Simulation method and device for plasma field distribution in vacuum arc-extinguishing chamber

Abstract

The invention discloses a simulation method and device for plasma field distribution in a vacuum arc-extinguishing chamber. The simulation method comprises the following steps: establishing a three-dimensional simulation model of the vacuum arc-extinguishing chamber in a pole-mounted circuit breaker; the method comprises the following steps: importing a three-dimensional simulation model of a vacuum arc extinguish chamber in a pole-mounted circuit breaker into COMSOL Multiphysics software, and setting a plasma mass conservation equation, a momentum equation, a cathode magnetic field boundary condition function and an anode magnetic field boundary condition function in combination with an MUMPS solver; in COMSOL Multiphysics software, initial calculation conditions are set, the rotating angular speed of a moving contact and an arc current value serve as input variables, multi-physics field coupling is achieved, and simulation of plasma field distribution in a vacuum arc extinguishing chamber in a pole-mounted circuit breaker is completed. By establishing a multi-physics-field coupled vacuum arc extinguish chamber inner plasma field calculation model, the spatio-temporal evolution law of plasmas under the action of a strong electric field and a magnetic field is accurately represented, and a theoretical basis is provided for optimizing the arc extinguish chamber structure design, restraining breaking overvoltage and preventing restrike.

Description

Technical Field

[0001] This invention belongs to the technical field of pole-mounted circuit breakers, specifically relating to a simulation method and device for plasma field distribution in a vacuum arc extinguishing chamber. Background Technology

[0002] As a key protection and control device in power distribution networks, the 10kV pole-mounted circuit breaker plays a crucial role in rapid fault isolation, flexible load transfer, and stable system operation. When a permanent fault such as a short circuit or grounding occurs in a power distribution line, the circuit breaker contacts separate under the drive of the mechanism, generating a high-temperature, high-pressure vacuum arc. If the arc cannot be successfully extinguished, it can lead to line burnout, equipment explosion, or even tripping of the substation's output switch, causing a power outage on the entire line. This not only seriously affects the reliability of power supply but also poses a direct threat to the safety and stability of the power grid. The vacuum interrupter, as the core arc-extinguishing component of the 10kV pole-mounted circuit breaker, directly affects the arc extinguishing effect and the equipment's insulation recovery capability due to the plasma characteristics within its internal plasma.

[0003] Currently, research on the dynamic behavior of vacuum arcs largely relies on simplified models or static assumptions, making it difficult to accurately reflect the interaction mechanism of multiple physical fields involving electricity, magnetism, heat, and fluid during actual interruption.

[0004] For example, patent CN115329688B discloses a method and system for obtaining parameters of a high-current vacuum arc under low-frequency current conditions, belonging to the field of vacuum switch process simulation technology. A three-dimensional model of the vacuum interrupter is established, and the vacuum arc plasma is simulated using magnetohydrodynamic theory, thus establishing a three-dimensional magnetohydrodynamic model of the vacuum arc plasma. In solving for the high-current vacuum arc parameters in the model, since ion parameters, electromagnetic field parameters, and electronic parameters are interdependent, based on the degree of dependence between each parameter, ion parameters and electromagnetic field parameters are calculated first, followed by electronic parameters, greatly improving the convergence of the calculation. Simultaneously, this invention introduces electric potential and vector magnetic potential to solve for the electromagnetic field parameters, reducing differential operations, lowering the computational complexity, and achieving high computational efficiency.

[0005] Traditional experimental observations are limited by the vacuum-sealed structure and microsecond-level transient characteristics, resulting in high measurement costs and difficulties in data acquisition. Therefore, establishing a computational model of the plasma field within a vacuum arc-extinguishing chamber coupled with multiple physics fields to characterize the spatiotemporal evolution of plasma under the influence of strong electric and magnetic fields is a pressing issue for those skilled in the art. This model aims to provide a theoretical basis for optimizing arc-extinguishing chamber structural design, suppressing overvoltage during interruption, and preventing severe breakdown, thereby ensuring the safe operation of power distribution networks and rapid fault isolation. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a simulation method and apparatus for plasma field distribution within a vacuum interrupter, specifically including: establishing a three-dimensional simulation model of the vacuum interrupter in a pole-mounted circuit breaker; importing the three-dimensional simulation model of the vacuum interrupter into COMSOL Multiphysics software, and using the MUMPS solver to set the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function; setting the initial calculation conditions in COMSOL Multiphysics software, using the moving contact rotation angular velocity and arc current value as input variables to achieve multi-physics coupling and complete the simulation of plasma field distribution within the vacuum interrupter in the pole-mounted circuit breaker.

