Multi-stage protection and rapid arc extinguishing method and system for internal arc fault of distribution box, cable branch box and metering box

Abstract

The application discloses a kind of for distribution box, cable branch box, internal arc fault multi-stage protection and fast arc extinguishing method and system of meter box, belong to electric power equipment safety protection field.The method includes: using arc light sensor and current sensor to carry out cooperative monitoring, when arc light intensity signal exceeds first preset threshold and detects that current rate of change exceeds second preset threshold in the time range that is not more than preset time window from the light signal detection moment, confirm that internal arc fault occurs;According to the amplitude of current rate of change and peak current, energy representation value is calculated, and arc fault is divided into low energy level or high energy level;According to fault level, the fast break switch of corresponding level is controlled to cut off fault loop, and arc extinguishing intensity is dynamically adjusted.The realization of arc fault fast detection and accurate identification can be differentially disposed according to fault severity, with the advantages of fast response, strong anti-interference capability and the like.

Description

Technical Field

[0001] This application relates to the field of power equipment safety protection, specifically to a method and system for multi-level protection and rapid arc extinguishing of internal arc faults in distribution boxes, cable branch boxes, and metering boxes. Background Technology

[0002] Distribution boxes, cable branch boxes, and metering boxes are key equipment in the power distribution network and are widely used in urban power distribution networks and industrial park power supply scenarios. Their operational stability directly affects the security and continuity of power supply. In actual operation, distribution boxes, cable branch boxes, and metering boxes are prone to internal arcing faults due to factors such as insulation aging, loose joints, and foreign object intrusion. The high temperature, high voltage, and strong light generated by the arc can quickly damage the internal structure of the equipment and even penetrate the cabinet shell, causing serious accidents such as equipment burnout and large-scale power outages. At the same time, it poses a great threat to the personal safety of on-site operation and maintenance personnel.

[0003] The existing arc fault protection schemes for distribution boxes, cable branch boxes, and metering boxes have obvious defects: the fault detection response is lagging, the traditional single sensor detection method is difficult to quickly capture arc fault signals, and it is easily affected by ambient light interference, which can lead to false triggering. The response time is usually more than 10ms, which leads to the amplification of the fault; the fault handling method is simplistic and lacks the ability to distinguish the severity of the fault. Regardless of whether the fault is minor or severe, the whole circuit is cut off, which sacrifices the continuity of power supply.

[0004] Therefore, developing a protection scheme for arc faults inside distribution boxes, cable branch boxes, and metering boxes with fast response speed, strong anti-interference ability, and good arc extinguishing effect has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method and system for multi-level protection and rapid arc extinguishing of internal arc faults in distribution boxes, cable branch boxes, and metering boxes.

[0006] In a first aspect, the present invention provides a multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes, comprising the following steps: S1. The arc light sensor and the current sensor are used to monitor the internal structure of the power distribution equipment in a coordinated manner, and the arc light intensity signal and the circuit current change rate are collected in real time. When the arc light intensity signal exceeds the first preset threshold, and the current change rate exceeds the second preset threshold within a time range that is no more than a preset time window away from the arc light intensity signal detection time, the main control unit confirms that an internal arc fault has occurred and executes S2. S2. The main control unit calculates the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and classifies the arc fault into low energy level or high energy level. S3. Based on the determined fault level, control the corresponding level of fast-disconnect switch to cut off the fault circuit and dynamically adjust the arc-extinguishing intensity, specifically including: If the fault is determined to be of low energy level, the local arc-extinguishing cavity at the corresponding switching element location is activated to maintain the basic effective participation of the composite arc-extinguishing medium for arc extinguishing. If the fault is determined to be of a high energy level, the linkage mechanism is triggered to increase the effective participation of the composite arc-extinguishing medium in the arc-extinguishing cavity and activate the multi-layer grid structure to divide and divert the arc.

