A new energy high-low voltage DC relay intelligent protection method

Abstract

The present application relates to a kind of new energy high-low voltage DC relay intelligent protection method, including monitoring the real-time spectral data of metal vapor in arc channel when relay breaks large current, determine radial heat flux density;Continuous radial heat flow distribution curve is generated, and the radial distribution unevenness of arc column temperature gradient is obtained;If radial distribution unevenness exceeds preset uneven threshold, and the formation trend of arc channel deflection angle is obtained;Arc trajectory curvature and the formation trend of arc channel deflection angle are dynamically modeled and forecasted analysis processing;Monitoring the radial convection velocity and heat convection velocity in arc chamber, determine the dynamic adjustment parameter of gas flow pattern;According to the dynamic adjustment parameter of gas flow pattern, adjust the airflow distribution in arc chamber and pressure gradient in channel;According to control scheme, adjust the airflow direction and radial convection velocity in arc chamber.The present application significantly improves the stability and safety of DC relay breaking, guarantees the reliable operation of equipment under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of power equipment operation and maintenance technology, specifically to a method for intelligent protection of high and low voltage DC relays in new energy sources. Background Technology

[0002] As a crucial hub in the power system, the wind farm booster station is responsible for efficiently transmitting the electricity generated by wind power to the power grid. The stable operation of its core equipment, the DC relay, is of paramount importance to the reliability of the system.

[0003] When a relay interrupts a large current, the plasma characteristics of the arc discharge between the contacts directly affect the equipment's lifespan and power grid safety. However, during the relay's high-current interruption process, the drastic change in metal vapor density within the arc channel becomes a key limiting factor. Increased metal vapor density not only alters the temperature distribution of the arc column, making it radially uneven, but also causes the arc channel to form a curved trajectory due to thermal convection and electromagnetic forces. Currently, the impact of changes in metal vapor density within the arc channel on the arc sustaining time is not precisely understood, nor is a dynamic adjustment mechanism for the gas flow pattern within the arc extinguishing chamber available. This results in poor relay contact protection and an inability to achieve rapid arc extinguishing. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a method for intelligent protection of high and low voltage DC relays in new energy sources. This method significantly improves the stability and safety of DC relay switching, effectively prevents arc reignition, and ensures reliable operation of equipment under complex working conditions.

[0005] The present invention discloses a method for intelligent protection of high and low voltage DC relays in new energy sources, comprising the following steps:

[0006] S1. Monitor the real-time spectral data of metal vapor in the arc channel when the relay interrupts a large current, analyze the data to obtain the arc plasma density and temperature gradient distribution, and determine the radial heat flux density.

[0007] S2. Generate a continuous radial heat flow distribution curve, analyze the heat conduction coefficient and radial energy dissipation inside the arc column, and obtain the radial distribution non-uniformity of the temperature gradient of the arc column.

[0008] S3. If the radial distribution non-uniformity exceeds a preset non-uniformity threshold, the electromagnetic force vector distribution and thermal convection velocity are calculated by coupling the magnetic field sensor array and the temperature field, and the formation trend of the arc channel deflection angle is obtained.

[0009] S4. Dynamically model and predictively analyze the formation trends of arc trajectory curvature and arc channel deflection angle to obtain the gas flow resistance in the arc extinguishing chamber and the pressure gradient in the channel, and determine the arc trajectory length.

[0010] S5. Monitor the radial convection velocity and thermal convection velocity inside the arc extinguishing chamber, and analyze them in conjunction with the airflow dynamics model and heat transfer characteristics to determine the dynamic adjustment parameters of the gas flow mode.

[0011] S6. Adjust the airflow distribution in the arc extinguishing chamber and the pressure gradient in the channel according to the dynamic adjustment parameters of the gas flow mode to obtain the optimized control scheme of airflow velocity distribution and arc column boundary temperature.

[0012] S7. Adjust the airflow direction and radial convection velocity in the arc extinguishing chamber according to the control scheme, and automatically adjust the radial diffusion angle of the airflow in conjunction with the changes in voltage and current in the contact gap, and link the circuit breaker protection mechanism to cut off the fault circuit.

[0013] Preferably, step S1 specifically includes:

[0014] Continuous spectral data of the relay contact gap region were collected to obtain characteristic spectral line data of metal atoms, and the spatial temperature distribution of the arc plasma was calculated.

[0015] The spectral signal intensity at different radial positions of the arc column is obtained by radial scanning. Based on the spectral signal intensity and temperature spatial distribution, the radial distribution function of the plasma particle number density is determined. The boundary position of the arc column is determined based on the radial distribution function, and the radial width of the arc column is obtained.

[0016] Based on the radial distribution function and the spatial temperature distribution, the temperature difference between adjacent radial positions is calculated, and the radial heat flux density at each radial position is calculated by combining the heat conduction and radiation heat flux.

[0017] Preferably, step S2 specifically includes:

[0018] The radial width of the electric arc column and the radial heat flux density are subjected to time-domain filtering to obtain a smooth time-domain signal sequence, and cubic spline interpolation is performed to obtain a continuous radial heat flux distribution curve.

[0019] Based on the radial heat flow distribution curve, calculate the temperature gradient between adjacent radial positions and determine the radial distribution data of the thermal conductivity coefficient;

[0020] Based on the radial distribution data of the thermal conductivity coefficient and the temperature gradient value, the radial heat dissipation is calculated, the energy dissipation rate at each radial location is determined, and the radial energy dissipation distribution is obtained.

[0021] Based on the radial energy dissipation distribution and the radial distribution data of the thermal conductivity coefficient, the temperature gradient values ​​at different radial positions are calculated, and the deviation between the temperature gradient at each position and the mean temperature gradient over the entire radial range is obtained. The radial distribution non-uniformity of the arc column temperature gradient is determined by the ratio of the deviation to the mean.

[0022] Preferably, step S3 specifically includes:

[0023] If the radial distribution non-uniformity exceeds a preset non-uniformity threshold, magnetic induction intensity data of the space around the electric arc are collected to obtain the three-dimensional magnetic field distribution.

[0024] The electromagnetic force vector distribution on the arc plasma is determined by coupling calculations based on the three-dimensional magnetic field distribution and the radial temperature gradient distribution.

[0025] Based on the electromagnetic force vector distribution and the density change caused by the temperature difference, the buoyancy distribution is calculated according to the product of the density difference and gravitational acceleration in different temperature regions. The momentum conservation equation is used to solve the velocity of the plasma under the combined action of electromagnetic force and buoyancy, and the thermal convection velocity field inside the electric arc is obtained.

[0026] Based on the thermal convection velocity field and electromagnetic force vector distribution, the position coordinate changes of each point on the center line of the electric arc are calculated, and the reciprocal of the local radius of curvature is calculated for the continuously recorded position coordinates to obtain the spatial distribution of the curvature of the electric arc trajectory.

[0027] For the spatial distribution of the curvature of the arc trajectory, calculate the angle between the tangent vector of the arc centerline and the initial straight line direction. If the rate of change of the angle along the axial position continues to increase, it is determined that there is a deflection trend in the arc channel. The formation trend of the arc channel deflection angle is determined by the cumulative change of the angle.

[0028] Preferably, step S4 specifically includes:

[0029] Temporal features were extracted from the data sequence of the changes in arc trajectory curvature and arc channel deflection angle over time, and time functions of the rate of change of curvature and the rate of increase of deflection angle were fitted to obtain parameters describing the trajectory evolution trend.