[0007] By establishing a multi-physics coupled plasma field calculation model in a vacuum interrupter, the spatiotemporal evolution of plasma under strong electric and magnetic fields can be accurately characterized, revealing the intrinsic relationship between dielectric recovery strength and arc energy. This provides a theoretical basis for optimizing the structural design of the interrupter, suppressing overvoltage during interruption, and preventing severe breakdown. It also has significant engineering value for ensuring the safe operation of power distribution networks and rapid fault isolation.

[0008] In a first aspect, the present invention provides a simulation method for plasma field distribution in a vacuum interrupter, the specific steps of which include: Establish a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker; The three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software. Combined with the MUMPS solver, the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function were set. In COMSOL Multiphysics software, the initial calculation conditions are set, and the rotational angular velocity of the moving contact and the arc current value are used as input variables to realize multi-physics coupling and complete the simulation of the plasma field distribution in the vacuum interrupter of the pole-mounted circuit breaker.

[0009] Furthermore, a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker is established, specifically including the following steps: Based on the tubular structure of the vacuum interrupter in the pole-mounted circuit breaker, a three-dimensional solid model of the moving contact, stationary contact, connecting rod and shielding cover in the tubular structure is established. By using Boolean operations, the three-dimensional solid models of the moving contact, stationary contact, connecting rod, and shielding cover in the tubular structure are combined, and the vacuum domain is preserved to form a sealed vacuum system, thus obtaining a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker.

[0010] Furthermore, the contact gap between the moving contact and the stationary contact, as well as the internal area of ​​the shield, are defined as the plasma simulation domain. Within the plasma simulation domain, the moving contact can rotate around its axis, and the rotational angular velocity of the moving contact can be determined.

[0011] Furthermore, the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software. Using the MUMPS solver, the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function were set, specifically including: The three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software to form a physical coupling model including electromagnetic field, fluid field and temperature field; Among them, the electromagnetic field model solves for the magnetic induction intensity vector and the electric field intensity vector, and applies a cathode magnetic field boundary condition function based on the assumption of a circular current sheet on the cathode surface. The cathode magnetic field boundary condition function is associated with the arc current value, the radius of the cathode spot cluster, and the position of the point on the cathode surface. An anode magnetic field boundary condition function based on sheath electromagnetic coupling is applied to the anode surface. The anode magnetic field boundary condition function is related to plasma conductivity, anode potential drop and electron temperature. The fluid field model solves for the ion migration velocity vector through the plasma mass conservation equation and momentum equation, and couples the Lorentz force density into the volume force source term. The Lorentz force density is composed of the vector product of the current density vector and the magnetic induction intensity vector. The temperature field model solves for the electron temperature distribution by pre-setting the electron temperature distribution or by using the Joule heat source function, which is directly constructed by the scalar product of the current density vector and the electric field intensity vector. The physical coupling model uses the MUMPS solver to achieve variable transfer and under-relaxation processing between the electromagnetic field model, fluid field model, and temperature field model.

[0012] Furthermore, the plasma mass conservation equation is specifically expressed as:

[0013] Where, n e m is the ion density. e v is the ion mass. e This is the ion migration velocity vector. For the Nabra operator.

[0014] Furthermore, the momentum equation is specifically expressed as:

[0015] Where, n e m is the ion density. ev is the ion mass. e This is the ion migration velocity vector. For the Brahman operator, p e For ion pressure, p i Let τ be the electron pressure, i be the current density vector, B be the magnetic induction vector, and τ be the magnetic flux density vector. i η is the ionic viscous stress, ω is the rotational angular velocity of the moving contact, and η is the instantaneous tangential linear velocity vector.

[0016] Furthermore, the boundary condition function for the cathode magnetic field is specifically expressed as follows:

[0017] The boundary condition function for the anode magnetic field is specifically expressed as follows:

[0018] Among them, B x B is the component of the magnetic flux density vector in the x-direction. y Let μ0 be the component of the magnetic flux density vector in the y-direction, i0 be the free permeability, I0 be the longitudinal current density, I0 be the arc current, l be the distance from the point on the cathode surface to the center of the cathode spot cluster, r0 be the radius of the cathode spot cluster, y be the ordinate of the point on the cathode surface, y0 be the ordinate of the center of the cathode spot cluster, σ be the plasma conductivity, ψ be the anode potential drop, and v be the component of the magnetic flux density vector in the y-direction. x Let v be the electron velocity in the x-direction. y Let v be the electron velocity in the y-direction. z Let n be the electron velocity in the z-direction. i Let be the electron density, e be the electron charge, q be the volume charge density, k be the Boltzmann constant, and T be the electron density. e Let λ be the electron temperature, and λ be a constant.

