Method and system for analyzing insulation aging mechanism of extra-high voltage converter transformer valve side outgoing line device

Abstract

The invention provides an insulation aging mechanism analysis method and system for an extra-high voltage converter transformer valve side outgoing line device. The method comprises the following steps: pretreating an insulating material, preparing an experimental sample, and collecting a near infrared spectrum of the experimental sample; constructing an insulation paper cellulose model, optimizing an atomic position through a conjugate gradient method, and optimizing a model structure through a simulated annealing algorithm; carrying out molecular dynamics simulation on the optimized model, simulating temperature by adopting a Nose temperature control method, calculating dipole moment and analyzing dielectric constant and system energy change; applying a strong electric field as external disturbance, observing chemical bond change in combination with a near infrared spectrum, and finally summarizing an aging related data rule. According to the method, the problems of insufficient molecular dynamics simulation accuracy and low aging mechanism model prediction precision and reliability are effectively solved, and the accuracy of insulating material aging state evaluation is improved.

Description

Technical Field

[0001] This invention relates to the fields of molecular dynamics and material aging simulation, specifically to a method and system for analyzing the insulation aging mechanism of ultra-high voltage converter transformer side outgoing line devices. Background Technology With the rapid construction and development of ultra-high voltage direct current (UHVDC) transmission projects, converter transformers, as core equipment, are crucial to the safety and stability of the entire power grid due to their operational reliability. The insulation materials of valve-side outgoing line devices are subjected to high electric fields, large currents, and complex thermal stresses for extended periods, making them prone to aging and deterioration, which can lead to insulation failures and severely impact equipment lifespan and system reliability. Therefore, accurate assessment and mechanistic research into the physicochemical changes of insulation material aging are of great significance.

[0002] Traditional methods for assessing the aging of insulating materials often rely on periodic power outage tests, physicochemical property tests, or partial discharge detection. These methods often have limitations, such as long testing cycles, damage to samples, and inability to reflect changes in the internal state of the material in real time. Furthermore, the aging of insulating materials is a complex process involving the coupling of physical, chemical, and electrical properties, and it is difficult to reveal its microscopic mechanisms by relying solely on macroscopic parameters.

[0003] Currently, although some studies have attempted to study the aging of insulating materials using molecular simulation methods, these are mostly limited to simulations under single-scale or ideal conditions, lacking effective verification with experimental data and making it difficult to promote their application in practical engineering. Existing technologies have not yet established an aging mechanism model for insulating materials that can integrate macroscopic-microscopic multi-scale information and combine it with experimental verification, resulting in insufficient understanding of the insulation aging process and limited assessment accuracy.

[0004] The existing invention patent application document CN117761472A, entitled "A Method for Aging Assessment of Insulating Materials Based on Polarization Integral Current and IRC," describes a method that obtains a key first time constant by integrating the polarization current and then uses this as a basis to perform a third-order exponential fitting on the IRC, thereby calculating the aging factor A, which characterizes the degree of aging. However, this existing method is time-consuming to test, requires high environmental stability, is easily affected by multiple factors such as temperature, and is difficult to comprehensively reflect the complex aging conditions of insulating materials across multiple mechanisms and scales.

[0005] The existing invention patent application document CN111766478A, entitled "A Method for Aging Assessment of Insulation Materials of High-Voltage Power Equipment Based on Cumulative Charge Characteristics," applies the DC current integration method to assess insulation aging. It evaluates the performance of the insulation material by measuring and comparing the initial charge amount with the cumulative charge amount at a specific time after pressurization. However, the effectiveness of this existing method largely depends on the selection of the specific time point; an inappropriate selection may lead to misjudgment of the aging state.

[0006] In summary, existing technologies suffer from low accuracy in molecular dynamics simulations and low predictive accuracy and reliability of aging mechanism models for insulating materials, which restricts the accuracy of aging state assessment for insulating materials. Summary of the Invention

[0007] The technical problem to be solved by this invention is: how to solve the technical problem that the accuracy of molecular dynamics simulation and the prediction accuracy and reliability of aging mechanism models of insulating materials are low in the existing technology, which restricts the accuracy of aging state assessment of insulating materials.

