Method and system for detecting metal particles in GIS handover test operation disconnector

Abstract

A method and system for detecting metal particles during a GIS handover test by operating an isolating switch. The method includes: determining the test voltage required for the handover test based on different VFTO amplitudes based on a GIS device simulation circuit model; performing a conventional withstand voltage test, a burn-in test, and a withstand voltage test on the GIS device; repeatedly operating the isolating switch several times at different preferred VFTO amplitudes, and recording the ultra-high frequency partial discharge (UHF) signal within the GIS device during these operations. The preferred VFTO amplitude for exciting metal particles is 1.6 pu; and determining whether metal particle defects exist in the GIS device under test based on the recorded UHF partial discharge signal. This method excites metal particles in the gas chamber without damaging the device's insulation, enabling monitoring of the partial discharge signal and thereby improving the detection rate of free metal particle defects in the GIS.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical equipment testing, and in particular relates to a method and system for detecting metal particles in a GIS handover test operation disconnect switch. Background Art

[0002] At present, my country's ultra-high voltage AC transmission system has fully applied gas-insulated metal-enclosed switchgear (GIS) equipment. However, based on years of operating experience, insulation failure of GIS equipment is unavoidable.

[0003] Domestic and international studies have shown that free metal particles cause the highest insulation failure rate in GIS equipment. During the production, transportation, installation, and operation of GIS, metal particles are inevitably generated due to vibration, friction, and mechanical movement. Under the influence of electric fields, these metal particles can undergo various movements, leading to insulator surface flashover or even gap breakdown, seriously compromising the insulation strength of GIS equipment.

[0004] In existing technologies, the detection of free metal particles in GIS primarily relies on the measurement of partial discharge signals. Ultra High Frequency (UHF) detection methods have strong anti-interference capabilities and high sensitivity, enabling relatively accurate detection of insulation defects within GIS. Research on the partial discharge phenomenon of moving metal particles in GIS has been conducted domestically and internationally, resulting in characteristic patterns of free metal particle defects, which are then used to rapidly identify internal defects and faults in GIS equipment. Tsinghua University's research on the discharge of metal particles within GIS equipment indicates that the apparent discharge is related to particle size: the larger the particle, the greater the discharge, and the more accurate the characteristic pattern for defect identification formed after the UHF sensor receives the signal. UHF detection requires determining the defect type during on-site measurement and accurately locating the discharge source within the equipment. Therefore, the apparent discharge is extremely important for UHF detection.

[0005] Very fast transient overvoltage (VFTO) caused by disconnector operation creates small disturbances that can dislodge hard-to-detect particles attached to insulator surfaces or deposited at the bottom of the gas chamber. These particles may bounce between the grounded casing and the high-voltage conductor, or form particle accumulations. This significantly increases the probability of particle discharge, leading to partial discharge. This increased discharge is highly beneficial for defect identification and source location during ultra-high frequency testing. The VFTO amplitude generated by the voltage input according to national standards during acceptance testing for metal particles is uncontrollable. This can easily lead to high VFTO amplitudes, resulting in equipment damage, or low VFTO amplitudes that fail to detect the desired results, making it difficult to effectively detect free metal particles. Summary of the Invention

[0006] To address the deficiencies in the prior art, the present invention provides a method and system for detecting metal particles during GIS handover test operation of an isolating switch. Based on conventional withstand voltage, the isolating switch is operated to cause a small disturbance called VFTO to excite the metal particles in the air chamber. A scientific and reasonable VFTO simulation model is constructed to control and select the appropriate VFTO small disturbance, with an amplitude not exceeding 1.6 pu. This allows the metal particles in the air chamber to be excited without damaging the insulation of the equipment, enabling monitoring of partial discharge signals and thereby improving the detection rate of GIS free metal particle defects.

[0007] The present invention adopts the following technical solutions.

[0008] A method for detecting metal particles by operating an isolating switch during a GIS handover test, comprising:

[0009] Step 1: Based on the GIS equipment simulation circuit model, determine the test voltage required for the handover test according to different VFTO amplitudes;

[0010] Step 2: Perform routine pressure test, aging test and pressure test on GIS equipment;

[0011] Step 3: Repeat the disconnector operation several times under different VFTO amplitude optimization values, and record the ultra-high frequency partial discharge signal in the GIS equipment during the operation;

[0012] Step 4: After repeating step 3, determine whether there is a metal particle defect in the GIS device to be tested based on the recorded ultra-high frequency partial discharge signal.