[0019] Furthermore, initial calculation conditions are set, using the rotational angular velocity of the moving contact and the arc current value as input variables to achieve multi-physics coupling. This specifically includes the following steps: The initial conditions are set by setting the initial magnetic field strength to 0 in the electromagnetic field model, the initial fluid velocity in the fluid field model to the cathode boundary velocity, and the initial electron temperature in the temperature field model to the electron temperature at the cathode boundary. The angular velocity of the moving contact and the value of the arc current are used as input variables and input into the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function; Based on the MUMPS solver, the electromagnetic field model and temperature field model under the initial conditions are solved, and the parameters in the fluid field model and temperature field model are corrected according to the momentum equation. By correcting the parameters of the plasma mass conservation equation, the ion density of the electromagnetic field after the first iteration is solved. Through iterative calculation, the plasma field distribution in the vacuum interrupter chamber of the pole-mounted circuit breaker is obtained.

[0020] Furthermore, a transient separation solution strategy is adopted, placing the momentum equation as the coupling hub at the core of the iteration: The iterative calculation process is executed according to the following timing sequence: At the current time step, the preset electron temperature and ion migration velocity are first fixed, and the electromagnetic field model is solved to obtain the predicted magnetic induction intensity. Then, by using the predicted magnetic induction intensity and initial current density, the momentum equation containing the Lorentz force term is solved to obtain the predicted ion migration velocity, and the plasma mass conservation equation is solved to correct the ion density. Next, the magnetic induction intensity and ion migration velocity are fixed, and the electron temperature is updated according to the temperature field model; The electromagnetic field model is re-solved to obtain the final magnetic induction intensity, and the momentum equation is solved again to obtain the final ion migration velocity, until the ion density convergence criterion and the electron temperature convergence criterion are satisfied.

[0021] Furthermore, the plasma field distribution within the vacuum interrupter of the pole-mounted circuit breaker is obtained by extracting three-dimensional spatial distribution data to characterize the plasma state within the vacuum interrupter, specifically including: The scalar field distribution of generated ion density is obtained, and its spatial gradient along the axial and radial directions is acquired. The scalar field distribution of generated electron temperature is used to identify the temperature gradient variation characteristics between the arc core region and the anode sheath region. The vector field distribution of magnetic induction intensity is generated, and its azimuth component modulus range and Ampere loop integral characteristics on the surface of the arc column are verified. The vector field distribution of generated plasma velocity is used to extract the axial velocity component of the cathode jet region and the radial velocity component of the arc column edge. The plasma state parameter distribution data, including the vector field distribution of ion density, electron temperature, magnetic induction intensity, and plasma flow velocity, can be exported into a general format or packaged into a model result file for evaluating the arc voltage characteristics, current zero-crossing arc extinguishing capability, and contact ablation distribution of the arc extinguishing chamber.

[0022] Secondly, the present invention also provides a simulation device for plasma field distribution in a vacuum arc-extinguishing chamber, specifically comprising: Modeling unit, used to create a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker; The analysis unit is used to import the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker into the COMSOL Multiphysics software, and, in conjunction with the MUMPS solver, set the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function. The simulation unit is used in COMSOL Multiphysics software to set the initial calculation conditions, take the rotational angular velocity of the moving contact and the arc current value as input variables, realize multi-physics coupling, and complete the simulation of the plasma field distribution in the vacuum interrupter of the pole-mounted circuit breaker.

[0023] The present invention provides a method and apparatus for simulating plasma field distribution in a vacuum interrupter, which has at least the following beneficial effects: (1) By establishing a multi-physics coupled plasma field calculation model in the vacuum arc extinguishing chamber, the spatiotemporal evolution law of plasma under the action of strong electric field and magnetic field can be accurately characterized, revealing the intrinsic relationship between dielectric recovery strength and arc energy. This provides a theoretical basis for optimizing the arc extinguishing chamber structure design, suppressing overvoltage and preventing heavy breakdown, and has important engineering value for ensuring the safe operation of the power distribution network and rapid fault isolation.

[0024] (2) By adopting a transient separation solution strategy and using the momentum equation as the coupling hub, the electromagnetic-fluid-thermal fully coupled problem is decomposed and iterated. While maintaining the physical coupling accuracy, the computational efficiency is improved, the computational complexity, memory usage and resource consumption are reduced, and the engineering accuracy requirements are met. While significantly reducing the computational resource requirements, the accuracy of the synchronization of the three fields of magnetic field, velocity and temperature at the moment of zero crossing of the vacuum arc is maintained, providing an efficient and reliable numerical means for evaluating the probability of re-breakdown under the recovery voltage of the pole-mounted circuit breaker. Attached Figure Description

[0025] Figure 1 A flowchart illustrating a simulation method for plasma field distribution within a vacuum interrupter, provided as an embodiment of the present invention; Figure 2 A flowchart illustrating the import of a three-dimensional simulation model of the vacuum interrupter in a pole-mounted circuit breaker, provided in an embodiment of the present invention; Figure 3 A flowchart of multiphysics coupling provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the plasma field distribution in the vacuum interrupter chamber of a pole-mounted circuit breaker provided in an embodiment of the present invention; Figure 5 This is a structural block diagram of a simulation device for plasma field distribution in a vacuum arc-extinguishing chamber, provided as an embodiment of the present invention.

