A mobile HGIS maximum breakdown field strength identification method

Abstract

The application discloses a kind of mobile HGIS maximum breakdown field strength identification method, comprising: establishing three-dimensional topological initial model;Developing mechanical environment simulation, input transport stage three-way acceleration time history data, calculate the mechanical stress and cumulative residual displacement of internal insulation gap to reconstruct three-dimensional model containing structural deformation;Developing flow-thermal coupling simulation, carry out gravity vector space coordinate transformation correction, introduce wide-area variable working condition environmental parameters and solve full gas chamber through real gas state equation, output three-dimensional non-uniform gas density field distribution dataset;Mapping dataset to reconstructed geometric model, introduce transient overvoltage waveform as time-varying excitation boundary condition, input transient electric field solver as time-varying excitation boundary condition, iteratively solve spatial transient maximum electric field strength, and identify output maximum breakdown field strength weak point and critical breakdown field strength under full dynamic history by point-by-point comparison with dynamic gas breakdown threshold value.The application greatly improves the engineering reliability of HGIS simulation identification result.

Description

Technical Field

[0001] This invention belongs to the field of CAE simulation analysis technology for high-voltage power equipment, specifically involving a method for identifying the maximum breakdown field strength of a mobile HGIS. Background Technology

[0002] Hybrid Gas Insulated Switchgear (HGIS), combining the compact structure of traditional GIS (Gas Insulated Switchgear) with the flexibility and economy of AIS (Air Insulated Switchgear), has become a core control and protection equipment in modern high-voltage and ultra-high-voltage transmission networks. In recent years, with the increasing urgency of emergency power supply in large cities, disaster relief, and rapid transition between regional power grids, 550kV vehicle-mounted mobile HGIS has seen rapid development as a high-voltage, high-capacity mobile emergency switchgear. Mobile HGIS highly integrates the circuit breakers, disconnectors, current transformers, and surge arresters of the entire bay onto a heavy-duty truck chassis, requiring wide-area environmental adaptability and rapid deployment capability with "quick-start" functionality.

[0003] However, the traditional methods for verifying the maximum breakdown field strength and identifying the insulation state of fixed HGIS (refer to Li Bin, SF6 High Voltage Electrical Apparatus Design (4th Edition), Beijing: Machinery Industry Press) are all based on rigid assumptions such as the equipment operating on a standard rigid cement foundation, under controlled indoor temperature and humidity, and in a long-term static state. When HGIS becomes "vehicle-mounted and mobile," the boundary conditions of its internal insulation undergo a fundamental change: First, heavy vehicles inevitably face triaxial random vibration and bumpy impacts during long-distance transportation, leading to micron-level cumulative mechanical fatigue deformation or axis displacement in the internal rigid cantilever conductors, contact systems, and insulating rods, causing anomalies in the designed coaxial clearance. Second, mobile equipment operates over a wide area, potentially traversing extreme altitudes and severe environmental temperature differences in a short time. Furthermore, when the vehicle-mounted hydraulic outriggers are leveled on uneven ground in the field, residual leveling angles inevitably remain. The introduction of these angles disrupts the axial symmetry of the natural convection of airflow within the chamber, and combined with sudden changes in environmental air pressure, results in localized areas of low density due to microscopic gradients. Furthermore, after vehicle-mounted deployment, grid connection and switching are frequent, and the mixed topology of cables and short busbars will lead to extremely complex waveforms of ultra-fast transient overvoltages (VFTOs). MHz-level high-frequency shock waves can easily cause a large accumulation of charge on the surface of basin insulators, inducing severe distortion of local field strength.

[0004] Existing CAE (Computer-Aided Engineering) simulation or field strength identification methods, as described in the reference [Ni Guangzheng. Numerical Calculation of Engineering Electromagnetic Fields. Beijing: Machinery Industry Press], mostly employ traditional steady-state solutions for electrostatic fields and the assumption of globally uniform gas density, with uniform mesh sizes. In high field strength gradient regions, overly coarse meshes can lead to charge accumulation and interpolation distortion, while overly dense meshes in low coupling regions result in computational redundancy. Furthermore, existing multiphysics interactions generally suffer from time-scale mismatches and "interface breaks" in the spatial coordinates of multiple datasets. This makes it impossible to effectively couple the deformation topology caused by transportation fatigue with the non-uniform dielectric density field and transient time-varying voltage waveforms caused by the environment across dimensions, resulting in an inability to accurately identify the maximum transient breakdown hazard point of a 550kV vehicle-mounted mobile HGIS under complex service conditions, leading to low engineering reliability of the simulation results. Summary of the Invention

[0005] In view of the above, the present invention provides a method for identifying the maximum breakdown field strength of mobile HGIS, which can solve the problem that the existing technology cannot effectively couple the non-uniform gas medium distribution caused by transport deformation, spatial tilt angle and high frequency transient voltage, resulting in the distortion of the identification of the maximum breakdown field strength of mobile high voltage HGIS and the unreliability of simulation results.

