Method for repairing contact damage through cooperation of pre-breakdown arc and hammering of vacuum circuit breaker

Abstract

The invention discloses a method for repairing contact damage through cooperation of pre-breakdown arc and hammering of a vacuum circuit breaker. The method comprises the steps that a damage mode is defined according to the use stage of a contact; establishing a dynamic evolution model of a switching-on pre-breakdown arc and a damage area, and obtaining the energy flux density and temperature on the surface of an electrode as initial conditions of mechanical hammering; a hammering model is constructed according to the deformation values, the deformation values of the contact under hammering in different damage modes are analyzed, and the movable dislocation density is obtained; on the basis of the density, analyzing the influence of dislocation configuration on mechanical properties, and constructing a microcosmic and macroscopic combined damage / repair evaluation system; an ideal hammering load capable of enabling the repaired contact to meet the requirement is determined through a pre-breakdown simulation experiment; a double-closed-loop hammering load self-regulation system is designed to carry out optimal cooperative regulation on the actual electric arc and the hammering load, so that the load tends to an ideal value to repair the contact until the requirement of the evaluation system is met; the surface damage of the contact can be repaired, and passive tolerance of the vacuum circuit breaker is changed into active repair.

Description

Technical Field

[0001] This invention relates to the field of vacuum circuit breaker contact surface modification technology, and in particular to a method for repairing contact damage in vacuum circuit breakers in conjunction with pre-breakdown arc and hammering. Background Technology

[0003] Existing research indicates that the main factors inducing re-breakdown include residual metal vapor and charged particles between contacts, adhesion of metal particles to the contact surface, and microscopic protrusions in the contacts themselves. Damage to the contact surface is a significant cause of these abnormalities and the most important factor affecting the probability of re-breakdown. Extensive practical statistics show that the re-breakdown rate of vacuum circuit breakers is high in the early stages of operation; however, as the number of opening and closing cycles increases, the re-breakdown rate caused by initial defects can rapidly decrease and stabilize. Previous practical experience by the project team shows that closing operations dominated by the pre-breakdown high-frequency inrush current closing process can significantly improve and repair contact surface damage defects and reduce the probability of re-breakdown. However, using the pre-breakdown arc generated by closing the capacitor bank to repair the contact surface has its unique characteristics: firstly, the closing inrush current frequency is high (kHz level), which causes high-frequency switching between the anode and cathode of the moving and stationary contacts; secondly, the pre-breakdown opening distance is short, the arcing time is short, and it disappears as the moving and stationary contacts come into contact; and thirdly, the inrush current amplitude with repair effect is relatively low. Under these conditions, how the contact surface develops and evolves, what the intrinsic relationship is between its evolution and the repair effect, and more importantly, how to ensure that the contacts do not exhibit severe ablation and arc cratering while simultaneously utilizing the effects of arc heating, electron and ion bombardment to repair the contact surface, all require further research. Previous studies on vacuum circuit breakers for capacitor banks have focused on contact ablation and post-breakdown re-breakdown, resulting in traditional vacuum circuit breakers only being able to passively withstand arc ablation and weld zone fracture, and being unable to dynamically repair themselves within the lifespan of the vacuum circuit breaker to maintain stable breaking performance. Summary of the Invention

[0004] This invention provides a method for repairing contact damage in a vacuum circuit breaker by combining pre-breakdown arc and hammer impact, thereby overcoming the aforementioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for repairing contact damage in a vacuum circuit breaker using a combination of pre-breakdown arcing and hammer impact includes: S1: Define different categories of damage modes on the surface of vacuum circuit breaker contacts according to different service stages of vacuum circuit breaker contacts; S2: Under the defined damage mode environment, establish a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment, as the initial conditions for the mechanical hammering effect. S3: Based on the initial conditions of the mechanical hammering effect, establish a hammering model of a typical damaged area after interaction with a vacuum arc. Use the mechanical hammering model to analyze the deformation of the contact during hammering under different types of damage modes in order to obtain the density of movable dislocations. S4: Based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of the contact is analyzed, and a damage / repair evaluation system is constructed. A pre-breakdown simulation experiment is conducted on the contact to determine the ideal hammer load for contact repair so that the repaired contact meets the requirements of the damage / evaluation system. S5: The hammer load self-sensing and self-regulating system adopts a dual closed-loop structure design to optimally coordinate and regulate the actual injected arc and hammer load, so that the hammer load tends to the ideal hammer load, repairing the contact surface until it meets the requirements of the damage / evaluation system, and completing the contact repair.

