Experimental verification method and device for calculation accuracy of direct-current gas-solid insulation interface electric field

Abstract

The invention discloses a direct-current gas-solid insulation interface electric field calculation accuracy experimental verification method, which comprises the following steps of: firstly, designing a surface potential online measurement system, and accurately measuring potential distribution of an insulation material gas-solid interface under an electrified condition; then, on the basis of actually measured potential data, a Lagrange interpolation method is reconstructed under a polar coordinate system, a shape function describing insulator surface potential space distribution characteristics is constructed, and the electric field intensity of the gas-solid interface of the insulating material is solved; the surface potential online measurement system designed by the invention provides actually measured data support for simulating a simulation potential result of an actual operation condition, and the proposed shape function method based on Lagrange interpolation can realize continuous expression of discrete potential data and reflect spatial distribution characteristics of electric field intensity; consistency of experimental calculation results and simulation results in spatial distribution forms and numerical values is compared, and accuracy of the simulation model is effectively verified.

Description

Technical Field

[0001] This invention belongs to the field of high voltage direct current transmission technology, specifically relating to an experimental verification method and apparatus for calculating the accuracy of electric field at a DC gas-solid insulation interface. Background Technology

[0002] The gas-solid interface is one of the weakest links in high-voltage insulation. Surface flashover occurs when the electric field strength at the interface exceeds the gas breakdown strength or the surface flashover strength of the solid insulator. Under the long-term influence of a unipolar DC electric field, charge accumulates at the gas-solid interface of the insulator. Excessive charge accumulation distorts the electric field, leading to surface flashover. Therefore, calculating and controlling the surface potential and electric field distribution is crucial for ensuring the safe and stable operation of equipment.

[0003] Current methods for measuring the gas-solid interface potential of insulators (electrostatic probe method, dust map method, Pockels effect method) all require the equipment to be powered off. This offline characteristic makes it difficult to characterize the surface potential distribution under actual operating conditions. Due to the limitations of offline measurement experimental methods, the simulated potential results that simulate actual operating conditions lack effective measured data support. Summary of the Invention

[0004] To address the issue of discrepancies between offline measurements and actual operating conditions, this invention proposes an experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation, providing a reliable experimental basis for the accuracy of simulation results.

[0005] According to one aspect of the present invention, an experimental verification method for the accuracy of calculating the electric field at a DC gas-solid interface is provided, comprising:

[0006] Step 1: Construct an online surface potential measurement system. The system includes: a measurement unit for measuring the potential of the gas-solid insulation interface; a transmission unit for driving the gas-solid insulation interface to rotate circumferentially to complete the potential measurement of each measurement node; a power supply for providing high voltage to the high voltage conductor of the gas-solid insulation interface; and a signal acquisition unit for synchronously acquiring potential signals and transmission signals.

[0007] Step 2: Set up several measurement nodes at the gas-solid insulation interface. During measurement, the potential signal and corresponding transmission signal of each measurement node are collected synchronously. The effective potential is selected according to the potential signal and the corresponding transmission signal, and the potential matrix of the gas-solid insulation interface is output.

[0008] Step 3: Based on the output gas-solid insulation interface potential matrix, reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the gas-solid interface potential, perform gradient calculation on the shape function, and solve for the electric field strength at the gas-solid insulation interface to verify the accuracy of the simulation model.

[0009] As a further technical solution, the construction of an online surface potential measurement system also includes:

[0010] A partial discharge monitoring unit is configured, which is encapsulated in a sealed, opaque cavity and installed close to the high-voltage conductor at the gas-solid insulation interface to monitor partial discharge signals generated at easily discharged locations.

[0011] As a further technical solution, the installation position of the partial discharge monitoring unit must meet the following requirements: the monitoring surface is directly facing the gas-solid insulation interface, and the distance between the two is not greater than a first set distance; and the distance between the outer shell of the partial discharge monitoring unit and the high-voltage conductor is not less than a second set distance.