[0006] A method for identifying the maximum breakdown field strength of mobile HGIS includes the following steps: (1) Establish a three-dimensional topology initial model based on the CAD drawings of the 550kV vehicle-mounted mobile HGIS equipment, and initialize the multi-source state dataset; (2) Conduct mechanical environment simulation, input the three-dimensional acceleration time history data of HGIS equipment during the transportation stage, calculate the mechanical stress and cumulative residual displacement of the internal key insulation gap, and reconstruct a three-dimensional reconstructed geometric model containing structural deformation based on the cumulative residual displacement. (3) Conduct fluid-thermal coupling simulation, obtain the tilt angle data of the vehicle platform and correct the gravity vector by spatial coordinate transformation, introduce wide-area variable working condition environmental parameters and solve the whole gas chamber space through the real gas state equation, and output a three-dimensional non-uniform gas density field distribution dataset. (4) The three-dimensional non-uniform gas density field distribution dataset is mapped to the spatial properties of the three-dimensional reconstructed geometric model to update the medium property parameters. The transient overvoltage waveform is introduced as the time-varying excitation boundary condition input to the transient electric field solver. The maximum transient electric field strength in space, including displacement current and surface charge accumulation effect of insulating component, is solved iteratively in the time domain. By comparing it with the dynamic gas breakdown threshold point by point, the weak point of the maximum breakdown field strength and the corresponding critical breakdown field strength under the whole dynamic process are identified.

[0007] Furthermore, in step (2), a three-dimensional reconstructed geometric model containing structural deformation is obtained based on the cumulative residual displacement. The specific implementation method is as follows: S21: Convert the triaxial acceleration time history data collected from the HGIS equipment during the vehicle transportation phase into random vibration acceleration power spectral density, and use it as a transient dynamic excitation source input to load onto the rigid main frame base of the equipment; S22: The spatial mechanical fatigue cumulative stress distribution of the overall equipment architecture, contact system and insulating tie rod is calculated by the finite element mechanics solver, and the residual axial eccentricity, residual tilt angle and contact opening distance shrinkage after mechanical deformation are extracted as structural displacement variation. S23: Using a geometric deformation derivation mechanism, based on the structural displacement variation, the spatial topology of the finite element mesh node coordinates in the initial model after transient dynamic deformation is updated, and the damaged three-dimensional geometric surfaces and solids are generated in reverse to form the three-dimensional reconstructed geometric model.

[0008] Furthermore, the specific implementation of step (3) is as follows: S31: Read the longitudinal tilt angle of the vehicle platform fed back by the leveling tilt sensor. i With lateral tilt angle The standard gravity vector [0, 0, -] g Transformation and correction to spatial tilt gravity vector[ g sin i cos , g sin i sin , - g cos i ], g It is the acceleration due to gravity; S32: Obtain the on-site altitude and instantaneous temperature difference of the external environment corresponding to the GPS location, and embed the non-ideal gas Beattie-Bridgeman equation of state into the flow and heat field solver through a user-defined function as follows: In the formula, P This refers to the transient pressure inside the air chamber. V For the molar volume of the gas, T The absolute temperature of the thermal field. R It is a universal gas constant. A 0、 a , B 0、 b , c All are characteristic constants of insulating gases; S33: The rated current-generating heat of the injected conductive rod is used as a volumetric heat source. Under the action of the tilted gravity vector in the space, the asymmetric natural convection state is calculated, and the three-dimensional non-uniform gas density field distribution dataset of the whole gas chamber grid element is exported. The data format is specified as "element number-three-dimensional spatial coordinates-dynamic density value".

[0009] Furthermore, the specific implementation of step (4) is as follows: S41: In the three-dimensional reconstruction geometric model, the relative permittivity of each mesh element in space is... e r ( x , y , z ) and dynamic density value r ( x , y , z Perform the following positive correlation function binding: In the formula: e r0 Standard gas density r The initial relative permittivity at 0; S42: Input a high-frequency ultra-fast transient overvoltage waveform in the MHz range as the boundary excitation of the high-voltage conductor, start the transient electric field time-domain solver, explicitly calculate the time-varying displacement current density across the entire field, and accumulate the surface charge density on the mesh nodes at the interface of the insulating component through time-domain integration. s s ( t ); S43: Iteratively solve for each mesh element using nanosecond-level time steps. s s ( t Maximum transient electric field intensity in space under the influence of distortion E max ( x , y , z , t Simultaneously, based on the dynamic density value corresponding to the grid cell... Solving for the time-varying breakdown field strength threshold : In the formula: E crit0 The reference breakdown field strength under standard atmospheric pressure. α This is the density non-uniformity correction index; when it satisfies E max ( x , y , z , t)≥ E crit ( x , y , z , t When determining the position of the corresponding grid cell, x , y , z ) and corresponding time t Localized dielectric breakdown occurs.

[0010] Furthermore, step (4) involves identifying the weak point with the maximum breakdown field strength under the full dynamic process and outputting the identification result, including: The transient evolution data file of the electric field uses a tabular matrix to record the unit number, three-dimensional spatial location description, field strength value at the peak of the VFTO impulse voltage, insulation margin coefficient, and optimization design suggestions for the grading ring dimensions; The heat-fluid multi-field coupled cloud map file uses hierarchical coloring to mark heat dissipation dead zones and local gas rarefaction high-temperature hot spots. The temperature range of 25℃ to 50℃ is blue, 50℃ to 80℃ is yellow, and 80℃ to 100℃ is orange. The interpolation accuracy self-verification report includes the energy conservation error variation curves of dynamic grid interfaces at each level, the flux continuity residual error of physical field interfaces, and a comparison table of original data from online sensor measurements.