[0006] Furthermore, under the defined damage mode environment, a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface is established to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment, including: S21. Combining the three fundamental equations of fluid dynamics and Maxwell's equations, the control equations of the vacuum arc in cylindrical coordinates are derived, as shown in formulas (1)-(4). (1) (2) (3) (4) In the formula, Ion density; For electron and ion velocities; Indicates time; Current density; B The self-generated circumferential magnetic induction intensity; It is a constant pressure heat capacity; These are the ion temperature and the electron temperature, respectively. For electron and ion pressure; The heat flux density of electrons and ions; It is an electronic thermal term; It is the ionic viscous stress tensor; It is an ionic viscous heat source. It serves as a heat source for collisions between ions and electrons; Current density is obtained by combining Maxwell's equations and generalized Ohm's law. and self-generated circumferential magnetic induction intensity B As shown in formulas (5)-(8), (5) (6) (7) (8) In the formula, For the Nabla operator, Volume charge density; The permeability of free space, The vacuum permittivity, Electric field strength; S22. Calculate the energy flux density injected into the anode and cathode according to the vacuum arc control equation. The specific steps are as follows: Formulas for calculating ion density and electron density are constructed, as shown in formulas (9) and (10). (9) (10) in, For ion mass. The average charge of the ions; The energy flux density of the anode is constructed as shown in formulas (11)-(13). (11) (12) (13) In the formula, The energy flux density injected into the anode by electrons; The longitudinal component of the electron velocity; Boltzmann's constant; The work function of electrons; This represents the energy flux density injected by ions into the anode. Ion density; This represents the longitudinal component of the ion velocity. Unit charge; The average charge of the ions; The potential drop of the anode sheath; It is the anodic ionization energy; This is the energy for anodic evaporation; Electron density; For ion mass, The energy flux density at the anode surface; The energy flux density of the cathode is constructed as shown in equations (14)-(18). (14) (15) (16) (17) (18) In the formula, The energy flux density at the cathode surface. The energy flux density of electrons injected into the cathode. This represents the energy flux density of ions injected into the cathode. The thermionic emission energy flux density, The energy flux density of evaporation at the cathode surface. The potential drops in the cathode region; This is the cathode condensation energy; This represents the metal evaporation flux. This represents the thermionic emission current density. S23. Using the three fundamental equations of fluid dynamics and energy flux density, establish a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface, as shown in formulas (19)-(21). (19) (20) (twenty one) In the formula, Density of the electrode material; For the electrode material velocity; For pressure; The current density flowing into the electrode; The specific heat of the electrode; The electrode temperature; The thermal conductivity of the electrode; The energy flux density injected onto the electrode surface varies depending on the electrode, i.e. and .

[0007] Furthermore, based on the initial conditions of the mechanical hammering effect, a hammering model of a typical damaged area after interaction with a vacuum arc is established. The mechanical hammering model is used to analyze the deformation of the contact during hammering under different damage modes to obtain the density of movable dislocations, including: S31. Calculate the equivalent hammer load of a typical damage area based on the moving contact speed, overtravel pressure, and the mass of the moving parts rigidly connected to the contact. F ; S32. Based on the equation of motion and Hook's law, according to the stress-strain curves of the contact material at different temperatures, the stress distribution and deformation equations of the damaged area on the contact surface after the pre-breakdown arc process are constructed, and the deformation of the contact surface after mechanical hammering is obtained, as shown in formulas (22)-(23). (twenty two) (twenty three) In the formula, This refers to the contact displacement; This is the equivalent hammer impact load; For stress; Young's modulus; This represents the total deformation of the contact surface; The density of the contact material at temperature T This represents the Young's modulus of the contact material at temperature T. S33. Based on the total deformation of the contact surface obtained in S32, construct a physical model of the movable dislocation density and total deformation, as shown in formula (24). (twenty four) in, The density of movable dislocations; It is a proportionality constant; It is the Bergman vector; This represents the dislocation motion rate.

[0008] Furthermore, based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of the contact is analyzed, thereby constructing a damage / repair evaluation system, including: S41. In terms of microstructure, based on the physical model of strain rate and movable dislocation density and crystal plasticity theory, the relationship between yield strength and movable dislocation density of contact material is obtained in order to analyze the influence of dislocation configuration on the mechanical properties of contact, so that the repaired contact meets the numerical requirements of yield strength. The relationship between the yield strength of the contact material and the density of movable dislocations is shown in formula (25). (25) in, Yield strength; It is lattice friction; It is a constant; b is the shear modulus; b is the Burgers vector. The density of movable dislocations; S42. In terms of macroscopic morphology, the peak and valley characteristics and the average height of the core area of ​​the contact surface are described by the number of peaks and valleys and the average peak spacing. Based on the peak and valley characteristics and the average height of the core area, the roughness of the contact surface used to evaluate the complexity of the morphology is calculated, so that the repaired contact meets the roughness requirements.

[0009] Furthermore, a self-sensing and self-regulating system for hammer impact load is designed using a dual closed-loop structure, including: S51. Design a load self-sensing loop, i.e., a hammer load self-sensing system, to obtain the actual hammer load of the contact. The self-sensing system includes a flux linkage observer, a PMA, and a load observer. The load observer includes a velocity observer and a hammer load observer. The flux linkage observer and PMA are used to input the coil voltage and current generated when the vacuum circuit breaker is opened and closed to the velocity observer for acceleration calculation, as shown in formulas (26) and (27). (26) (27) in, The voltage across the coil; The coil current; The coil resistance; For coil flux; The electromagnetic force on the moving iron core; according to the equivalent magnetic circuit equation, It is a function of position, current, and rate of change of magnetic flux derived from the equivalent magnetic circuit equation; For displacement; The velocity of the moving iron core; according to the voltage balance equation and the law of electromagnetic induction, It is a function of position, magnetic flux, and rate of change of magnetic flux, derived from the voltage balance equation and the law of electromagnetic induction. The load reaction force refers to the gravity, the reaction force of the trip spring, and the friction force acting on the moving parts; The function is used to describe the switching between the excitation and motion phases in d'Alembert's equations of motion; For the mass of the moving parts of the permanent magnet operating mechanism; For magnetic linkage; The hammer load observer is used to calculate the actual hammer load based on the moving core speed output by the mass and speed observer of the moving parts of the permanent magnet operating mechanism, and inputs the actual hammer load into the self-regulating system. The actual hammer load is shown in formula (28). (28) In the formula: For hammer impact load, For the mass of the moving parts of the permanent magnet operating mechanism. For closing speed, The contact area is... This refers to the closing collision time; S52. Design a load self-regulating loop, i.e., a hammer load self-regulating system, to compare the actual hammer load with the ideal hammer load, and based on the comparison result, enable the actual hammer load to dynamically track the ideal hammer load, i.e., adjust the actual hammer load to approach the value of the ideal hammer load. The self-regulating system includes a load tracker, an inner loop tracker, and a magnetic flux observer shared with the self-sensing system. The load tracker is used to calculate the error between the input ideal hammer load and the actual hammer load output by the hammer load observer, and to track the ideal coil flux to the ideal hammer load based on the error calculation, and input it to the inner loop tracker. The flux observer, shared with the self-sensing system, is used to input the actual coil flux into the inner loop tracker to track the ideal coil flux. The inner loop tracker is used to calculate the flux linkage error between the ideal coil flux linkage and the actual coil flux linkage, and calculates the ideal voltage based on the flux linkage error. The ideal voltage is then input into the PMA in the self-sensing system so that the actual coil voltage tracks the ideal voltage, thereby enabling the actual moving iron core speed to track the ideal moving iron core speed corresponding to the ideal hammer load. This allows the actual hammer load to be adjusted to approach the value of the ideal hammer load, as shown in formula (29). (29) in, They represent the coil flux linkages respectively. Speed ​​of movement of the moving iron core and motion displacement The state vector, Indicates coil flux The velocity v and displacement of the moving iron core , is the state vector; Indicates the position of the moving contact. This indicates the coil voltage.