[0008] This invention solves the above-mentioned technical problems by employing the following technical solution: A method for analyzing the insulation aging mechanism of UHV converter transformer valve-side outgoing line devices includes: S1. Based on the differential aging strategy, the insulation material of the UHV converter valve side outgoing line device is pre-treated, and insulation material samples are pre-placed. S2. Collect near-infrared spectra of the insulation material samples being searched; S3. Construct a cellulose model for insulating paper based on the preset degree of polymerization data; S4. Optimize the atomic positions of the insulating paper cellulose model using the conjugate gradient method; S5. Optimize the structure of the insulating paper cellulose model using the simulated annealing algorithm to obtain a suitable insulating paper cellulose model; S6. Perform molecular dynamics simulations on the applicable insulating paper cellulose model; S7. Use the Nose temperature control method to simulate temperature, and record the trajectory files and topology files of all atomic coordinates and velocities for each frame during the simulation process; S8. Calculate the dipole moment based on the atomic charges and coordinates in the topology file, perform molecular dynamics (MD) analysis based on the trajectory file, observe the changes in dielectric constant and system energy, and obtain the comparison results of dielectric constant values ​​at different times and system energy change data. S9. Apply a strong electric field as an external disturbance source and use near-infrared spectroscopy to analyze the changes in chemical bonds; S10. Based on the comparison results of dielectric constant values ​​at different times, system energy change data, and chemical bond changes, the changes in dielectric constant, system energy, and chemical bonds of the insulating paper samples under the differential aging strategy are summarized and analyzed.

[0009] This invention studies the aging mechanism of insulation materials in UHV converter transformer side outgoing line devices. By constructing a cellulose model, relevant data of insulation paper are presented on a computer. Near-infrared spectroscopy and molecular dynamics simulation and analysis are used to observe and statistically analyze the changes in physicochemical data related to the aging of insulation paper.

[0010] In a more specific technical solution, in S4, the initial structure is set, and the initial position coordinates of the atoms to be optimized are obtained: And set convergence criteria; Calculate the initial position coordinates of atoms Energy at the location Calculate the potential gradient , the first conjugate direction Set as the initial negative gradient direction; Start loop iteration , along the current conjugate direction Find the optimal step size This makes the function:

[0011] Along the conjugate direction Find the minimum value; update the positions of all atoms using the found optimal step size:

[0012] Calculate the coordinates of the new atom positions Energy at the location harmony ; like If the iteration ends, then proceed; otherwise, calculate the next conjugate direction. Construct new conjugate directions:

[0013] Jump to execute the steps to obtain the optimal step size and update all atomic positions until the convergence criterion is met.

[0014] In a more specific technical solution, in S5, given an initial temperature and initial point , representing the initial atomic configuration of cellulose; calculate the objective function. Atomic energy ; Based on the current point Randomly generated disturbances New points were obtained:

[0015] Calculate the function value at the new point And energy difference: ; Execute the Metropolis procedure; Complete one Metropolis process, use exponential cooling to lower the control temperature, repeat the Metropolis process, until a preset number of cyclic annealing simulations are performed.

[0016] In a more specific technical solution, the Metropolis process includes: like If so, the new point is accepted as the initial point for the next simulated annealing; like Then calculate the acceptance probability of the new point. ,produce uniformly distributed pseudo-random numbers on the interval ,like If the new point is accepted, it will be used as the initial point for the next simulation; otherwise, the original point will be used as the initial point for the next annealing simulation.

[0017] In a more specific technical solution, in S6, an insulating paper cellulose model will be applied, and a pre-set molecular dynamics simulation program will be read in to construct an amorphous system. Polymer compatibility force field (PCFF) is chosen to describe the interactions between atoms; The applicable insulating paper cellulose model is placed in a box that satisfies the periodic boundary condition PBC to eliminate surface effects; the applicable insulating paper cellulose model is then immersed in solvent molecules to perform environmental simulation.

