Process-adaptive gas insulated substation inductance type coupling clamp design method

Abstract

The invention relates to the technical field of transformer substation inductance type coupling clamps, and particularly discloses a process-adaptive gas insulation transformer substation inductance type coupling clamp design method, which comprises the following steps of: establishing a process-constrained quantitative model and a process and electrical performance association relationship, and combining test requirements and field installation conditions of a gas insulation transformer substation to obtain a process-adaptive gas insulation transformer substation inductance type coupling clamp design model; determining a working frequency band and parameter constraints of the coupling clamp; an electromagnetic simulation model of the coupling clamp is constructed, key design parameters are obtained through simulation, and parameter allowance is set in combination with production process deviation and material batch fluctuation; according to high-frequency transient characteristics of a gas insulated substation, on the premise of meeting magnetic saturation requirements, magnetic core materials are selected by taking cost and process suitability as optimization targets, so that the problems that a traditional coupling clamp is narrow in frequency band coverage range and cannot adapt to special wide-frequency-band transient electromagnetic disturbance detection of a GIS are solved; secondary circuit transient common-mode current and shell surface current signals can be effectively coupled.

Description

Technical Field

[0001] This invention relates to the field of inductive coupling clamp technology for substations, and in particular to a process-adaptive design method for inductive coupling clamps in gas-insulated substations. Background Technology

[0002] For gas-insulated substations (GIS), high-frequency transients propagate within the metal casing containing SF6 gas. Theoretically, due to the skin effect, these transients are confined within the casing and do not cause problems. However, the discontinuities in the casing cause some transients to propagate to the outer surface, leading to an increase in casing potential. The current flowing on the outer surface generates radiated electromagnetic fields in the substation environment, which not only affect the surrounding electromagnetic environment but may also interfere with the normal operation of nearby electronic equipment. The rise in transient ground potential is the direct source of transient common-mode currents in the secondary circuits. The radiated electromagnetic fields also induce common-mode currents in the secondary circuits. Measurements show that the maximum frequency of significant components of the spectral density of these currents can reach as high as 30MHz~50MHz, potentially leading to increased sampling errors in secondary equipment, communication interruptions, and other problems, thus affecting the safe and stable operation of the substation.

[0003] High-frequency transient-related ultrafast transient overvoltages (VFTOs) can lead to uneven electric field distribution, exacerbate dielectric loss in insulating materials, reduce surface flashover voltage of basin insulators, increase the probability of discharge in the air gaps inside the insulating materials, reduce equipment insulation performance, and pose a risk of insulation breakdown.

[0004] As substations shrink in size, the use of gas-insulated substations (GIS) and the installation of electronic equipment are closer to switchgear, resulting in reduced bay spacing. Consequently, the frequency environment of high-voltage substations (GS, including AIS) has become more severe than in the past. This exposes secondary equipment to more complex electromagnetic interference, and current standard tests for damped oscillating wave immunity and damped oscillating magnetic field immunity are insufficient to effectively assess the immunity of localized secondary equipment in substations to relevant transient electromagnetic disturbances. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is the shortcomings of existing coupling clamps in terms of frequency band coverage, anti-saturation capability, anti-interference performance and process adaptability.

[0006] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a process-adaptive design method for inductive coupling clamps in gas-insulated substations, which includes establishing a quantitative model of process constraints and the correlation between process and electrical performance, and determining the operating frequency band and parameter constraints of the coupling clamp in combination with the testing requirements and on-site installation conditions of the gas-insulated substation. An electromagnetic simulation model of the coupling clamp was constructed, key design parameters were obtained through simulation, and parameter margins were set in combination with production process deviations and material batch fluctuations. Based on the high-frequency transient characteristics of gas-insulated substations, and with cost and process adaptability as optimization objectives, core materials were selected while meeting magnetic saturation requirements. The magnetic permeability of the magnetic core is tested. If the test passes, the magnetic circuit parameters are output. If the test fails, the magnetic core material is reselected. Based on the magnetic circuit parameters and processing errors, the magnetic assembly structure parameters are determined, and the shell design parameters are determined in combination with the processing difficulty, lightweighting, electromagnetic shielding and heat dissipation requirements. Based on the actual usage environment limit parameters, material batch data and aging coefficient, the design parameters of the magnetic assembly and the shell were modified. The frequency performance of the coupling clamp after parameter correction is verified. If the verification is successful, the design is completed. If it fails, the magnetic core is reselected or the magnetic assembly and housing parameters are optimized.

[0007] In a preferred embodiment of the process-adaptive design method for inductive coupling clamps in gas-insulated substations described in this invention: the quantification model of the process constraints includes a quantification library of the capability boundaries of the core processing technology; the process and electrical performance correlation is a mapping rule between the core process parameters and the electrical performance of the coupling clamp; the low-frequency end of the operating frequency band covers the fundamental wave and low-frequency harmonics of the target transient current, while the high-frequency end reserves spectral redundancy; the parameter constraints include at least clamp size adaptability, magnetic circuit leakage flux ratio, withstand voltage, frequency response flatness, and output impedance matching constraints.

[0008] In a preferred embodiment of the design method for an inductive coupling clamp in a gas-insulated substation adapted to the process described in this invention: the electromagnetic simulation model is a three-dimensional model, which includes at least equivalent modules of a magnetic core, clamp housing, windings, and the cable under test, and can simulate the electromagnetic environment of the substation site; the process of obtaining the key design parameters includes determining the coupling coefficient, number of coil turns, winding method, magnetic circuit air gap, and housing shielding structure parameters through simulation; the parameter margin is set based on the simulation results of the influence of process errors and material fluctuations on the electromagnetic performance of the coupling clamp.