[0007] As a preferred embodiment of the technical solution of the present invention, in S1, before confirming the occurrence of an internal arc fault, the method further includes interference suppression preprocessing of the arc intensity signal, specifically including: Continuously monitor the background light intensity of each arc light sensor and dynamically update the background light intensity reference value; When the current light intensity signal of a certain arc light sensor exceeds a preset multiple of the background light intensity reference value, the light intensity change rate analysis of the area where the arc light sensor is located is initiated; only when the light intensity change rate exceeds a preset light intensity change rate threshold, the current light intensity signal is marked as a valid arc light signal, otherwise it is filtered out as ambient light interference. The current light intensity signal, which is marked as a valid arc light signal, is used as the arc light intensity signal to perform the judgment step that the arc light intensity signal exceeds a first preset threshold.

[0008] It effectively eliminates the interference of ambient light on the arc light sensor, avoids false triggering caused by external light source interference, and improves the accuracy of arc fault detection and the reliability of system operation.

[0009] As a preferred embodiment of the technical solution of the present invention, S2 specifically includes: The energy characterization value is calculated using the following formula. E :

[0010] in, The maximum absolute value of the rate of change of current. This is the peak current. The time it takes for the loop current to rise from its initial value to the peak current; , , These are the preset reference current change rate, reference peak current, and reference rise time, respectively. , For the preset weighting coefficients, and + =1; The calculated energy characterization value Compare with a preset energy threshold, when When the energy level is less than the stated energy threshold, it is determined to be a low-energy level fault; when If the energy level is greater than or equal to the energy threshold, it is determined to be a high-energy-level fault.

[0011] By normalizing and fusing fault characteristic parameters from three dimensions—current change rate, peak current, and rise time—a quantitative assessment of arc fault energy can be achieved. This avoids the one-sidedness of relying on a single parameter in traditional solutions.

[0012] As a preferred embodiment of the technical solution of the present invention, the fast disconnect switches at different levels include branch fast disconnect switches disposed in each branch circuit and a main fast disconnect switch disposed in the main circuit. S3 dynamically adjusts the arc extinguishing intensity based on the determined fault level, specifically including the following graded disconnection strategies: When a low-energy level fault is detected, the branch circuit where the fault is located is determined based on the sensor location that detects the effective arc light signal and the current change rate of the corresponding branch circuit. The branch fast disconnect switch of that branch circuit is triggered to maintain the normal operation of the main circuit and other branch circuits, thus forming selective protection. When a high-energy-level fault is detected, the main fast disconnect switch and all branch fast disconnect switches are triggered simultaneously to achieve full circuit disconnection.

[0013] In the event of a low-energy fault, only the branch circuit where the fault is located is disconnected, while the main circuit and other branch circuits remain in normal operation, thus achieving selective protection and maximizing the power supply continuity in non-faulty areas. In the event of a high-energy fault, the main switch and all branch switches are disconnected simultaneously, achieving full circuit disconnection and ensuring that the fault energy is completely isolated.

[0014] As a preferred embodiment of the technical solution of the present invention, the arc extinguishing chamber is provided with multiple independent medium storage chambers, and each medium storage chamber is provided with a controllable release channel and a corresponding linkage valve between it and the main arc extinguishing chamber; In S3, when a high-energy-level fault is detected, the steps to trigger the linkage mechanism to increase the effective participation of the composite arc-extinguishing medium in the arc-extinguishing chamber include: The multi-layer grid structure is activated simultaneously, and the first-stage controllable release channel is opened, allowing the first portion of the composite arc-extinguishing medium to enter the main arc-extinguishing chamber. If, after a preset time interval, the real-time monitored rate of change of gas pressure in the arc-extinguishing chamber still exceeds the safety threshold, the subsequent controllable release channels at each level will be opened sequentially, allowing the composite arc-extinguishing medium to be gradually replenished into the main arc-extinguishing chamber until the rate of change of gas pressure drops below the safety threshold, or all the controllable release channels have been opened.

[0015] The on-demand delivery mechanism avoids media waste and ensures that there is enough media to participate in arc extinguishing during high-energy faults, thereby improving the utilization efficiency of arc extinguishing resources.