[0030] Based on the arc morphology determined by the trajectory evolution trend parameters, the pressure distribution around the arc channel is calculated, and the gas flow resistance distribution at each location is determined.

[0031] For the gas flow resistance distribution and the pressure distribution around the arc channel, calculate the pressure change rate along the arc channel axis to obtain the pressure gradient inside the channel. If the pressure gradient exceeds the preset stability threshold, it is determined that the arc has a risk of instability, and the arc trajectory stability index is determined.

[0032] The arc trajectory length is determined based on the arc trajectory stability index and the trajectory evolution trend parameters, combined with the constraint effect of flow resistance distribution on trajectory expansion.

[0033] Preferably, step S5 specifically includes:

[0034] Based on the arc trajectory stability index and the arc trajectory length, tracer particles are scattered in the arc extinguishing chamber using the particle image velocimetry method, and the ratio of particle displacement to time interval in adjacent frame images is calculated to obtain real-time distribution data of radial convection velocity field and thermal convection velocity field.

[0035] Based on the real-time distribution data of the radial convection velocity field and the thermal convection velocity field, and combined with the relationship between gas density and temperature, the Reynolds number is calculated. If the Reynolds number exceeds the preset turbulence threshold, the current turbulent flow state is determined. The airflow velocity control coefficient is determined based on the ratio of the root mean square value of velocity fluctuation to the average flow velocity.

[0036] Based on the real-time distribution data of the airflow velocity control coefficient and the radial convection velocity field, the ratio of the radial velocity component to the axial velocity component is calculated, and the radial convection intensity adjustment factor is determined to obtain the optimized radial flow control parameters.

[0037] Based on the radial convection intensity adjustment factor and thermal convection velocity field data, the pressure difference in different regions of the arc-extinguishing chamber is calculated, and the channel pressure balance parameters are determined to obtain a dynamic adjustment parameter set including the airflow velocity control coefficient, the radial convection intensity adjustment factor, and the channel pressure balance parameters.

[0038] Preferably, step S6 specifically includes:

[0039] Based on the airflow velocity control coefficient, radial convection intensity adjustment factor, and channel pressure balance parameters of the dynamically adjusted parameter set, the airflow velocity control coefficient and the inlet flow area are multiplied, and the radial convection intensity adjustment factor and the exhaust port position are corresponded. The airflow velocity values ​​of each region are calculated to obtain the adjusted airflow distribution field.

[0040] Based on the adjusted airflow distribution field, the pressure gradient distribution in the new channel is determined by calculating the ratio of the pressure difference between adjacent regions to the distance. If the pressure gradient shows a decreasing trend in the arc region, it is determined that the airflow adjustment direction is correct. The optimized airflow velocity distribution is obtained based on the coupling relationship between the pressure gradient and the airflow velocity.

[0041] For the optimized airflow velocity distribution, the convective heat transfer coefficient at the boundary of the electric arc column is calculated. The convective heat transfer intensity is controlled by adjusting the airflow velocity in the boundary region. Combined with the equilibrium condition that the heat inflow equals the heat outflow, the airflow parameters required to maintain the target boundary temperature are determined, and the electric arc column boundary temperature control scheme is obtained.

[0042] Preferably, step S7 specifically includes:

[0043] According to the arc column boundary temperature control scheme, the airflow direction is changed by adjusting the angle of the flow guiding structure in the arc extinguishing chamber, the airflow rate is adjusted according to the airflow velocity parameters, and the adjusted radial convection velocity value is determined.

[0044] Based on the adjusted radial convection velocity value, the voltage signal at both ends of the contact gap and the current signal through the contact are collected in real time. The voltage change rate and current change rate are calculated. If the voltage change rate exceeds the preset change rate threshold and the current shows a downward trend, it is determined that the arc intensity is weakening. The instantaneous power value is determined based on the product of voltage and current.

[0045] For the instantaneous power value and the radial convection velocity value, obtain the corresponding optimal diffusion angle value, adjust the airflow guiding device to achieve the diffusion angle, and obtain an airflow distribution adapted to the electric arc state;

[0046] Based on the airflow distribution adapted to the arc state and the continuously monitored rate of change of current, the output control signal triggers the circuit breaker protection mechanism to perform the tripping action and disconnect the fault circuit.

[0047] The intelligent protection method for high and low voltage DC relays in new energy sources described in this invention has the following advantages:

[0048] This invention provides a method for intelligent protection of high and low voltage DC relays in new energy systems. By monitoring real-time spectral data of metal vapor within the arc channel, it directly obtains key parameters such as plasma density and temperature gradient, providing accurate initial data for subsequent protection and control. This avoids the errors of traditional methods that rely on indirect parameters to infer the arc state. By analyzing the radial distribution non-uniformity of the arc column and combining multi-physics field coupling calculations such as electromagnetic force and thermal convection, it identifies the formation trend of risks such as arc channel deflection and trajectory abnormalities in advance, breaking the limitation of traditional protection methods that can only passively respond to faults. Based on airflow dynamics models and heat transfer characteristics, it generates dynamic adjustment parameters for gas flow patterns in real time, precisely controlling the airflow distribution, pressure gradient, and radial diffusion angle within the arc extinguishing chamber to ensure that arc energy can be efficiently suppressed and dissipated. From arc state monitoring and risk prediction to airflow control and then to the linkage circuit breaker protection mechanism cutting off the fault circuit, a closed-loop intelligent protection chain is formed, avoiding the limitations of single protection measures and significantly improving the safety and reliability of the relay when interrupting large currents, reducing the risk of faults such as ablation. The intelligent protection method for high and low voltage DC relays in new energy significantly improves the stability and safety of DC relay switching, effectively prevents arc reignition, and ensures reliable operation of equipment under complex working conditions. Attached Figure Description

[0049] Figure 1 This is a flowchart of a method for intelligent protection of high and low voltage DC relays for new energy sources, as described in this invention. Detailed Implementation

[0050] like Figure 1 As shown, the intelligent protection method for high and low voltage DC relays in new energy sources according to the present invention includes the following steps:

[0051] S1. Monitor the real-time spectral data of metal vapor in the arc channel when the relay interrupts a large current, analyze the data to obtain the arc plasma density and temperature gradient distribution, and determine the radial heat flux density.

[0052] S2. Generate a continuous radial heat flow distribution curve, analyze the heat conduction coefficient and radial energy dissipation inside the arc column, and obtain the radial distribution non-uniformity of the temperature gradient of the arc column.

[0053] S3. If the radial distribution non-uniformity exceeds the preset non-uniformity threshold, the electromagnetic force vector distribution and thermal convection velocity are calculated by coupling the magnetic field sensor array and the temperature field, and the formation trend of the arc channel deflection angle is obtained.

[0054] S4. Dynamically model and predictively analyze the formation trends of arc trajectory curvature and arc channel deflection angle to obtain the gas flow resistance in the arc extinguishing chamber and the pressure gradient in the channel, and determine the arc trajectory length.

[0055] S5. Monitor the radial convection velocity and thermal convection velocity inside the arc extinguishing chamber, and analyze them in conjunction with the airflow dynamics model and heat transfer characteristics to determine the dynamic adjustment parameters of the gas flow mode.

[0056] S6. Adjust the airflow distribution in the arc extinguishing chamber and the pressure gradient in the channel according to the dynamic adjustment parameters of the gas flow mode to obtain the optimized control scheme of airflow velocity distribution and arc column boundary temperature.