[0009] In a preferred embodiment of the design method for inductive coupling clamps in gas-insulated substations adapted to the process described in this invention: the initial selection criteria for the magnetic core material are the high-frequency magnetic properties, mechanical properties, and environmental resistance of the material; the evaluation indicators for process adaptability include the stability of the magnetic properties after material processing and the batch processing yield; the criteria for judging the magnetic saturation requirement are the comparison results between the critical saturation magnetic flux density of the magnetic core and the actual working magnetic flux density, as well as the saturation inflection point characteristics of the hysteresis loop.

[0010] In a preferred embodiment of the gas-insulated substation inductive coupling clamp design method adapted to the process described in this invention: the critical saturation magnetic flux density of the magnetic core is calculated based on the maximum transient current of the substation and the magnetic circuit structure parameters of the coupling clamp; the actual working magnetic flux density is obtained by applying an equivalent transient excitation signal to the magnetic core and detecting it using a hysteresis loop tester.

[0011] In a preferred embodiment of the gas-insulated substation inductive coupling clamp design method adapted to the process described in this invention: the permeability test is performed by winding a test coil on the magnetic core and connecting it to an impedance testing device, scanning within a preset frequency band to obtain the inductance value to calculate the permeability; the conditions for passing the test include that the permeability value meets the standard and the permeability deviation of the magnetic cores in the same batch is within a preset threshold.

[0012] In a preferred embodiment of the gas-insulated substation inductive coupling clamp design method adapted to the process described in this invention: the magnetic assembly structural parameters include at least the magnetic core selection, magnetic core geometry, clamp jaw structure dimensions, and magnetic core protective coating parameters; the housing design parameters include at least the housing material, structural dimensions, high-frequency signal interface specifications, and heat dissipation structure.

[0013] In a preferred embodiment of the design method for inductive coupling clamps in gas-insulated substations adapted to the process described in this invention: the actual operating environment limit parameters include at least extreme temperature and humidity parameters; the material aging coefficient includes at least the performance degradation coefficient of the magnetic core protective coating and the shell protective material; the correction method is to perform redundancy compensation or performance calibration on the original design parameters based on the above parameters.

[0014] In a preferred embodiment of the gas-insulated substation inductive coupling clamp design method adapted to the process described in this invention: the frequency performance verification method is to connect the coupling clamp to a standard test cable and obtain the frequency response curve of the coupling clamp through a signal generation and acquisition device; the verification pass criteria are that the full-band signal response is normal, the amplitude fluctuation meets the requirements, and the interference suppression capability meets the standard.

[0015] In a preferred embodiment of the inductive coupling clamp design method for gas-insulated substations adapted to the process described in this invention: the testing requirement of the gas-insulated substation is the coupling acquisition requirement of transient common-mode current of the secondary circuit and surface current of the casing, and the field installation conditions include the secondary cable specifications and outdoor electromagnetic, temperature and humidity environmental conditions.

[0016] The beneficial effects of this invention are as follows: By combining the spectral characteristics of high-frequency transient current in GIS, the operating frequency band of the coupling clamp is determined to be 1MHz~60MHz. The low-frequency end covers the fundamental wave and low-frequency harmonics of transient current, and the high-frequency end reserves 10MHz of redundancy. It can accurately cover the key interference frequency band of 30MHz~50MHz, which solves the problem that the traditional coupling clamp has a narrow frequency band coverage and cannot be adapted to the wide-band transient electromagnetic interference detection unique to GIS. It can effectively couple the transient common-mode current of the secondary circuit and the current signal of the shell surface, providing comprehensive data support for the electromagnetic interference tracing of GIS.

[0017] The critical saturation magnetic flux density of the magnetic core was calculated using Ohm's law for magnetic circuits, and the saturation characteristics of the magnetic core were verified using a hysteresis loop tester. Magnetic core materials with actual magnetic flux densities far below the critical value under the maximum transient current of GIS were selected. At the same time, the material characteristic parameters were corrected by combining process trial processing to ensure that the magnetic core has no saturation inflection point under complex working conditions. This solved the problem that traditional coupling clamp magnetic cores are prone to saturation under large transient currents, leading to signal coupling failure, and ensured the continuity and accuracy of the test data.

[0018] By optimizing the shielding structure of the clamp housing through three-dimensional electromagnetic simulation, and adopting a design with an inner wall 0.1mm copper foil shielding layer and single-point grounding, the external electromagnetic interference attenuation can be ≥40dB. At the same time, the housing meets the IP65 and above protection level, and can resist outdoor humid, dusty and strong radiation electromagnetic environments. This solves the problems of weak anti-interference ability and low signal-to-noise ratio caused by background electromagnetic field interference in traditional coupling clamps, and ensures the reliability of test data.

[0019] First, parametric modeling of the core process of coupling clamp machining was carried out to form a quantitative constraint library and establish the mapping relationship between process parameters and electrical performance. In the core selection stage, process adaptability scoring was added. At the same time, parameter margins were set for material batch fluctuations and process errors. In addition, an integrated die-cast shell and standardized snap-fit ​​interface and other easy mass production structures were adopted. This solved the problems of disconnect between traditional coupling clamp design and actual processing, low batch production yield and poor performance consistency. It achieved precise alignment between theoretical design and mass production process and reduced production and manufacturing costs.