[0016] As a preferred embodiment of the technical solution of the present invention, in S3, when a high-energy-level fault is determined, the activation of the multi-layer grid structure to divide and guide the arc specifically includes: The multi-layer grid structure is made of copper-tungsten alloy material, and the grid surface is provided with annular arc-extinguishing grooves, and the grid spacing is distributed in a gradient decreasing distribution along the direction of arc movement; The main control unit controls the electromagnetic current guiding device located at the entrance of the multi-layer grid structure to be energized, generating a directional magnetic field to forcibly guide the electric arc to the central region of the multi-layer grid structure; As the electric arc penetrates deeper into the multi-layer grid structure, it is divided into multiple sub-arcs connected in series by the multi-layer grid, causing the total arc voltage to rise above the system power supply voltage, thereby forcing the arc to extinguish or preventing it from reigniting when the current crosses zero.

[0017] This technology enables efficient segmentation and diversion of high-energy electric arcs. The gradient-decreasing spacing causes the arc voltage to increase non-linearly, and the multi-layered grid divides the long arc into multiple short arcs connected in series, causing the total arc voltage to rapidly rise above the system power supply voltage, forcing the arc to extinguish. This improves arc extinguishing speed and reliability, effectively preventing arc reignition.

[0018] As a preferred embodiment of the technical solution of the present invention, it further includes a gradient protection step for the anti-arc sputtering layer, specifically including: During the process of triggering internal arc protection from S1 to S3, passive protection is provided by using a multi-layer composite anti-arc sputtering layer attached to the inside of the cabinet door panel. The multi-layer composite anti-arc sputtering layer consists of an outer stainless steel mesh layer, a middle epoxy resin-based composite material layer, and an inner ceramic fiber cloth layer, from the outside to the inside. The outer stainless steel mesh layer is used to intercept and break up high-temperature metal particles sputtered by electric arc; the middle epoxy resin-based composite material layer is used to absorb the heat radiated by electric arc and the energy of shock waves through ablation, melting and vaporization processes; the inner ceramic fiber cloth layer is used to form a thermal insulation barrier to control the temperature of the outer surface of the door panel below a safe threshold.

[0019] The three-layer synergistic effect effectively prevents arc sputtering from penetrating the cabinet, protecting the structural integrity of the cabinet and the safety of maintenance personnel, and solving the shortcomings of traditional protection that only focuses on cutting off fault circuits while ignoring sputtering protection.

[0020] As a preferred embodiment of the technical solution of the present invention, the multilayer composite anti-arc sputtering layer is also equipped with an integrity monitoring function, specifically including: The impedance changes of each protective layer are monitored in real time by conductive detection circuits connected in series in the outer stainless steel mesh layer and the middle epoxy resin-based composite material layer to determine the integrity status. When a sudden impedance change signal is detected in the conductive detection circuit due to the fracture of the outer stainless steel mesh layer or the breakdown of the intermediate epoxy resin-based composite material layer, a maintenance alarm signal is output.

[0021] This solves the technical problem of not being able to detect the failure of the protective layer in a timely manner, making it easier for maintenance personnel to inspect and replace it in a timely manner, and ensuring that the protective function is always in an effective state.

[0022] As a preferred embodiment of the technical solution of the present invention, it further includes a self-diagnosis and state locking step after a fault, specifically including: After S1 to S3 are completed, the main control unit records the time of the fault occurrence, the fault level, the location of the fault circuit and the arc extinguishing process parameters, and generates a fault event log. The main control unit outputs a cabinet locking signal to control the electromagnetic lock device installed on the cabinet door to maintain the cabinet in a locked state. The main control unit detects the status of the quick-break switch. If it detects that any branch quick-break switch or the main quick-break switch is not in the fully disconnected state, it outputs an emergency alarm signal and triggers the backup trip circuit. Only after maintenance personnel complete on-site inspection and input a manual reset command will the main control unit release the cabinet lockout and allow the system to be re-energized.