[0011] Preferably, in the simulation stages of steps (2) and (3), a differentiated mesh generation strategy is used for mesh adjustment for different multi-physics coupling regions, specifically: The internal high-voltage contact gap and the surface of the basin insulator are divided into an extremely strong coupling zone. The element type is a quadratic tetrahedral element, with element size controlled between 0.8 and 1.2 mm. Curvature refinement control is enabled at chamfered edges with a radius of curvature less than or equal to 5 mm. Three boundary layers are generated at the fluid-structure interface, with the first layer height corresponding to... y The + value should be controlled between 5 and 10; The surface of the insulating tie rod and shield is divided into a strong coupling zone. A hybrid mesh is used, with hexahedral elements used in the regular conductor area and tetrahedral elements used in the complex irregular area. The element size is controlled between 1.2 and 1.8 mm. At the interface between the metal and the insulating medium, a common node mesh topology connection is enabled to control the mesh distortion rate to be less than or equal to 0.4. The SF6 main heat dissipation channel in the air chamber is divided into a medium coupling zone. A swept mesh technique is used to divide a hexahedral dominant mesh, with the unit size controlled between 2.0 and 5.0 mm. Five expansion layers are set along the flow direction, and the mesh size transition rate is less than or equal to 1.5. The outer metal shell of the equipment and the external support frame are divided into weakly coupled areas. An automatic division mechanism is used to generate coarse hexahedral elements with the element size controlled between 5.0 and 15.0 mm. Non-core fastening bolts are hidden by the suppression function and replaced by beam elements with equivalent stiffness.

[0012] Preferably, the multi-source state dataset is subjected to real-time feedback and closed-loop correction via on-site sensor components, specifically: Fiber optic temperature sensors and high-frequency partial discharge ultra-high frequency sensors are respectively installed on the outside of the arc-extinguishing chamber, the outer wall of the gas chamber, and the high-voltage bushing base of the HGIS equipment to obtain the measured benchmark dataset under service conditions in real time. Define a multi-scale time-coupled iterative mechanism and set the electric field update interval coefficient. N , where 30≤ N ≤100, each time execution complete N After each transient calculation step of the thermal field, the steady-state electromagnetic loss is solved again and converted into a volume heat source and input into the thermal field solver. The simulation output of temperature and field strength results is calculated to compare the field difference between the actual measured benchmark dataset and the field difference. If the relative error of any grid cell position is greater than 10%, the interpolation weight correction process is triggered: the proportion of electric field error, thermal field error and flow field error to the total accumulated error is calculated as the weight adjustment coefficient. The difference between each weight adjustment coefficient and the average weight adjustment coefficient is calculated. After the initial weight of the physical field is corrected in a directed manner, the binary quadratic surface fitting interpolation calculation is performed again. The iteration is stopped after the global simulation error is approximated to less than or equal to 1%. Finally, multiple standard simulation result files are obtained, including the electric field transient matrix, the graded thermal resistance heat dissipation dead angle cloud map and the accuracy self-verification report.

[0013] A computer device includes a memory and a processor, wherein the memory stores a computer program and the processor executes the computer program to implement the above-described mobile HGIS maximum breakdown field strength identification method.

[0014] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described mobile HGIS maximum breakdown field strength identification method.

[0015] Based on the above technical solution, the present invention has the following beneficial technical effects: 1. This invention first conducts mechanical environment dynamics simulation of vehicle-mounted mobile HGIS, extracts fatigue stress and displacement caused by triaxial acceleration during long-distance transportation, and reversely reconstructs a three-dimensional topological geometric model after damage and deformation. This overturns the assumption of traditional simulation based on ideal, lossless symmetrical topology, and realizes the accurate quantification of the influence of cumulative damage of transportation machinery on the microscopic distortion of internal high and low voltage insulation gaps.

[0016] 2. The method of this invention introduces the spatial coordinate transformation of the vehicle leveling tilt angle to accurately correct the standard gravity vector, and combines the Beattie-Bridgeman equation of state for non-ideal gas to solve the flow and heat field. It accurately fits the local convection asymmetric distribution and micro-density rarefaction field of SF6 gas inside the gas chamber under uneven deployment in the field and wide-area temperature difference, altitude and air pressure change, thus eliminating the safety hazard of excessive field strength margin caused by the "globally uniform medium" of traditional simulation.

[0017] 3. The method of this invention dynamically binds the density-property mapping function in the reconstructed spatial grid, uses the MHz-level high-frequency transient VFTO overvoltage waveform as the time-varying excitation, comprehensively considers the dynamic accumulation distortion effect of insulation surface charge caused by large displacement current under microsecond-level impulse voltage, and performs point-by-point scanning with nanosecond-level step size in conjunction with the time-varying breakdown field strength threshold formula, effectively solving the iterative divergence problem caused by the fracture of multi-physics spatial interface and the large time scale difference.

[0018] 4. The method of this invention, by setting multi-scale time coupling coefficients and adaptively correcting the interpolation weight matrix based on the closed-loop feedback mechanism of measured fiber optic temperature measurement and partial discharge sensor, ensures that the simulation error is controlled within the engineering extreme range. This significantly improves the accuracy and reliability of identifying the maximum breakdown weak point of the 550kV vehicle-mounted mobile HGIS throughout its service life and under extremely harsh grid connection conditions. It has significant engineering practical significance for ensuring the safety of long-distance power emergency repair in my country and improving the operation and maintenance level of UHV compact switchgear. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the maximum breakdown field strength identification method for mobile HGIS of the present invention. Detailed Implementation

[0020] To describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown in the figure, this embodiment provides a method for identifying the maximum breakdown field strength of a mobile HGIS. The specific implementation process is as follows: (1) Establish a three-dimensional topology initial model based on the CAD drawings of the 550kV vehicle-mounted mobile HGIS equipment, and initialize the basic multi-source state dataset.

