing phase, the overall test circuit impedance is measured using a transformer DC resistance meter to ensure that the impedance is ≤0.5Ω. If the test passes, the test proceeds; if it fails, wiring or equipment problems are promptly investigated to ensure the test circuit is complete and effective. The key technical parameters in the above execution steps are shown in Table 1.

[0054] Table 1

[0055] Operating steps Key Indicators Standard value Measuring tools Grounding switch closed Contact resistance ≤500μΩ Micro-European Watch (100A) Grounding connection removal Insulation resistance ≥100MΩ 2500V megohmmeter Test clamp installation Contact pressure 70±5N pressure sensor Overall circuit circuit impedance ≤0.5Ω Transformer DC resistance meter

[0056] Step S4: Test the insulation performance of the plug-in transformer by using an insulation testing instrument to measure the winding DC resistance, dielectric loss factor, and leakage current.

[0057] It should be noted that the plug-in transformer was tested sequentially using an insulation testing instrument to measure the winding DC resistance, dielectric loss factor, and leakage current, and the test data were recorded. The test data are shown in Table 2.

[0058] Table 2

[0059] Test Project Disassembly test value No disassembly test value Error rate winding DC resistance 0.352Ω 0.355Ω 0.85% Dielectric loss factor 0.42% 0.41% 1.20% Leakage current 28μA 28.5μA 1.80%

[0060] The test data of this invention has an error rate of ≤1.8% compared with traditional head-disassembly test data, including a winding DC resistance error rate of ≤0.85%, a dielectric loss factor error rate of ≤1.20%, and a leakage current error rate of ≤1.80%, ensuring the reliability and accuracy of the data.

[0061] The arc flash protection system was activated throughout the entire test (action time ≤ 5ms). Within a 10-meter radius of the test site, 35kV insulating rods, fire blankets, and sandboxes were installed. Emergency communication was directly connected to the dispatch center with redundant channels.

[0062] After the test is completed, following the principle of "disassemble first, then reassemble, and operate in reverse order," remove the test leads and test wiring components in sequence. Reinstall the grounding connector of the grounding switch and tighten the bolts. Switch the GIS grounding switch ES to the open state and confirm this through both mechanical and electrical signals. Remove the on-site safety warning signs, clean the test wiring components and safety protection components, and complete the entire test process.

[0063] Compared with the prior art, the insulation test method for non-disassembly connection of GIS and plug-in transformer provided by the embodiments of the present invention has the following beneficial effects:

[0064] 1. Enables disassembly-free operation, significantly improving test efficiency: Test access points can be constructed directly using existing GIS and transformer structures, eliminating the need to disassemble the high-voltage side plugs, saving 100% of disassembly and reassembly time, and significantly improving test preparation efficiency.

[0065] 2. High reliability of test data, meeting industry standards: The constructed test circuit completely covers the key parts of transformer insulation testing. Actual verification shows that the test data has an error rate of ≤1.8% compared with traditional disassembly test, which can accurately reflect the actual insulation performance of the transformer and meet the test accuracy requirements of the power system.

[0066] 3. Speed ​​up emergency response and reduce economic losses: By eliminating the plug-in disassembly step, the fault diagnosis time is shortened from more than 8 hours to less than 2 hours, which can quickly locate equipment faults and greatly reduce production and power supply losses caused by fault delays.

[0067] 4. Eliminate safety hazards and improve test safety: Avoid the problem of reduced sealing performance caused by repeated disassembly and reassembly of plugs and connectors, thus eliminating the risk of SF6 gas leakage at the source; at the same time, through improved safety protection components and standardized operating procedures, the risk of personnel electrical operation is reduced.