[0012] As a further technical solution, the transmission signal represents the motion state of the electrostatic probe. The motion state of the electrostatic probe is output by the transmission unit and encoded into a rectangular pulse sequence. Based on the rectangular pulse sequence, the potential signal measured when the electrostatic probe is stationary is selected as the effective potential.

[0013] As a further technical solution, the potential signals of each measurement node are collected, including:

[0014] The gas-solid insulation interface is divided into m rings, and each ring is divided into n parts. After the electrostatic probe moves to the target measurement point, it stops. The transmission unit drives the gas-solid insulation interface to rotate one revolution, completing the potential measurement of the node to be measured on this circle. This process is repeated until all preset measurement points are traversed, completing the potential measurement of the entire surface.

[0015] As a further technical solution, the potential information output by the measurement node is a potential matrix:

[0016] Introducing shape functions used in finite element analysis Expression potential matrix: .

[0017] As a further technical solution, based on the output gas-solid interface potential matrix, the Lagrange interpolation method is reconstructed in polar coordinates to construct shape functions describing the spatial distribution characteristics of the gas-solid interface potential, including:

[0018] Lagrange interpolation is performed between every two measurement nodes, starting with the j-th measurement node in the i-th cycle. and the (j+1)th measurement node The Lagrange interpolation expression between them is: , in , Measurement node , The measured value of the electric potential; , Measurement node , Angle;

[0019] The reconstructed shape function expression in polar coordinates is: , in Polar radius, Polar angle, It is the unit vector in the x-direction. It is the unit vector in the y-direction.

[0020] As a further technical solution, the electric field intensity matrix at the gas-solid insulation interface... for: , The point to be determined is the polar angle. Polar diameter .

[0021] As a further technical solution, when acquiring potential signals, voltage is continuously applied to the gas-solid insulation interface through a high-voltage conductor to achieve online measurement, and the applied voltage does not exceed the electrostatic potential measurement range.

[0022] According to one aspect of the present invention, an experimental verification device for calculating the accuracy of electric field at a DC gas-solid interface is provided, comprising:

[0023] An online surface potential measurement system, comprising: a measurement unit for measuring the potential of a gas-solid insulation interface; a transmission unit for driving the gas-solid insulation interface to rotate circumferentially to complete the potential measurement of each measurement node; and a signal acquisition unit for synchronously acquiring potential signals and transmission signals.

[0024] The data processing system is used to filter effective potentials based on potential signals and corresponding transmission signals, and output the gas-solid insulation interface potential matrix; and based on the output gas-solid insulation interface potential matrix, to reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the gas-solid interface potential, perform gradient calculation on the shape function, and solve for the electric field strength of the gas-solid insulation interface to verify the accuracy of the simulation model.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention designs an online surface potential measurement system to accurately measure the potential distribution at the gas-solid interface of insulators under charged conditions. Based on the measured potential data, a Lagrange interpolation method is reconstructed in polar coordinates to construct a shape function describing the spatial distribution characteristics of the insulator surface potential, and the electric field strength at the gas-solid interface is solved. The online surface potential measurement system of this invention provides measured data support for the simulation potential results simulating actual operating conditions. The proposed Lagrange interpolation-based shape function method enables the continuous expression of discrete potential data, reflecting the spatial distribution characteristics of the electric field strength. Furthermore, comparing the experimental calculation results with the simulation results in terms of spatial distribution shape and numerical magnitude effectively verifies the accuracy of the simulation model. Attached Figure Description

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

[0028] Figure 1 This is a schematic diagram of an insulator structure provided in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of an online measurement system for the interface potential of gas-solid insulation provided in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the surface potential scanning path provided in an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the experimental calculation results of the electric field on the surface of an insulator provided in an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of the simulation calculation results of the electric field on the surface of the insulator provided in an embodiment of the present invention. Detailed Implementation

[0033] This invention provides an experimental verification method for calculating the accuracy of the electric field at the interface of a DC gas-solid insulation system. The method uses the surface of an insulator to simulate the surface of a gas-solid insulation system. The implementation of this method relies on two key technical means: First, designing an online surface potential measurement system to accurately measure the potential distribution at the gas-solid interface of the insulator under charged conditions; Second, based on the measured potential data, proposing a shape function method based on Lagrange interpolation to accurately solve for the interface electric field strength.