[0057] S7. Adjust the airflow direction and radial convection velocity in the arc extinguishing chamber according to the control scheme, and automatically adjust the radial diffusion angle of the airflow in conjunction with the changes in voltage and current in the contact gap, and link the circuit breaker protection mechanism to cut off the fault circuit.

[0058] Furthermore, in this embodiment, step S1 specifically includes:

[0059] Continuous spectral data of the relay contact gap region was collected to obtain characteristic spectral line data of metal atoms and calculate the spatial temperature distribution of the arc plasma. The continuous spectral data was collected by a high-speed spectrometer to obtain characteristic spectral line data of metal atoms in the 400-800 nm band. Based on the intensity ratio of the characteristic spectral lines of copper atoms at 521.8 nm and 578.2 nm, combined with the Boltzmann distribution law, the spatial temperature distribution data of the arc plasma was calculated.

[0060] The spectral signal intensity at different radial positions of the arc column is obtained by radial scanning. Based on the spectral signal intensity and temperature spatial distribution, the radial distribution function of the plasma particle number density is determined. The boundary position of the arc column is determined based on the radial distribution function, and the radial width of the arc column is obtained.

[0061] Based on the radial distribution function and spatial temperature distribution, the temperature difference between adjacent radial positions is calculated. Combining this with heat conduction and radiative heat flux, the radial heat flux density at each radial position is calculated. Specifically, the radial heat flux component caused by heat conduction is determined according to Fourier's law, and the radiative heat flux component is calculated using the Stefan-Boltzmann law based on temperature data. The two components are then superimposed to obtain the heat flux density value at each radial position. The Fourier's law calculation formula is as follows:

[0062]

[0063] Where, q cond (r) represents the heat flux density at radial position r; κ(T(r)) represents the thermal conductivity at temperature T(r); Radial temperature gradient;

[0064] Specifically, during the process of a relay breaking a large current, the electric arc generated between the contacts is a high-temperature and high-density plasma phenomenon. When the contacts separate, electrons are emitted from the metal surface under the action of a strong electric field to form an initial current channel. Subsequently, a large number of metal atoms are evaporated and ionized to form an electric arc plasma rich in metal vapor. The temperature of this plasma can reach thousands to tens of thousands of Kelvin. The atoms and ions inside are in excited states at different energy levels and generate characteristic spectra through spontaneous emission.

[0065] Copper is the main material for relay contacts. Its atoms are excited to different energy levels under the high temperature of an electric arc. When these excited atoms fall back to the ground state or a lower energy level, they will emit spectral lines of a specific wavelength.

[0066] The 521.8 nm and 578.2 nm spectral lines of copper atoms correspond to different energy level transitions, and the intensity ratio of these two spectral lines directly reflects the proportion of atoms in different excited states.

[0067] According to Boltzmann's distribution law, this ratio has a definite functional relationship with the plasma temperature, and the temperature value can be deduced by measuring the ratio of spectral line intensities.

[0068] For example, when using a high-speed spectrometer for radial scanning measurements, the cylindrical symmetry of the arc column needs to be considered. From the center of the arc to the edge, the temperature and density exhibit a gradient distribution, with the highest temperature and particle density in the central region, gradually decreasing outwards.

[0069] The spectrometer receives an integrated signal along the line of sight, which includes contributions from different radial positions. By acquiring spectral data at different radial positions and combining it with the mathematical method of inverse Abelian transform, the radial distribution of local emission coefficients can be reconstructed from the integrated data.

[0070] The determination of plasma particle number density depends on the comprehensive analysis of spectral line intensity and temperature. The spectral line intensity is not only proportional to the number of excited-state atoms, but also modulated by the excitation probability under the influence of temperature.

[0071] By normalizing the temperature spatial distribution data, the interference of temperature changes on density measurement can be eliminated, and the true radial distribution of particle number density can be obtained. When the density gradient change rate changes abruptly, it indicates that the boundary of the electric arc column has been reached. Based on this, the radial width of the electric arc column can be accurately determined.

[0072] The calculation of radial heat flux density needs to consider both heat conduction and radiation heat transfer mechanisms. Heat conduction follows Fourier's law, and heat flux density is proportional to the temperature gradient. In arc plasma, it is mainly caused by the thermal motion of electrons and ions.

[0073] Radiation heat transfer, according to the Stefan-Boltzmann law, is proportional to the fourth power of temperature and plays an important role in high-temperature electric arcs. The total radial heat flux density distribution is obtained by superimposing the heat flux components generated by the two mechanisms.

[0074] Furthermore, in this embodiment, step S2 specifically includes:

[0075] The radial width and radial heat flux density of the electric arc column are filtered in the time domain to obtain a smooth time domain signal sequence, and cubic spline interpolation is performed to obtain a continuous radial heat flux distribution curve.

[0076] Based on the radial heat flow distribution curve, calculate the temperature gradient between adjacent radial locations and determine the radial distribution data of the thermal conductivity coefficient;

[0077] Based on the radial distribution data of thermal conductivity and temperature gradient values, the radial heat flux is calculated to determine the energy dissipation rate at each radial location and obtain the radial energy dissipation distribution. The radial heat flux represents the net outflow of heat per unit volume. If the energy dissipation rate of a certain radial region exceeds a preset threshold, it is determined that there is a strong energy loss in that region.

[0078] Based on the radial energy dissipation distribution and the radial distribution data of the thermal conductivity coefficient, the temperature gradient values ​​at different radial positions are calculated, and the deviation of the temperature gradient at each position from the mean temperature gradient over the entire radial range is obtained. The radial distribution non-uniformity of the arc column temperature gradient is determined by the ratio of the deviation to the mean.

[0079] Specifically, in the process of arc plasma diagnosis, due to the sampling frequency limitation of the measuring equipment and the influence of electromagnetic interference, the obtained radial heat flux density data often exhibits a discrete distribution and contains noise. Time-domain filtering becomes a key means to eliminate these interferences. The moving average method effectively suppresses the influence of random noise by averaging the data at multiple consecutive time points.

[0080] For the heat flux density time series at each radial position, a weighted average can be calculated by selecting 5 sampling points before and after the point, with the center point having the largest weight and decreasing towards both sides. This preserves the main trend of the signal while eliminating high-frequency disturbances.

[0081] The filtered discrete data points still cannot be directly used for subsequent differential operations and gradient calculations. Cubic spline interpolation technology ensures the continuity and smoothness of the curve by constructing a cubic polynomial function between adjacent data points.

[0082] The above method not only makes the function value continuous at the nodes, but also keeps its first and second derivatives continuous, which is crucial for subsequent calculation of temperature gradient. The continuous radial heat flux distribution curve obtained after interpolation can provide heat flux density values ​​at any radial position, laying the foundation for accurate analysis.

[0083] For example, Fourier's law of heat conduction reveals the linear relationship between heat flux density and temperature gradient, and the thermal conductivity coefficient, as a proportionality constant, reflects the ability of a medium to transfer heat.

[0084] In electric arc plasma, the thermal conductivity coefficient is not constant, but varies with temperature, particle density and ionization degree. The thermal conductivity coefficient at a given location can be obtained by dividing the measured heat flux density by the temperature gradient at that location. From the center of the arc to the edge, the thermal conductivity coefficient exhibits a significant radial variation as the temperature and ionization degree decrease.

[0085] The application of the energy conservation equation in cylindrical coordinates reveals the physical mechanism of energy dissipation. For any infinitesimal volume within an arc column, the difference between the heat flowing in and the heat flowing out is the energy dissipation within that volume.