[0068] Furthermore, this invention also provides an electronic device, including a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor. The transceiver, the memory, and the processor are connected via the bus. When the computer program is executed by the processor, it implements the various processes of the above-described method for insulation testing of a GIS and a pluggable transformer without disassembly, and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0069] Furthermore, this embodiment of the invention also provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the various processes of the above-described insulation test method embodiment for non-disassembly connection of GIS and plug-in transformer, and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An insulation testing system for GIS and plug-in transformers that allows for non-disassembly connection, characterized in that... The characteristics include: GIS switchgear, pluggable transformers, test wiring assemblies and insulation testing instruments; The GIS combined electrical appliance includes an interconnected GIS disconnect switch and a grounding switch, wherein the grounding switch is connected to the high-voltage side plug-in head of the plug-in transformer; The pluggable transformer is equipped with a grounding switch with a grounding connector. After the grounding connector is removed, the exposed lead-out terminals of the grounding switch are used as test access points. The test wiring assembly is adapted to be installed at the test access point and is used to connect the insulation testing instrument to the test access point; The insulation testing instrument is connected to the test access point through the test wiring assembly and is used to test the insulation performance of plug-in transformers, including winding DC resistance, dielectric loss factor, and leakage current.

2. The insulation test system for GIS and plug-in transformer without disassembly as described in claim 1, characterized in that, The test current loop constructed by the insulation testing instrument is as follows: insulation testing instrument → test access point → grounding switch → transformer winding → high voltage side plug-in connector → cable → GIS disconnect switch → grounding switch → test access point → insulation testing instrument.

3. The insulation test system for GIS and plug-in transformer without disassembly as described in claim 1, characterized in that, The test wiring assembly includes a test clamp, a test lead, and an insulating protective cover. The test clamp is a spring clamp with a current carrying capacity of 200A. The contact surface of the test clamp is coated with conductive grease. The insulating protective cover has an IP54 protection rating and is suitable for installation at the grounding switch after the grounding connector has been removed.

4. The insulation test system for non-disassembly connection of GIS and plug-in transformer according to claim 1, characterized in that, The insulation testing instruments include a DC resistance tester, a dielectric loss tester, and a leakage current tester, which are used to perform insulation performance tests on winding DC resistance, dielectric loss factor, and leakage current.

5. The insulation test system for non-disassembly connection of GIS and plug-in transformer according to claim 1, characterized in that, It also includes safety protection components, which include Class III insulation protection equipment.

6. An insulation test method for non-disassembly connection of GIS and plug-in transformer, characterized in that, Includes the following steps: Step S1: Confirm that the GIS grounding switch is in the open state, disconnect the power supply to the corresponding bay of the substation, and set a safety warning. Step S2: Close the grounding switch on the GIS side, remove the grounding connector of the grounding switch on the transformer side, install an insulating protective cover at the grounding switch after removing the grounding connector, use the exposed lead-out terminals of the grounding switch as the test access point, and install the test wiring assembly on the test access point so that the test wiring assembly connects the insulation testing instrument to the test access point. Step S3: Detect the loop impedance of the entire test circuit. After passing the test, proceed to the test stage. Step S4: Test the insulation performance of the plug-in transformer by using an insulation testing instrument to measure the winding DC resistance, dielectric loss factor, and leakage current.

7. The insulation test method for the non-disassembly connection of GIS and plug-in transformer according to claim 6, characterized in that, Step S1 further includes: detecting the SF6 gas density of the GIS equipment, wherein an SF6 gas density greater than or equal to 0.4 MPa is considered qualified, and activating an arc light protection system with an action time of less than or equal to 5 ms.

8. The insulation test method for the non-disassembly connection of GIS and plug-in transformer according to claim 6, characterized in that, In step S2, before closing the GIS side grounding switch, the initial state of the switch is confirmed by both the mechanical position indicator and the electrical signal. The switch is closed using an insulated operating rod. After closing, the contact resistance of the grounding switch is measured to be less than or equal to 500μΩ to be considered qualified. During the operation, the operator wears Class III insulated protective equipment.

9. The insulation test method for non-disassembly connection of GIS and plug-in transformer according to claim 6, characterized in that, In step S2, before removing the grounding connector, verify that there is no voltage. After removal, the insulation resistance of the exposed terminal to ground is greater than or equal to 100MΩ to be considered qualified.

10. The insulation test method for the non-disassembly connection of GIS and plug-in transformer according to claim 6, characterized in that, The test wiring assembly includes a test clamp, a test lead, and an insulating protective cover. The test clamp is a spring clamp with a current carrying capacity of 200A. The contact surface of the test clamp is coated with conductive grease. The insulating protective cover has an IP54 protection rating.

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