[0018] This invention digitally characterizes the complex material aging process using molecular models, and extracts and quantifies the simulation results to form calculable aging characteristic data, which is beneficial for the application and iteration of simulation algorithms. Furthermore, optimization algorithms such as simulated annealing and conjugate gradients are used to precisely optimize the molecular configuration, improving the accuracy of molecular dynamics simulations and thus significantly enhancing the predictive accuracy and reliability of the aging mechanism model for insulating materials.

[0019] In a more specific technical solution, in S7, a target temperature is set. Hot bath quality The location for initializing all examples and speed and coefficient of friction ; Calculate the forces acting on all atoms, update momentum by half a step, calculate and update position, and update... A half-step process yields the complete updated momentum; Repeat the steps of calculating the forces acting on all atoms, updating momentum by half a step, updating position, calculating the force at the new position, and calculating the complete momentum update until the simulation is completed, to obtain a trajectory file and corresponding topology file that record the coordinates and velocities of all atoms in each frame of the simulation.

[0020] In a more specific technical solution, the following logic is used, based on the current atomic position. Calculate the forces acting on all atoms: ; Using a numerical integrator, simultaneously integrate the particle equation and The equation is used to calculate the half-step momentum update: ; Calculate the update position using the following logic: ; Calculate the force at the new position and instantaneous kinetic energy ,renew Half a step: ; The complete update momentum is determined using the following logic: .

[0021] In a more specific technical solution, in S8, the dipole moment vector of each cellulose molecule is calculated based on the atomic charges and coordinates in the topology file. Sum of total dipole moments:

[0022] In the formula, It is atomic charge. It is the atoms in time The position vector; According to the statistical total dipole moment Calculate the dot product of the dipole moments at the initial time and all subsequent time points, and take the average to obtain the time autocorrelation function (ACF). Calculate the static dielectric constant using the following logic:

[0023] In the formula For the simulated volume of cellulose, Boltzmann's constant, For temperature, The time average of the square of the total dipole moment. The square of the time average of the total dipole moment. The variance of the total dipole moment is the fluctuation. By comparing the dielectric constant values ​​at different times, the changes in the dielectric constant were observed. MD analysis is performed on the trajectory file to obtain a plottable data file, and a curve of energy change over time is plotted.

[0024] In a more specific technical solution, S9 determines the intensity, direction, and form of the applied electric field. In the molecular dynamics simulation program, the electric field is applied using... Calculate the additional force exerted on each charged atom and add it to the interatomic interaction force.

[0025] This invention addresses the challenges of the complex and difficult-to-observe aging mechanisms of insulating materials. It employs a combination of molecular dynamics simulation and near-infrared spectroscopy to perform multi-scale simulation and verification of the aging process of insulating paper cellulose under multiple physical fields. This method links the observation of changes in microscopic chemical bonds with the analysis of macroscopic dielectric properties, avoiding the significant errors that traditional single methods produce in aging analysis and providing a guarantee for accurately assessing the aging state of insulating materials.