[0020] Multi-dimensional adaptability enhances ease of use in the field. The coupling clamp designed in this invention features a hinged opening and closing structure, with an opening diameter suitable for GIS secondary cables ranging from 10 to 30 mm. After closure, the magnetic circuit gap can be compensated for mechanical errors by elastic pads. Furthermore, the lightweight housing design, equipped with an anti-slip handle and a quick-locking device, balances ease of installation with magnetic circuit stability. It can efficiently serve the localized secondary equipment immunity assessment in substations, providing strong technical support for the safe and stable operation of the power grid. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A flowchart is shown showing the design method of inductive coupling clamp for gas-insulated substations with process adaptation. Figure 2 A schematic diagram of the coupling clamp structure is shown, illustrating a design method for an inductive coupling clamp in a gas-insulated substation with process adaptability. Figure 3 An example of a design method for an inductive coupling clamp in a gas-insulated substation with process adaptation is shown, with simulation results of the coupling clamp. Figure 4 A 100A time-domain test diagram is shown for the design method of inductive coupling clamp for gas-insulated substations with process adaptation. Figure 5 A 200A time-domain test diagram of the design method of inductive coupling clamp for gas-insulated substations with process adaptation is shown. Figure 6 A 300A time-domain test diagram of the design method of inductive coupling clamp for gas-insulated substations with process adaptation is shown. Figure 7 A 400A time-domain test diagram of the design method of inductive coupling clamp for gas-insulated substations with process adaptation is shown. Figure 8 A 500A time-domain test diagram of the design method of inductive coupling clamp for gas-insulated substations adapted to the process is shown. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0023] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0024] Reference Figures 1-3 This embodiment provides a process-adaptive design method for inductive coupling clamps in gas-insulated substations, including: S1: Establish a quantitative model of process constraints and the correlation between process and electrical performance. Combine the testing requirements of gas-insulated substations with on-site installation conditions to determine the operating frequency band and parameter constraints of the coupling clamp. S2: Construct an electromagnetic simulation model of the coupling clamp, obtain key design parameters through simulation, and set parameter margins in combination with production process deviations and material batch fluctuations; S3: Based on the high-frequency transient characteristics of gas-insulated substations, and with cost and process adaptability as optimization objectives, core materials are selected while meeting magnetic saturation requirements. S4: Perform a permeability test on the magnetic core. If the test passes, output the magnetic circuit parameters; otherwise, reselect the magnetic core material. S5: Based on the magnetic circuit parameters and processing errors, determine the magnetic assembly structure parameters, and combine the processing difficulty, lightweighting, electromagnetic shielding and heat dissipation requirements to determine the shell design parameters; S6: Based on the actual usage environment limit parameters, material batch data and aging coefficient, the design parameters of the magnetic assembly and the shell are corrected; S7: Verify the frequency performance of the coupling clamp after parameter correction. If the verification is successful, the design is completed. If it fails, the magnetic core is reselected or the magnetic assembly and housing parameters are optimized.

[0025] Reference Figures 1-3 As an optional embodiment, the quantification model of the process constraints includes a capability boundary quantification library for the core processing technology, and the process and electrical performance correlation is a mapping rule between the core process parameters and the electrical performance of the coupling clamp; the low-frequency end of the operating frequency band covers the fundamental wave and low-frequency harmonics of the target transient current, and the high-frequency end reserves spectral redundancy; the parameter constraints include at least clamp size adaptability, magnetic circuit leakage flux ratio, withstand voltage, frequency response flatness and output impedance matching constraints.

[0026] The electromagnetic simulation model is a three-dimensional model, which includes at least equivalent modules of the magnetic core, clamp housing, winding, and the cable under test, and can simulate the electromagnetic environment of the substation site; the process of obtaining the key design parameters includes determining the coupling coefficient, number of coil turns, winding method, magnetic circuit air gap, and housing shielding structure parameters through simulation; the parameter margin is set based on the simulation results of the influence of process error and material fluctuation on the electromagnetic performance of the coupling clamp.

[0027] The initial selection criteria for the magnetic core material are its high-frequency magnetic properties, mechanical properties, and environmental resistance. The evaluation indicators for process adaptability include the stability of the magnetic properties after material processing and the batch processing yield. The criteria for judging the magnetic saturation requirement are the comparison between the critical saturation magnetic flux density of the magnetic core and the actual working magnetic flux density, as well as the saturation inflection point characteristics of the hysteresis loop.

[0028] Reference Figures 1-3In one embodiment provided in this application, the critical saturation magnetic flux density of the magnetic core is calculated based on the maximum transient current of the substation and the structural parameters of the coupling clamp magnetic circuit; the actual working magnetic flux density is obtained by applying an equivalent transient excitation signal to the magnetic core and detecting it with a hysteresis loop tester.

[0029] The permeability test is performed by winding a test coil on the magnetic core and connecting it to an impedance testing device, scanning within a preset frequency band to obtain the inductance value and calculate the permeability; the conditions for passing the test include that the permeability value meets the standard and the permeability deviation of magnetic cores in the same batch is within a preset threshold.

[0030] The magnetic assembly structural parameters include at least the magnetic core selection, magnetic core geometry, jaw structure dimensions, and magnetic core protective coating parameters; the housing design parameters include at least the housing material, structural dimensions, high-frequency signal interface specifications, and heat dissipation structure.

[0031] The actual operating environment limit parameters include at least extreme temperature and humidity parameters; the material aging coefficient includes at least the performance degradation coefficient of the magnetic core protective coating and the shell protective material; the correction method is to perform redundancy compensation or performance calibration on the original design parameters based on the above parameters.