[0034] This invention constructs an online surface potential measurement system integrating a power supply, a measurement unit, a transmission unit, a signal acquisition unit, and a partial discharge monitoring unit. Measurement nodes are set on the insulator surface. Based on the measured node potential values ​​and spatial coordinates, a shape function is constructed to solve for the electric field strength at the gas-solid interface, ultimately verifying the effectiveness of the simulation calculation model. The specific steps are as follows:

[0035] Step 1: Build a measurement unit integrating an electrostatic probe and an electrostatic potentiometer; then assemble a transmission unit including a translation slide, a rotary table, and a lifting mechanism; connect an oscilloscope to the measurement unit and the transmission unit to form a signal acquisition unit; finally, install the partial discharge monitoring unit and connect the power supply.

[0036] Step 2: Set measurement nodes on the surface of the insulator, write an automated program to coordinate the movement of the transmission unit and the triggering of the measurement unit, and synchronously transmit the real-time collected node potential signals and corresponding transmission signals to the signal acquisition unit, and write a program to filter valid potential information.

[0037] Step 3: Based on the potential values ​​and spatial coordinates of discrete measurement nodes, the Lagrange interpolation method is used to construct shape functions to realize the continuous expression of discrete potential data. The shape function expression is reconstructed in polar coordinates, and finally the electric field strength at the gas-solid interface is solved to verify the accuracy of the simulation model.

[0038] Furthermore, in step 1, the electrostatic probe is installed on the translation slide of the transmission unit, the insulator is installed on the rotary table, the rotary table is installed on the top of the lifting mechanism, a guide rod is added at the center of the insulator, and voltage is continuously applied through the guide rod throughout the measurement process, with the applied voltage not exceeding 20kV (electrostatic potential measurement range).

[0039] Preferably, the translation slide includes a horizontal slide and a vertical slide, enabling the probe to move freely in a two-dimensional plane; the insulator is fixed to the rotary table through threaded holes and bolts to ensure stability during rotation, thereby supporting the measurement of materials with different inclination angles; the rotary table is equipped with an adjustable limiter to constrain the material; the insulator is preferably a rotationally symmetric body to simplify measurement and reduce interference.

[0040] Furthermore, throughout the measurement process, the partial discharge status is monitored in real time by a partial discharge monitoring unit to prevent partial discharge from interfering with the accuracy of the potential measurement results.

[0041] Preferably, the partial discharge monitoring unit is a silicon photomultiplier tube (SiPM) sensor based on optical detection technology. The SiPM sensor is encapsulated in a sealed, opaque cavity to shield against ambient light interference; its installation position is near the three-junction point of the insulator to monitor the light signal generated at this easily discharged location. The monitoring surface must face the insulator directly, with a distance of no more than 10 cm between them to ensure complete reception of the light signal generated by the partial discharge; the distance between the outer shell of the monitoring unit and the guide rod is no less than 3 cm to ensure insulation safety.

[0042] Furthermore, the measurement process is as follows: the electrostatic probe moves to the target measurement point and stops, the rotary table drives the insulator to rotate one revolution, and the potential measurement of the node to be measured on the circumference is completed; this process is repeated until all preset measurement points are traversed, and the potential measurement of the entire surface of the material is completed.

[0043] Preferably, given the above scanning measurement method, when setting the measurement node in step 2, the material surface is divided into m circles along the radial direction, and each circle is divided into n equal parts along the circumference according to the angle; a control program is written to drive the transmission unit to accurately position the measurement unit to the preset node position. At the node, the measurement unit is triggered to collect the potential signal and simultaneously record the transmission signal.