[0022] In practice, the CAD 2D drawings of the 550kV single-bay vehicle-mounted mobile HGIS equipment are imported into the 3D CAE preprocessing software. To achieve high-precision multiphysics simulation, the model is divided into three independent physical layers: conductor layer, insulation layer, and shell support structure layer. Redundant auxiliary lines and frames, such as chamfer annotations and mechanism linkage fasteners, which are irrelevant to the solution of electricity, heat, and flow, are strictly removed.

[0023] 1.1 Modeling of the High-Voltage Conductor Layer: The conductor layer mainly includes the double-break arc-extinguishing chamber of the high-voltage circuit breaker, the coaxial main busbar, the bushing center guide rod, and the disconnector contact system. A cylindrical symmetrical structure is established using a sketch-space rotation method, with the main axis of rotation strictly coinciding with the axis of the arc-extinguishing chamber. The two-dimensional limit geometric accuracy of the sketch is controlled within ±0.05mm. The junction assembly of the arc-extinguishing chamber copper-tungsten contacts and the operating mechanism connecting rod is merged using Boolean union commands, with its axial overlap length set to 150mm. The main busbar tube is constructed using multi-segment spatial line stretching. The radius of curvature at bends of long straight busbar segments is set to 15mm to prevent electric field concentration at the edge tips under high voltage. The bend angle of the busbar corners is set to 60°, and a standard high-voltage SF6 gas insulation circulation and heat dissipation main channel with a width of 30mm is reserved between the outer edge of the conductor rod and the inner wall of the stainless steel shell.

[0024] 1.2 Modeling of the Insulation Layer: The insulation layer mainly consists of epoxy resin basin insulators, high-voltage bushing insulating cylinders, and insulating operating rods. The basin insulators are constructed using a "two-dimensional cross-section scanning rotation + local shelling" method, with the asymmetric web thickness of the shelled insulator strictly controlled to 20mm. When assembling the resin sub-body and the metal self-balancing expansion joint, the merge command is prohibited; the binding contact constraint must be invoked. In this case, the system will only retain the conformal geometric contact interface between the two, thus ensuring accurate identification of the three-phase boundary of "metal-solid insulation-gas" in the subsequent electromagnetic transient charge accumulation simulation. The operating insulating rod is embedded with a corrugated tube. A pitch-matched helical trajectory is generated and stretched along the trajectory. The tube wall thickness is set to 3mm to ensure that the simulation requirements for large displacement fatigue compensation of ±20mm in the lateral and axial directions under severe vehicle transportation bumps are met.

[0025] 1.3 Modeling of the outer shell support structure layer: including the steel base, vehicle-mounted hydraulic leveling support legs, aluminum alloy outer shell, and external equalizing ring. The axial spacing of the double-bellows external flanges is set to 150mm. The main support channel steel component is generated by stretching a regular cross-section body, and the equivalent cylindrical web diameter of the channel steel is 50mm. The mechanical contact area between the support structure and the bottom of the shell is cut using a Boolean intersection process to ensure zero gap and zero interference deformation deviation in the contact stress.

[0026] After completing the geometric modeling, measurement tools and interference checking algorithms are used to verify the model, ensuring that the effective contact overlap area is not less than 500 mm².2 Furthermore, the absolute value of unintentional interference in the static state of the fully assembled assembly is 0.

[0027] (2) Conduct mechanical environment simulation, input the three-dimensional acceleration time history data of the mobile HGIS equipment during the transportation stage, calculate the mechanical stress and cumulative residual displacement of the internal key insulation gap, and reconstruct a three-dimensional reconstructed geometric model containing structural deformation based on the cumulative residual displacement.

[0028] 550kV vehicle-mounted mobile HGIS needs to withstand severe transportation over long distances or in roadless conditions. High-frequency random vibrations during transport can cause mechanical fatigue and minor residual deformation in the long cantilevered high-voltage busbars and shielding within the equipment, leading to a reduction in the fracture gap and significantly decreasing the electric field breakdown safety margin. Therefore, dynamic calculations using a mechanical solver are necessary.

[0029] In this embodiment, the three-dimensional (axial) measurements obtained from previous on-vehicle highway measurements will be used. X Horizontal Y ,vertical Z The original acceleration time history waveform was converted into an acceleration power spectral density curve, which was then used as a random vibration excitation source and applied to the rigid main frame base of the vehicle. The input values ​​for the 550kV aluminum alloy shell were 250MPa, the elastic modulus of the epoxy resin insulator was 12GPa, and the Poisson's ratio was 0.32. The spatial mechanical fatigue stress distribution curves at the arc-extinguishing chamber contact point and the cantilever equalizing cover were calculated after 50 hours of continuous transport stress oscillation. The structural deformation after the end of transport was extracted from these curves: the busbar guide rod experienced a residual axial eccentricity Δ. d =0.35mm, the insulating tie rod produced Δ i With a slight residual tilt angle of 0.12°, the contact gap shrank by 0.48 mm due to stress accumulation.