[0032] Reference Figures 1-3 In some implementations, the frequency performance verification method is to connect the coupling clamp to a standard test cable and obtain the frequency response curve of the coupling clamp through a signal generation and acquisition device; the criteria for passing the verification are that the full-band signal response is normal, the amplitude fluctuation meets the requirements, and the interference suppression capability meets the standards.

[0033] The testing requirements for the gas-insulated substation include the coupling acquisition of transient common-mode current in the secondary circuit and surface current in the casing. The on-site installation conditions include the specifications of the secondary cables and the outdoor electromagnetic, temperature, and humidity environmental conditions.

[0034] This invention can simultaneously consider the testing requirements, on-site installation environment, and processing conditions of the coupling clamp in gas-insulated substation scenarios, achieving precise alignment between the theoretical parameters of the coupling clamp and actual production. The design principles of this invention are explained below with examples.

[0035] First, parametric modeling of process constraints is performed to identify the capability boundaries of the core process for inductive coupling clamp manufacturing, forming a quantitative constraint library. For the core process, a mapping relationship between process parameters and electrical performance is established. For the testing requirements and on-site installation environment in gas-insulated substation scenarios, the operating frequency range and parameter constraints of the inductive coupling clamp are determined by combining the quantitative constraint library and the mapping relationship between process parameters and electrical performance.

[0036] Regarding the operating frequency range, for the testing requirements in GIS scenarios, the core testing objects of the coupling clamp are clearly defined: first, the transient common-mode current directly caused by the rise of transient ground potential on the secondary circuit; second, the common-mode current induced on the secondary circuit by the radiated electromagnetic field. At the same time, the coupling acquisition of the current flowing on the outer surface of the casing should also be taken into account to provide data support for electromagnetic interference tracing and secondary equipment immunity assessment.

[0037] Based on the spectral characteristics of the high-frequency transient current in GIS, the operating frequency band of the coupling clamp is determined to be 1MHz~60MHz: the low-frequency end covers the fundamental wave and low-frequency harmonic components of the transient current, and the high-frequency end reserves 10MHz of redundancy to avoid detection failure due to spectral peak shift. Finally, according to the GIS field installation environment, the core constraints of the coupling clamp are determined: ① The clamp jaw opening diameter must be compatible with the GIS secondary cable, and the magnetic leakage flux ratio after closure must be ≤5%; ② Rated withstand voltage ≥2kV (AC) to adapt to the humid outdoor environment of substations with high electromagnetic radiation; ③ Frequency response flatness: amplitude fluctuation ≤±3dB within the 1MHz~60MHz frequency band; ④ Output impedance matching: matched with subsequent acquisition equipment to ensure no signal reflection distortion.

[0038] Regarding parameter constraints, considering actual process limitations, this invention also identifies the capability boundaries of core processes, forming a quantitative constraint library. This includes parameters such as machining accuracy, winding machine tension range, and allowable distributed capacitance threshold for welding. These parameters are used as design inputs, replacing the ideal values ​​in the original theory. For critical processes, a mapping relationship between "process parameters and electrical performance" is established, allowing for direct parameter determination during design.

[0039] Key design parameters are determined through simulation analysis.

[0040] Figure 2This is a structural diagram of the coupling clamp. A three-dimensional electromagnetic simulation model of the coupling clamp is constructed using AnsysMaxwell or COMSOL software. This model includes the magnetic core, clamp housing, secondary winding, and an equivalent model of the cable under test, simulating the electromagnetic environment of the GIS site, including background electromagnetic field strength and cable laying method. Based on the three-dimensional electromagnetic simulation model of the coupling clamp, the coupling coefficient is determined through simulation iteration for the operating frequency range of the inductive coupling clamp. Based on the principle of electromagnetic induction, the influence of different number of turns on the output voltage is simulated to determine the number of coil turns. The frequency response of single-layer dense winding and multi-layer sparse winding is simulated, and the coil winding method is determined based on the simulation results. The influence of air gap on leakage flux is simulated to determine the magnetic circuit air gap. The interference of the electromagnetic field radiated by the GIS housing on the coupling clamp is simulated, and the shielding structure parameters of the clamp housing, including grounding method and shielding layer thickness, are optimized based on the simulation results. Then, process error parameters and material batch fluctuation data are imported into AnsysMaxwell software to simulate the influence of parameter deviations in actual production on the coupling coefficient and frequency response. Parameter margins for each parameter are set based on the simulation results.

[0041] In this embodiment, simulation optimization is mainly performed on the following key parameters: Coupling coefficient target value: For the core frequency band of 30MHz~50MHz, the coupling coefficient is determined to be ≥0.85 through simulation iteration to ensure that transient small signals can be effectively coupled; Coil turns design: Based on the principle of electromagnetic induction, the effect of different turns on the output voltage was simulated, and the final number of turns was determined to be 25 turns; Coil winding method: Simulating the frequency response of single-layer dense winding and multi-layer sparse winding, it was determined that single-layer dense winding method should be adopted, with coil length ≤20mm, to reduce the attenuation of high-frequency signals by inter-turn distributed capacitance; Air gap control in magnetic circuit: Simulate the effect of air gap on leakage flux and determine that the air gap is ≤0.2mm to ensure the closure of the magnetic circuit.

[0042] The interference of electromagnetic fields radiated by the GIS shell on the coupling clamp is simulated. The shielding structure of the clamp shell, such as the grounding method and the thickness of the shielding layer, is optimized through simulation to ensure that the interference signal attenuation is ≥40dB and to avoid background interference from masking the measured signal.