[0010] Beneficial Effects: This invention provides a method for the coordinated repair of contact damage in vacuum circuit breakers using a pre-breakdown arc and mechanical hammering. Based on a clear understanding of the overlapping effects of the pre-breakdown arc and mechanical hammering on the contact surface, it maximizes the continuous repair of contact surface damage and reduces the probability of re-breakdown, transforming the vacuum circuit breaker from a traditional passive withstand mechanism to an active repair mechanism. The research results provide a new approach to reducing the probability of re-breakdown in vacuum circuit breakers for capacitor banks in 500kV and below power grids. This is of great significance for improving the performance indicators of next-generation vacuum circuit breakers and ensuring the safe and stable operation of the power grid in the future. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0012] Figure 1 A flowchart of a method for repairing contact damage of a vacuum circuit breaker by coordinating pre-breakdown arc during closing and mechanical hammering, provided in an embodiment of the present invention; Figure 2 A three-dimensional structural diagram of manufacturing defect type damage provided for an embodiment of the invention; Figure 3 The simulation results of the vacuum arc provided for the embodiments of the invention; Figure 4 A flowchart of the contact surface condition evaluation system provided for embodiments of the invention; Figure 5 A flowchart for determining the ideal load for contact surface repair provided in the embodiments of the invention; Figure 6 Design diagram of a self-sensing and self-regulating system provided for embodiments of the invention. Detailed Implementation

[0013] 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.

[0014] This embodiment provides a method for repairing contact damage in a vacuum circuit breaker through a combination of pre-breakdown arc during closing and mechanical hammering. Figure 1 As shown, it includes: S1: Define different categories of damage modes on the surface of vacuum circuit breaker contacts according to different service stages of vacuum circuit breaker contacts; S2: Under the defined damage mode environment, establish a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment, as the initial conditions for the mechanical hammering effect. S3: Based on the initial conditions of the mechanical hammering effect, establish a hammering model of a typical damaged area after interaction with a vacuum arc. Use the mechanical hammering model to analyze the deformation of the contact during hammering under different types of damage modes in order to obtain the density of movable dislocations. S4: Based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of the contact is analyzed, and a damage / repair evaluation system is constructed. A pre-breakdown simulation experiment is conducted on the contact to determine the ideal hammer load for contact repair so that the repaired contact meets the requirements of the damage / evaluation system. S5: The hammer load self-sensing and self-regulating system adopts a dual closed-loop structure design to optimally coordinate and regulate the actual injected arc and hammer load, so that the hammer load tends to the ideal hammer load, repairing the contact surface until it meets the requirements of the damage / evaluation system, and completing the contact repair.

[0015] Specifically, this invention defines different damage modes for the contact surface; establishes a dynamic evolution model of the pre-breakdown arc during closing and typical areas of the contact surface to obtain the variation laws of contact surface morphology, phase transition, and physical property parameters, and clarifies the initial conditions of the mechanical hammering effect; establishes a mechanical hammering model to analyze the deformation evolution law of the contact during the hammering process under different damage modes; establishes a damage / repair evaluation system to clarify the critical range of each parameter with repair effect, and formulates an ideal hammering load suitable for the repair of the contact surface of capacitor bank vacuum circuit breakers; and designs a self-sensing and self-regulating hammering load system to achieve optimal coordinated control of the injected arc energy and hammering load at any time. This invention aims to explore a new methodological system to continuously repair contact surface damage to the greatest extent possible throughout the entire life cycle, reduce the probability of re-breakdown, and transform vacuum circuit breakers from traditional passive withstand to active repair. It provides a new approach to reducing the probability of re-breakdown of capacitor bank vacuum circuit breakers in 500kV and below power grids.

[0016] In a specific embodiment, the scheme for defining different categories of damage modes on the surface of vacuum circuit breaker contacts according to different stages of use of the vacuum circuit breaker contacts is as follows: Contact surfaces often exhibit various damage modes, including manufacturing defects, arc erosion, and weld zone fracture. These modes differ in their interaction with the arc and their spatial scale. Therefore, based on the morphological characteristics of different damage modes, representative damage regions are selected using fractal theory. The three-dimensional morphological data of these selected regions are obtained, defining the physical structure and initial state of the damaged regions on the contact surface. Manufacturing defects on the contact surface, such as… Figure 2 As shown.