[0086] Radial heat flux divergence characterizes the net outflow rate of heat flux per unit volume. When the divergence is positive, it indicates that the region is dissipating energy outward.

[0087] The central region of the electric arc generates a large amount of energy due to Joule heating, while the peripheral region mainly loses energy through heat conduction and radiation, forming a complex energy balance relationship.

[0088] The non-uniformity of temperature gradient distribution directly affects the stability and ablation characteristics of the electric arc. By calculating the ratio of the deviation between the temperature gradient at each radial position and the average temperature gradient, the degree of non-uniformity can be quantitatively assessed.

[0089] When the temperature gradient in a certain area deviates significantly from the average value, it indicates the presence of local hot spots or cold zones, which are often the origin of arc instability.

[0090] Furthermore, in this embodiment, step S3 specifically includes:

[0091] If the radial distribution non-uniformity exceeds the preset non-uniformity threshold, magnetic induction intensity data of the space around the electric arc is collected to obtain the three-dimensional magnetic field distribution; the magnetic induction intensity data is collected through a magnetic field sensor array.

[0092] The electromagnetic force vector distribution on the arc plasma is determined by coupling calculations based on the three-dimensional magnetic field distribution and the radial temperature gradient distribution; specifically, the electromagnetic force vector distribution on the arc plasma is determined by the cross product of current density and magnetic induction intensity.

[0093] Based on the electromagnetic force vector distribution and density changes caused by temperature differences, the buoyancy distribution is calculated by multiplying the density difference in different temperature regions by gravitational acceleration. The momentum conservation equation is used to solve for the velocity of the plasma under the combined action of electromagnetic force and buoyancy, thus obtaining the thermal convection velocity field inside the electric arc. The buoyancy distribution calculation process is as follows:

[0094] f b =(ρ0-ρ arc )*g

[0095] Among them, f b ρ represents the buoyancy volume force vector; ρ0 represents the ambient gas density; ρ arc The electric arc plasma density is represented by g; g represents the gravitational acceleration vector.

[0096] Calculate f for each spatial point b The buoyancy distribution can then be obtained;

[0097] Based on the distribution of thermal convection velocity field and electromagnetic force vector, the position coordinate changes of each point on the center line of the electric arc are calculated, and the reciprocal of the local radius of curvature is calculated for the continuously recorded position coordinates to obtain the spatial distribution of the curvature of the electric arc trajectory.

[0098] For the spatial distribution of the curvature of the arc trajectory, calculate the angle between the tangent vector of the arc centerline and the initial straight line direction. If the rate of change of the angle along the axial position continues to increase, it is determined that there is a deflection trend in the arc channel. The formation trend of the arc channel deflection angle is determined by the cumulative change of the angle.

[0099] Specifically, the non-uniform distribution of the temperature gradient in the arc column is a key factor triggering arc instability. When significant asymmetry occurs in the radial temperature distribution, it means that there are local hot spots or cold zones inside the arc, and this non-uniformity will cause changes in the motion state of the arc plasma.

[0100] The purpose of setting a non-uniformity threshold is to identify this abnormal state. When the deviation exceeds the normal range, it indicates that the electric arc has deviated from the ideal cylindrical symmetry state.

[0101] The magnetic field sensor array is arranged in a ring distribution, with multiple Hall sensors or fluxgate sensors set at different positions and heights around the electric arc.

[0102] Each sensor measures three components of the magnetic field strength at its location, and the three-dimensional magnetic field distribution of the entire arc region is reconstructed through a spatial interpolation algorithm.

[0103] The magnetic field generated by the arc current in space is closely related to the current density distribution, while the non-uniformity of the temperature gradient directly affects the current density distribution. Therefore, the coupled calculation of magnetic field data and temperature data can accurately reflect the actual state of the arc.

[0104] For example, the calculation of electromagnetic force is based on the classical electromagnetic principle that charged particles in an electric arc plasma are subjected to the Lorentz force when moving in a magnetic field, and the magnitude of the force is equal to the cross product of the current density and the magnetic induction intensity.

[0105] Because the current density and magnetic field strength vary at different locations inside the electric arc, the electromagnetic force exhibits a complex spatial distribution. This non-uniform electromagnetic force distribution is the main driving force for the deflection of the electric arc.

[0106] The formation mechanism of thermal convection involves density changes caused by temperature. The plasma density in high-temperature regions is lower, and under the action of gravity, it generates an upward buoyancy.

[0107] The density is higher in the low-temperature region, and it tends to sink. The buoyancy generated by this density difference and the electromagnetic force work together to drive the macroscopic flow of the plasma. The momentum conservation equation connects the action of these forces with the velocity change. By solving this equation, the convection velocity at each point can be obtained.

[0108] The tracking of the electric arc trajectory is achieved by recording the spatiotemporal evolution of the arc centerline, which is defined as the line connecting the points where the maximum current density is located on each cross section.

[0109] Over time, under the combined action of electromagnetic force and thermal convection, this center line will bend. The three-point method is a classic geometric method for calculating curvature: select three consecutive points on the trajectory, and a unique arc can be determined through these three points. The reciprocal of the radius of the arc is the curvature value at that position. The greater the curvature, the more severe the bending of the arc.

[0110] The formation of the arc deflection angle is a gradual process. Initially, the arc is in a straight line. As the asymmetric electromagnetic force generated by the non-uniform temperature field continues to act, the arc gradually deviates from the original path.

[0111] By calculating the change in the angle between the arc tangent direction and the initial direction, the degree of deflection can be quantitatively assessed. When the rate of change of the angle continues to increase, it indicates that the deflection trend will further intensify, which provides early warning information for taking corresponding control measures.

[0112] Furthermore, in this embodiment, step S4 specifically includes:

[0113] Temporal features were extracted from the data sequence of the changes in arc trajectory curvature and arc channel deflection angle over time, and time functions of the rate of change of curvature and the rate of increase of deflection angle were fitted to obtain parameters describing the trajectory evolution trend.

[0114] Based on the arc morphology determined by the trajectory evolution trend parameters, the pressure distribution around the arc channel is calculated, and the gas flow resistance distribution at each location is determined; by solving the gas continuity equation and momentum conservation equation in the arc extinguishing chamber, the pressure distribution around the arc channel is calculated.

[0115] For the gas flow resistance distribution and the pressure distribution around the arc channel, the pressure change rate along the arc channel axis is calculated to obtain the pressure gradient inside the channel. If the pressure gradient exceeds the preset stability threshold, it is determined that the arc has a risk of instability, and the arc trajectory stability index is determined. The arc trajectory stability index is determined by the ratio of pressure driving force to flow resistance.

[0116] The arc trajectory length is determined based on the arc trajectory stability index and trajectory evolution trend parameters, combined with the constraint effect of flow resistance distribution on trajectory expansion.

[0117] Specifically, the dynamic evolution of the arc trajectory is a complex time-varying process, with its curvature and deflection angle constantly changing over time;

[0118] The core of time-domain feature extraction lies in identifying potential patterns of change from discrete measurement data. By performing differential operations on the curvature values ​​at multiple consecutive moments, the rate of curvature change can be obtained. This rate of change reflects the trend of intensification or de-intensification of the arc bending.

[0119] Least squares fitting finds the functional relationship that best represents the trend of data change by minimizing the sum of squared errors between the measured data and the fitted curve.

[0120] The trajectory evolution trend parameters include key indicators such as curvature growth coefficient and deflection angle acceleration. These parameters not only describe the current state of the electric arc, but more importantly, predict the future development direction.