[0043] Based on the optimized theoretical key parameters, the limiting parameters of the actual use environment are first collected, and combined with material batch test data, the material characteristic parameters in the theoretical design are corrected. Then, the material aging coefficient is added, and redundancy design is performed on parameters such as core coating thickness and shell protection level, thus completing the optimization of key design parameters. Preferably, the allowable range of parameter fluctuations can also be set based on supplier capacity and batch difference data. For example, the batch deviation of magnetic core permeability is ≤3%, and the coil turn tolerance is ±1 turn. These tolerances are incorporated into the simulation model during the design to verify the impact of parameter fluctuations on performance; or the capability parameters of automated production equipment can be used as constraints in parameter design, such as the turn accuracy of an automatic winding machine being ±0.5 turns, which is used as a constraint in the coil turn design to adapt to the equipment accuracy.

[0044] Select the magnetic core material.

[0045] Based on the high-frequency transient characteristics of GIS, candidate types of magnetic core materials are determined by comprehensively considering relative permeability, hysteresis loss angle, mechanical strength, and environmental resistance. While meeting magnetic saturation requirements, the lowest cost and highest process compatibility score are considered when selecting one of the candidate magnetic material types as the core material. The process for determining magnetic saturation requirements includes: calculating the critical saturation flux density of the core based on the maximum transient current and the size of the coupling clamp magnetic circuit in the GIS site; and conducting saturation characteristic tests on the selected core using a hysteresis loop tester. Specifically, within a preset operating frequency range, an excitation signal equivalent to a transient current is applied. If the actual flux density of the tested core is less than the critical saturation flux density, and the hysteresis loop shows no obvious saturation inflection point, the core is considered unsaturated; otherwise, a new core material is selected.

[0046] In this example, considering the high-frequency transient characteristics of GIS, the core material must meet the following requirements: ① Stable high-frequency permeability: within the 1MHz~60MHz frequency band, the relative permeability μr ≥ 100 and the fluctuation ≤ ±10%; ② Low loss factor: at 50MHz, the hysteresis loss tangent tanδ ≤ 0.05 to avoid performance drift caused by core heating at high frequencies; ③ Mechanical strength: compressive strength ≥ 100MPa to adapt to the mechanical stress of jaw opening and closing; ④ Environmental resistance: temperature range -40℃~85℃, moisture resistant and aging resistant.

[0047] Based on the above criteria, three candidate materials were selected: ① Nanocrystalline alloys: high high-frequency permeability and low loss, but higher cost; ② Permalloy: stable permeability, but slightly higher high-frequency loss than nanocrystalline alloys; ③ Ferrites: low cost and good temperature resistance, but faster high-frequency permeability decay. Considering both performance and cost, nanocrystalline alloys were initially selected as the core material. In the 30MHz~50MHz frequency band, μr≈150 and tanδ≈0.03 meet the requirements for high-frequency response and low loss, and their mechanical strength and environmental resistance are suitable for GIS field applications.

[0048] Process compatibility verification should also be incorporated into the material selection stage. In addition to magnetic saturation and cost requirements, a material process compatibility score should be added, such as the processing difficulty of nanocrystalline alloys and the batch processing yield of ferrites. Combined with cost weighting, materials that meet performance standards and are process-friendly should be selected. For the selected materials, at least three batches of samples should be obtained in advance for trial processing to test the changes in magnetic permeability and loss factor after processing, and the material characteristic parameters should be adjusted accordingly.

[0049] Based on the maximum transient current at the GIS site (typical peak value ≤ 100A) and the dimensions of the coupling clamp magnetic circuit, the critical saturation magnetic flux density of the magnetic core is calculated using Ohm's law for magnetic circuits. Where N is the number of coil turns, I is the maximum current, μ is the core permeability, S is the core cross-sectional area, and l is the magnetic path length, the core saturation flux density Bsat ≥ 0.8T is determined to avoid a sharp drop in the coupling coefficient due to core saturation under the maximum transient current. The saturation characteristics of the nanocrystalline alloy core are tested using a hysteresis loop tester: at a frequency of 50MHz, an excitation signal equivalent to a 100A transient current is applied. The actual flux density of the core is tested to be approximately 0.6T, and the hysteresis loop shows no obvious saturation inflection point, indicating that the core is not saturated. If the test results show that the core flux density ≥ Bsat, a new core is selected; in this design, the nanocrystalline alloy core meets the magnetic saturation requirement, and we proceed to the next step.

[0050] Core permeability test.

[0051] After winding a test coil around the magnetic core, connect it to an impedance analyzer. Within the preset operating frequency range, scan in 1MHz steps to measure the inductance of the coil and calculate the relative permeability. Record the permeability data at different frequencies. Select three magnetic cores from the same batch for repeated testing. If the maximum deviation of the permeability is less than the preset deviation threshold, the magnetic core permeability test is considered passed, and the magnetic circuit parameters are output.

[0052] In this example, an impedance analyzer is used to test the permeability using the equivalent impedance method of the coil and magnetic core: a test coil with 10 turns is wound around the magnetic core and connected to the impedance analyzer. The inductance L of the coil is measured in 1MHz steps within the 1MHz~60MHz frequency band, and then calculated using the formula... Where f is the test frequency, r is the core radius, and l is the core length. Calculate the relative permeability. .