[0023] It prevents accidental closing operations when the fault has not been eliminated, avoids secondary accidents, and provides data support for fault analysis and equipment maintenance, thereby improving the safety and maintainability of the system.

[0024] Secondly, the technical solution of the present invention also provides a multi-level protection and rapid arc extinguishing system for internal arc faults in distribution boxes, cable branch boxes, and metering boxes, comprising: The arc fault rapid detection unit includes at least one arc light sensor installed in a key area inside the power distribution equipment cabinet, and at least one current sensor installed in the main circuit and each branch circuit, for real-time acquisition of arc light intensity signals and circuit current change rate. The main control unit, connected to the arc light sensor and the current sensor, is used to confirm the occurrence of an internal arc fault when the arc light intensity signal exceeds a first preset threshold and the current change rate exceeds a second preset threshold within a time range that is no more than a preset time window away from the detection time of the arc light intensity signal; the main control unit is also used to calculate the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and to classify the arc fault into a low energy level or a high energy level; The graded disconnection unit includes branch quick disconnection switches installed in each branch circuit and a main quick disconnection switch installed in the main circuit. The branch quick disconnection switches and the main quick disconnection switch are electrically connected to the main control unit and are used to perform corresponding level disconnection actions according to the determined fault level. The high-efficiency arc extinguishing unit includes arc extinguishing cavities located inside the cabinet corresponding to the positions of each switching element. Each arc extinguishing cavity is filled with a composite arc extinguishing medium and has a multi-layer grid structure. The arc extinguishing cavity is equipped with a linkage mechanism to dynamically adjust the arc extinguishing intensity according to the fault level determined by the main control unit: when a low-energy fault is determined, the local arc extinguishing cavity at the corresponding switching element position is activated, and the basic effective participation of the composite arc extinguishing medium is maintained; when a high-energy fault is determined, the effective participation of the composite arc extinguishing medium in the arc extinguishing cavity is increased, and the multi-layer grid structure is activated to divide and divert the arc.

[0025] As can be seen from the above technical solutions, this application has the following advantages: Through the coordinated monitoring of the arc flash sensor and the current sensor, the timing-based joint judgment of photoelectric dual signals is achieved, effectively solving the problem of delayed response in traditional single-sensor detection. Simultaneously, by calculating the energy characterization value based on the current change rate amplitude and peak current, arc faults are classified into low-energy or high-energy levels, achieving quantitative identification of fault severity. Based on this, the cutting-off level of the fast-disconnect switch is differentiated according to the fault level, and the arc-extinguishing intensity is dynamically adjusted. For low-energy faults, only the local arc-extinguishing cavity is activated to maintain basic arc extinguishing, avoiding unnecessary full-circuit disconnection and ensuring power supply continuity; for high-energy faults, the dielectric participation is increased and the multi-layer grid structure is activated, providing enhanced arc-extinguishing capability. This improves the response speed, power supply reliability, and arc-extinguishing efficiency of arc fault protection within power distribution equipment. Attached Figure Description

[0026] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a flowchart illustrating the method provided in an embodiment of the present invention.

[0028] Figure 2 A block diagram of a system provided in an embodiment of the present invention. Detailed Implementation

[0029] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this application and in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] like Figure 1 As shown, this embodiment of the invention provides a multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes. The cabinets of the distribution boxes, cable branch boxes, and metering boxes are made of cold-rolled steel plates. The method includes the following steps: S1. The arc light sensor and current sensor are used to monitor the internal structure of the power distribution equipment in a coordinated manner, and the arc light intensity signal and the loop current change rate are collected in real time. When the arc light intensity signal exceeds the first preset threshold, and the current change rate exceeds the second preset threshold within a time window that is no more than the time when the arc light intensity signal is detected, the main control unit confirms that an internal arc fault has occurred and executes S2. The power distribution equipment includes a distribution box, a cable branch box, and a metering box. Two arc flash sensors are installed in each of the busbar compartment, cable compartment, and circuit breaker compartment of the cabinet. Current sensors are connected in series in the main circuit and each branch circuit, and the current surge detection threshold is set to 40% / ms of the rated current by the main control unit.