[0013] Step 1 includes:

[0014] Step 1.1: Model the GIS equipment using the electromagnetic transient equivalent method to obtain a simulation circuit model of the GIS equipment;

[0015] Step 1.2, determining a probability model of the VFTO amplitude based on experimental data, and determining that the optimal value of the VFTO amplitude that can excite metal particles is 1.6 pu according to the probability model;

[0016] In step 1.3, based on the GIS equipment simulation circuit model, determine the corresponding test voltage according to the preferred value of the VFTO amplitude.

[0017] The VFTO amplitude shows a normal distribution between 1.0 pu and 2.2 pu, and the optimal value range of the VFTO amplitude is 1.4 to 1.8 pu.

[0018] In step 3, a pause of 3 to 5 seconds is performed between each two operations. After the current operation is completed, the next operation is performed after the voltage stabilizes. The voltage fluctuation after stabilization does not exceed ±5% of the test voltage.

[0019] Step 3 includes:

[0020] Step 3.1, when the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the isolating switch operation is repeated several times, and the ultra-high frequency partial discharge signal of the insulating basin during the operation is recorded; among them, U max is the maximum value of the line voltage;

[0021] Step 3.2, when the VFTO amplitude is preferably 1.2 pu, adjust the test voltage to After that, repeat the disconnector operation several times and record the ultra-high frequency partial discharge signal at the insulating basin during the operation;

[0022] Step 3.3: When the VFTO amplitude is preferably 1.6 pu, adjust the test voltage to U max After that, repeat the disconnector operation several times and record the ultra-high frequency partial discharge signal at the insulating basin during the operation;

[0023] Step 3.4: When the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the disconnector operation was repeated several times, and the ultra-high frequency partial discharge signal at the insulating basin during the operation was recorded.

[0024] Repeat the isolating switch operation 10 to 20 times.

[0025] In step 4, if the UHF partial discharge signal still appears after repeatedly operating the disconnector, the detection is correct and the GIS equipment needs to be opened and inspected.

[0026] If breakdown occurs during the test or the VFTO amplitude exceeds the lightning impulse voltage withstand value, the test fails and the GIS equipment must be opened for inspection and retested.

[0027] Place UHF sensors at the corresponding positions of the insulating basins on both sides of the disconnector to be operated in the GIS equipment;

[0028] UHF sensor, used to detect UHF partial discharge signals;

[0029] The UHF sensor is connected to the UHF partial discharge detector through a UHF amplifier, and the detector is connected to a computer screen through corresponding software to realize real-time monitoring of partial discharge signals.

[0030] A system for detecting metal particles in a GIS handover test operation disconnect switch, comprising:

[0031] Digital simulation module, test voltage generation module, partial discharge signal detection module, verification module. The digital simulation module is connected to the test voltage generation module, the test voltage generation module and the partial discharge signal detection module are respectively connected to the GIS device to be tested, and the verification module is connected to the test voltage generation module.

[0032] The digital simulation module is used to determine the test voltage required for the handover test based on the GIS equipment simulation circuit model according to different VFTO amplitudes. The digital simulation module sends a signal to control the test voltage to the test voltage generation module;

[0033] The test voltage generating module is used to apply the test voltage to the GIS equipment under test, as well as the test voltage required for the conventional withstand voltage test, the test voltage required for the aging test, and the test voltage required during the withstand voltage test;

[0034] The partial discharge signal detection module is used to record the ultra-high frequency partial discharge signal at the insulating basin during the operation when the disconnector is repeatedly operated several times under different VFTO amplitude optimization values;

[0035] The verification module is used to control the test voltage generation module to perform repeated tests according to the ultra-high frequency partial discharge signal to obtain test results, and to determine whether there are metal particle defects in the GIS equipment to be tested based on the test results.

[0036] The beneficial effect of the present invention is that, compared with the prior art, the method and system proposed in the present invention can excite the metal particles in the gas chamber without damaging the insulation of the equipment, realize the monitoring of partial discharge signals, and thus improve the detection rate of GIS free metal particle defects.