[0030] At this point, traditional non-destructive CAD models can no longer reflect the real spatial electric field environment. This invention employs a finite element geometric topology reverse update engine, which reads the residual displacement vectors of all mesh nodes after the vibration calculation is completed. These micrometer-level deformations are then superimposed onto the node coordinates of the initial mesh. Using a spatial surface smoothing fitting technique, the boundary of the deformed and eccentric 3D entity is refitted inversely, ultimately outputting a 3D reconstructed geometric model containing the characteristics of damaged mechanical deformation, which serves as the mesh topology benchmark for subsequent electric field calculations.

[0031] (3) Conduct fluid-thermal coupling simulation, obtain the tilt angle data of the vehicle platform and correct the gravity vector by spatial coordinate transformation, introduce wide-area variable working condition environmental parameters and solve the whole gas chamber space through the real gas state equation, and output a three-dimensional non-uniform gas density field distribution dataset.

[0032] When 550kV vehicle-mounted HGIS is deployed in the field as emergency equipment, it is constrained by complex terrain. Although hydraulic outriggers are used for mechanical leveling, there is often a slight residual leveling tilt. Furthermore, the external temperature and air pressure fluctuate drastically with altitude. The high-voltage, high-current conductive rod generates significant heat, and even a slight tilt can disrupt the axisymmetric state of natural convection of SF6 gas inside the chamber. This causes hot gas to accumulate in the upper part of the casing, while the lower part cools and contracts, resulting in a highly non-uniform density gradient of the internal insulating gas in the microscopic space. Areas with weak electric fields are prone to breakdown. Therefore, the specific implementation process of this step is as follows: 3.1 Spatial Coordinate Transformation and Gravity Correction: Residual data from the dual-axis tilt sensors mounted on the vehicle platform is read to determine the current longitudinal tilt angle. i =1.8°, lateral tilt angle is f =0.5°. In the finite volume solver for the thermal flow field, the traditional standard gravity acceleration setting is broken, and the default gravity vector [0, 0, -] is changed. g Perform a spatial rotation matrix transformation to correct it into a spatially tilted gravity vector: 3.2 Adaptive Correction Based on Real Gas Equation of State: By embedding user-defined functions (UDFs), the ideal gas equation of state is replaced with the Beattie-Bridgeman equation of state for high-pressure non-ideal gases to accurately characterize the critical compressibility characteristics of SF6 under varying high and low pressures. The environmental boundary data transmitted from the device's built-in GPS is as follows: Altitude of the deployment site is 500m (basic atmospheric pressure). P The pressure dropped to 0.096 MPa, and the absolute temperature of the external environment... T The temperature is 25℃. According to the formula, the compressibility factor and expansion term characteristic constant of SF6 gas are input into the system: A 0 = 15.78 a =0.103、 B 0 = 0.124 b =0.082、 c =1.35×10 6 .

[0033] 3.3 Multiphysics Field Fluid-Thermal Coupling Solution: Ohmic loss was calculated. A working current of 3150A was applied to the high-voltage main conductor rod. The volumetric heat source of the conductor was calculated, and the convective heat transfer coefficient of the outer wall of the shell was set at 15 W / (m²). 2 ·K). Employing nonlinearity. kSteady-state calculations were performed using the -ω SST (Shear Stress Transport) turbulence model. After the calculations, due to the shift in the gravity vector, the thermal convection plume tilted towards the tilted side, deriving the spatial density field of all finite volume elements within the fluid domain. The data was output strictly according to the standard array format, generating a three-dimensional non-uniform gas density field distribution dataset. Its core underlying data structure is defined as [element ID, X coordinate, Y coordinate, Z Coordinates, dynamic density value r ].

[0034] (4) The three-dimensional non-uniform gas density field distribution dataset is mapped to the spatial properties of the three-dimensional reconstructed geometric model to update the medium property parameters. The transient overvoltage waveform is introduced as the time-varying excitation boundary condition input transient electric field solver. The maximum transient electric field strength in space, including displacement current and surface charge accumulation effect of insulating component, is solved iteratively in the time domain. By comparing it with the dynamic gas breakdown threshold point by point, the weak point of the maximum breakdown field strength and the corresponding critical breakdown field strength under the full dynamic process are identified and output.

[0035] Mobile HGIS, used for emergency grid connection, involves extremely frequent switching of disconnecting switches, resulting in high-frequency VFTO (Voltage-Fault Overvoltage) in the MHz range. In the deformed geometry and non-uniform density field generated in the above steps, high-frequency impulse overvoltages not only generate conduction currents but also induce severe charge accumulation on the surface of epoxy resin basin insulators through displacement currents, leading to extreme distortion of the local electric field. Therefore, the specific implementation of the electric field-dielectric dynamic coupling identification algorithm in this step is as follows: 4.1 Spatial topology alignment of data attributes and reconstruction of material properties: In the CAE integration platform, the volume data transfer interface is called to transfer the dynamic density value based on the non-uniform fluid element output in step (3). r ( x , y , z This is mapped to the spatial coordinates of the three-dimensional reconstructed geometric model with transport deformation characteristics generated in step (2). Since the electrophysical properties of the gas are directly controlled by its microscopic density, the dynamic relative permittivity of each spatial grid cell of the gas is expressed through a physical function. e r ( x , y , z Dynamically bind the density to the spatial location: Where: the initial dielectric constant under standard temperature and pressure. e r0 =1.00204, baseline density r 0 = 6.14 kg / m 3Using this formula, the spatial non-uniform adaptive evolution of medium properties is realized in the reconstructed electric field solution grid.