[0017] In a specific embodiment, under the defined damage mode environment, a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface is established to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment. The scheme for the initial condition of the mechanical hammering effect is as follows: S21. Combining the three fundamental equations of fluid dynamics and Maxwell's equations, the control equations of the vacuum arc in cylindrical coordinates are derived, as shown in formulas (30)-(33). (30) (31) (32) (33) In the formula, Ion density; For electron and ion velocities; Indicates time; Current density; B The self-generated circumferential magnetic induction intensity; It is a constant pressure heat capacity; These are the ion temperature and the electron temperature, respectively. For electron and ion pressure; The heat flux density of electrons and ions; It is an electronic thermal term; It is the ionic viscous stress tensor; It is an ionic viscous heat source. The vacuum arc acts as a heat source for ion-electron collisions. Unlike typical metallic media, the current density of a vacuum arc is affected not only by the electromagnetic field but also by fluid pressure gradients, temperature gradients, and the Hall effect. Simulation results for vacuum arcs are as follows: Figure 3 As shown, this scheme adopts the three fundamental equations of fluid dynamics, namely the mass conservation equation, the momentum conservation equation, and the energy conservation equation, and derives the vacuum arc control equation in cylindrical coordinates by combining Maxwell's equations. The electric and magnetic fields of a vacuum arc are strongly coupled, which has a certain influence on the plasma flow state and plasma characteristic parameters. Current density and magnetic induction intensity The current density can be obtained from Maxwell's equations and generalized Ohm's law. Therefore, this scheme combines Maxwell's equations and generalized Ohm's law to obtain the current density. and self-generated circumferential magnetic induction intensity As shown in formulas (34)-(37), (34) (35) (36) (37) In the formula, For the Nabla operator, Volume charge density; The permeability of free space, The vacuum permittivity, Electric field strength; S22. Calculate the energy flux density injected into the anode and cathode according to the vacuum arc control equation. The specific steps are as follows: Formulas for calculating ion density and electron density are constructed, as shown in formulas (38) and (39). (38) (39) in, For ion mass, The average charge of the ions; The energy flux density of the anode is constructed as shown in formulas (40)-(42). (40) (41) (42) In the formula, The energy flux density injected into the anode by electrons; The longitudinal component of the electron velocity; Boltzmann's constant; The work function of electrons; This represents the energy flux density injected by ions into the anode. Ion density; This represents the longitudinal component of the ion velocity. Unit charge; The average charge of the ions; The potential drop of the anode sheath; It is the anodic ionization energy; This is the energy for anodic evaporation; Electron density; For ion mass, The energy flux density at the anode surface; The energy flux density of the cathode is constructed as shown in formulas (43)-(47). (43) (44) (45) (46) (47) In the formula, The energy flux density at the cathode surface. The energy flux density of electrons injected into the cathode. This represents the energy flux density of ions injected into the cathode. The thermionic emission energy flux density, The energy flux density of evaporation at the cathode surface. The potential drops in the cathode region; This is the cathode condensation energy; This represents the metal evaporation flux. This represents the thermionic emission current density. S23. The dynamic evolution model mainly describes the temperature rise and phase change process of the damaged area on the contact surface during the pre-breakdown arc. Therefore, fluid equations, including the mass equation, momentum equation and heat transfer equation, are also used to describe this physical process. That is, the three basic equations of fluid dynamics and energy flow density are used to establish the dynamic evolution model of the pre-breakdown arc and typical areas on the contact surface, as shown in formulas (48)-(50). (48) (49) (50) In the formula, Density of the electrode material; For the electrode material velocity; For pressure; The current density flowing into the electrode; The specific heat of the electrode; The electrode temperature; The thermal conductivity of the electrode; The energy flux density injected onto the electrode surface varies depending on the electrode, i.e. and .

[0018] There are two interfaces between the vacuum arc and the contact: the arc-cathode interface and the arc-anode interface. Energy exchange between the arc and the contact is realized by constructing a vacuum arc model and a contact dynamic evolution model. The overall solution environment can rely on computational fluid dynamics software, and the equations are discretized using the finite element method. The time, temperature, pressure and velocity mentioned in the equations are adjusted according to the defined damage mode environment. When obtaining different types of damage modes on the contact surface, the three-dimensional morphology data are simulated. Simulation software is a common technique used by those skilled in the art. During the simulation process, the values ​​of electrode material density, electric field strength and other values ​​that change with different environments can be obtained through simulation software.

[0019] In a specific embodiment, a hammering model of a typical damaged area after interaction with a vacuum arc is established based on the initial conditions of the mechanical hammering effect. The mechanical hammering model is then used to analyze the deformation of the contact during hammering under different types of damage modes to obtain the movable dislocation density. The scheme is as follows: S31. Calculate the equivalent hammer load of a typical damage area based on the moving contact speed, overtravel pressure, and the mass of the moving parts rigidly connected to the contact. F The load F can be obtained through dynamic analysis (such as applying the momentum theorem), which is a conventional technical means of solving engineering problems using classical mechanics principles. Those skilled in the art know how to calculate the load based on velocity, pressure, and mass, so the specific calculation process will not be elaborated here. S32. Based on the equation of motion and Hook's law, according to the stress-strain curves of the contact material at different temperatures, the stress distribution and deformation equations of the damaged area on the contact surface after the pre-breakdown arc process are constructed, and the deformation of the contact surface after mechanical hammering is obtained, as shown in formulas (51)-(52). (51) (52) In the formula, This refers to the contact displacement; This is the equivalent hammer impact load; For stress; Young's modulus; This represents the total deformation of the contact surface; The density of the contact material at temperature T This represents the Young's modulus of the contact material at temperature T. Therefore, the hammering depth, hammering radius, stress distribution, and deformation can be calculated for different damage modes after being subjected to a pre-breakdown arc and mechanical hammering.