[0121] When the curvature growth coefficient is positive and gradually increases, it indicates that the electric arc is accelerating its bending. When the deflection angle acceleration continues to increase, it means that the electric arc is deviating from the initial path at an accelerated speed.

[0122] The gas flow in the arc-extinguishing chamber follows the basic laws of fluid dynamics. The continuity equation ensures the conservation of mass, that is, the mass of gas flowing into a certain area per unit time is equal to the mass flowing out plus the change in mass in that area.

[0123] The momentum conservation equation describes the motion of gas under the action of pressure difference, viscous force and external force. When a high-temperature electric arc exists, the heat it generates will cause the surrounding gas to expand, forming a complex pressure distribution.

[0124] The viscosity coefficient of a gas is a physical quantity that characterizes the internal friction properties of a gas. It increases with increasing temperature. In the high-temperature region of an electric arc, the viscosity coefficient of a gas can be several times that at room temperature. The calculation of flow resistance is based on the relationship between velocity gradient and viscosity coefficient: the greater the velocity difference between adjacent flow layers, the higher the viscosity coefficient, and the greater the resistance generated. This resistance will hinder the free movement of the electric arc and affect its trajectory development.

[0125] The pressure gradient is formed due to the uneven release of energy from the electric arc. The center of the arc has the highest temperature and the strongest thermal expansion effect, forming a high-pressure zone; while the area far from the arc has a lower temperature and relatively lower pressure.

[0126] This pressure difference drives the gas to flow from the high-pressure area to the low-pressure area, forming convection. The balance between the pressure gradient and the flow resistance determines the stability of the electric arc: when the pressure driving force is greater than the flow resistance, the electric arc can maintain a stable shape; otherwise, the electric arc may oscillate irregularly or break.

[0127] The calculation of the arc trajectory length involves the arc length integral of the space curve. For a curve with a known curvature function, its length can be accurately calculated through integration.

[0128] However, the presence of flow resistance limits the extension of the arc: in areas of high resistance, the arc tends to choose a path with less resistance, which may result in a shorter trajectory or a change in direction.

[0129] Furthermore, in this embodiment, step S5 specifically includes:

[0130] Based on the arc trajectory stability index and arc trajectory length, tracer particles were scattered in the arc extinguishing chamber using the particle image velocimetry method, and the ratio of particle displacement to time interval in adjacent frames was calculated to obtain real-time distribution data of radial convection velocity field and thermal convection velocity field.

[0131] Based on the real-time distribution data of the radial and thermal convection velocity fields, and combined with the relationship between gas density and temperature, the Reynolds number is calculated. If the Reynolds number exceeds the preset turbulence threshold, the current flow state is determined to be turbulent. The airflow velocity control coefficient is determined based on the ratio of the root mean square value of velocity fluctuation to the average flow velocity. The Reynolds number is obtained by dividing the product of the characteristic length and the kinematic viscosity by the flow velocity.

[0132] Based on the real-time distribution data of the airflow velocity control coefficient and the radial convection velocity field, the ratio of the radial velocity component to the axial velocity component is calculated, and the radial convection intensity adjustment factor is determined to obtain the optimized radial flow control parameters.

[0133] Based on the radial convection intensity adjustment factor and thermal convection velocity field data, the pressure difference in different regions of the arc-extinguishing chamber is calculated, and the channel pressure balance parameters are determined to obtain a dynamic adjustment parameter set including the airflow velocity control coefficient, the radial convection intensity adjustment factor, and the channel pressure balance parameters.

[0134] Specifically, particle image velocimetry is a non-contact flow field measurement method. Its core principle is to infer the velocity distribution of the fluid by tracking the movement of tracer particles in the fluid.

[0135] In the arc-extinguishing chamber, these tracer particles are usually made of high-temperature resistant alumina or zirconium oxide microparticles with a particle size controlled in the range of 1-10 micrometers. They can follow the airflow well and generate sufficient scattered light intensity. A high-speed camera captures the positional changes of the particles in a very short time interval by continuously shooting at a rate of thousands of frames per second.

[0136] The measurement of the radial convection velocity field requires multiple measurement planes to be arranged at different radial positions in the arc-extinguishing chamber. A specific plane is illuminated by a laser sheet, causing the particles in that plane to emit light, and a camera is used to take pictures perpendicular to the direction of the laser sheet.

[0137] The position of the same particle in two adjacent frames is removed by the frame time interval, which gives the instantaneous velocity of that point. The thermal convection velocity field reflects the gas motion driven by the temperature gradient. In the high-temperature region of the electric arc, the gas expands and rises due to heating, forming an obvious convection circulation.

[0138] The calculation of the Reynolds number involves several fluid characteristic parameters. The characteristic length is usually taken as the equivalent diameter of the arc channel, while the kinematic viscosity changes significantly with temperature. At room temperature, the kinematic viscosity of air is about 15 square millimeters per second, but it can increase by more than 100 times in the high-temperature region of the arc.

[0139] When the calculated Reynolds number exceeds the critical value of 2300, the flow changes from laminar to turbulent. In turbulent flow, the root mean square value of velocity fluctuation reflects the degree of irregularity of the flow, and its ratio to the average velocity is the turbulence intensity, with a typical value between 0.05 and 0.25.

[0140] The ratio of the radial velocity component to the axial velocity component directly affects the stability of the electric arc. When the radial velocity is too large, the electric arc is prone to lateral oscillation, which reduces the reliability of the breaking. This correlation shows a negative correlation: for every 0.1 increase in the ratio, the stability index decreases by about 15%.

[0141] Based on this relationship, the linear interpolation method performs interpolation calculations between known discrete data points to determine the radial convection intensity adjustment factor corresponding to any ratio.

[0142] Bernoulli's equation describes the fundamental law of conservation of fluid energy: in an arc-extinguishing chamber, the total pressure equals the static pressure plus the dynamic pressure.

[0143] In high-speed flow regions, the dynamic pressure is higher and the static pressure is correspondingly lower; in low-speed regions, the opposite is true. This pressure difference drives the gas to flow from high-pressure regions to low-pressure regions.

[0144] When the pressure driving force is exactly equal to the sum of viscous drag and form drag, the flow reaches dynamic equilibrium. This equilibrium state is distinguished by pressure balance parameters, which are usually between 0.8 and 1.2. A deviation from 1.0 indicates the presence of net driving force or drag.

[0145] The three dynamic adjustment parameters are interconnected and work together. The airflow velocity control coefficient determines the overall flow intensity, the radial convection intensity adjustment factor controls the lateral disturbance, and the channel pressure balance parameter maintains longitudinal stability.

[0146] By monitoring and adjusting these parameters in real time, the gas flow state in the arc-extinguishing chamber can be optimized, the arc breaking performance can be improved, and the service life of the equipment can be extended.

[0147] Furthermore, in this embodiment, step S6 specifically includes:

[0148] Based on the airflow velocity control coefficient, radial convection intensity adjustment factor, and channel pressure balance parameters of the dynamic adjustment parameter set, the airflow velocity control coefficient and the inlet flow area are multiplied by the product relationship, and the radial convection intensity adjustment factor and the exhaust port position are corresponded by the relationship. The airflow velocity values ​​of each region are calculated to obtain the adjusted airflow distribution field.