[0036] 4.2 Solving for Time-Varying Impact Excitation and Transient Electric Field: In the time-domain solver, the MHz-level VFTO full-time-domain overvoltage waveform previously calculated using EMTP (Electromagnetic Transient Procedure) circuit simulation software is used. U ( t The waveform is used as the input for a time-varying discrete curve, applied to the boundaries of the eccentric high-voltage contact and conductive rod. The highest peak voltage reaches 725kV, with a main frequency of 1.2MHz. The time step for solving the time-domain electric field is set to a fixed 5ns to ensure that the high-frequency wavefront is captured.

[0037] In the transient solution loop, the solver not only calculates the classical conduction electric field, but also explicitly calculates the displacement current density. Maxwell's equations. In epoxy resin (conductivity) s solid =1×10 -15 At the mesh nodes of the interface between S / m and SF6 gas, the surface charge density caused by the difference between leakage current and displacement current is accumulated by performing step integration along the time domain. : In the formula: D is the electric displacement vector. This represents the total current density vector on the gas medium side. This represents the total current density vector on the solid insulating dielectric side. n The unit normal vector of the interface.

[0038] Due to the presence of surface charge, the maximum transient electric field intensity at the three-phase point of the concave edge and conductor tip of the basin-type insulator is [high / low]. E max ( x , y , z , t The solution is obtained in real time.

[0039] 4.3 Dynamic Breakdown Threshold Point-by-Point Scanning and Identification: For any gas-fluid element within the entire field, its insulation withstand capability decreases significantly as the gas becomes rarefied due to heating. Therefore, this invention incorporates a dynamic breakdown field strength criterion equation based on local time-varying density during the solution process: Where: 550kV reference pure gas steady-state breakdown field strength E crit0 =8.9kV / mm, density correction empirical index α =1.15.

[0040] The recognition algorithm traverses all grid cells in the entire domain at each time step, and when the condition is met... E max ( x , y , z , t )≥ E crit ( x , y , z , t When the point is determined to be at a certain coordinate, a partial breakdown of the dielectric insulation occurs; ultimately, the cause is identified as transport eccentricity Δ. d Platform tilt angle i The system identifies the critical breakdown field strength weakness point and the absolute moment of occurrence under the combined effects of thermal convection rarefaction and VFTO charge accumulation, achieving adaptive identification of the maximum breakdown field strength. The identification results include: The transient evolution data file of the electric field uses a tabular matrix to record the unit number, three-dimensional spatial location description, field strength value at the peak of the VFTO impulse voltage, insulation margin coefficient, and optimization design suggestions for the grading ring.

[0041] The thermal-fluid multi-field coupled cloud map file uses hierarchical coloring to mark heat dissipation dead zones and local gas rarefaction high-temperature hot spots. Temperatures between 25℃ and 50℃ are marked in blue, between 50℃ and 80℃ in yellow, and between 80℃ and 100℃ in orange.

[0042] The interpolation accuracy self-verification report includes the energy conservation error variation curves of dynamic grid interfaces at each level, the flux continuity residual error of physical field interfaces, and a comparison table of original data from online sensor measurements.

[0043] To improve computational accuracy and convergence efficiency, this embodiment employs a differentiated mesh generation strategy for different multi-physics coupling regions at various stages of simulation execution. Specifically: The internal high-voltage contact gap and the surface of the basin insulator are divided into an extremely strong coupling zone. The element type is a quadratic tetrahedral element, with element size controlled between 0.8 and 1.2 mm. Curvature refinement control is enabled at chamfered edges with a radius of curvature less than or equal to 5 mm. Three boundary layers are generated at the fluid-structure interface, with the first layer height corresponding to... y The + value should be controlled between 5 and 10; y + represents the dimensionless wall distance, a dimensionless scale used in computational fluid dynamics to characterize the distance from the center of the first layer of mesh cells near a solid wall to the surface of a conductor. It is used to determine whether a fluid mesh can correctly resolve the fluid flow boundary layer. When fluid flows near a solid wall such as a high-pressure contactor, it forms a distinct boundary layer due to viscous drag. Along the wall normal direction from the inside out, it is divided into: a viscous sublayer (...).y +<5), Buffer layer / transition layer (5< y +<30) and the logarithmic law layer ( y +>30).

[0044] The surface of the insulating tie rod and shield is divided into a strong coupling zone. A hybrid mesh is used, with hexahedral elements used in the regular conductor area and tetrahedral elements used in the complex irregular area. The element size is controlled between 1.2 and 1.8 mm. At the interface between the metal and the insulating medium, a common node mesh topology connection is enabled to control the mesh distortion rate to be less than or equal to 0.4. The SF6 main heat dissipation channel in the air chamber is divided into a medium coupling zone. A swept mesh technique is used to divide a hexahedral dominant mesh, with the unit size controlled between 2.0 and 5.0 mm. Five expansion layers are set along the flow direction, and the mesh size transition rate is less than or equal to 1.5. The outer metal shell of the equipment and the external support frame are divided into weakly coupled areas. An automatic division mechanism is used to generate coarse hexahedral elements with the element size controlled between 5.0 and 15.0 mm. Non-core fastening bolts are hidden by the suppression function and replaced by beam elements with equivalent stiffness.