[0053] Test results show that the nanocrystalline alloy core has μr≈180 at 1MHz, μr≈150 at 30MHz, μr≈130 at 50MHz, and μr≈110 at 60MHz, meeting the design requirement of μr≥100 and fluctuation≤±10% in the 1MHz~60MHz frequency band. Simultaneously, permeability data at different frequencies were recorded to provide a basis for subsequent frequency response calibration. Three cores from the same batch were selected for repeated testing to ensure that the maximum permeability deviation was ≤5%, avoiding poor consistency in coupling clamp performance due to batch differences in materials.

[0054] Core size and housing design.

[0055] Based on the magnetic circuit parameters determined by simulation and combined with the permeability test results, the magnetic assembly structure parameters, including core type, core size, jaw size, and core surface coating, are determined. According to the requirements of lightweighting, electromagnetic shielding, and heat dissipation, the design of shell material, shell structure size, high-frequency interface, and heat dissipation groove structure is completed.

[0056] For the magnetic core structure design, a modular and fault-tolerant design is adopted. Based on the magnetic circuit parameters determined by simulation, combined with the permeability test results and machining errors, the specific dimensions of the magnetic core are determined. Taking this example, the magnetic core type is selected as a toroidal open-close structure with an outer diameter D=40mm, an inner diameter d=25mm, and a thickness h=15mm. The clamp adopts a hinged opening and closing structure, and the gap between the magnetic cores after closure is ≤0.2mm. Mechanical errors are compensated by elastic shims to reduce magnetic leakage. The surface of the magnetic core is coated with epoxy resin to enhance insulation and mechanical protection. The magnetic core mating surface is designed with chamfers to accommodate machining errors. A 0.5mm gap is reserved in the coil winding area to avoid inter-turn short circuits caused by winding tension fluctuations.

[0057] For the shell structure design, an integrated molding process is preferred to reduce assembly steps; the interface adopts a standardized snap-fit ​​structure to reduce welding process requirements, while ensuring a shell wall thickness of ≥2mm. The shell material is aluminum alloy, combining lightweight design with electromagnetic shielding performance; the shell adopts a fully enclosed design with a 0.1mm thick copper foil shielding layer on the inner wall, and the shielding layer is grounded at a single point to suppress external electromagnetic interference; the shell is equipped with a non-slip handle and a quick-locking device to ensure uniform pressure after the jaws are closed, preventing vibration from increasing the magnetic circuit gap; a pre-installed SMA high-frequency interface is provided on the side of the shell for outputting coupled signals, with an interface protection rating of ≥IP67, suitable for outdoor environments.

[0058] Considering the slight heating of the magnetic core and coil at high frequencies, the housing is designed with heat dissipation slots to enhance air convection heat dissipation; the overall housing adopts a sealed structure and is filled with waterproof silicone to meet the IP65 protection level and adapt to the humid and dusty outdoor environment of GIS.

[0059] Determine if the frequency operating requirements are met. The designed inductive coupling clamp is clamped onto a standard test cable. A sinusoidal current signal with a preset operating frequency range is output through a signal generator and injected into the cable through a power amplifier. The output voltage of the coupling clamp is acquired using an oscilloscope, and a frequency response curve is plotted. If the test results show no response in any frequency band, excessive amplitude fluctuation, or insufficient interference suppression, the process returns to step S3 to reselect the magnetic core material or returns to step S5 to re-optimize the magnetic assembly structure parameters and housing design parameters. Otherwise, it is determined that all indicators meet the frequency operating requirements, and the coupling clamp design is completed.

[0060] In this example, a test platform was set up: a coupling clamp was attached to a standard test cable, and a sinusoidal current signal with an amplitude of 10mA and a frequency range of 1MHz to 60MHz was output through a signal generator. This signal was then injected into the cable through a power amplifier. The output voltage of the coupling clamp was acquired using an oscilloscope, and a frequency response curve was plotted. Testing showed that the output voltage had a stable response within the 1MHz to 60MHz frequency band, with no obvious cutoff phenomenon; within the core frequency band of 30MHz to 50MHz, the output voltage amplitude fluctuation was ≤±2dB, meeting the design requirements; at 60MHz, the output voltage amplitude was 92% of that at 50MHz, with an attenuation of ≤8%, meeting the expected high-frequency response; under GIS simulated electromagnetic conditions, the signal-to-noise ratio of the coupling clamp output signal was ≥30dB, indicating that the interference suppression effect met the standards. (See also...) Figure 3 The insertion loss at 30MHz is less than -3dB, indicating that the inductive coupling clamp can be used normally at 30MHz and meets the coupling requirements of 30MHz.

[0061] This embodiment addresses the immunity testing requirements of secondary equipment in a 110kV gas-insulated substation. It designs an adaptable inductive coupling clamp that can acquire transient common-mode current coupling in the 1MHz~60MHz frequency band and meet the installation compatibility requirements of secondary cables, outdoor IP65 protection level, and process compatibility requirements for mass production.

[0062] S1: Process constraint modeling and operating parameter determination Quantitative Modeling of Process Constraints The capability boundaries of the core processing technology of coupling clamp were identified, and a quantitative constraint library was formed: the minimum gap between magnetic cores in mechanical processing can be 0.15mm, the tension of the winding machine can be controlled within the range of 0.5~1.5N, and the distributed capacitance threshold allowed by the welding process is ≤1pF; at the same time, the mapping relationship between process parameters and electrical performance was established. For example, when the grounding resistance of the shielding layer is ≤0.8Ω, the attenuation of external electromagnetic interference can reach more than 40dB.