[0044] Furthermore, after the signal acquisition unit synchronously records the potential signal and the transmission signal, it filters the valid potential data. Since the electrostatic probe is only valid for signals acquired in a stationary state (signals acquired in a moving state are invalid), the transmission unit precisely controls the moving / stationary state of the probe, encodes the probe's motion state in the transmission signal, writes a data processing program, analyzes the probe's motion state based on the synchronously acquired transmission signal, and filters out the valid potential information acquired in a stationary state accordingly.

[0045] Furthermore, in step 3, the electric field on the insulator surface is solved based on the potential information. This invention introduces the shape function method used in finite element analysis. Based on discrete measurement node potential signals and node coordinate signals, a shape function of potential and coordinates is constructed to realize the continuous expression of discrete potential data, thereby solving the electric field of the entire gas-solid interface. In this invention, the Lagrange interpolation method is used to construct the shape function, and the shape function expression is reconstructed in the polar coordinate system to simplify the calculation. Finally, the electric field strength of the gas-solid interface is solved to verify the accuracy of the simulation model. The specific steps are as follows:

[0046] Step 3.1: Import the nodal potential matrix and introduce the shape function expression of the nodal potential matrix.

[0047] The material surface is divided into m concentric rings along the radial direction, and each ring is equally divided into n parts, for a total of There are several measurement nodes, and the node potential matrix is ​​as follows: as follows: .

[0048] Introducing shape functions used in finite element analysis At this time, the potential matrix is: .

[0049] Step 3.2: Solve for the negative gradient of the potential matrix to obtain the electric field intensity matrix. .

[0050] Electric field strength E is electric potential Negative gradient: , in It is the unit vector in the x-direction. It is the unit vector in the y-direction.

[0051] Expressing electric field intensity using shape functions: , At this time, the electric field matrix of the gas-solid interface measurement node for: .

[0052] Step 3.3: Construct the shape function using the Lagrange interpolation method and reconstruct the shape function in the polar coordinate system.

[0053] Lagrange interpolation is performed between every two nodes, at the j-th measurement node of the i-th cycle. and the (j+1)th node The Lagrange interpolation expression (shape function) between them is: , in , It is a node , The measured value of the electric potential; , It is a node , Angle (in radians).

[0054] This invention uses the radius of a node as its polar radius and the angle of a node as its polar angle, transforming the Cartesian coordinates of the node into polar coordinates. The corresponding relationship is as follows: , in Polar radius, It is the polar angle.

[0055] The reconstructed shape function expression in polar coordinates is: .

[0056] Step 3.4: Solve for the electric field intensity matrix To verify the simulation results.

[0057] , For the polar angle is The polar radius is The electric field intensity of the point to be determined is expressed as follows:

[0058] Electric field intensity matrix of the entire gas-solid interface for: .

[0059] By inputting the measured data, the electric field intensity matrix is ​​calculated. The accuracy of the numerical model is verified by comparing the measured electric field distribution with the simulation results.

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0061] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0062] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be decomposed, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0063] In this embodiment, the object to be tested is as follows: Figure 1 As shown, it is a frustum-shaped alumina / epoxy resin composite insulator with a bottom radius of 45mm, a top radius of 15mm, and an inclination angle of 15°. A guide rod is added to the top of the insulator, and a grounding ring is installed at the bottom.

[0064] In this example, the structure of the gas-solid interface potential measurement system is as follows: Figure 2 As shown, it mainly includes the following components:

[0065] 1. Electrostatic probe; 2. Rotary stage; 3. Lifting mechanism; 4. Horizontal slide; 5. Vertical slide; 6. Right-angle commutator; 7. Cylindrical roller; 8. Limit switch; 9. Electrostatic potentiometer; 10. Oscilloscope; 11. Power supply; 12. Silicon photomultiplier (SiPM) sensor.