[0149] Based on the adjusted airflow distribution field, the pressure gradient distribution within the new channel is determined by calculating the ratio of the pressure difference between adjacent regions to their distance. If the pressure gradient shows a decreasing trend in the arc region, the airflow adjustment direction is considered correct. The optimized airflow velocity distribution is obtained based on the coupling relationship between the pressure gradient and airflow velocity. The pressure gradient is the core indicator for determining the correctness of the airflow adjustment direction, defined as the ratio of the pressure difference between adjacent regions to the distance between regions (along the airflow direction, either axial or radial).

[0150]

[0151] Where ▽P represents the pressure gradient between adjacent regions, in Pa / m; ΔP=P2-P1 represents the pressure difference between two adjacent regions, in Pa, where P2 is the downstream pressure and P1 is the upstream pressure; ΔL=L2-L1 represents the geometric distance between two adjacent regions, in m;

[0152] For the optimized airflow velocity distribution, the convective heat transfer coefficient at the boundary of the electric arc column is calculated. The convective heat transfer intensity is controlled by adjusting the airflow velocity in the boundary region. Combined with the equilibrium condition that the heat inflow equals the heat outflow, the airflow parameters required to maintain the target boundary temperature are determined, and the electric arc column boundary temperature control scheme is obtained. Among them, the convective heat transfer coefficient at the boundary of the electric arc column is calculated according to the power function relationship between the Nusselt number and the Reynolds number.

[0153] Specifically, the airflow regulation inside the arc-extinguishing chamber is a precise fluid dynamics process, the core of which lies in changing the internal flow field distribution by adjusting the parameters of the intake and exhaust structures.

[0154] The airflow velocity control coefficient, as the dominant parameter, directly determines the effective flow area of ​​the air inlet. When the coefficient is 1.2, it means that the standard air inlet area needs to be increased by 20%. This increase is achieved through adjustable blade angles or sliding baffles. The increase in air intake will increase the overall airflow velocity and enhance the cooling effect on the electric arc.

[0155] The radial convection intensity adjustment factor affects the arrangement of the exhaust ports. Traditional axial exhaust is prone to forming a straight flow channel, while by setting multiple radial exhaust ports on the side wall of the arc-extinguishing chamber, the airflow can be guided to generate spiral motion.

[0156] When the adjustment factor is 0.8, it means that the opening of the radial exhaust port needs to be adjusted to 80% of the design value. This adjustment changes the movement trajectory of the airflow, causing it to form a rotating flow field around the electric arc, which effectively enhances the radial heat transport.

[0157] The application of the continuity equation ensures the rationality of airflow regulation. This equation shows that, under steady-state conditions, the mass flow rate of the gas flowing into the arc-extinguishing chamber must be equal to the mass flow rate flowing out.

[0158] By measuring airflow velocity and density at different cross sections, it can be verified whether the adjusted flow field satisfies mass conservation. If an abnormal increase in flow velocity occurs in a certain area, it often indicates that there is flow channel contraction or blockage, and further optimization of the structural design is required.

[0159] The formation of pressure gradients is closely related to airflow velocity. According to Bernoulli's principle, regions with high flow velocity have lower pressure, while regions with low flow velocity have higher pressure.

[0160] In the arc region, the ideal pressure gradient should gradually increase from the center outwards to prevent high-temperature gas from lingering in the center of the arc.

[0161] The decreasing pressure gradient indicates that the airflow can effectively carry away heat from the center of the electric arc, avoiding local overheating;

[0162] The relationship between the Nusselt number and the Reynolds number reveals the laws governing convective heat transfer. The Nusselt number characterizes the intensity of convective heat transfer, while the Reynolds number reflects the ratio of inertial forces to viscous forces in the flow.

[0163] Under turbulent conditions, the Nusselt number is usually proportional to the 0.8 power of the Reynolds number. This means that when the airflow velocity doubles, the Reynolds number doubles, but the convective heat transfer coefficient only increases by about 74%. Therefore, simply relying on increasing the flow velocity to enhance heat transfer has the problem of diminishing efficiency.

[0164] The key to controlling the boundary temperature of the electric arc column lies in establishing thermal equilibrium. The heat sources at the boundary include heat conduction and radiation inside the electric arc, while heat loss is achieved through convective heat transfer.

[0165] By precisely controlling the airflow velocity in the boundary region, the intensity of convective heat transfer can be adjusted to achieve a balance between heat input and output.

[0166] When the boundary temperature is maintained at the set value, it can ensure the stable combustion of the electric arc and prevent excessive ablation of the contact material, thus significantly improving the service life and reliability of the switching device.

[0167] Furthermore, in this embodiment, step S7 specifically includes:

[0168] According to the arc column boundary temperature control scheme, the airflow direction is changed by adjusting the angle of the guide structure in the arc extinguishing chamber, the airflow rate is adjusted according to the airflow velocity parameters, and the adjusted radial convection velocity value is determined.

[0169] Based on the adjusted radial convection velocity value, the voltage signal at both ends of the contact gap and the current signal through the contact are collected in real time. The voltage change rate and current change rate are calculated. If the voltage change rate exceeds the preset change rate threshold and the current shows a decreasing trend, it is determined that the arc intensity is weakening. The instantaneous power value is determined based on the product of voltage and current. The voltage change rate and current change rate are calculated by dividing the difference between adjacent sampling points by the sampling time interval.

[0170] For the instantaneous power value and radial convection velocity value, the corresponding optimal diffusion angle value is obtained, and the airflow guiding device is adjusted to achieve the diffusion angle to obtain an airflow distribution adapted to the electric arc state;

[0171] Based on the airflow distribution adapted to the arc state and the continuously monitored rate of change of current, the output control signal triggers the circuit breaker protection mechanism to perform the tripping action and disconnect the fault circuit.

[0172] Specifically, the angle adjustment of the flow guide structure is the key to achieving precise control of the airflow direction. Inside the arc extinguishing chamber, the flow guide structure usually adopts a rotatable blade group design, with each blade connected to the central control shaft through a gear transmission mechanism.

[0173] When the control scheme requires a change in airflow direction, the servo motor drives the central shaft to rotate, causing all blades to deflect synchronously.

[0174] When the blade angle is adjusted from 0 degrees to 45 degrees, the airflow gradually changes from axial flow to spiral flow. This change in flow pattern directly affects the stability of the electric arc and the cooling efficiency.

[0175] The determination of radial convection velocity involves the basic principles of fluid mechanics. The intake flow rate is measured in real time by a flow meter, while the effective cross-sectional area changes dynamically according to the angle of the guide vanes.

[0176] When the blades are fully open, the cross-sectional area is at its maximum. As the blade angle increases, the effective flow area decreases. The velocity value is equal to the volumetric flow rate divided by the effective cross-sectional area. This simple relationship ensures that the actual radial convection velocity can be accurately calculated under different operating conditions.

[0177] The acquisition of voltage and current signals uses a high-speed data acquisition system with a sampling frequency that typically reaches more than 100,000 times per second. This high-frequency sampling is crucial for capturing the dynamic changes of the electric arc.

[0178] The rate of change is calculated using the difference method: take the difference between two adjacent sampling points and divide it by the sampling time interval. When the rate of change of voltage is positive and exceeds the set threshold, and the current shows a downward trend, it indicates that the arc is being stretched and the resistance is increasing. This is a typical characteristic of the arc about to be extinguished.

[0179] The relationship between instantaneous power and diffusion angle is established based on a large amount of experimental data. When the power is high, the arc energy is concentrated, and a smaller diffusion angle is required to maintain a stable arc column.