[0032] Before confirming the occurrence of an internal arc fault, the main control unit performs interference suppression preprocessing, the specific process of which is as follows: The main control unit continuously monitors the background light intensity of each arc light sensor and dynamically updates the background light intensity reference value every 10ms. For example, during normal operation, the background light intensity reference value of a certain sensor is 50 lux.

[0033] When the current light intensity signal of a certain arc light sensor exceeds three times the background light intensity reference value, the main control unit initiates light intensity change rate analysis for the area where the sensor is located. The main control unit calculates the light intensity change rate of the sensor within a 1ms time window, for example, from 150 lux to 300 lux, the change rate is 150 lux / ms.

[0034] The main control unit compares the calculated rate of change of light intensity with a preset threshold for the rate of change of light intensity. If the rate of change of light intensity exceeds the threshold, the current light intensity signal is marked as a valid arc light signal; otherwise, it is filtered out as ambient light interference.

[0035] The main control unit uses the current light intensity signal marked as a valid arc light signal as the arc light intensity signal to perform the subsequent judgment step that the arc light intensity signal exceeds the first preset threshold.

[0036] The main control unit monitors the arc light intensity signal and the loop current change rate in real time. When the arc light intensity signal exceeds a first preset threshold, the main control unit records the detection time T_light. Within a preset time window before and after T_light, the main control unit detects whether the loop current change rate exceeds a second preset threshold. For example, if the current change rate reaches 50% / ms of the rated current 2ms after T_light, exceeding the second preset threshold, then...

[0037] When both of the above conditions are met, the main control unit confirms that an internal arc fault has occurred and executes step S2.

[0038] S2. The main control unit calculates the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and classifies the arc fault into low energy level or high energy level. The energy characterization value is calculated using the following formula. E :

[0039] in, The maximum absolute value of the rate of change of current. This is the peak current. The time it takes for the loop current to rise from its initial value to the peak current; , , These are the preset reference current change rate, reference peak current, and reference rise time, respectively. , For the preset weighting coefficients, and + =1; The calculated energy characterization value Compare with a preset energy threshold, when When the energy level is less than the stated energy threshold, it is determined to be a low-energy level fault; when If the energy level is greater than or equal to the energy threshold, it is determined to be a high-energy-level fault.

[0040] S3. Based on the determined fault level, control the corresponding level of fast-disconnect switch to cut off the fault circuit and dynamically adjust the arc-extinguishing intensity, specifically including: If the fault is determined to be of low energy level, the local arc-extinguishing cavity at the corresponding switching element location is activated to maintain the basic effective participation of the composite arc-extinguishing medium for arc extinguishing. If the fault is determined to be of a high energy level, the linkage mechanism is triggered to increase the effective participation of the composite arc-extinguishing medium in the arc-extinguishing cavity and activate the multi-layer grid structure to divide and divert the arc.

[0041] It should be noted that the fast disconnect switches at different levels include branch fast disconnect switches installed in each branch circuit and the main fast disconnect switch installed in the main circuit. When the fault is determined to be of a low energy level: The main control unit determines the branch circuit where the fault is located based on the sensor location that detected a valid arc light signal and the corresponding branch circuit's current change rate. For example, if sensor number 3 in the cable compartment detects a valid arc light signal and the current change rate of that branch circuit is abnormal, then the fault is determined to occur in branch circuit number 3. The main control unit only triggers the branch fast-break switch of that branch circuit to maintain the normal operation of the main circuit and other branch circuits, thus forming selective protection.

[0042] When the fault is determined to be of a high energy level: The main control unit simultaneously triggers the main fast disconnect switch and all branch fast disconnect switches to achieve full circuit disconnection.

[0043] The arc-extinguishing chamber is made of high-temperature resistant ceramic material. The arc-extinguishing chamber has three independent medium storage chambers, and each storage chamber is connected to the main arc-extinguishing chamber by a release channel controlled by an electromagnetic valve.