[0066] in:

[0067] (1) The electrostatic probe selected is the TREK 3455ET model from the American company TREK;

[0068] (2) The matching electrostatic potentiometer is Model 341B, with a measurement range of ±20 kV and an accuracy better than ±0.1%;

[0069] (3) The oscilloscope selected is the Tektronix DPO70000 series, with a maximum sampling rate of 100 GS / s and a bandwidth range of 4 GHz to 33 GHz;

[0070] (4) The output voltage range of the DC high voltage power supply is 0-100 kV.

[0071] In this embodiment, the electrostatic probe 1 is mounted on the vertical slide 5 of the transmission unit, and the insulator is mounted on the rotary table 2. The rotary table 2 is mounted on the top of the lifting mechanism 3. The height of the insulator can be adjusted by the lifting mechanism 3. During the entire measurement process, voltage is continuously applied to the insulator through the guide rod.

[0072] In this embodiment, the experimental procedure for verifying the accuracy of the method for calculating the electric field at the DC gas-solid interface is performed according to the following steps:

[0073] Step 1: Wipe the surface of the insulator with a lint-free cloth soaked in anhydrous ethanol to remove stains; use an ion blower to continuously blow the surface for 1-2 minutes to eliminate residual charge; use a surface potential measurement system to measure the surface potential of the insulator at multiple points, and start the experiment after the potential at all measurement points has stabilized at a reference level of ≤10V.

[0074] Step 2: Connect the output terminal of DC power supply 11 to the center conductor of the insulator using a high-voltage conductor, and apply a +1kV voltage for 120 minutes in an SF6 gas atmosphere of 0.1MPa.

[0075] Step 3: Maintain pressure and scan the surface potential of the insulator in real time through electrostatic probe 1. Electrostatic potentiometer 9 outputs surface potential signal. During the measurement, SiPM sensor 12 monitors the partial discharge state throughout the process.

[0076] Step 4: Use oscilloscope 10 to acquire signals, write a data processing program in MATLAB, filter valid potential data, and output the surface potential matrix of the insulator.

[0077] Step 5: Based on the surface potential matrix data obtained in Step 4, reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the potential on the insulator surface, perform gradient calculation on the potential shape function, and solve for the electric field strength on the insulator surface.

[0078] Step 6: Based on the actual pressurized structure (including geometric dimensions and material properties) from the experiment, a 1:1 scale finite element simulation model was accurately constructed in COMSOL Multiphysics simulation software. The same +10kV DC voltage was applied to the simulation model, simulating the charge steady state after 120 minutes. The surface electric field intensity of the insulator was derived from the simulation results. The surface electric field intensity distribution calculated from the experimental data in Step 5 was compared in detail with the simulation results in Step 6 to analyze the consistency between the two in terms of spatial distribution and magnitude.

[0079] Furthermore, before performing the surface potential measurement operation described in step 1, the measurement system needs to be calibrated and positioned. The angle of the vertical slide 5 is adjusted using the cylindrical roller 7 so that the vertical slide 5 is parallel to the insulator surface. The electrostatic probe 1 is adjusted in orientation using the right-angle commutator 6 so that it is perpendicular to the insulator surface. During measurement, the distance between the electrostatic probe 1 and the insulator surface is adjusted using the horizontal slide 4; the ideal measurement distance is 2-3 mm.

[0080] Furthermore, when performing the insulator surface potential measurement described in step 3, the scanning path of the electrostatic probe 1 is as follows: Figure 3As shown. When setting the measurement nodes, the insulator surface is divided into 30 equal concentric circles along the radial direction. Each concentric circle is further divided into 360 equal parts along its circumference, resulting in a total of 30 * 360 = 10800 measurement nodes on the insulator surface. During measurement, the electrostatic probe 1 is first driven by the vertical slide 5 to the target measurement point of the first concentric circle. The rotary table 2 then rotates the insulator one full circle, completing the potential measurement of all nodes on that circle. After this, the vertical slide 5 moves the electrostatic probe radially along the insulator to the target measurement point of the second concentric circle and stops. This measurement process is repeated until all preset measurement points have been traversed, completing the potential scan of the insulator surface.