[0020] S33. Based on the total deformation of the contact surface obtained in S32, construct a physical model of the movable dislocation density and total deformation, as shown in formula (53). (53) in, The density of movable dislocations; It is a proportionality constant; It is the Bergman vector; This represents the dislocation motion rate.

[0021] By using a hammer impact model, the density of movable dislocations was analyzed to determine the deformation, establishing a direct correlation between macroscopic repair behavior and microscopic material evolution. This enabled the "predictable and designable" repair effect. The model can predict what kind of dislocation structure will be generated inside the material when a specific hammer impact is applied to a specific arc damage. Before implementing the repair, the model can simulate the effects under different hammer impact parameters (force, speed, number of impacts) to select the optimal parameters and achieve "forward design" of the repair process.

[0022] In a specific embodiment, based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of the contact is analyzed, and a damage / repair evaluation system is constructed. A pre-breakdown simulation experiment is then conducted on the contact to determine the ideal hammer load for contact repair so that the repaired contact meets the requirements of the damage / evaluation system. S41. In terms of microstructure, based on the physical model of strain rate and movable dislocation density and crystal plasticity theory, the relationship between yield strength and movable dislocation density of contact material is obtained in order to analyze the influence of dislocation configuration on the mechanical properties of contact, so that the repaired contact meets the numerical requirements of yield strength. The relationship between the yield strength of the contact material and the density of movable dislocations is shown in formula (54). (54) in, Yield strength; It is lattice friction; It is a constant; b is the shear modulus; b is the Burgers vector. This refers to the density of movable dislocations; an increase in the density of movable dislocations leads to a significant improvement in its strength and hardness. S42. In terms of macroscopic morphology, the peak and valley characteristics and the average height of the core area of ​​the contact surface are described by the number of peaks and valleys and the average peak spacing. Based on the peak and valley characteristics and the average height of the core area, the roughness of the contact surface used to evaluate the complexity of the morphology is calculated, so that the repaired contact meets the roughness requirements. A pre-breakdown simulation experiment was conducted on the contacts. This scheme uses a breakdown gap measurement test circuit to evaluate the contact insulation withstand voltage level. The specific evaluation process is as follows: Figure 4 As shown, First, the contacts to be evaluated are removed from the capacitor bank vacuum circuit breaker for dual-path analysis: Path A: Perform the above analysis on the influence of dislocation configuration on the mechanical properties of the contact and evaluate the complexity of its morphology; Path B: Circuit for determining breakdown distance Figure 4 The bottom circuit is the test circuit, which consists of a high-voltage DC power supply, a current-limiting resistor R5, a high-voltage probe, a CB switch, and a detachable arc-extinguishing chamber (with built-in test contact pair and adjustable variable opening distance). The high-voltage probe is used to monitor the voltage. With the contacts fixed, gradually increase their spacing (breakdown gap), apply a standard lightning impulse voltage (or DC high voltage) multiple times at each gap, and record the probability of breakdown.

[0023] Data analysis: Organize the experimental data and plot a statistical curve (usually conforming to a Weibull distribution) with "breakdown gap / mm" as the x-axis and "compensation cumulative probability%" (i.e., breakdown probability) as the y-axis.

[0024] Results: This curve directly characterizes the "insulation withstand voltage characteristics" of the contact. A rightward shift of the curve (i.e., a larger breakdown gap under the same probability) indicates better insulation performance. Therefore, the effectiveness of the contact can be evaluated through pre-breakdown simulation tests, and the performance of the repaired contact can be determined through these tests. Figure 4 The standard.

[0025] The ideal hammer load for contact repair was determined using pre-breakdown simulation tests, such as... Figure 5 As shown, Part 1: Forward Deduction 1. Establish a quantitative relationship between "phase → inrush flow → opening distance". As shown in the circuit diagram, when the capacitor bank is switched on and off, the power supply voltage is at different pre-breakdown phases at the instant of closing; different phase angles directly determine the amplitude of the inrush current. In a vacuum interrupter, whether a certain contact gap can be broken down depends on the gap electric field strength, which is related to voltage (the instantaneous value is determined by phase) and current. Therefore, the minimum gap required for breakdown under a specific inrush current, i.e., the "pre-breakdown gap", can be calculated using electromagnetic field and plasma physics models. Calculating the minimum gap required for breakdown under a specific inrush current using electromagnetic field and plasma physics models is a conventional technique in the fields of vacuum insulation and arc physics, and those skilled in the art know how to perform the calculation to obtain the results. 2. Establish the relationship between "arc burning time" and speed and opening distance. Given the contact opening distance and the moving contact velocity at the moment of pre-breakdown. From the moment of pre-breakdown until the contacts are fully closed (opening distance is zero), the arc exists continuously. Therefore, the arcing time is the time required for the contacts to move across the contact opening distance at a given speed. The energy injected into the arc can be described by the pre-breakdown phase and the velocity of the moving contact. The calculation method is a common technique used by those skilled in the art, therefore the specific calculation formula will not be explained. The results are as follows: Figure 5 As shown in the mid-curved surface; Part Two: Reverse Constraints Objective: To achieve "optimal synergistic repair," meaning the best possible combination of hammering and electric arc. This requires the injected arc energy to be within an ideal range; too high an energy level will cause new damage, while too low an energy level will render the repair ineffective.