[0044] The first storage chamber accounts for 40% of the total capacity, while the second and third storage chambers each account for 30%. Each storage chamber is filled with a composite arc-quenching medium, which is a mixture of modified quartz sand and magnesium fluoride.

[0045] The multi-layer grid structure is made of copper-tungsten alloy and consists of 8 grid layers. The surface of each grid layer has annular arc-extinguishing grooves with a width of 2 mm and a depth of 1 mm. The spacing between the grid layers gradually decreases from 12 mm to 6 mm along the direction of arc movement (gradual decrease). An electromagnetic current-guiding device is installed at the entrance of the multi-layer grid structure.

[0046] When a high-energy-level fault is detected, the main control unit executes the following steps: Step ①: Synchronously activate the grid structure and open the first-level channel; The main control unit simultaneously activates the multi-layer grid structure and opens the first-stage solenoid valve, allowing the first portion (40%) of the composite arc-extinguishing medium to enter the main arc-extinguishing chamber from the first storage chamber. At the same time, the main control unit controls the electromagnetic current-guiding device to be energized, generating a 0.2T directional magnetic field, which forcibly guides the arc to the central region of the multi-layer grid structure.

[0047] Step 2: Pressure feedback replenishes gradually; The main control unit monitors the rate of change of air pressure within the arc-extinguishing chamber in real time using a pressure sensor installed inside the chamber. The preset safety threshold is 0.3 MPa / ms, and the preset time interval is 5 ms.

[0048] Five milliseconds after the first-stage solenoid valve opens, the main control unit reads the current gas pressure change rate. If the gas pressure change rate is 0.45 MPa / ms, exceeding the safety threshold of 0.3 MPa / ms, the main control unit opens the second-stage solenoid valve, allowing the second portion (30%) of the composite arc-extinguishing medium to enter the main arc-extinguishing chamber.

[0049] After another 5ms, the main control unit reads the pressure change rate again. If the pressure change rate drops to 0.25MPa / ms, which is below the safety threshold, the main control unit stops subsequent releases and does not open the third-stage solenoid valve. If the pressure change rate still exceeds the safety threshold, the third-stage solenoid valve continues to open until the pressure change rate drops below the safety threshold or all controllable release channels are open.

[0050] Step ③: Grid segmentation for current diversion and arc extinguishing; Under the influence of the directional magnetic field generated by the electromagnetic current guiding device, the electric arc is forcibly guided to the central region of the multi-layer grid structure. As the arc penetrates deeper into the multi-layer grid structure, the annular arc-extinguishing grooves on the surface of the copper-tungsten alloy grid increase the contact area between the arc and the grid, accelerating arc cooling.

[0051] Because the spacing between the grid plates decreases gradually along the direction of arc movement, the arc experiences progressively stronger compression as it passes through each grid layer. The arc is divided into multiple short arcs connected in series by eight grid layers, with the arc column length of each short arc being much smaller than the original arc.

[0052] According to the principle of arc voltage superposition, the total arc voltage is equal to the sum of the voltages of each series-connected short arc. As the arc is divided into more short arcs, the total arc voltage increases progressively. When the total arc voltage exceeds the system power supply voltage, the arc cannot be sustained and is forced to extinguish. Even when the current crosses zero, the arc cannot reignite because the arc gaps have been sufficiently deionized.

[0053] During the process of triggering internal arc protection from S1 to S3, passive protection is provided by using a multi-layer composite anti-arc sputtering layer attached to the inside of the cabinet door panel. The multi-layer composite anti-arc sputtering layer consists of an outer stainless steel mesh layer, a middle epoxy resin-based composite material layer, and an inner ceramic fiber cloth layer, from the outside to the inside. The outer stainless steel mesh layer is used to intercept and break up high-temperature metal particles sputtered by electric arc; the middle epoxy resin-based composite material layer is used to absorb the heat radiated by electric arc and the energy of shock waves through ablation, melting and vaporization processes; the inner ceramic fiber cloth layer is used to form a thermal insulation barrier to control the temperature of the outer surface of the door panel below a safe threshold.