[0081] Furthermore, the SiPM sensor 12 described in step 3, as a miniature single-photon detector, has advantages in strong anti-interference capability, high detection confidence, and robust characterization performance. In this embodiment, to prevent interference from external light sources, the SiPM sensor 12 is installed in a sealed, opaque cavity and adhered to the upper cover plate of the cavity. Considering that partial discharge is prone to occur at the junction of the conductor, insulator, and SF6 gas, the SiPM sensor 12 is installed near the junction, with the monitoring surface facing the insulator. In this embodiment, the distance between the two is 8 cm to ensure complete reception of the light signal generated by partial discharge; the distance between the outer shell of the monitoring unit and the conductor is 5 cm to ensure insulation safety. The output signal of the SiPM sensor 12 is connected to the oscilloscope 10 for real-time acquisition of partial discharge signals that may occur in the connecting wires. This monitoring mechanism aims to identify and prevent partial discharge phenomena from interfering with the accuracy of electrostatic potential measurement results in real time.

[0082] Further, in step 4, the oscilloscope 10 synchronously acquires the insulator surface potential signal from the electrostatic potentiometer 9 and the probe motion state signal from the transmission unit. The encoding rule for the probe motion state signal is as follows: when the electrostatic probe 1 is stationary, the transmission unit outputs a high-level signal (4V); when the electrostatic probe is in motion, the transmission unit outputs a zero-level signal. This motion state is output by the transmission unit and encoded as a rectangular pulse sequence. During data processing, valid potential signals are filtered based on this rectangular pulse sequence, that is, the potential signals measured when the electrostatic probe is stationary are selected as valid data. In this embodiment, 10,800 measurement nodes are set on the insulator surface, and each measurement node is measured 10 times repeatedly, for a total of 108,000 valid potential measurement values. In this embodiment, the total sampling length of the oscilloscope 10 is set to 200k, and the sampling frequency is set to 1kS / s.

[0083] Furthermore, in this embodiment, the average potential value of each measurement node is taken to obtain the potential matrix of the measurement nodes on the insulator surface:

[0084]

[0085] Substituting the nodal potential values, we obtain the electric field intensity matrix on the insulator surface:

[0086]

[0087] in It is the unit vector in the x-direction. It is the unit vector in the y-direction. , , , Given the polar angle of the point to be determined, the surface electric field intensity distribution calculated from experimental data is as follows: Figure 4 As shown.

[0088] Furthermore, when constructing the simulation model described in step 6 using COMSOL Multiphysics simulation software: In this embodiment, a 1:1 accurate model is built based on the actual experimental structure; the physical parameters required for model construction are accurately obtained through both literature review and experimental methods; a Poisson field-particle flow coupled model is constructed to calculate the electric field intensity distribution on the insulator surface, dynamically combining the generation, recombination, and diffusion processes of positive and negative ions in the gas with the current conduction on the insulator surface to achieve dynamic simulation of charge accumulation at the gas-solid interface. The specific operation steps are as follows:

[0089] 1. Constructing a geometric model: Based on the actual dimensions of the experimental object, construct a frustum-shaped insulator with a bottom radius of 45mm, a top radius of 15mm, and an inclination angle of 15°.