[0026] Among them, 201 is the modeling unit; 202 is the analysis unit; and 203 is the simulation unit. Detailed Implementation

[0027] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0029] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0030] This invention discloses a simulation method for plasma field distribution in a vacuum interrupter, specifically including: establishing a three-dimensional simulation model of the vacuum interrupter in a pole-mounted circuit breaker; importing the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker into COMSOL Multiphysics software, and setting the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function in conjunction with the MUMPS solver; setting the initial calculation conditions in COMSOL Multiphysics software, using the moving contact rotation angular velocity and arc current value as input variables to achieve multi-physics coupling and complete the simulation of plasma field distribution in the vacuum interrupter in the pole-mounted circuit breaker.

[0031] A three-dimensional simulation model of the vacuum interrupter chamber in a 10kV pole-mounted circuit breaker was established. The simulation model was meshed, and the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function were set according to the characteristics of vacuum arc. Based on the electromagnetic field-fluid field-temperature field coupling theory, the initial calculation conditions were set, and the rotational angular velocity of the moving contact and the arc current value were used as input variables to calculate the plasma field distribution in the vacuum interrupter chamber. The intrinsic relationship between the dielectric recovery intensity and the arc energy was revealed, providing a theoretical basis for optimizing the structural design of the interrupter chamber, suppressing overvoltage during interruption, and preventing re-breakdown. It has strong practical value.

[0032] like Figure 1 As shown, this invention provides a simulation method for plasma field distribution in a vacuum interrupter, the specific steps of which are as follows: S101: Establish a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker.

[0033] Furthermore, a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker is established, specifically including the following steps: Based on the tubular structure of the vacuum interrupter in the pole-mounted circuit breaker, a three-dimensional solid model of the moving contact, stationary contact, connecting rod and shielding cover in the tubular structure is established. By using Boolean operations, the three-dimensional solid models of the moving contact, stationary contact, connecting rod, and shielding cover in the tubular structure are combined, and the vacuum domain is preserved to form a sealed vacuum system, thus obtaining a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker.

[0034] Specifically, the contact gap between the moving contact and the stationary contact, as well as the internal area of ​​the shield, are defined as the plasma simulation domain. Within the plasma simulation domain, the moving contact can rotate around its axis, and the rotational angular velocity of the moving contact is determined.

[0035] In a specific example, the 3D simulation model of the vacuum interrupter in a pole-mounted circuit breaker includes a moving contact, a stationary contact, a connecting rod, a shield, and a bellows. The tubular structure of the vacuum interrupter in the pole-mounted circuit breaker is a bellows, which assembles the moving contact, stationary contact, connecting rod, shield, and bellows into a completely sealed vacuum chamber. 3D solid models of each structure are constructed according to the actual situation. For example, the 3D solid model parameters for the moving contact include 16 cup-shaped longitudinal magnetic grooves, an outer diameter of 60mm, an inner diameter of 40mm, and a height of 30mm. The 3D solid model for the stationary contact is mirror-symmetrical to the moving contact, but with an M12 screw hole in the center for connection to the connecting rod. The 3D solid model for the connecting rod is a stainless steel round rod, with one end screwed into the stationary contact and the other end extending outside the shield. The 3D solid model for the shield is a 1mm thick oxygen-free copper cylinder, surrounding the contact, 5mm from the outer wall of the contact, and its length covers the entire opening distance stroke. The bellows is welded to the tail of the moving contact to ensure an axial gap of 0–20mm and vacuum sealing. The bellows is a Φ120mm stainless steel round tube with a wall thickness of 2mm. Using Boolean operations in CAD software, the moving contact, stationary contact, connecting rod, shield, and bellows are assembled into a "sealed vacuum system," where all internal gaps are merged, and an external "vacuum domain" is retained to form a vacuum cavity. This completes the establishment of a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker.

[0036] S102: Import the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker into COMSOL Multiphysics software, and set the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function using the MUMPS solver.