[0063] Determination of operating frequency band and parameter constraints Based on the spectral characteristics of high-frequency transient current in GIS, the operating frequency band of the coupling clamp is determined to be 1MHz~60MHz, with the low-frequency end covering the fundamental transient current and the high-frequency end reserving 10MHz redundancy. According to the on-site installation environment, the parameter constraints are defined as follows: the clamp opening diameter is compatible with 10~30mm secondary cables, and the magnetic leakage rate of the magnetic circuit after closure is ≤5%; the rated withstand voltage is ≥2kV (AC); the frequency response amplitude fluctuation in the 1MHz~60MHz frequency band is ≤±3dB; and the output impedance is matched with a 50Ω acquisition device.

[0064] S2: Three-dimensional electromagnetic simulation and key parameter determination Simulation model construction A three-dimensional electromagnetic simulation model of the coupling clamp was constructed in AnsysMaxwell software. The model includes an annular open and closed magnetic core, an aluminum alloy shell, a 25-turn secondary winding, and an equivalent module of the cable under test. It also simulates the electromagnetic environment of the background electromagnetic field strength and the cable laying method.

[0065] Simulation iteration of key parameters For the 1MHz~60MHz frequency band, the coupling coefficient was determined to be ≥0.85 through simulation iteration; based on the principle of electromagnetic induction, the influence of 10~50 turns of coil on the output voltage was simulated, and the number of coil turns was finally determined to be 25 turns; comparing the frequency response of single-layer dense winding and multi-layer sparse winding, the single-layer dense winding method was selected; the influence of 0.1~0.5mm air gap on leakage magnetic rate was simulated, and the magnetic circuit air gap was determined to be ≤0.2mm; the shell radiation interference was simulated, and the shell shielding structure was optimized to be an inner wall 0.1mm copper foil shielding layer + single-point grounding.

[0066] Parameter margin setting By importing process error parameters and material batch fluctuation data, the influence of parameter deviation on the coupling coefficient is simulated, and finally the coil turns tolerance is set to ±1 turn and the magnetic core permeability fluctuation margin is set to ±10%.

[0067] S3: Selection of magnetic core material Candidate material screening Based on the high-frequency transient characteristics of GIS, three candidate magnetic core materials were selected: nanocrystalline alloy, permalloy, and Mn-Zn ferrite. Among them, nanocrystalline alloy has a relative permeability μr≈150, hysteresis loss tangent tanδ≈0.03, and compressive strength ≥100MPa in the 30MHz~50MHz frequency band, which meets the basic performance requirements.

[0068] Magnetic saturation verification Based on the maximum transient current of 100A and the magnetic circuit dimensions at the GIS site, the critical saturation magnetic flux density Bsat≥0.8T of the magnetic core was calculated. Using a hysteresis loop tester, an equivalent excitation signal of 100A was applied at 50MHz, and the actual magnetic flux density of the nanocrystalline alloy was measured to be ≈0.6T. Moreover, the hysteresis loop had no saturation inflection point, thus meeting the magnetic saturation requirement.

[0069] Process compatibility verification: Three batches of process trial processing were carried out on the three candidate materials. The test found that the permeability of the nanocrystalline alloy decreased to 140 after processing, and the batch processing yield was 92%; the ferrite processing yield was 95%, but the high-frequency permeability decreased to 80; the permalloy loss factor exceeded the standard. Finally, the nanocrystalline alloy with the highest process compatibility score was selected as the core material.

[0070] S4: Core Permeability Test A test coil with 10 turns of nanocrystalline alloy magnetic core was wound and connected to an Agilent 4294A impedance analyzer. The inductance was measured and the relative permeability was calculated in the 1MHz~60MHz frequency band with a step size of 1MHz: μr≈180 at 1MHz, μr≈150 at 30MHz, μr≈130 at 50MHz, and μr≈110 at 60MHz, all ≥100 and with fluctuation ≤±10%. Three magnetic cores from the same batch were selected for repeated testing. The maximum deviation of permeability was ≤5%. The test was passed and the magnetic circuit parameters were output.

[0071] S5: Magnetic Assembly and Shell Structure Design Determination of magnetic assembly structural parameters Based on the magnetic circuit parameters and processing errors, the magnetic assembly structure was determined to be: a ring-shaped open and closed nanocrystalline alloy magnetic core with a hinged jaw structure and a 0.5mm epoxy resin protective coating on the surface of the magnetic core.

[0072] housing design The housing is made of die-cast aluminum alloy with a wall thickness of ≥2mm. It is equipped with an SMA high-frequency interface (IP67 protection level) and heat dissipation grooves. The whole structure is sealed and filled with waterproof silicone to meet the IP65 protection level.

[0073] S6: Design Parameter Correction By collecting extreme environmental parameters from the site and combining them with material batch data and aging coefficients, the core coating thickness was corrected to 0.6mm, and the housing protection level was enhanced to IP67.

[0074] S7: Frequency Performance Verification Set up a test platform, clamp the coupling clamp onto the standard test cable, output a 1MHz~60MHz, 10mA sinusoidal current signal through a signal generator, inject it into the cable through a power amplifier, and use a 100MHz oscilloscope to acquire the output voltage and plot the frequency response curve. It exhibits stable response across the entire frequency band, with no cutoff phenomenon; The amplitude fluctuation of the 30MHz~50MHz core frequency band is ≤±2dB, which meets the design requirements; The output voltage at 60MHz is 92% of that at 50MHz, with an attenuation of ≤8%. With a background interference of 50V / m, the output signal-to-noise ratio is ≥30dB, the interference suppression meets the standard, and the coupling clamp design is deemed complete.