[0026] In the simulation of the breakdown distance measurement test, different arc energies are input for "virtual repair" to predict the performance of the contact after repair and compare it with the results. Figure 4The evaluation criteria were compared to determine the minimum and maximum energies at which the "insulation withstand voltage characteristic curve" of the contact began to show measurable improvement, which served as numerical constraints on the arc energy. Constraining the speed of the moving contact is a conventional technique for those skilled in the art, therefore the determination method will not be described in detail. Geometrizing the feasible region under constraints: exist Figure 5 In the 3D surface diagram, the surface is intercepted by two planes with maximum and minimum energy, and simultaneously constrained in the velocity direction by two planes with maximum and minimum velocity. After interception, there are six planes that enclose a cuboid region in space. This cuboid represents the set of all points that simultaneously satisfy the energy and velocity constraints, i.e., the feasible region.

[0027] This transparent "cubic prism" intersects with the "energy surface" at a point in space. Each point on this curve represents a combination of phase, velocity, and energy that can be physically realized (on the surface) and also satisfies the engineering constraints (within the cuboid).

[0028] Projecting this three-dimensional spatial intersection line onto the "pre-breakdown phase" coordinate axis yields one or more projection intervals.

[0029] The "optimal pre-breakdown phase window" is the shortest and most concentrated segment within this projection interval. The control switch operates when the grid voltage phase is within this window, ensuring that the generated arc energy automatically meets the "ideal range" while the speed is also within a feasible range, thus providing perfect and controllable thermal pretreatment conditions for subsequent precise mechanical hammering repair.

[0030] In the pre-breakdown simulation experiment, the repair effect is comprehensively judged by analyzing the density of movable dislocations generated inside the contact under different hammer loads and their effect on improving the yield strength, as well as the degree of repair on the surface morphology. Finally, the ideal hammer load scheme that can make the repaired contact simultaneously meet the target yield strength and surface roughness requirements is determined. Therefore, this scheme constructs an evaluation system for damage repair by analyzing the movable dislocation density, and obtains the ideal hammer load that meets the repair requirements. This scheme establishes an evaluation standard centered on the intrinsic properties of materials. The constructed evaluation system is directly related to dislocation configuration, a fundamental factor that determines the strength, toughness, and fatigue life of materials, making the evaluation more essential and scientific.

[0031] The repair process is "pre-tested" and optimized in the digital space: through pre-breakdown simulation experiments, a large number of hammering parameter combinations are traversed in the computer. Using the evaluation system as the criterion, the "ideal hammering load" is automatically optimized and the theoretical optimal solution is found. This greatly reduces the cost, risk and blindness of physical tests and ensures the ideality of the repair effect.

[0032] In a specific embodiment, such as Figure 6 As shown, a self-sensing and self-regulating system for hammer load is designed with a dual closed-loop structure. This system optimally coordinates the actual injected arc and the hammer load to bring the hammer load closer to the ideal hammer load, thereby repairing the contact surface until it meets the requirements of the damage / evaluation system. The contact repair scheme is as follows: S51. Design a load self-sensing loop, i.e., a hammer load self-sensing system, to obtain the actual hammer load of the contact. The self-sensing system includes a flux linkage observer, a PMA, and a load observer. The load observer includes a velocity observer and a hammer load observer. The flux linkage observer and PMA are used to input the coil voltage and current generated when the vacuum circuit breaker is opened and closed to the velocity observer for acceleration calculation, as shown in formulas (55) and (56). (55) (56) in, The voltage across the coil; The coil current; The coil resistance; For coil flux; The electromagnetic force on the moving iron core; according to the equivalent magnetic circuit equation, The solution is a common technique in the field of electromagnet design, which is derived from the equivalent magnetic circuit equation as a function of position, current, and flux change rate. For displacement; The velocity of the moving iron core; according to the voltage balance equation and the law of electromagnetic induction, The function of position, flux linkage, and rate of change of flux linkage is derived from the voltage balance equation and the law of electromagnetic induction. The solution process is a common technique in the field of electromagnet design. The load reaction force refers to the gravity, the reaction force of the trip spring, and the friction force acting on the moving parts; The function is used to describe the switching between the excitation and motion phases in d'Alembert's equations of motion; For the mass of the moving parts of the permanent magnet operating mechanism; For magnetic linkage; The hammer load observer is used to calculate the actual hammer load based on the moving core speed output by the mass and speed observer of the moving parts of the permanent magnet operating mechanism, and inputs the actual hammer load into the self-regulating system. The actual hammer load is shown in formula (57). (57) In the formula: For hammer impact load, For the mass of the moving parts of the permanent magnet operating mechanism. For closing speed, The contact area is... This refers to the closing collision time; S52. Design a load self-regulating loop, i.e., a hammer load self-regulating system, to compare the actual hammer load with the ideal hammer load, and based on the comparison result, enable the actual hammer load to dynamically track the ideal hammer load, i.e., adjust the actual hammer load to approach the value of the ideal hammer load. The self-regulating system includes a load tracker, an inner loop tracker, and a magnetic flux observer shared with the self-sensing system. The load tracker is used to calculate the error between the input ideal hammer load and the actual hammer load output by the hammer load observer, and to track the ideal coil flux to the ideal hammer load based on the error calculation, and input it to the inner loop tracker. The flux observer, shared with the self-sensing system, is used to input the actual coil flux into the inner loop tracker to track the ideal coil flux. These are all common technical methods in the field of motors and motion control. Those skilled in the art can know how to perform the calculations, so the formulas will not be described in detail. The inner loop tracker is used to calculate the flux linkage error between the ideal coil flux linkage and the actual coil flux linkage, and calculates the ideal voltage based on the flux linkage error. The ideal voltage is then input into the PMA in the self-sensing system so that the actual coil voltage tracks the ideal voltage, thereby enabling the actual moving iron core speed to track the ideal moving iron core speed corresponding to the ideal hammer load. This allows the actual hammer load to be adjusted to approach the value of the ideal hammer load, as shown in formula (58). (58) in, They represent the coil flux linkages respectively. Speed ​​of movement of the moving iron core and motion displacement The state vector, Indicates coil flux The velocity v and displacement of the moving iron core , is the state vector; Indicates the position of the moving contact. This indicates the coil voltage.