[0037] Obtain a scientific and effective VFTO digital simulation system to guide the on-site handover test of free metal particle detection of GIS equipment, avoiding insulation loss and energy waste BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a method for detecting metal particles by operating an isolating switch during a GIS handover test proposed by the present invention;

[0039] Figure 2 This is a diagram of a simulation circuit model of a GIS device established in an embodiment of the present invention;

[0040] Figure 3 is a waveform diagram of the test voltage applied in an embodiment of the present invention;

[0041] Figure 42. It is a schematic diagram of ultra-high frequency partial discharge signal detection in an embodiment of the present invention;

[0042] Figure 4 The reference numerals in the figures are described as follows:

[0043] 1-conductive rod; 2-insulating basin; 3-housing; 4-UHF sensor; 5-UHF amplifier; 6-UHF partial discharge detector;

[0044] Figure 5 This is a structural diagram of a system for operating an isolating switch for a GIS equipment handover test proposed by the present invention;

[0045] Figure 5 The reference numerals in the figures are described as follows:

[0046] 10-digital simulation module; 20-test voltage generation module; 30-partial discharge signal detection module; 40-verification module; 50-GIS equipment to be tested. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] The present invention proposes a method for detecting metal particles in a GIS handover test operation isolating switch, such as Figure 1 As shown in FIG, the method for using the VFTO digital simulation system to guide the handover test operation of the disconnector includes:

[0049] Step 1: Based on the GIS equipment simulation circuit model, determine the test voltage required for the handover test according to different VFTO amplitudes.

[0050] When operating disconnectors in GIS, the slow movement of the contacts causes multiple re-strikes across the disconnector gap, generating abrupt traveling waves. These waves are then refracted, reflected, and superimposed at nodes where the GIS's wave impedance changes, resulting in VFTO (Voltage Forward Transient) (VFTO). VFTO is characterized by high amplitude (up to 2.5 pu), steep wavefronts (several nanoseconds to tens of nanoseconds), high frequency (up to tens of megahertz), and multiple continuous pulses. GIS equipment generally uses the Lightning Impulse Withstand Voltage (LIWV) level as the basis for VFTO insulation coordination. IEC insulation coordination standards require a 20% insulation margin for GIS LIWV tolerance. However, the VFTO waveform rises rapidly and steeply, making GIS less resistant to VFTO and requiring more stringent insulation assessments for GIS at the same voltage level.

[0051] With the widespread adoption of GIS, research on VFTO has long been a hot topic among scholars both domestically and internationally. However, relevant standards, both domestically and internationally, have yet to define typical waveforms and withstand voltage values ​​for VFTO testing. This is because VFTO is closely related to the specific wiring configuration of GIS, making it extremely unrealistic to attempt to determine VFTO characteristics under various conditions through field testing. Typically, VFTO researchers simply conduct simulations to study VFTO waveform characteristics, frequency, and other properties, without attempting to develop a VFTO simulation system to guide various field tests. During the handover test for metal particles, the VFTO amplitude generated by the voltage input according to national standards is uncontrollable, resulting in high-amplitude VFTO that can damage the equipment, or low-amplitude VFTO that fails to achieve the desired detection results. While there is no fixed standard for the specific equivalent model of a GIS simulation model, this paper addresses the pain point of metal particle detection during GIS equipment handover testing by developing an innovative and scientifically effective simulation model system based on past experience and extensive field testing. This provides a proven approach and method. Therefore, a scientifically effective VFTO digital simulation system is established to guide field handover testing for free metal particle detection in GIS equipment.

[0052] Specifically, step 1 includes:

[0053] Step 1.1: Use the electromagnetic transient equivalent method to model the GIS equipment and obtain a simulation circuit model of the GIS equipment.

[0054] The present invention uses the electromagnetic transient equivalent method to carry out scientific and systematic modeling of GIS equipment. The obtained GIS equipment simulation circuit model is as follows: Figure 2As shown, the GIS equipment simulation circuit model includes but is not limited to: power source A, power source B, pipeline, transformer, bushing, current transformer (CT), circuit breaker, disconnector, disconnector to be operated, grounding switch, and insulating basin. The transformer is equivalent to an input capacitor and a series inductor; the pipeline, bushing, and current transformer (CT) can be considered as a lossless transmission line; the closed circuit breaker (CB11), closed disconnector (DS12), grounding switch, and insulating basin are equivalent to grounding capacitors. The model of the disconnector to be operated includes: fixed arc resistance (R0), arc path inductance (L0), controllable switch (S0), first ground capacitance (C1), second ground capacitance (C2), and shunt capacitance (C). The remaining GIS equipment components have little impact and can be ignored. Power source B simulates the short busbar charge on the load side of the disconnector, with opposite polarity to that of power source A and a peak value equal to that of power source A. U1 is the source-side voltage of the disconnector to be operated, and U2 is the load-side voltage of the disconnector to be operated.