[0037] Furthermore, the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software. Using the MUMPS solver, the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function were set, referring to... Figure 2 Specifically, it includes: The three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software to form a physical coupling model including electromagnetic field, fluid field and temperature field; The electromagnetic field model solves for the magnetic induction intensity vector and the electric field intensity vector. A cathode magnetic field boundary condition function based on the circular current plate assumption is applied to the cathode surface. The cathode magnetic field boundary condition function is related to the arc current value, the radius of the cathode spot cluster, and the position of the point on the cathode surface. An anode magnetic field boundary condition function based on the electromagnetic coupling of the sheath is applied to the anode surface. The anode magnetic field boundary condition function is related to the plasma conductivity, the anode potential drop, and the electron temperature. The fluid field model solves for the ion migration velocity vector through the plasma mass conservation equation and momentum equation, and couples the Lorentz force density into the volume force source term. The Lorentz force density is composed of the vector product of the current density vector and the magnetic induction intensity vector. The temperature field model solves for the electron temperature distribution by pre-setting the electron temperature distribution or by using the Joule heat source function, which is directly constructed by the scalar product of the current density vector and the electric field intensity vector. The physical coupling model uses the MUMPS solver to achieve variable transfer and under-relaxation processing between the electromagnetic field model, fluid field model, and temperature field model.

[0038] The Joule heat source function represents the work done by the electric field on the conduction current per unit volume and per unit time. The volumetric force source term is the term that generates or consumes momentum "out of thin air" within the control volume, representing the "non-contact" force experienced by each cubic meter of fluid.

[0039] Specifically, the plasma mass conservation equation is expressed as follows:

[0040] Where, n e m is the ion density. e v is the ion mass. e This is the ion migration velocity vector. For the Nabra operator.

[0041] Specifically, the momentum equation is the momentum equation for plasma in the vacuum arc state, and is expressed as follows:

[0042] Where, n e m is the ion density. e v is the ion mass. e This is the ion migration velocity vector. For the Brahman operator, p e For ion pressure, p i Let τ be the electron pressure, i be the current density, B be the magnetic flux density, and τ be the magnetic flux density. i η is the ionic viscous stress, ω is the rotational angular velocity of the moving contact, and η is the instantaneous tangential linear velocity vector. For volumetric force source term, i×B is the Lorentz force density.

[0043] Specifically, the cathode magnetic field boundary condition function is expressed as follows:

[0044] Specifically, the boundary condition function for the anode magnetic field is expressed as follows:

[0045] Among them, B x B is the component of magnetic flux density in the x-direction. y B is the component of magnetic flux density in the y-direction. z E represents the component of the magnetic flux density in the z-direction. x E represents the component of the electric field intensity vector in the x-direction. y Let μ0 be the component of the electric field intensity vector in the y-direction, μ0 be the free permeability, i0 be the longitudinal current density, I0 be the arc current value, l be the distance from the point on the cathode surface to the center of the cathode spot cluster, r0 be the radius of the spot cluster, y be the ordinate of the point on the cathode surface, y0 be the ordinate of the center of the cathode spot cluster, σ be the plasma conductivity, ψ be the anode potential drop, and v0 be the component of the electric field intensity vector in the y-direction. x Let v be the electron velocity in the x-direction. y Let v be the electron velocity in the y-direction. z Let n be the electron velocity in the z-direction. i Let be the electron density, e be the electron charge, q be the volume charge density, k be the Boltzmann constant, and T be the electron density. e Let λ be the electron temperature, and λ be a constant. In this example, λ is taken as 5 / 2. In other examples, it can be adjusted according to the actual situation, and there is no limitation on it.

[0046] S103: In COMSOL Multiphysics software, set the initial calculation conditions, take the rotational angular velocity of the moving contact and the arc current value as input variables, realize multi-physics coupling, and complete the simulation of the plasma field distribution in the vacuum interrupter in the pole-mounted circuit breaker.

[0047] Furthermore, initial calculation conditions are set, using the rotational angular velocity of the moving contact and the arc current value as input variables to achieve multi-physics coupling, referring to... Figure 3 Specifically, it includes the following steps: The initial conditions are set by setting the initial magnetic field strength to 0 in the electromagnetic field model, the initial fluid velocity in the fluid field model to the cathode boundary velocity, and the initial electron temperature in the temperature field model to the electron temperature at the cathode boundary. The angular velocity of the moving contact and the value of the arc current are used as input variables and input into the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function; Based on the MUMPS solver, the electromagnetic field model and temperature field model under the initial conditions are solved, and the parameters in the fluid field model and temperature field model are corrected according to the momentum equation. By correcting the parameters of the plasma mass conservation equation, the ion density of the electromagnetic field after the first iteration is solved. Through iterative calculation, the plasma field distribution in the vacuum interrupter chamber of the pole-mounted circuit breaker is obtained.