[0180] When the power decreases, the electric arc tends to disperse, and increasing the diffusion angle helps to accelerate heat dissipation;

[0181] The lookup table method is a commonly used method in engineering practice. The optimal diffusion angle corresponding to different power values ​​is obtained in advance through experiments and stored in the controller. During actual operation, the corresponding angle is quickly looked up based on the calculated power value.

[0182] Fault diagnosis employs a multi-confirmation mechanism to improve reliability; the monitoring of current change rate is not based on a single-point judgment, but on a comprehensive evaluation of multiple consecutive sampling cycles.

[0183] For example, a fault condition is identified only when the rate of change of current exceeds the threshold in 4 out of 5 consecutive sampling periods. This judgment method effectively avoids malfunctions caused by instantaneous interference.

[0184] Once a fault is confirmed, the control signal is transmitted to the circuit breaker protection mechanism via optical fiber to ensure that the tripping action is completed within microseconds.

[0185] The entire intelligent protection process is a closed-loop control system. From airflow regulation to electrical parameter monitoring, and then to fault diagnosis and protection actions, each link is interconnected and works in concert. Compared with traditional fixed threshold protection, this intelligent protection scheme can dynamically adjust protection parameters according to actual working conditions, which not only improves the sensitivity of protection, but also reduces the probability of false operation. It is particularly suitable for application scenarios with frequent current fluctuations in new energy systems.

[0186] Furthermore, based on the optimized airflow velocity distribution and arc column boundary temperature control scheme, the radial diffusion angle adjustment amount is determined by using the blade angle adjustment mechanism of the airflow guide device and the linear mapping relationship between the boundary temperature and the target temperature deviation value. The blades are adjusted to make the airflow diffuse at a determined angle, forming a directional airflow field pointing towards the high temperature zone of the arc, thus obtaining an enhanced cooling airflow distribution state.

[0187] Based on the arc characteristics under the enhanced cooling airflow distribution, the voltage signal across the contact gap and the current signal flowing through the contact are monitored in real time. The time interval from the detection of arc generation to the current dropping to zero is recorded by a timer. If the time interval exceeds the upper limit of the arc extinguishing time determined by the airflow intensity, the arc duration is judged to be abnormal. At the same time, it is detected whether the current drops below the disconnection judgment value close to zero to determine the current disconnection completeness status.

[0188] In cases where the arc duration is abnormal or the current disconnection status does not meet the requirements, a trigger signal is output to the actuator of the circuit breaker protection mechanism to drive the contacts to quickly separate and perform the tripping action. By increasing the contact gap distance, the current path in the main circuit is cut off, and the current is completely interrupted.

[0189] Based on the complete interruption of current and the continuous effect of the directional airflow field, the voltage rise rate at both ends of the contact gap is monitored. If the voltage rise rate is lower than the recovery rate lower limit determined by the airflow cooling intensity, the airflow diffusion angle is increased to enhance cooling. Through the timing coordination of airflow regulation and protection mechanism action, a multi-level fault protection system including preventive airflow regulation and emergency tripping protection is established.

[0190] Specifically, the blade angle adjustment of the airflow guide device is the core mechanism for achieving precise airflow control, and the establishment of the linear mapping relationship is based on the fitting results of a large amount of experimental data;

[0191] When the boundary temperature is 10 degrees Celsius higher than the target temperature, the radial diffusion angle needs to be increased by 15 degrees; when the temperature deviation is 20 degrees Celsius, the diffusion angle is increased by 30 degrees accordingly. This proportional relationship ensures the linear predictability of the adjustment response.

[0192] The blades are driven by a stepper motor, with each pulse corresponding to a 0.5-degree angle change, achieving precise angle control;

[0193] The formation of a directional airflow field depends on the principles of fluid dynamics. When multiple blades deflect synchronously at the calculated angle, the airflow that was originally flowing axially is guided to diffuse radially.

[0194] The larger the diffusion angle, the stronger the radial component of the airflow, and the more obvious the cooling effect on the side of the arc. This directional cooling is more efficient than traditional uniform cooling because it concentrates the cooling airflow on the high-temperature core region of the arc.

[0195] The duration of the electric arc is monitored using a high-precision timing circuit. The timer starts the instant a voltage drop is detected, which marks the beginning of contact separation and the generation of an electric arc.

[0196] Under normal circumstances, under the enhanced airflow cooling effect, the DC arc should be extinguished within milliseconds. The upper limit of the arc extinguishing time takes into account the influence of airflow intensity: for every 10 m / s increase in airflow speed, the allowable arc extinguishing time can be shortened by about 20%. This dynamic threshold is more adaptable to different working conditions than a fixed threshold.

[0197] Determining whether the current is completely disconnected is crucial. Even if the current drops to a very small value, if there is still a weak current present, it may cause the arc to reignite when conditions change.

[0198] The disconnection threshold is typically set below 0.1% of the rated current. This extremely low threshold ensures the complete disconnection of the current path, while monitoring both voltage and current parameters, providing a dual protection mechanism.

[0199] The rapid response of the circuit breaker protection mechanism is a key link in the entire protection system. The actuator usually adopts an electromagnet or permanent magnet operating mechanism, which can complete the action within 2-3 milliseconds after receiving the trigger signal.

[0200] The contact separation speed can reach several meters per second. The rapidly opening gap, combined with enhanced airflow cooling, works together to quickly extinguish the electric arc. This electromechanical coordination is more reliable than relying on either method alone.

[0201] The establishment of a multi-layered fault protection system embodies the concept of defense in depth. The first layer is preventive airflow control, which prevents the abnormal development of electric arcs through optimized airflow distribution.

[0202] The second layer is real-time monitoring and judgment to promptly detect abnormal states;

[0203] The third layer is fast trip protection, which provides a last resort when the first two layers fail to control the situation effectively.

[0204] This hierarchical design greatly improves the reliability of the system, and is particularly suitable for application scenarios in new energy systems with large voltage fluctuations and complex fault modes.

[0205] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.

[0206] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for intelligent protection of high and low voltage DC relays in new energy sources, characterized in that, Includes the following steps: S1. Monitor the real-time spectral data of metal vapor in the arc channel when the relay interrupts a large current, analyze the data to obtain the arc plasma density and temperature gradient distribution, and determine the radial heat flux density. S2. Generate a continuous radial heat flow distribution curve, analyze the heat conduction coefficient and radial energy dissipation inside the arc column, and obtain the radial distribution non-uniformity of the temperature gradient of the arc column. S3. When the radial distribution non-uniformity exceeds a preset non-uniformity threshold, the electromagnetic force vector distribution and thermal convection velocity are calculated by coupling the magnetic field sensor array and the temperature field, and the formation trend of the arc channel deflection angle is obtained. S4. Dynamically model and predictively analyze the formation trends of arc trajectory curvature and arc channel deflection angle to obtain the gas flow resistance in the arc extinguishing chamber and the pressure gradient in the channel, and determine the arc trajectory length. S5. Monitor the radial convection velocity and thermal convection velocity inside the arc extinguishing chamber, and analyze them in conjunction with the airflow dynamics model and heat transfer characteristics to determine the dynamic adjustment parameters of the gas flow mode. S6. Adjust the airflow distribution in the arc extinguishing chamber and the pressure gradient in the channel according to the dynamic adjustment parameters of the gas flow mode to obtain the optimized control scheme of airflow velocity distribution and arc column boundary temperature. S7. Adjust the airflow direction and radial convection velocity in the arc extinguishing chamber according to the control scheme, and automatically adjust the radial diffusion angle of the airflow in conjunction with the changes in voltage and current in the contact gap, and link the circuit breaker protection mechanism to cut off the fault circuit.

2. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 1, characterized in that, Step S1 specifically includes: Continuous spectral data of the relay contact gap region were collected to obtain characteristic spectral line data of metal atoms, and the spatial temperature distribution of the arc plasma was calculated. The spectral signal intensity at different radial positions of the arc column is obtained by radial scanning. Based on the spectral signal intensity and temperature spatial distribution, the radial distribution function of the plasma particle number density is determined. The boundary position of the arc column is determined based on the radial distribution function, and the radial width of the arc column is obtained. Based on the radial distribution function and the spatial temperature distribution, the temperature difference between adjacent radial positions is calculated, and the radial heat flux density at each radial position is calculated by combining the heat conduction and radiation heat flux.

3. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 2, characterized in that, Step S2 specifically includes: The radial width of the electric arc column and the radial heat flux density are subjected to time-domain filtering to obtain a smooth time-domain signal sequence, and cubic spline interpolation is performed to obtain a continuous radial heat flux distribution curve. Based on the radial heat flow distribution curve, calculate the temperature gradient between adjacent radial positions and determine the radial distribution data of the thermal conductivity coefficient; Based on the radial distribution data of the thermal conductivity coefficient and the temperature gradient value, the radial heat dissipation is calculated, the energy dissipation rate at each radial location is determined, and the radial energy dissipation distribution is obtained. Based on the radial energy dissipation distribution and the radial distribution data of the thermal conductivity coefficient, the temperature gradient values ​​at different radial positions are calculated, and the deviation between the temperature gradient at each position and the mean temperature gradient over the entire radial range is obtained. The radial distribution non-uniformity of the arc column temperature gradient is determined by the ratio of the deviation to the mean.

4. The method for intelligent protection of high and low voltage DC relays for new energy sources according to claim 1, characterized in that, Step S3 specifically includes: If the radial distribution non-uniformity exceeds a preset non-uniformity threshold, magnetic induction intensity data of the space around the electric arc are collected to obtain the three-dimensional magnetic field distribution. The electromagnetic force vector distribution on the arc plasma is determined by coupling calculations based on the three-dimensional magnetic field distribution and the radial temperature gradient distribution. Based on the electromagnetic force vector distribution and the density change caused by the temperature difference, the buoyancy distribution is calculated according to the product of the density difference and gravitational acceleration in different temperature regions. The momentum conservation equation is used to solve the velocity of the plasma under the combined action of electromagnetic force and buoyancy, and the thermal convection velocity field inside the electric arc is obtained. Based on the thermal convection velocity field and electromagnetic force vector distribution, the position coordinate changes of each point on the center line of the electric arc are calculated, and the reciprocal of the local radius of curvature is calculated for the continuously recorded position coordinates to obtain the spatial distribution of the curvature of the electric arc trajectory. For the spatial distribution of the curvature of the arc trajectory, calculate the angle between the tangent vector of the arc centerline and the initial straight line direction. If the rate of change of the angle along the axial position continues to increase, it is determined that there is a deflection trend in the arc channel. The formation trend of the arc channel deflection angle is determined by the cumulative change of the angle.

5. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 1, characterized in that, Step S4 specifically includes: Temporal features were extracted from the data sequence of the changes in arc trajectory curvature and arc channel deflection angle over time, and time functions of the rate of change of curvature and the rate of increase of deflection angle were fitted to obtain parameters describing the trajectory evolution trend. Based on the arc morphology determined by the trajectory evolution trend parameters, the pressure distribution around the arc channel is calculated, and the gas flow resistance distribution at each location is determined. For the gas flow resistance distribution and the pressure distribution around the arc channel, calculate the pressure change rate along the arc channel axis to obtain the pressure gradient inside the channel. If the pressure gradient exceeds the preset stability threshold, it is determined that the arc has a risk of instability, and the arc trajectory stability index is determined. The arc trajectory length is determined based on the arc trajectory stability index and the trajectory evolution trend parameters, combined with the constraint effect of flow resistance distribution on trajectory expansion.

6. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 5, characterized in that, Step S5 specifically includes: Based on the arc trajectory stability index and the arc trajectory length, tracer particles are scattered in the arc extinguishing chamber using the particle image velocimetry method, and the ratio of particle displacement to time interval in adjacent frame images is calculated to obtain real-time distribution data of radial convection velocity field and thermal convection velocity field. Based on the real-time distribution data of the radial convection velocity field and the thermal convection velocity field, and combined with the relationship between gas density and temperature, the Reynolds number is calculated. If the Reynolds number exceeds the preset turbulence threshold, the current turbulent flow state is determined. The airflow velocity control coefficient is determined based on the ratio of the root mean square value of velocity fluctuation to the average flow velocity. Based on the real-time distribution data of the airflow velocity control coefficient and the radial convection velocity field, the ratio of the radial velocity component to the axial velocity component is calculated, and the radial convection intensity adjustment factor is determined to obtain the optimized radial flow control parameters. Based on the radial convection intensity adjustment factor and thermal convection velocity field data, the pressure difference in different regions of the arc-extinguishing chamber is calculated, and the channel pressure balance parameters are determined to obtain a dynamic adjustment parameter set including the airflow velocity control coefficient, the radial convection intensity adjustment factor, and the channel pressure balance parameters.

7. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 6, characterized in that, Step S6 specifically includes: Based on the airflow velocity control coefficient, radial convection intensity adjustment factor, and channel pressure balance parameters of the dynamically adjusted parameter set, the airflow velocity control coefficient and the inlet flow area are multiplied, and the radial convection intensity adjustment factor and the exhaust port position are corresponded. The airflow velocity values ​​of each region are calculated to obtain the adjusted airflow distribution field. Based on the adjusted airflow distribution field, the pressure gradient distribution in the new channel is determined by calculating the ratio of the pressure difference between adjacent regions to the distance. If the pressure gradient shows a decreasing trend in the arc region, it is determined that the airflow adjustment direction is correct. The optimized airflow velocity distribution is obtained based on the coupling relationship between the pressure gradient and the airflow velocity. For the optimized airflow velocity distribution, the convective heat transfer coefficient at the boundary of the electric arc column is calculated. The convective heat transfer intensity is controlled by adjusting the airflow velocity in the boundary region. Combined with the equilibrium condition that the heat inflow equals the heat outflow, the airflow parameters required to maintain the target boundary temperature are determined, and the electric arc column boundary temperature control scheme is obtained.

8. The method for intelligent protection of high and low voltage DC relays in new energy sources according to claim 7, characterized in that, Step S7 specifically includes: According to the arc column boundary temperature control scheme, the airflow direction is changed by adjusting the angle of the flow guiding structure in the arc extinguishing chamber, the airflow rate is adjusted according to the airflow velocity parameters, and the adjusted radial convection velocity value is determined. Based on the adjusted radial convection velocity value, the voltage signal at both ends of the contact gap and the current signal through the contact are collected in real time. The voltage change rate and current change rate are calculated. If the voltage change rate exceeds the preset change rate threshold and the current shows a downward trend, it is determined that the arc intensity is weakening. The instantaneous power value is determined based on the product of voltage and current. For the instantaneous power value and the radial convection velocity value, obtain the corresponding optimal diffusion angle value, adjust the airflow guiding device to achieve the diffusion angle, and obtain an airflow distribution adapted to the electric arc state; Based on the airflow distribution adapted to the arc state and the continuously monitored rate of change of current, the output control signal triggers the circuit breaker protection mechanism to perform the tripping action and disconnect the fault circuit.

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