[0090] 2. Setting model physical property parameters: The mobility of positive and negative ions, the formation rate of ion pairs, and the recombination rate are minimally affected by changes in the state of SF6. Using measurement results from existing literature, the mobility of positive ions is 6.42 × 10⁻⁶. -5 m 2 V -1 s -1 The negative ion mobility is 5.70 × 10⁻⁶. -5 m 2 V -1 s -1 The ion pair formation rate is 20.0 cm⁻¹. -3 ·s -1 The ion-pair recombination rate was 10.89 × 10⁻⁶. -13 ·m 3 / s. The three-electrode method is used to measure the conductivity of the insulator core and its surface. Based on the measured surface conductivity versus electric field curve, the surface conductivity sensitivity coefficient can be calculated. The advantage of the three-electrode method is that a protective electrode can be set, effectively eliminating the influence of edge effects and stray currents, and ensuring a uniform electric field distribution below the measuring electrodes, thereby effectively reducing measurement errors. The measured conductivity of the insulator core is 2 × 10⁻⁶. -5S / m, basic surface conductivity 1×10 -16 S, the surface conductivity sensitivity coefficient is 1.25 mm / kV. In this embodiment, the relative permittivity of the alumina / epoxy resin composite insulator was measured to be 5.3 using a broadband dielectric spectrometer (NOVOCONTROL Concept 80). The weight of the insulator in air and when immersed in water was measured, and the density of the insulator was determined to be 1673 kg / m³ using a density balance. 3 .

[0091] 3. Setting up the physical field: In the simulation modeling of this embodiment, to accurately characterize the coupling effect between the electric field and the particle flow, a complete physical model was constructed based on the multi-physics coupling mechanism by calling the corresponding electric field and particle flow physical field interfaces and their coupling settings. Based on actual experimental conditions, this model simulates the charge stabilization state of an insulator after continuously applying a +1kV DC voltage to it for 120 minutes in a 0.1MPa SF6 gas atmosphere.

[0092] The simulation results of the electric field intensity distribution on the insulator surface are as follows: Figure 5 As shown in the figure, by comparing the surface electric field intensity distribution calculated from experimental data with the simulation results, both exhibit a characteristic of decreasing electric field intensity along the radial gradient of the insulator. Near the central conductor, the peak electric field intensity obtained from both experiments and simulations is close to -1 kV / m, while near the grounding ring, it is close to 0 kV / m. The experimental and simulation results show good consistency in spatial distribution and numerical magnitude. This comparison effectively verifies the accuracy of the simulation model in calculating the electric field at the DC gas-solid insulation interface, thus proving the reliability of the experimental verification method for calculating the accuracy of the DC gas-solid insulation interface electric field proposed in this invention.

[0093] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides an experimental verification device for calculating the accuracy of electric field at a DC gas-solid interface, comprising:

[0094] An online surface potential measurement system, comprising: a measurement unit for measuring the potential of a gas-solid insulation interface; a transmission unit for driving the gas-solid insulation interface to rotate circumferentially to complete the potential measurement of each measurement node; and a signal acquisition unit for synchronously acquiring potential signals and transmission signals.

[0095] The data processing system is used to filter effective potentials based on potential signals and corresponding transmission signals, and output the gas-solid insulation interface potential matrix; and based on the output gas-solid insulation interface potential matrix, to reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the gas-solid interface potential, perform gradient calculation on the shape function, and solve for the electric field strength of the gas-solid insulation interface to verify the accuracy of the simulation model.

[0096] The surface potential online measurement system designed in this invention provides measured data support for the simulation potential results under actual operating conditions. The shape function method based on Lagrange interpolation proposed by the data processing system can realize the continuous expression of discrete potential data, reflecting the spatial distribution characteristics of electric field intensity. Furthermore, the consistency between experimental calculation results and simulation results in spatial distribution shape and numerical magnitude is compared, effectively verifying the accuracy of the simulation model.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. An experimental verification method for the accuracy of calculating the electric field at a DC gas-solid insulation interface, characterized in that, include: Step 1: Construct an online surface potential measurement system. The system includes: a measurement unit for measuring the potential of the gas-solid insulation interface; a transmission unit for driving the gas-solid insulation interface to rotate circumferentially to complete the potential measurement of each measurement node; a power supply for providing high voltage to the high voltage conductor of the gas-solid insulation interface; and a signal acquisition unit for synchronously acquiring potential signals and transmission signals. Step 2: Set up several measurement nodes at the gas-solid insulation interface. During measurement, the potential signal and corresponding transmission signal of each measurement node are collected synchronously. The effective potential is selected according to the potential signal and the corresponding transmission signal, and the potential matrix of the gas-solid insulation interface is output. Step 3: Based on the output gas-solid insulation interface potential matrix, reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the gas-solid interface potential, perform gradient calculation on the shape function, and solve for the electric field strength at the gas-solid insulation interface to verify the accuracy of the simulation model.

2. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 1, characterized in that, When setting up an online surface potential measurement system, the following are also included: A partial discharge monitoring unit is configured, which is encapsulated in a sealed, opaque cavity and installed close to the high-voltage conductor at the gas-solid insulation interface to monitor partial discharge signals generated at easily discharged locations.

3. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 2, characterized in that, The installation position of the partial discharge monitoring unit must meet the following requirements: the monitoring surface is directly facing the gas-solid insulation interface, and the distance between the two is not greater than a first set distance; and the distance between the outer shell of the partial discharge monitoring unit and the high-voltage conductor is not less than a second set distance.

4. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 1, characterized in that, The transmission signal represents the motion state of the electrostatic probe. The motion state of the electrostatic probe is output by the transmission unit and encoded into a rectangular pulse sequence. Based on the rectangular pulse sequence, the potential signal measured when the electrostatic probe is stationary is selected as the effective potential.

5. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 1, characterized in that, Acquire the potential signals of each measurement node, including: The gas-solid insulation interface is divided into m rings, and each ring is divided into n parts. After the electrostatic probe moves to the target measurement point, it stops. The transmission unit drives the gas-solid insulation interface to rotate one revolution, completing the potential measurement of the node to be measured on this circle. This process is repeated until all preset measurement points are traversed, completing the potential measurement of the entire surface.

6. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 5, characterized in that, The potential information output by the measurement node is a potential matrix: ， Introducing shape functions used in finite element analysis Expression potential matrix: 。 7. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 6, characterized in that, Based on the output gas-solid interface potential matrix, the Lagrange interpolation method is reconstructed in polar coordinates to build shape functions describing the spatial distribution characteristics of the gas-solid interface potential, including: Lagrange interpolation is performed between every two measurement nodes, starting with the j-th measurement node in the i-th cycle. and the (j+1)th measurement node The Lagrange interpolation expression between them is: ， in , Measurement node , The measured value of the electric potential; , Measurement node , Angle; The reconstructed shape function expression in polar coordinates is: ， in Polar radius, Polar angle, It is the unit vector in the x-direction. It is the unit vector in the y-direction.

8. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 7, characterized in that, Electric field intensity matrix of gas-solid insulation interface for: ， The point to be determined is the polar angle. Polar diameter .

9. The experimental verification method for the accuracy of DC gas-solid insulation interface electric field calculation according to claim 1, characterized in that, When acquiring potential signals, voltage is continuously applied to the gas-solid insulation interface through a high-voltage conductor to achieve online measurement. The applied voltage does not exceed the electrostatic potential measurement range.

10. An experimental verification device for the accuracy of calculating the electric field at a DC gas-solid insulation interface, characterized in that, include: An online surface potential measurement system, comprising: a measurement unit for measuring the potential of a gas-solid insulation interface; a transmission unit for driving the gas-solid insulation interface to rotate circumferentially to complete the potential measurement of each measurement node; and a signal acquisition unit for synchronously acquiring potential signals and transmission signals. The data processing system is used to filter effective potentials based on potential signals and corresponding transmission signals, and output the gas-solid insulation interface potential matrix; and based on the output gas-solid insulation interface potential matrix, to reconstruct the Lagrange interpolation method in polar coordinates, construct a shape function describing the spatial distribution characteristics of the gas-solid interface potential, perform gradient calculation on the shape function, and solve for the electric field strength of the gas-solid insulation interface to verify the accuracy of the simulation model.

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