[0033] This solution achieves a closed loop from "theoretical optimality" to "precise execution in practice": the dual closed-loop control system can overcome uncertainties such as friction, inertia, and disturbances in the actual system, ensuring that the actual applied hammer load stably and accurately approaches this ideal value; It is adaptive: the system can sense the actual injected arc energy and the applied hammering effect in real time and compare it with the model prediction and evaluation system. Once a deviation occurs, it can automatically adjust the subsequent hammering strategy to ensure that the predetermined repair standard can be achieved under different working conditions, with extremely high reliability.

[0034] 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; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for repairing contact damage in a vacuum circuit breaker using a combination of pre-breakdown arc and hammer impact, characterized in that, include: S1: Define different categories of damage modes on the surface of vacuum circuit breaker contacts according to different service stages of vacuum circuit breaker contacts; S2: Under the defined damage mode environment, establish a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment, as the initial conditions for the mechanical hammering effect. S3: Based on the initial conditions of the mechanical hammering effect, establish a hammering model of a typical damaged area after interaction with a vacuum arc. Use the mechanical hammering model to analyze the deformation of the contact during hammering under different types of damage modes in order to obtain the density of movable dislocations. S4: Based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of the contact is analyzed, and a damage / repair evaluation system is constructed. A pre-breakdown simulation experiment is conducted on the contact to determine the ideal hammer load for contact repair so that the repaired contact meets the requirements of the damage / evaluation system. S5: The hammer load self-sensing and self-regulating system adopts a dual closed-loop structure design to optimally coordinate and regulate the actual injected arc and hammer load, so that the hammer load tends to the ideal hammer load, repairing the contact surface until it meets the requirements of the damage / evaluation system, and completing the contact repair.

2. The method for repairing contact damage in a vacuum circuit breaker using a pre-breakdown arc and hammer impact in synergistic repair according to claim 1, characterized in that, Under the defined damage mode environment, a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface is established to obtain the energy flux density and electrode temperature of the injected electrode surface in the typical damage area under the damage mode environment, including: S21. Combining the three fundamental equations of fluid dynamics and Maxwell's equations, the control equations of the vacuum arc in cylindrical coordinates are derived, as shown in formulas (1)-(4). （1） （2） （3） （4） In the formula, Ion density; For electron and ion velocities; Indicates time; Current density; B The self-generated circumferential magnetic induction intensity; It is a constant pressure heat capacity; These are the ion temperature and the electron temperature, respectively. For electron and ion pressure; The heat flux density of electrons and ions; It is an electronic thermal term; It is the ionic viscous stress tensor; It is an ionic viscous heat source. It serves as a heat source for collisions between ions and electrons; Current density is obtained by combining Maxwell's equations and generalized Ohm's law. and self-generated circumferential magnetic induction intensity B As shown in formulas (5)-(8), （5） （6） （7） （8） In the formula, For the Nabla operator, Volume charge density; The permeability of free space, The vacuum permittivity, Electric field strength; S22. Calculate the energy flux density injected into the anode and cathode according to the vacuum arc control equation. The specific steps are as follows: Formulas for calculating ion density and electron density are constructed, as shown in formulas (9) and (10). （9） （10） in, For ion mass, The average charge of the ions; The energy flux density of the anode is constructed as shown in formulas (11)-(13). （11） （12） （13） In the formula, The energy flux density injected into the anode by electrons; The longitudinal component of the electron velocity; Boltzmann's constant; The work function of electrons; This represents the energy flux density injected by ions into the anode. Ion density; This represents the longitudinal component of the ion velocity. Unit charge; The average charge of the ions; The potential drop of the anode sheath; It is the anodic ionization energy; This is the energy for anodic evaporation; Electron density; For ion mass, The energy flux density at the anode surface; The energy flux density of the cathode is constructed as shown in equations (14)-(18). （14） （15） （16） （17） （18） In the formula, The energy flux density at the cathode surface. The energy flux density of electrons injected into the cathode. This represents the energy flux density of ions injected into the cathode. The thermionic emission energy flux density, The energy flux density of evaporation at the cathode surface. The potential drops in the cathode region; This is the cathode condensation energy; This represents the metal evaporation flux. This represents the thermionic emission current density. S23. Using the three fundamental equations of fluid dynamics and the energy flux density formula, establish a dynamic evolution model of the pre-breakdown arc and typical areas of the contact surface, as shown in formulas (19)-(21). （19） （20） （21） In the formula, Density of the electrode material; For the electrode material velocity; For pressure; The current density flowing into the electrode; The specific heat of the electrode; The electrode temperature; The thermal conductivity of the electrode; The energy flux density injected onto the electrode surface varies depending on the electrode, i.e. and .