[0048] Furthermore, a transient separation solution strategy is adopted, placing the momentum equation as the coupling hub at the core of the iteration: The iterative calculation process is executed according to the following timing sequence: At the current time step, the preset electron temperature and ion migration velocity are first fixed, and the electromagnetic field model is solved to obtain the predicted magnetic induction intensity. Then, by using the predicted magnetic induction intensity and initial current density, the momentum equation containing the Lorentz force term is solved to obtain the predicted ion migration velocity, and the plasma mass conservation equation is solved to correct the ion density. Next, the magnetic induction intensity and ion migration velocity are fixed, and the electron temperature is updated according to the temperature field model; The electromagnetic field model is re-solved to obtain the final magnetic induction intensity, and the momentum equation is solved again to obtain the final ion migration velocity, until the ion density convergence criterion and the electron temperature convergence criterion are satisfied.

[0049] The ion density convergence criterion and the electron temperature convergence criterion are set according to the actual situation and are not limited here.

[0050] In one specific implementation, relevant parameters are determined according to different simulation scenarios. For example, the opening distance of the bellows is 10mm, the diameter of the moving contact (cathode) is 60mm, there are 16 longitudinal magnetic grooves, the initial electron temperature is 2eV, the radius of the cathode spot cluster is 1.5mm, and the coordinates of the center position of the cathode spot cluster are (x0, y0, z0).

[0051] The correction formula for ion density is specifically expressed as follows:

[0052] The correction formula for electron temperature is specifically expressed as follows:

[0053] The correction formula for ion migration rate is specifically expressed as follows:

[0054] in, Let S be the ion density obtained in the k-th iteration, Δt be the time step size of each iteration, and S be the ion density obtained in the k-th iteration. cu T is the mass flux source for cathode copper evaporation. cath The surface temperature of the cathode spot. The electron temperature is obtained in the k-th iteration. Let τ be the ion migration velocity vector obtained in the k-th iteration. i Let σ be the ionic viscous stress, σ be the plasma conductivity, i be the current density, and q be the plasma conductivity. e Let m be the electron heat flux, k be the Boltzmann constant, and m be the heat flux. e Let ω be the ion mass and ω be the angular velocity of the moving contact.

[0055] Furthermore, the plasma field distribution within the vacuum interrupter of the pole-mounted circuit breaker is obtained by extracting three-dimensional spatial distribution data to characterize the plasma state within the vacuum interrupter, specifically including: The scalar field distribution of generated ion density is obtained, and its spatial gradient along the axial and radial directions is acquired. The scalar field distribution of generated electron temperature is used to identify the temperature gradient variation characteristics between the arc core region and the anode sheath region. The vector field distribution of magnetic induction intensity is generated, and its azimuth component modulus range and Ampere loop integral characteristics on the surface of the arc column are verified. The vector field distribution of generated plasma velocity is used to extract the axial velocity component of the cathode jet region and the radial velocity component of the arc column edge. The plasma state parameter distribution data, including the vector field distribution of ion density, electron temperature, magnetic induction intensity, and plasma flow velocity, can be exported into a general format or packaged into a model result file for evaluating the arc voltage characteristics, current zero-crossing arc extinguishing capability, and contact ablation distribution of the arc extinguishing chamber.

[0056] In a specific example, a 1:1 equivalent 3D simulation model of the vacuum interrupter in a 10kV pole-mounted circuit breaker was built using SolidWorks. This model was then imported into COMSOL software, and the solver was set to the MUMPS solver. The plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function were then configured. Initial calculation conditions were set in COMSOL software, using the moving contact rotational angular velocity and arc current as input variables to achieve electromagnetic-fluid-temperature multiphysics coupling, thus completing the calculation of the plasma field distribution within the vacuum interrupter of the 10kV pole-mounted circuit breaker.