[0026] In a more specific technical solution, the insulation aging mechanism analysis system for the UHV converter transformer valve side outgoing line device includes: The sample preparation module is used to pre-treat the insulation material of the UHV converter transformer valve side outgoing line device according to the differential aging strategy and to pre-set insulation material samples. The spectral acquisition module is used to acquire near-infrared spectra of the search insulation material samples. The spectral acquisition module is connected to the sample preparation module. The insulating paper model building module is used to build an insulating paper cellulose model based on preset polymerization degree data; The insulating paper model optimization module is used to optimize the atomic positions of the insulating paper cellulose model using the conjugate gradient method. The insulating paper model optimization module is connected to the insulating paper model construction module. The insulating paper model structure optimization module is used to optimize the structure of the insulating paper cellulose model using a simulated annealing algorithm to obtain a suitable insulating paper cellulose model. The insulating paper model structure optimization module is connected to the insulating paper model construction module. The molecular dynamics simulation module is used to perform molecular dynamics simulations on the applicable insulating paper cellulose model. The molecular dynamics simulation module is connected to the insulating paper model structure optimization module. The temperature simulation module is used to simulate temperature using the Nose temperature control method, and records the trajectory files and topology files of all atomic coordinates and velocities for each frame during the simulation process; The dielectric constant numerical comparison module is used to calculate the dipole moment based on the atomic charges and coordinates in the topology file, perform molecular dynamics (MD) analysis based on the trajectory file, observe the changes in dielectric constant and system energy, and obtain the comparison results of dielectric constant values ​​at different times and system energy change data. The dielectric constant numerical comparison module is connected to the temperature simulation module. The chemical bond change analysis module is used to apply a strong electric field as an external disturbance source and use near-infrared spectroscopy to analyze and obtain the results of chemical bond changes. The chemical bond change analysis module is connected to the dielectric constant value comparison module. The summary and analysis module is used to summarize and analyze the changes in dielectric constant, system energy, and chemical bonds of the insulating paper sample under the differential aging strategy based on the comparison results of dielectric constant values ​​at different times, system energy change data, and chemical bond changes. The summary and analysis module is connected to the dielectric constant value comparison module and the chemical bond change analysis module.

[0027] The present invention has the following advantages over the prior art: This invention studies the aging mechanism of insulation materials in UHV converter transformer side outgoing line devices. By constructing a cellulose model, relevant data of insulation paper are presented on a computer. Near-infrared spectroscopy and molecular dynamics simulation and analysis are used to observe and statistically analyze the changes in physicochemical data related to the aging of insulation paper.

[0028] This invention digitally characterizes the complex material aging process using molecular models, and extracts and quantifies the simulation results to form calculable aging characteristic data, which is beneficial for the application and iteration of simulation algorithms. Furthermore, optimization algorithms such as simulated annealing and conjugate gradients are used to precisely optimize the molecular configuration, improving the accuracy of molecular dynamics simulations and thus significantly enhancing the predictive accuracy and reliability of the aging mechanism model for insulating materials.

[0029] This invention addresses the challenges of the complex and difficult-to-observe aging mechanisms of insulating materials. It employs a combination of molecular dynamics simulation and near-infrared spectroscopy to perform multi-scale simulation and verification of the aging process of insulating paper cellulose under multiple physical fields. This method links the observation of changes in microscopic chemical bonds with the analysis of macroscopic dielectric properties, avoiding the significant errors that traditional single methods produce in aging analysis and providing a guarantee for accurately assessing the aging state of insulating materials.

[0030] This invention solves the technical problems in the prior art, such as the low accuracy of molecular dynamics simulations and the low prediction accuracy and reliability of aging mechanism models for insulating materials, which restrict the accuracy of aging state assessment of insulating materials. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the basic steps of the insulation aging mechanism analysis method for the UHV converter transformer valve side outgoing line device in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of data stream processing for the insulation aging mechanism analysis method of the UHV converter transformer side outgoing line device in Embodiment 1 of the present invention. Detailed Implementation

[0032] 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 in conjunction with the embodiments of the present invention. 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.

[0033] Example 1 like Figure 1 and Figure 2 As shown, the method for analyzing the insulation aging mechanism of the UHV converter transformer valve side outgoing line device provided by the present invention includes the following basic steps: S1. Pre-treat the insulation material of the UHV converter transformer side outgoing line device according to different aging strategies, and prepare experimental samples. In this embodiment, the insulating paper roll is placed in a vacuum oil-impregnation box and dried for 48 hours at a temperature of 90°C and a pressure of 50Pa to remove moisture from the paper, so that the moisture content of the insulating paper sample is below 0.5%. While maintaining a vacuum, hot oil at 40°C is introduced into the vacuum tank to soak the insulating paper in oil for 48 hours, and then cooled to room temperature. The insulating paper sample that has undergone vacuum impregnation and new oil are placed in a glass bottle with an oil-to-paper ratio of 10:1, and an appropriate amount of copper sheet is added. Place the flask in a vacuum nitrogen-filled chamber, evacuate the chamber, and fill it with nitrogen to one standard atmosphere under vacuum. Then seal the flask in a closed, nitrogen-filled environment. The sealed glass bottles were placed in different aging chambers and accelerated aging tests were conducted at three temperatures: 90℃, 110℃, and 130℃.