[0045] Meanwhile, to eliminate the fundamental deviations caused by pure numerical calculations and improve the absolute engineering reliability of the simulation results, this embodiment adopts a dynamic interpolation iterative technique based on closed-loop correction of field sensor data: fiber optic temperature sensors and high-frequency partial discharge ultra-high-frequency sensors are pre-embedded at symmetrical positions of the contacts on the inner wall of the vehicle-mounted HGIS housing, and a multi-scale time coupling coefficient is defined. N =50, meaning that every 50 steps of fluid transient calculation, the volumetric heat source with electrical loss is recalculated, and the inter-field contribution weight is calculated using the Pearson correlation coefficient; when the relative error between the simulated value and the measured sensor data is greater than 10%, the weight correction process is triggered, and the initial interpolation weights are assigned correction coefficients by calculating the cumulative proportion of electric field error, thermal field error, and flow field error to the total residual. In the formula: The corrected interpolation weights for the physical field. The initial physics interpolation weights before adjustment. For physical fields s The weighting adjustment coefficient, in its physical essence, is the physical field. s The proportion of field error to the sum of the total residuals of electric field error, thermal field error and flow field error; The average weighting adjustment coefficient is the arithmetic mean of the weighting adjustment coefficients of electric field error, thermal field error, and flow field error.

[0046] After updating the weights, the quadratic bivariate surface fitting and interpolation calculation is performed again. The iteration stops only after the global simulation error is brought close to less than or equal to 1%. Finally, the integrated output includes multiple standard simulation result files, including the electric field transient matrix, the graded thermal resistance heat dissipation dead zone cloud map, and the accuracy self-verification report.

[0047] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A method for identifying the maximum breakdown field strength of a mobile HGIS, characterized in that, The steps include the following: (1) Establish a three-dimensional topology initial model based on the CAD drawings of the 550kV vehicle-mounted mobile HGIS equipment, and initialize the multi-source state dataset; (2) Conduct mechanical environment simulation, input the three-dimensional acceleration time history data of HGIS equipment during the transportation stage, calculate the mechanical stress and cumulative residual displacement of the internal key insulation gap, and reconstruct a three-dimensional reconstructed geometric model containing structural deformation based on the cumulative residual displacement. (3) Conduct fluid-thermal coupling simulation, obtain the tilt angle data of the vehicle platform and correct the gravity vector by spatial coordinate transformation, introduce wide-area variable working condition environmental parameters and solve the whole gas chamber space through the real gas state equation, and output a three-dimensional non-uniform gas density field distribution dataset. (4) The three-dimensional non-uniform gas density field distribution dataset is mapped to the spatial properties of the three-dimensional reconstructed geometric model to update the medium property parameters. The transient overvoltage waveform is introduced as the time-varying excitation boundary condition input to the transient electric field solver. The maximum transient electric field strength in space, including displacement current and surface charge accumulation effect of insulating component, is solved iteratively in the time domain. By comparing it with the dynamic gas breakdown threshold point by point, the weak point of the maximum breakdown field strength and the corresponding critical breakdown field strength under the whole dynamic process are identified.

2. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, In step (2), a three-dimensional reconstructed geometric model containing structural deformation is obtained based on the cumulative residual displacement. The specific implementation method is as follows: S21: Convert the triaxial acceleration time history data collected from the HGIS equipment during the vehicle transportation phase into random vibration acceleration power spectral density, and use it as a transient dynamic excitation source input to load onto the rigid main frame base of the equipment; S22: The spatial mechanical fatigue cumulative stress distribution of the overall equipment architecture, contact system and insulating tie rod is calculated by the finite element mechanics solver, and the residual axial eccentricity, residual tilt angle and contact opening distance shrinkage after mechanical deformation are extracted as structural displacement variation. S23: Using a geometric deformation derivation mechanism, based on the structural displacement variation, the spatial topology of the finite element mesh node coordinates in the initial model after transient dynamic deformation is updated, and the damaged three-dimensional geometric surfaces and solids are generated in reverse to form the three-dimensional reconstructed geometric model.

3. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, The specific implementation method of step (3) is as follows: S31: Read the longitudinal tilt angle of the vehicle platform fed back by the leveling tilt sensor. θ With lateral tilt angle The standard gravity vector [0, 0, -] g Transformation and correction to spatial tilt gravity vector[ g sin θ cos , g sin θ sin , - g cos θ ], g It is the acceleration due to gravity; S32: Obtain the on-site altitude and instantaneous temperature difference of the external environment corresponding to the GPS location, and embed the non-ideal gas Beattie-Bridgeman equation of state into the flow and heat field solver through a user-defined function as follows: In the formula, P This refers to the transient pressure inside the air chamber. V For the molar volume of the gas, T The absolute temperature of the thermal field. R It is a universal gas constant. A 0、 a , B 0、 b , c All are characteristic constants of insulating gases; S33: The rated current-generating heat of the injected conductive rod is used as a volumetric heat source. Under the action of the tilted gravity vector in the space, the asymmetric natural convection state is calculated, and the three-dimensional non-uniform gas density field distribution dataset of the whole gas chamber grid element is exported. The data format is specified as "element number-three-dimensional spatial coordinates-dynamic density value".

4. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, The specific implementation method of step (4) is as follows: S41: In the three-dimensional reconstruction geometric model, the relative permittivity of each mesh element in space is... ε r ( x , y , z ) and dynamic density value ρ ( x , y , z Perform the following positive correlation function binding: In the formula: ε r0 Standard gas density ρ The initial relative permittivity at 0; S42: Input a high-frequency ultra-fast transient overvoltage waveform in the MHz range as the boundary excitation of the high-voltage conductor, start the transient electric field time-domain solver, explicitly calculate the time-varying displacement current density across the entire field, and accumulate the surface charge density on the mesh nodes at the interface of the insulating component through time-domain integration. σ s ( t ); S43: Iteratively solve for each mesh element using nanosecond-level time steps. σ s ( t Maximum transient electric field intensity in space under the influence of distortion E max ( x , y , z , t Simultaneously, based on the dynamic density value corresponding to the grid cell... Solving for the time-varying breakdown field strength threshold : In the formula: E crit0 The reference breakdown field strength under standard atmospheric pressure. α This is the density non-uniformity correction index; when it satisfies E max ( x , y , z , t )≥ E crit ( x , y , z , t When determining the position of the corresponding grid cell, x , y , z ) and corresponding time t Localized dielectric breakdown occurs.

5. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, Step (4) involves identifying the weak points with the maximum breakdown field strength under the full dynamic process and outputting the identification results, including: The transient evolution data file of the electric field uses a tabular matrix to record the unit number, three-dimensional spatial location description, field strength value at the peak of the VFTO impulse voltage, insulation margin coefficient, and optimization design suggestions for the grading ring dimensions; The heat-fluid multi-field coupled cloud map file uses hierarchical coloring to mark heat dissipation dead zones and local gas rarefaction high-temperature hot spots. The temperature range of 25℃ to 50℃ is blue, 50℃ to 80℃ is yellow, and 80℃ to 100℃ is orange. The interpolation accuracy self-verification report includes the energy conservation error variation curves of dynamic grid interfaces at each level, the flux continuity residual error of physical field interfaces, and a comparison table of original data from online sensor measurements.

6. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, In the simulation phases of steps (2) and (3), a differentiated mesh generation strategy is used to adjust the mesh for different multi-physics coupling regions. Specifically: The internal high-voltage contact gap and the surface of the basin insulator are divided into an extremely strong coupling zone. The element type is a quadratic tetrahedral element, with element size controlled between 0.8 and 1.2 mm. Curvature refinement control is enabled on chamfered edges with a radius of curvature less than or equal to 5 mm. Three boundary layers are generated at the fluid-structure interface, with the first layer height corresponding to... y The + value should be controlled between 5 and 10; The surface of the insulating tie rod and shield is divided into a strong coupling zone. A hybrid mesh is used, with hexahedral elements used in the regular conductor area and tetrahedral elements used in the complex irregular area. The element size is controlled between 1.2 and 1.8 mm. At the interface between the metal and the insulating medium, a common node mesh topology connection is enabled to control the mesh distortion rate to be less than or equal to 0.

4. The SF6 main heat dissipation channel in the air chamber is divided into a medium coupling zone. A swept mesh technique is used to divide a hexahedral dominant mesh, with the unit size controlled between 2.0 and 5.0 mm. Five expansion layers are set along the flow direction, and the mesh size transition rate is less than or equal to 1.

5. The outer metal shell of the equipment and the external support frame are divided into weakly coupled areas. An automatic division mechanism is used to generate coarse hexahedral elements with the element size controlled between 5.0 and 15.0 mm. Non-core fastening bolts are hidden by the suppression function and replaced by beam elements with equivalent stiffness.

7. The method for identifying the maximum breakdown field strength of mobile HGIS according to claim 1, characterized in that, The multi-source state dataset is fed back and closed-loop corrected in real time through on-site sensor components, specifically: Fiber optic temperature sensors and high-frequency partial discharge ultra-high frequency sensors are respectively installed on the outside of the arc-extinguishing chamber, the outer wall of the gas chamber, and the high-voltage bushing base of the HGIS equipment to obtain the measured benchmark dataset under service conditions in real time. Define a multi-scale time-coupled iterative mechanism and set the electric field update interval coefficient. N , where 30≤ N ≤100, each time execution complete N After each transient calculation step of the thermal field, the steady-state electromagnetic loss is solved again and converted into a volume heat source and input into the thermal field solver. The simulation output of temperature and field strength results is calculated to compare the field difference between the actual measured benchmark dataset and the field difference. If the relative error of any grid cell position is greater than 10%, the interpolation weight correction process is triggered: the proportion of electric field error, thermal field error and flow field error to the total accumulated error is calculated as the weight adjustment coefficient. The difference between each weight adjustment coefficient and the average weight adjustment coefficient is calculated. After the initial weight of the physical field is directionally corrected, the binary quadratic surface fitting interpolation calculation is performed again. The iteration is stopped after the global simulation error is approximated to less than or equal to 1%. Finally, multiple standard simulation result files are obtained, including the electric field transient matrix, the graded thermal resistance heat dissipation dead angle cloud map and the accuracy self-verification report.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: The processor is used to execute the computer program to implement the mobile HGIS maximum breakdown field strength identification method as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the mobile HGIS maximum breakdown field strength identification method as described in any one of claims 1 to 7.

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