[0057] For example, taking the ZW32-12 pole-mounted circuit breaker as an example, the parameters of the pole-mounted circuit breaker include rated voltage, rated current, rated frequency, arc-extinguishing chamber contact opening distance, and arc-extinguishing chamber bounce time. Specifically, the rated voltage is 12kV, the rated current is 630A, the rated frequency is 50Hz, the arc-extinguishing chamber contact opening distance is 9±1mm, and the arc-extinguishing chamber bounce time is ≤3ms. In the 3D simulation model of the vacuum arc-extinguishing chamber in the 10kV pole-mounted circuit breaker, the stationary and moving end covers of the arc-extinguishing chamber are made of copper, the air domain inside the main shield of the arc-extinguishing chamber is set to a vacuum environment, the shield of the vacuum arc-extinguishing chamber is made of rubber, and the remaining components of the vacuum arc-extinguishing chamber are made of alloy steel. Then, mesh generation is performed: the domain elements of the entire vacuum arc-extinguishing chamber are divided into 78565 mesh elements, the edge elements into 5536 mesh elements, and the boundary element table into 27961 mesh elements. The initial conditions for the calculation were set as follows: the initial value of the magnetic field was set to 0, the initial velocity of the fluid field was set to 1.1 × 10⁴ m / s, the initial electron temperature was set to 1.5 eV, the angular velocity of the moving contact was 5° / ms, the input arc current was 600 A, and the contact gap was set to 3 mm. Then, the electromagnetic field model and temperature field model under the initial conditions were solved. The COMSOL software corrected the parameters of the fluid field model and temperature field model according to the solution results, and solved the ion density of the electromagnetic field. After iterative calculation, the plasma field distribution in the vacuum interrupter chamber of the 10 kV pole-mounted circuit breaker was finally obtained.

[0058] Reference Figure 4Analysis of the longitudinal plasma density of the vacuum arc within the vacuum interrupter chamber revealed that the highest plasma density (4.07 × 10²⁰ / m³) was observed in the arc center region, gradually decreasing towards the inner wall of the chamber, with a minimum value of approximately 3.16 × 10¹⁹ / m³. This is because the plasma in the vacuum arc is primarily generated by the cathode spots. These ions diffuse outwards under the drive of the pressure gradient, resulting in the highest plasma density at the arc center. The plasma density gradually decreases with increasing distance from the initial position of the cathode spot cluster until it reaches a certain minimum value. This distribution pattern is closely related to the discharge characteristics of the vacuum arc and the constraint effect of the contact structure on plasma diffusion, providing a visual basis for optimizing the arc interrupter chamber structural design, suppressing overvoltage during interruption, and preventing re-breakdown.

[0059] Reference Figure 5 This invention provides a simulation device for plasma field distribution in a vacuum arc-extinguishing chamber, comprising: Modeling unit 201 is used to establish a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker; Analysis unit 202 is used to import the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker into the COMSOL Multiphysics software, and in conjunction with the MUMPS solver, set the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function. Simulation unit 203 is used in COMSOL Multiphysics software to set the initial calculation conditions, take the rotational angular velocity of the moving contact and the arc current value as input variables, realize multi-physics coupling, and complete the simulation of the plasma field distribution in the vacuum interrupter in the pole-mounted circuit breaker.

[0060] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0061] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and variations of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A simulation method for plasma field distribution in a vacuum interrupter chamber, characterized in that, Specifically, the steps include the following: Establish a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker; The three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software. Combined with the MUMPS solver, the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function were set. In COMSOL Multiphysics software, the initial calculation conditions are set, and the rotational angular velocity of the moving contact and the arc current value are used as input variables to realize multi-physics coupling and complete the simulation of the plasma field distribution in the vacuum interrupter of the pole-mounted circuit breaker.

2. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 1, characterized in that, Establishing a three-dimensional simulation model of the vacuum interrupter in a pole-mounted circuit breaker includes the following steps: Based on the tubular structure of the vacuum interrupter in the pole-mounted circuit breaker, a three-dimensional solid model of the moving contact, stationary contact, connecting rod and shielding cover in the tubular structure is established. By using Boolean operations, the three-dimensional solid models of the moving contact, stationary contact, connecting rod, and shielding cover in the tubular structure are combined, and the vacuum domain is preserved to form a sealed vacuum system, thus obtaining a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker.

3. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 2, characterized in that, The contact gap between the moving contact and the stationary contact, as well as the internal area of ​​the shield, are defined as the plasma simulation domain. Within the plasma simulation domain, the moving contact can rotate around its axis, and the rotational angular velocity of the moving contact is determined.

4. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 1, characterized in that, The 3D simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software. Using the MUMPS solver, the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function were set, specifically including: The three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker was imported into COMSOL Multiphysics software to form a physical coupling model including electromagnetic field, fluid field and temperature field; Among them, the electromagnetic field model solves for the magnetic induction intensity vector and the electric field intensity vector, applies a cathode magnetic field boundary condition function based on the circular current plate assumption to the cathode surface, and applies an anode magnetic field boundary condition function based on the sheath electromagnetic coupling to the anode surface. The fluid field model solves for the ion migration velocity vector through the plasma mass conservation equation and momentum equation, and couples the Lorentz force density into the volume force source term. The Lorentz force density is composed of the vector product of the current density vector and the magnetic induction intensity vector. The temperature field model solves for the electron temperature distribution by pre-setting the electron temperature distribution or by using the Joule heat source function, which is directly constructed by the scalar product of the current density vector and the electric field intensity vector. The physical coupling model uses the MUMPS solver to achieve variable transfer and under-relaxation processing between the electromagnetic field model, fluid field model, and temperature field model.

5. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 4, characterized in that, The plasma mass conservation equation is specifically expressed as: ； Where, n e m is the ion density. e v is the ion mass. e This is the ion migration velocity vector. For the Nabra operator.

6. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 4, characterized in that, The momentum equation is specifically expressed as: ； Where, n e m is the ion density. e v is the ion mass. e This is the ion migration velocity vector. For the Brahman operator, p e For ion pressure, p i Let τ be the electron pressure, i be the current density vector, B be the magnetic induction vector, and τ be the magnetic flux density vector. i η is the ionic viscous stress, ω is the rotational angular velocity of the moving contact, and η is the instantaneous tangential linear velocity vector.

7. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 4, characterized in that, The cathode magnetic field boundary condition function is specifically expressed as follows: ； The boundary condition function for the anode magnetic field is specifically expressed as follows: ； Among them, B x B is the component of the magnetic flux density vector in the x-direction. y B is the component of the magnetic flux density vector in the y-direction. z Let μ be the component of magnetic flux density in the z-direction, μ0 be the free permeability, i0 be the longitudinal current density, I0 be the arc current, l be the distance from the point on the cathode surface to the center of the cathode spot cluster, r0 be the radius of the cathode spot cluster, y be the ordinate of the point on the cathode surface, y0 be the ordinate of the center of the cathode spot cluster, σ be the plasma conductivity, ψ be the anode potential drop, and v be the component of magnetic flux density in the z-direction. x Let v be the electron velocity in the x-direction. y Let v be the electron velocity in the y-direction. z Let n be the electron velocity in the z-direction. i Let be the electron density, e be the electron charge, q be the volume charge density, k be the Boltzmann constant, and T be the electron density. e Let λ be the electron temperature, and λ be a constant.

8. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 4, characterized in that, Setting initial calculation conditions, using the rotational angular velocity of the moving contact and the arc current value as input variables, and achieving multi-physics coupling, specifically includes the following steps: The initial conditions are set by setting the initial magnetic field strength to 0 in the electromagnetic field model, the initial fluid velocity in the fluid field model to the cathode boundary velocity, and the initial electron temperature in the temperature field model to the electron temperature in the cathode boundary. The angular velocity of the moving contact and the value of the arc current are used as input variables and input into the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function and anode magnetic field boundary condition function; Based on the MUMPS solver, the electromagnetic field model and temperature field model under the initial conditions are solved, and the parameters in the fluid field model and temperature field model are corrected according to the momentum equation. By correcting the parameters of the plasma mass conservation equation, the ion density of the electromagnetic field after the first iteration is solved. Through iterative calculation, the plasma field distribution in the vacuum interrupter chamber of the pole-mounted circuit breaker is obtained.

9. The simulation method for plasma field distribution in a vacuum interrupter chamber as described in claim 8, characterized in that, A transient separation solution strategy is adopted, placing the momentum equation as the coupling hub at the core of the iteration: The iterative calculation process is executed according to the following timing sequence: At the current time step, the preset electron temperature and ion migration velocity are first fixed, and the electromagnetic field model is solved to obtain the predicted magnetic induction intensity. Then, by using the predicted magnetic induction intensity and initial current density, the momentum equation containing the Lorentz force term is solved to obtain the predicted ion migration velocity, and the plasma mass conservation equation is solved to correct the ion density. Next, the magnetic induction intensity and ion migration velocity are fixed, and the electron temperature is updated according to the temperature field model; The electromagnetic field model is re-solved to obtain the final magnetic induction intensity, and the momentum equation is solved again to obtain the final ion migration velocity, until the ion density convergence criterion and the electron temperature convergence criterion are satisfied.

10. A simulation device for plasma field distribution in a vacuum interrupter chamber, characterized in that, The method for plasma field distribution in a vacuum interrupter as described in any one of claims 1-9 specifically includes: Modeling unit, used to create a three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker; The analysis unit is used to import the three-dimensional simulation model of the vacuum interrupter in the pole-mounted circuit breaker into the COMSOL Multiphysics software, and, in conjunction with the MUMPS solver, set the plasma mass conservation equation, momentum equation, cathode magnetic field boundary condition function, and anode magnetic field boundary condition function. The simulation unit is used in COMSOL Multiphysics software to set the initial calculation conditions, take the rotational angular velocity of the moving contact and the arc current value as input variables, realize multi-physics coupling, and complete the simulation of the electromagnetic field distribution in the vacuum interrupter chamber of the pole-mounted circuit breaker.

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