[0034] S2. Near-infrared spectroscopy is performed on the prepared insulation material samples; In this embodiment, diffuse reflectance near-infrared spectra of different groups of insulating paper experimental samples were collected. The incident light underwent multiple diffuse reflections on the paper sample and the integrating sphere surface. The reflected light was transmitted to the spectrometer through the light metering window and optical fiber for spectral dispersion. The original near-infrared spectrum of the paper sample was obtained by comparing it with the standard spectrum of the reference white board.

[0035] S3. Construct a cellulose model of insulating paper; In this embodiment, the main component of the insulating paper is cellulose. In reality, the chain length of cellulose can be as high as several thousand, while the performance difference of cellulose with a degree of polymerization below 100 is not significant. However, since computer performance and calculation speed generally do not use a degree of polymerization of several thousand, a degree of polymerization of 10 can be used to construct a cellulose model of the insulating paper to obtain a pure cellulose model of the insulating paper.

[0036] S4. Optimize the atomic positions of the cellulose model using the conjugate gradient method; In this embodiment, an initial structure is set, and the initial coordinates of the atoms to be optimized are obtained. And set a convergence criterion, namely, the force on the atom is less than ; Calculate the initial position coordinates of atoms Energy at the location Simultaneously calculate the potential energy gradient , the first conjugate direction Set it to the initial negative gradient direction, that is, let ; Start loop iteration , along the current conjugate direction Find an optimal step size , making the function The minimum value can be obtained along this direction, and then the position of all atoms can be updated using the found optimal step size. ; Calculate the new atomic position coordinates Energy at the location harmony ; like If the iteration ends, proceed to the next step; otherwise, continue to the next step. Calculate the next conjugate direction Constructing new conjugate directions Proceed to the step of obtaining the optimal step size to update the positions of all atoms until the convergence criterion is met.

[0037] S5. Optimize the structure of the cellulose model using the simulated annealing algorithm; In this embodiment, an initial temperature is given. For 800K and the initial point That is, the initial atomic configuration of cellulose, and the corresponding objective function is calculated. That is, the energy of an atom ; At the current point Randomly generate perturbations based on , obtain new points Calculate the function value at the new point. sum and difference That is, the energy difference; The Metropolis process includes: like If so, the new point is accepted as the initial point for the next simulated annealing; like Then calculate the acceptance probability of the new point. ,produce uniformly distributed pseudo-random numbers on the interval .like If the new point is accepted as the initial point for the next simulation, then the original point will be used as the initial point for the next annealing simulation. In this embodiment, after completing one Metropolis process, exponential cooling can be used to gradually reduce the control temperature and repeat the Metropolis process until five cycles of annealing simulation are performed.

[0038] S6. Perform molecular dynamics simulations on the optimized cellulose model of insulating paper; The optimized insulating paper cellulose model was read into the molecular dynamics simulation program, and an amorphous system was constructed using the Amorphous Cell module in the software. The Polymer Consistent Force Field (PCFF) is chosen to describe the interactions between atoms; The insulating paper cellulose model is placed within a box with periodic boundary conditions (PBC) to eliminate surface effects. Simultaneously, the cellulose model is immersed in solvent molecules to simulate a real-world environment.