[0055] Step 1.2: Determine a probability model for the VFTO amplitude based on experimental data, and determine that the optimal value of the VFTO amplitude that can excite metal particles is 1.6 pu according to the probability model.

[0056] According to State Grid's VFTO tests and extensive field data, VFTO amplitudes exhibit a normal distribution between 1.0 pu and 2.2 pu, with amplitudes between 1.4 and 1.8 pu having a higher probability of occurring. The inventors of this application collected extensive field test data to construct a VFTO digital simulation model. Based on this field test data and previous operational experience, and after comprehensive comparison and optimization, they concluded that an amplitude of 1.6 pu is sufficient to excite difficult-to-detect metal particles, enabling UHF sensors to detect signals of metal particle defects that are undetectable in conventional handover tests. However, an amplitude that is too high can easily cause insulation loss and waste energy.

[0057] In step 1.3, based on the GIS equipment simulation circuit model, determine the corresponding test voltage according to the preferred value of the VFTO amplitude.

[0058] In this embodiment of the present invention, the input value of Power Supply A is simulated and calculated based on the desired VFTO amplitude, and vice versa. A simulation circuit model of the GIS equipment is used to guide the test voltage during on-site acceptance testing, ensuring that the appropriate VFTO is achieved to activate the metal particles within the gas chamber without damaging the equipment insulation. Within the rated lightning impulse withstand voltage range, the test voltage is positively correlated with the VFTO amplitude caused by operating the disconnector.

[0059] The VFTO amplitude generated by the voltage input according to the national standard during the acceptance test for metal particle detection is uncontrollable, which can easily lead to high-amplitude VFTO during the acceptance test, causing equipment damage, or low-amplitude VFTO failing to achieve the detection effect. However, the simulation model can set the desired VFTO amplitude and infer the corresponding test voltage. By inputting this test voltage value during the on-site test, the desired VFTO amplitude is generated, which is beneficial for metal particle detection.

[0060] Step 2: Perform routine pressure test, aging test and pressure test on GIS equipment.

[0061] Specifically, when GIS equipment is handed over, a routine voltage test is first carried out, and then a step-by-step voltage increase is carried out according to the current national standards to complete the aging test and voltage test process.

[0062] Step 3: Repeat the disconnector operation several times at different VFTO amplitude optimization values ​​and record the ultra-high frequency partial discharge signal in the GIS equipment during the operation; wherein, a pause of 3 to 5 seconds is allowed between each operation; after the current operation is completed, wait until the voltage stabilizes (the voltage fluctuation after stabilization does not exceed ±5% of the test voltage) before performing the next operation.

[0063] Specifically, in step 3, different VFTO amplitude optimization values ​​correspond to different test voltages. The on-site handover test performs isolating switch operation under different test voltages, which can excite metal particles in the gas chamber without damaging the insulation of the equipment, realize the monitoring of partial discharge signals, and thus improve the detection rate of GIS free metal particle defects.

[0064] Specifically, step 3 includes:

[0065] Step 3.1, when the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the isolating switch operation is repeated several times, and the ultra-high frequency partial discharge signal of the insulating basin during the operation is recorded; among them, U max is the maximum value of the line voltage.

[0066] Step 3.2, when the VFTO amplitude is preferably 1.2 pu, adjust the test voltage to After that, the disconnector operation was repeated several times, and the ultra-high frequency partial discharge signal at the insulating basin during the operation was recorded.

[0067] Step 3.3: When the VFTO amplitude is preferably 1.6 pu, adjust the test voltage to U max After that, the disconnector operation was repeated several times, and the ultra-high frequency partial discharge signal at the insulating basin during the operation was recorded.

[0068] Step 3.4: When the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the disconnector operation was repeated several times, and the ultra-high frequency partial discharge signal at the insulating basin during the operation was recorded.