[0054] The multi-layer composite anti-arc sputtering layer is also equipped with an integrity monitoring function, specifically including: A conductive detection circuit is connected in series within the outer stainless steel mesh layer and the intermediate epoxy resin-based composite material layer. This conductive detection circuit is connected to the main control unit, which continuously applies a small detection current to the conductive detection circuit and monitors the loop impedance. Under normal conditions, the detection loop impedance of the stainless steel mesh layer is approximately 0.5Ω, and the impedance of the conductive circuit embedded in the epoxy resin layer is approximately 10kΩ.

[0055] When the stainless steel mesh layer breaks, the detection circuit impedance jumps from 0.5Ω to infinity (open circuit), and the main control unit detects the impedance jump signal (impedance change rate exceeds 50%), determining that the outer layer is broken. When the epoxy resin-based composite material layer breaks down, the embedded conductive lines are destroyed, and the impedance jumps from 10kΩ to infinity, and the main control unit determines that the middle layer is broken down.

[0056] The main control unit outputs corresponding maintenance alarm signals based on the test results, prompting maintenance personnel to check and replace the anti-splash layer in a timely manner.

[0057] After S1 to S3 are completed, the main control unit performs the following self-diagnosis and status locking operations: The main control unit records the time of fault occurrence, fault level, fault circuit location, and arc extinguishing process parameters, and generates a fault event log. The main control unit outputs a cabinet locking signal, controlling the electromagnetic lock device installed on the cabinet door to activate, keeping the electromagnetic lock engaged and preventing the cabinet from opening. This prevents personnel from accidentally entering a live compartment if the fault has not been resolved.

[0058] The main control unit detects the status of the fast-disconnect switches and reads the open / closed positions of each switch through auxiliary contacts. If any switch is detected as not fully disconnected or as having contact adhesion (no feedback on the opening status is received within a specified time after the opening signal is issued), an emergency alarm signal is output, and the backup tripping circuit is triggered.

[0059] The backup trip circuit is implemented using hardware circuitry independent of the main control unit. When the main control unit fails or communication is interrupted, this backup trip circuit can directly drive the trip coil to operate, achieving redundant protection. In the event of switch contact adhesion, an emergency alarm signal is output to prompt manual intervention.

[0060] Only after maintenance personnel complete on-site inspection and input a manual reset command will the main control unit release the cabinet lockout and allow the system to be re-energized.

[0061] like Figure 2 As shown, this embodiment of the invention also provides a multi-level protection and rapid arc extinguishing system for internal arc faults in distribution boxes, cable branch boxes, and metering boxes, comprising: The arc fault rapid detection unit includes at least one arc light sensor installed in a key area inside the power distribution equipment cabinet, and at least one current sensor installed in the main circuit and each branch circuit, for real-time acquisition of arc light intensity signals and circuit current change rate. The main control unit, connected to the arc light sensor and the current sensor, is used to confirm the occurrence of an internal arc fault when the arc light intensity signal exceeds a first preset threshold and the current change rate exceeds a second preset threshold within a time range that is no more than a preset time window away from the detection time of the arc light intensity signal; the main control unit is also used to calculate the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and to classify the arc fault into a low energy level or a high energy level; The graded disconnection unit includes branch quick disconnection switches installed in each branch circuit and a main quick disconnection switch installed in the main circuit. The branch quick disconnection switches and the main quick disconnection switch are electrically connected to the main control unit and are used to perform corresponding level disconnection actions according to the determined fault level. The high-efficiency arc extinguishing unit includes arc extinguishing cavities located inside the cabinet corresponding to the positions of each switching element. Each arc extinguishing cavity is filled with a composite arc extinguishing medium and has a multi-layer grid structure. The arc extinguishing cavity is equipped with a linkage mechanism to dynamically adjust the arc extinguishing intensity according to the fault level determined by the main control unit: when a low-energy fault is determined, the local arc extinguishing cavity at the corresponding switching element position is activated, and the basic effective participation of the composite arc extinguishing medium is maintained; when a high-energy fault is determined, the effective participation of the composite arc extinguishing medium in the arc extinguishing cavity is increased, and the multi-layer grid structure is activated to divide and divert the arc.