[0039] S7. Simulate temperature using the Nose temperature control method; Set target temperature Hot bath quality The location for initializing all examples and speed and coefficient of friction ; Based on the current atomic position Calculate the forces acting on all atoms. ; Using a numerical integrator, simultaneously integrate the particle equation and The equation updates momentum in half a step. Update location at the same time Calculate the force at the new position and instantaneous kinetic energy Update again Half a step Complete update momentum ; Repeat the steps of calculating the forces acting on all atoms, updating momentum by half a step, updating position, calculating the force at the new position, and calculating the complete momentum update until the simulation is complete. This will produce a trajectory file and a corresponding topology file that record the coordinates and velocities of all atoms in each frame of the simulation.

[0040] S8. Calculate the dipole moment and perform molecular dynamics (MD) analysis to observe the changes in dielectric constant and system energy; Calculate the dipole moment vector of each cellulose molecule based on the atomic charges and coordinates in the topology file. The total dipole moment vector in It is atomic charge. It is the atoms in time The position vector; According to the statistical total dipole moment Calculate the dot product of the dipole moments at the initial time and all subsequent time points, and take the average to obtain the Time Autocorrelation Function (ACF). ; Calculate the static dielectric constant In the formula For the simulated volume of cellulose, Boltzmann's constant, For temperature, The time average of the square of the total dipole moment. The square of the time average of the total dipole moment. This represents the variance of the total dipole moment. By comparing the dielectric constant values ​​at different times, the change in the dielectric constant can be observed. By performing MD analysis on the trajectory file and using the analysis commands provided by the relevant software, a plottable data file can be obtained. By plotting the energy change curve over time, the changes in the system's energy can be observed.

[0041] S9. Apply a strong electric field as an external disturbance source and use near-infrared spectroscopy to analyze and observe changes in chemical bonds; In this embodiment, the strength, direction, and form of the applied electric field are determined. Applying an electric field in a molecular dynamics simulation program is equivalent to applying an additional force to each charged atom; therefore, the method used... Calculate this force and add it to the interatomic interaction force calculated from the force field.

[0042] Referring to step S2, a near-infrared spectrometer is used to obtain the near-infrared spectrum of the insulating paper cellulose model after applying a strong electric field. Under the action of the electric field, the polarized positively charged carbon atoms and negatively charged hydrogen and oxygen atoms in the molecule move in the positive and negative directions of the electric field, respectively, thereby lengthening the glycosidic bonds between the cellulose molecular chains. Therefore, the cleavage of cellulose molecules, i.e. the changes in chemical bonds, can be observed by the near-infrared spectra before and after applying a strong electric field.

[0043] S10. Summarize the changes in data related to the aging of insulating paper; Based on the comparison of dielectric constant values ​​at different times, changes in system energy, and changes in chemical bonds, the changes in dielectric constant, system energy, and chemical bonds of insulating paper samples under different aging strategies are summarized and analyzed.

[0044] In summary, this invention studies the aging mechanism of insulation materials in UHV converter transformer side outgoing line devices. By constructing a cellulose model, relevant data of insulation paper are presented on a computer. Near-infrared spectroscopy and molecular dynamics simulation and analysis are used to observe and statistically analyze the changes in physicochemical data related to the aging of insulation paper.

[0045] This invention digitally characterizes the complex material aging process using molecular models, and extracts and quantifies the simulation results to form calculable aging characteristic data, which is beneficial for the application and iteration of simulation algorithms. Furthermore, optimization algorithms such as simulated annealing and conjugate gradients are used to precisely optimize the molecular configuration, improving the accuracy of molecular dynamics simulations and thus significantly enhancing the predictive accuracy and reliability of the aging mechanism model for insulating materials.

[0046] This invention addresses the challenges of the complex and difficult-to-observe aging mechanisms of insulating materials. It employs a combination of molecular dynamics simulation and near-infrared spectroscopy to perform multi-scale simulation and verification of the aging process of insulating paper cellulose under multiple physical fields. This method links the observation of changes in microscopic chemical bonds with the analysis of macroscopic dielectric properties, avoiding the significant errors that traditional single methods produce in aging analysis and providing a guarantee for accurately assessing the aging state of insulating materials.