[0075] The inductive coupling clamp designed using this method has successfully achieved stable operation in a wide frequency band of 1MHz~60MHz. It can accurately couple transient common-mode currents of secondary circuits and surface currents of the housing. The clamp jaws are easy to open and close and are compatible with 10~30mm secondary cables. The mass production yield is ≥90%, providing accurate data support for GIS electromagnetic interference tracing and secondary equipment immunity assessment.

[0076] Insertion loss test results from 1kHz to 100kHz

[0077] Instruments used for insertion loss testing

[0078] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A design method for an inductive coupling clamp in a gas-insulated substation with process adaptability, characterized in that: The method includes, Establish a quantitative model of process constraints and the correlation between process and electrical performance. Combine the testing requirements of gas-insulated substations with on-site installation conditions to determine the operating frequency band and parameter constraints of the coupling clamp. An electromagnetic simulation model of the coupling clamp was constructed, key design parameters were obtained through simulation, and parameter margins were set in combination with production process deviations and material batch fluctuations. Based on the high-frequency transient characteristics of gas-insulated substations, and with cost and process adaptability as optimization objectives, core materials were selected while meeting magnetic saturation requirements. The magnetic permeability of the magnetic core is tested. If the test passes, the magnetic circuit parameters are output. If the test fails, the magnetic core material is reselected. Based on the magnetic circuit parameters and processing errors, the magnetic assembly structure parameters are determined, and the shell design parameters are determined in combination with the processing difficulty, lightweighting, electromagnetic shielding and heat dissipation requirements. Based on the actual usage environment limit parameters, material batch data and aging coefficient, the design parameters of the magnetic assembly and the shell were modified. The frequency performance of the coupling clamp after parameter correction is verified. If the verification is successful, the design is completed. If it fails, the magnetic core is reselected or the magnetic assembly and housing parameters are optimized.

2. The design method for inductive coupling clamps in gas-insulated substations with process adaptation according to claim 1, characterized in that: The quantitative model of the process constraints includes a quantitative library of the capability boundaries of the core processing technology. The relationship between the process and electrical performance is a mapping rule between the core process parameters and the electrical performance of the coupling clamp. The low-frequency end of the operating frequency band covers the fundamental wave and low-frequency harmonics of the target transient current, while the high-frequency end reserves spectral redundancy. The parameter constraints include at least clamp size adaptability, magnetic circuit leakage flux ratio, withstand voltage, frequency response flatness, and output impedance matching constraints.

3. The design method for inductive coupling clamps in gas-insulated substations with process adaptation according to claim 2, characterized in that: The electromagnetic simulation model is a three-dimensional model, which includes at least equivalent modules of the magnetic core, clamp housing, winding, and the cable under test, and can simulate the electromagnetic environment of the substation site; the process of obtaining the key design parameters includes determining the coupling coefficient, number of coil turns, winding method, magnetic circuit air gap, and housing shielding structure parameters through simulation; the parameter margin is set based on the simulation results of the influence of process error and material fluctuation on the electromagnetic performance of the coupling clamp.

4. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 3, characterized in that: The initial selection criteria for the magnetic core material are its high-frequency magnetic properties, mechanical properties, and environmental resistance. The evaluation indicators for process adaptability include the stability of the magnetic properties after material processing and the batch processing yield. The criteria for judging the magnetic saturation requirement are the comparison between the critical saturation magnetic flux density of the magnetic core and the actual working magnetic flux density, as well as the saturation inflection point characteristics of the hysteresis loop.

5. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 4, characterized in that: The critical saturation magnetic flux density of the magnetic core is calculated based on the maximum transient current of the substation and the structural parameters of the coupled clamp magnetic circuit; the actual working magnetic flux density is obtained by applying an equivalent transient excitation signal to the magnetic core and detecting it with a hysteresis loop tester.

6. The design method for inductive coupling clamps in gas-insulated substations with process adaptation according to claim 5, characterized in that: The permeability test is performed by winding a test coil on the magnetic core and connecting it to an impedance testing device, scanning within a preset frequency band to obtain the inductance value and calculate the permeability; the conditions for passing the test include that the permeability value meets the standard and the permeability deviation of magnetic cores in the same batch is within a preset threshold.

7. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 6, characterized in that: The magnetic assembly structural parameters include at least the magnetic core selection, magnetic core geometry, jaw structure dimensions, and magnetic core protective coating parameters; the housing design parameters include at least the housing material, structural dimensions, high-frequency signal interface specifications, and heat dissipation structure.

8. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 7, characterized in that: The actual operating environment limit parameters include at least extreme temperature and humidity parameters; the material aging coefficient includes at least the performance degradation coefficient of the magnetic core protective coating and the shell protective material; the correction method is to perform redundancy compensation or performance calibration on the original design parameters based on the above parameters.

9. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 8, characterized in that: The frequency performance verification method is to connect the coupling clamp to a standard test cable and obtain the frequency response curve of the coupling clamp through a signal generation and acquisition device; the verification pass criteria are that the full-band signal response is normal, the amplitude fluctuation meets the requirements, and the interference suppression capability meets the standard.

10. The design method for an inductive coupling clamp in a gas-insulated substation with process adaptation according to claim 9, characterized in that: The testing requirements for the gas-insulated substation include the coupling acquisition of transient common-mode current in the secondary circuit and surface current in the casing. The on-site installation conditions include the specifications of the secondary cables and the outdoor electromagnetic, temperature, and humidity environmental conditions.

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