[0069] In a non-limiting preferred embodiment, the test voltage waveform applied is as follows: Figure 3 As shown, from t = 0, the test voltage is gradually applied until At this time, the corresponding VFTO amplitude is preferably 1.0pu. Repeat the isolation switch operation several times for 3 to 5 minutes, and then continue to gradually increase the voltage to Repeat the isolating switch operation several times for 3 to 5 minutes, and then gradually increase the voltage to U max Repeat the isolating switch operation several times for 1 minute, and then gradually reduce the voltage to Repeat the isolating switch operation several times for 3 to 5 minutes.

[0070] Step 4: After repeating step 3, determine whether there is a metal particle defect in the GIS device to be tested based on the recorded ultra-high frequency partial discharge signal.

[0071] In a non-limiting preferred embodiment, the isolating switch operation is repeated 10 to 20 times. The occurrence of the metal particle partial discharge signal must be excluded as accidental. If the signal still appears after repeated isolating switch operation, the detection is correct and the cover needs to be opened for inspection.

[0072] In a non-limiting preferred embodiment, if breakdown occurs during the test or the VFTO amplitude exceeds the lightning impulse voltage withstand value, the test fails and the GIS equipment needs to be opened for inspection and retested.

[0073] In a non-limiting preferred embodiment, before the field test begins, Figure 4 As shown, UHF sensors 4 are placed at the windows on the housing 3 corresponding to the insulating basins 2 on both sides of the disconnector to be operated. The UHF sensors 4 are connected to a UHF partial discharge detector 6 through a UHF amplifier 5. The detector is connected to a computer screen through corresponding software to realize real-time monitoring of partial discharge signals.

[0074] In order to improve the measurement accuracy, the UHF sensor placed at the window can be wrapped with electromagnetic shielding cloth to isolate external interference, and then another UHF sensor can be arranged outside the electromagnetic shielding cloth to monitor the background signal.

[0075] The insulating basin 2 is used to support the conductive rod 1. When the disconnector is repeatedly operated, the ultra-high frequency partial discharge signal at the insulating basin during the operation is recorded.

[0076] The present invention also proposes a system for detecting metal particles by operating a disconnector during a GIS handover test. Figure 5 Shown, including:

[0077] Digital simulation module 10, test voltage generation module 20, partial discharge signal detection module 30, verification module 40. The digital simulation module is connected to the test voltage generation module, the test voltage generation module and the partial discharge signal detection module are respectively connected to the GIS device 50 to be tested, and the verification module is connected to the test voltage generation module.

[0078] The digital simulation module is used to determine the test voltage required for the handover test based on the GIS equipment simulation circuit model according to different VFTO amplitudes. The digital simulation module sends a signal to control the test voltage to the test voltage generation module.

[0079] The test voltage generating module is used to apply the test voltage to the GIS equipment to be tested, as well as the test voltage required for the conventional withstand voltage test, the test voltage required for the aging test, and the test voltage required for the withstand voltage test process.

[0080] In a non-limiting preferred embodiment, a series resonant voltage withstand test device is selected to generate the test voltage. The test voltage is an AC voltage, the voltage waveform is a sine wave, and the difference between the positive half-wave peak and the negative half-wave peak is less than 5%, and the voltage frequency is 30 to 300 Hz.

[0081] The partial discharge signal detection module is used to record the ultra-high frequency partial discharge signal at the insulating basin during the operation when the disconnector is repeatedly operated several times under different VFTO amplitude preferred values.

[0082] In a non-limiting preferred embodiment, the partial discharge signal detection module is disposed at the insulating basin portion of the GIS device to be tested. In this embodiment, a UHF partial discharge signal sensor is used for detection.

[0083] The verification module is used to control the test voltage generation module to perform repeated tests according to the ultra-high frequency partial discharge signal to obtain test results, and to determine whether there are metal particle defects in the GIS equipment to be tested based on the test results.

[0084] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0085] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0086] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0087] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., utilizing an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be personalized by utilizing the state information of the computer-readable program instructions. The electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for detecting metal particles during GIS handover test operation of an isolating switch, characterized in that: include: Step 1: Based on the GIS equipment simulation circuit model, determine the test voltage required for the handover test according to different VFTO amplitudes; Step 2: Perform routine pressure test, aging test and pressure test on GIS equipment; Step 3: Repeat the disconnector operation several times at different VFTO amplitude optimization values, and record the ultra-high frequency partial discharge signal in the GIS equipment during the operation; wherein, the optimization value of the VFTO amplitude that can excite metal particles is 1.6 pu; Step 4: After repeating step 3, determine whether there is a metal particle defect in the GIS device to be tested based on the recorded ultra-high frequency partial discharge signal.

2. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 1 is characterized in that: Step 1 includes: Step 1.1: Model the GIS equipment using the electromagnetic transient equivalent method to obtain a simulation circuit model of the GIS equipment; Step 1.2, determining a probability model of the VFTO amplitude based on experimental data, and determining that the optimal value of the VFTO amplitude that can excite metal particles is 1.6 pu according to the probability model; In step 1.3, based on the GIS equipment simulation circuit model, determine the corresponding test voltage according to the preferred value of the VFTO amplitude.

3. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 2, characterized in that: The VFTO amplitude shows a normal distribution between 1.0 pu and 2.2 pu, and the optimal value range of the VFTO amplitude is 1.4 to 1.8 pu.

4. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 1, characterized in that: In step 3, a pause of 3 to 5 seconds is performed between each two operations. After the current operation is completed, the next operation is performed after the voltage stabilizes. The voltage fluctuation after stabilization does not exceed ±5% of the test voltage.

5. The method for detecting metal particles during GIS handover test operation of disconnector according to claim 4, characterized in that: Step 3 includes: Step 3.1, when the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the isolating switch operation is repeated several times, and the ultra-high frequency partial discharge signal of the insulating basin during the operation is recorded; among them, U max is the maximum value of the line voltage; Step 3.2, when the VFTO amplitude is preferably 1.2 pu, adjust the test voltage to After that, repeat the disconnector operation several times and record the ultra-high frequency partial discharge signal at the insulating basin during the operation; Step 3.3: When the VFTO amplitude is preferably 1.6 pu, adjust the test voltage to U max After that, repeat the disconnector operation several times and record the ultra-high frequency partial discharge signal at the insulating basin during the operation; Step 3.4: When the VFTO amplitude is preferably 1.0 pu, adjust the test voltage to After that, the disconnector operation was repeated several times, and the ultra-high frequency partial discharge signal at the insulating basin during the operation was recorded.

6. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 5, characterized in that: Repeat the isolating switch operation 10 to 20 times.

7. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 6, characterized in that: In step 4, if the UHF partial discharge signal still appears after repeatedly operating the disconnector, the detection is correct and the GIS equipment needs to be opened and inspected.

8. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 1, characterized in that: If breakdown occurs during the test or the VFTO amplitude exceeds the lightning impulse voltage withstand value, the test fails and the GIS equipment must be opened for inspection and retested.

9. The method for detecting metal particles during GIS handover test operation of disconnect switches according to claim 1, characterized in that: Place UHF sensors at the corresponding positions of the insulating basins on both sides of the disconnector to be operated in the GIS equipment; UHF sensor, used to detect UHF partial discharge signals; The UHF sensor is connected to the UHF partial discharge detector through a UHF amplifier, and the detector is connected to a computer screen through corresponding software to realize real-time monitoring of partial discharge signals.

10. A system for detecting metal particles in a GIS handover test operation disconnector, used to implement the method according to any one of claims 1 to 9, characterized in that: include: Digital simulation module, test voltage generation module, partial discharge signal detection module, verification module; wherein the digital simulation module is connected to the test voltage generation module, the test voltage generation module and the partial discharge signal detection module are respectively connected to the GIS device to be tested, and the verification module is connected to the test voltage generation module; The digital simulation module is used to determine the test voltage required for the handover test based on the GIS equipment simulation circuit model and different VFTO amplitudes. The digital simulation module sends a signal to the test voltage generation module to control the test voltage. The preferred VFTO amplitude that can excite metal particles is 1.6 pu. The test voltage generating module is used to apply the test voltage to the GIS equipment under test, as well as the test voltage required for the conventional withstand voltage test, the test voltage required for the aging test, and the test voltage required during the withstand voltage test; The partial discharge signal detection module is used to record the ultra-high frequency partial discharge signal at the insulating basin during the operation when the disconnector is repeatedly operated several times under different VFTO amplitude optimization values; The verification module is used to control the test voltage generation module to perform repeated tests according to the ultra-high frequency partial discharge signal to obtain test results, and to determine whether there are metal particle defects in the GIS equipment to be tested based on the test results.

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