[0047] This invention solves the technical problems in the prior art, such as the low accuracy of molecular dynamics simulations and the low prediction accuracy and reliability of aging mechanism models for insulating materials, which restrict the accuracy of aging state assessment of insulating materials.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing the insulation aging mechanism of the outgoing line device on the valve side of an ultra-high voltage converter transformer, characterized in that, The method includes: S1. Based on the differential aging strategy, the insulation material of the UHV converter valve side outgoing line device is pre-treated, and insulation material samples are pre-placed. S2. Collect near-infrared spectra of the insulation material samples being searched; S3. Construct a cellulose model for insulating paper based on the preset degree of polymerization data; S4. Optimize the atomic positions of the insulating paper cellulose model using the conjugate gradient method; S5. Optimize the structure of the insulating paper cellulose model using the simulated annealing algorithm to obtain a suitable insulating paper cellulose model; S6. Perform molecular dynamics simulations on the applicable insulating paper cellulose model; S7. Use the Nose temperature control method to simulate temperature, and record the trajectory files and topology files of all atomic coordinates and velocities for each frame during the simulation process; S8. Calculate the dipole moment based on the atomic charges and coordinates in the topology file, perform molecular dynamics (MD) analysis based on the trajectory file, observe the changes in dielectric constant and system energy, and obtain the comparison results of dielectric constant values ​​at different times and system energy change data. S9. Apply a strong electric field as an external disturbance source, and use the near-infrared spectrum to analyze the changes in chemical bonds; S10. Based on the comparison results of the dielectric constant values ​​at different times, the system energy change data, and the chemical bond changes, the changes in dielectric constant, system energy, and chemical bonds of the insulating paper sample under the differential aging strategy are summarized and analyzed.

2. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In step S4, the initial structure is set, and the initial position coordinates of the atoms to be optimized are obtained: And set convergence criteria; Calculate the initial position coordinates of the atom Energy at the location Calculate the potential gradient , the first conjugate direction Set as the initial negative gradient direction; Start loop iteration , along the current conjugate direction Find the optimal step size This makes the function: Along the conjugate direction Find the minimum value; update the positions of all atoms using the found optimal step size: Calculate the coordinates of the new atom positions Energy at the location harmony ; like If the iteration ends, then proceed; otherwise, calculate the next conjugate direction. Construct new conjugate directions: Jump to the next step to obtain the optimal step size and update all atomic positions until the convergence criterion is met.

3. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In S5, an initial temperature is given. and initial point , indicating the initial atomic configuration of cellulose; Calculate the objective function Atomic energy ; Based on the current point Randomly generated disturbances New points were obtained: Calculate the function value at the new point And energy difference: ； Execute the Metropolis procedure; After completing one Metropolis process, use exponential cooling to lower the control temperature and repeat the Metropolis process until a preset number of cyclic annealing simulations are performed.

4. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 3, characterized in that, The Metropolis process includes: like If so, the new point is accepted as the initial point for the next simulated annealing; like Then calculate the acceptance probability of the new point. ,produce uniformly distributed pseudo-random numbers on the interval ,like If the new point is accepted, it will be used as the initial point for the next simulation; otherwise, the original point will be used as the initial point for the next annealing simulation.

5. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In step S6, the applicable insulating paper cellulose model is read into a preset molecular dynamics simulation program to construct an amorphous system. Polymer compatibility force field (PCFF) is chosen to describe the interactions between atoms; The applicable insulating paper cellulose model is placed in a box that satisfies the periodic boundary condition PBC to eliminate surface effects. The applicable insulating paper cellulose model was immersed in solvent molecules to simulate the environment.

6. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In step S7, the target temperature is set. Hot bath quality The location for initializing all examples and speed and coefficient of friction ; Calculate the forces acting on all atoms, update momentum by half a step, calculate and update position, and update... A half-step process yields the complete updated momentum; Repeat the steps of calculating the forces acting on all atoms, updating momentum half-steps, updating positions, calculating the forces at the new positions, and calculating the complete update momentum until the simulation is completed, to obtain a trajectory file and corresponding topology file that record the coordinates and velocities of all atoms in each frame of the simulation.

7. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 6, characterized in that, Using the following logic, based on the current atom position Calculate the forces acting on all the atoms: ； Using a numerical integrator, simultaneously integrate the particle equation and The equation is used to calculate the half-step of the updated momentum: ； The update position is calculated using the following logic: ； Calculate the force at the new position and instantaneous kinetic energy Update the above Half a step: ； The complete updated momentum is determined using the following logic: 。 8. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In step S8, the dipole moment vector of each cellulose molecule is calculated based on the atomic charges and coordinates in the topology file. Sum of total dipole moments: In the formula, It is atomic charge. It is the atoms in time The position vector; According to the statistical total dipole moment Calculate the dot product of the dipole moments at the initial time and all subsequent time points, and take the average to obtain the time autocorrelation function (ACF). Calculate the static dielectric constant using the following logic: In the formula For the simulated volume of cellulose, Boltzmann's constant, For temperature, The time average of the square of the total dipole moment. The square of the time average of the total dipole moment. The variance of the total dipole moment is the fluctuation. By comparing the dielectric constant values ​​at different times, the changes in the dielectric constant were observed. MD analysis is performed on the trajectory file to obtain a plottable data file, and a curve of energy change over time is plotted.

9. The method for analyzing the insulation aging mechanism of the UHV converter transformer valve-side outgoing line device according to claim 1, characterized in that, In step S9, the strength, direction, and form of the applied electric field are determined. In the molecular dynamics simulation program, the electric field is applied using... Calculate the additional force applied to each charged atom and add that additional force to the interatomic interaction force.

10. An analysis system for the insulation aging mechanism of the valve-side outgoing line device of an ultra-high voltage converter transformer, characterized in that, The system includes: The sample preparation module is used to pre-treat the insulation material of the UHV converter transformer valve side outgoing line device according to the differential aging strategy and to pre-set insulation material samples. A spectral acquisition module is used to acquire near-infrared spectra of the search insulation material sample, and the spectral acquisition module is connected to the sample preparation module; The insulating paper model building module is used to build an insulating paper cellulose model based on preset polymerization degree data; An insulating paper model optimization module is used to optimize the atomic positions of the insulating paper cellulose model using the conjugate gradient method. The insulating paper model optimization module is connected to the insulating paper model construction module. An insulating paper model structure optimization module is used to optimize the structure of the insulating paper cellulose model using a simulated annealing algorithm to obtain a suitable insulating paper cellulose model. The insulating paper model structure optimization module is connected to the insulating paper model construction module. A molecular dynamics simulation module is used to perform molecular dynamics simulations on the applicable insulating paper cellulose model, and the molecular dynamics simulation module is connected to the insulating paper model structure optimization module; The temperature simulation module is used to simulate temperature using the Nose temperature control method, and records the trajectory files and topology files of all atomic coordinates and velocities for each frame during the simulation process; The dielectric constant numerical comparison module is used to calculate the dipole moment based on the atomic charges and coordinates in the topology file, perform molecular dynamics (MD) analysis based on the trajectory file, observe the changes in dielectric constant and system energy, and obtain the comparison results of dielectric constant values ​​at different times and system energy change data. The dielectric constant numerical comparison module is connected to the temperature simulation module. The chemical bond change analysis module is used to apply a strong electric field as an external disturbance source and use the near-infrared spectrum to analyze and obtain the results of chemical bond changes. The chemical bond change analysis module is connected to the dielectric constant value comparison module. The summary and analysis module is used to summarize and analyze the changes in dielectric constant, system energy, and chemical bonds of the insulating paper sample under the differential aging strategy based on the comparison results of dielectric constant values ​​at different times, the system energy change data, and the chemical bond change results. The summary and analysis module is connected to the dielectric constant value comparison module and the chemical bond change analysis module.

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