3. The method for repairing contact damage in a vacuum circuit breaker using a pre-breakdown arc and hammer impact in synergistic repair according to claim 2, characterized in that, Based on the initial conditions of the mechanical hammering effect, a hammering model of a typical damaged area after interaction with a vacuum arc is established. The mechanical hammering model is used to analyze the deformation of the contact during hammering under different damage modes to obtain the mobile dislocation density, including: S31. Calculate the equivalent hammer load of a typical damage area based on the moving contact speed, overtravel pressure, and the mass of the moving parts rigidly connected to the contact. F ; S32. Based on the equation of motion and Hook's law, according to the stress-strain curves of the contact material at different temperatures, the stress distribution and deformation equations of the damaged area on the contact surface after the pre-breakdown arc process are constructed, and the deformation of the contact surface after mechanical hammering is obtained, as shown in formulas (22)-(23). （22） （23） In the formula, For contact displacement; This is the equivalent hammer impact load; For stress; Young's modulus; This represents the total deformation of the contact surface; The density of the contact material at temperature T This represents the Young's modulus of the contact material at temperature T. S33. Based on the total deformation of the contact surface obtained in S32, construct a physical model of the movable dislocation density and total deformation, as shown in formula (24). （24） in, The density of movable dislocations; It is a proportionality constant; It is the Bergman vector; This represents the dislocation motion rate.

4. The method for repairing contact damage in a vacuum circuit breaker using a pre-breakdown arc and hammer impact in synergistic repair according to claim 3, characterized in that, Based on the analysis of movable dislocation density, the influence of dislocation configuration on the mechanical properties of contacts is analyzed, and a damage / repair evaluation system is constructed, including: S41. In terms of microstructure, based on the physical model of strain rate and movable dislocation density and crystal plasticity theory, the relationship between yield strength and movable dislocation density of contact material is obtained in order to analyze the influence of dislocation configuration on the mechanical properties of contact, so that the repaired contact meets the numerical requirements of yield strength. The relationship between the yield strength of the contact material and the density of movable dislocations is shown in formula (25). （25） in, Yield strength; It is lattice friction; It is a constant; b is the shear modulus; b is the Burgers vector. The density of movable dislocations; S42. In terms of macroscopic morphology, the peak and valley characteristics and the average height of the core area of ​​the contact surface are described by the number of peaks and valleys and the average peak spacing. Based on the peak and valley characteristics and the average height of the core area, the roughness of the contact surface used to evaluate the complexity of the morphology is calculated, so that the repaired contact meets the roughness requirements.

5. The method for repairing contact damage in a vacuum circuit breaker using a combination of pre-breakdown arc and hammer impact, as described in claim 1, is characterized in that... A self-sensing and self-regulating system for hammer impact load is designed with a dual closed-loop structure, including: S51. Design a load self-sensing loop, i.e., a hammer load self-sensing system, to obtain the actual hammer load of the contact. The self-sensing system includes a flux linkage observer, a PMA, and a load observer. The load observer includes a velocity observer and a hammer load observer. The flux linkage observer and PMA are used to input the coil voltage and current generated when the vacuum circuit breaker is opened and closed to the velocity observer for acceleration calculation, as shown in formulas (26) and (27). （26） （27） in, The voltage across the coil; The coil current; The coil resistance; For coil flux; The electromagnetic force on the moving iron core; according to the equivalent magnetic circuit equation, It is a function of position, current, and rate of change of magnetic flux derived from the equivalent magnetic circuit equation; For displacement; The velocity of the moving iron core; according to the voltage balance equation and the law of electromagnetic induction, It is a function of position, magnetic flux, and rate of change of magnetic flux, derived from the voltage balance equation and the law of electromagnetic induction. The load reaction force refers to the gravity, the reaction force of the trip spring, and the friction force acting on the moving parts; The function is used to describe the switching between the excitation and motion phases in d'Alembert's equations of motion; For the mass of the moving parts of the permanent magnet operating mechanism; For magnetic linkage; The hammer load observer is used to calculate the actual hammer load based on the moving core speed output by the mass and speed observer of the moving parts of the permanent magnet operating mechanism, and inputs the actual hammer load into the self-regulating system. The actual hammer load is shown in formula (28). （28） In the formula: For hammer impact load, For the mass of the moving parts of the permanent magnet operating mechanism. For closing speed, The contact area is... This refers to the closing collision time; S52. Design a load self-regulating loop, i.e., a hammer load self-regulating system, to compare the actual hammer load with the ideal hammer load, and based on the comparison result, enable the actual hammer load to dynamically track the ideal hammer load, i.e., adjust the actual hammer load to approach the value of the ideal hammer load. The self-regulating system includes a load tracker, an inner loop tracker, and a magnetic flux observer shared with the self-sensing system. The load tracker is used to calculate the error between the input ideal hammer load and the actual hammer load output by the hammer load observer, and to track the ideal coil flux to the ideal hammer load based on the error calculation, and input it to the inner loop tracker. The flux observer, shared with the self-sensing system, is used to input the actual coil flux into the inner loop tracker to track the ideal coil flux. The inner loop tracker is used to calculate the flux linkage error between the ideal coil flux linkage and the actual coil flux linkage, and calculates the ideal voltage based on the flux linkage error. The ideal voltage is then input into the PMA in the self-sensing system so that the actual coil voltage tracks the ideal voltage, thereby enabling the actual moving iron core speed to track the ideal moving iron core speed corresponding to the ideal hammer load. This allows the actual hammer load to be adjusted to approach the value of the ideal hammer load, as shown in formula (29). （29） in, They represent the coil flux linkages respectively. Speed ​​of movement of the moving iron core and motion displacement The state vector, Indicates coil flux The velocity v and displacement of the moving iron core , is the state vector; Indicates the position of the moving contact. This indicates the coil voltage.

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