[0062] In some embodiments, the main control unit is further configured with an interference suppression preprocessing module, used for: continuously monitoring the background light intensity of each arc light sensor and dynamically updating the background light intensity reference value; when the current light intensity signal exceeds a preset multiple of the background light intensity reference value, starting light intensity change rate analysis, marking the current light intensity signal as a valid arc light signal only when the light intensity change rate exceeds a preset light intensity change rate threshold, otherwise filtering it out; and using the signal marked as a valid arc light signal as the arc light intensity signal.

[0063] In some embodiments, the main control unit calculates the energy characterization value using the following formula. E :

[0064] in, The maximum absolute value of the rate of change of current. This is the peak current. The time it takes for the loop current to rise from its initial value to the peak current; , , These are the preset reference current change rate, reference peak current, and reference rise time, respectively. , For the preset weighting coefficients, and + =1; The calculated energy characterization value Compare with a preset energy threshold, when When the energy level is less than the stated energy threshold, it is determined to be a low-energy level fault; when If the energy level is greater than or equal to the energy threshold, it is determined to be a high-energy-level fault.

[0065] In some embodiments, the main control unit is configured with a graded disconnection control strategy: when a low-energy-level fault is determined, the faulty branch circuit is determined based on the sensor location that detects the effective arc light signal and the current change rate of the corresponding branch circuit, and only the branch fast disconnection switch of that branch circuit is triggered; when a high-energy-level fault is determined, the main fast disconnection switch and all the branch fast disconnection switches are triggered simultaneously.

[0066] In some embodiments, the arc-extinguishing chamber is provided with multiple independent medium storage chambers, and each medium storage chamber is provided with a controllable release channel and a corresponding linkage valve between it and the main arc-extinguishing chamber. The main control unit is configured to: when a high-energy-level fault is determined, simultaneously activate the multi-layer grid structure and open the first-level controllable release channel, so that the first portion of the composite arc-extinguishing medium enters the main arc-extinguishing chamber; after a preset time interval, if the real-time monitored gas pressure change rate in the arc-extinguishing chamber still exceeds the safety threshold, then sequentially open the subsequent controllable release channels at each level, so that the composite arc-extinguishing medium is gradually replenished into the main arc-extinguishing chamber, until the gas pressure change rate drops below the safety threshold or all controllable release channels have been opened.

[0067] In some embodiments, the multi-layer grid structure is made of copper-tungsten alloy material, the grid surface is provided with annular arc-extinguishing grooves, and the grid spacing is distributed in a gradient decreasing distribution along the direction of arc movement; the system also includes an electromagnetic current guiding device disposed at the entrance of the multi-layer grid structure, electrically connected to the main control unit, used to generate a directional magnetic field when a high-energy level fault is determined, and to forcibly guide the arc to the central region of the multi-layer grid structure.

[0068] In some embodiments, an arc-sputter protection layer is also included, which is attached to the inner side of the cabinet door panel. The arc-sputter protection layer consists of an outer stainless steel mesh layer, an intermediate epoxy resin-based composite material layer, and an inner ceramic fiber cloth layer from the outside to the inside. The outer stainless steel mesh layer is used to intercept and break up high-temperature metal particles sputtered by the arc. The intermediate epoxy resin-based composite material layer is used to absorb arc radiation heat and shock wave energy through ablation, melting, and vaporization processes. The inner ceramic fiber cloth layer is used to form a thermal insulation barrier.

[0069] In some embodiments, the anti-arc sputtering layer is also equipped with an integrity monitoring function: the system further includes conductive detection circuits connected in series in the outer stainless steel mesh layer and the intermediate epoxy resin-based composite material layer, respectively, and electrically connected to the main control unit, for real-time monitoring of impedance changes of each protective layer; the main control unit is configured to output a maintenance alarm signal when an impedance change signal is detected due to the fracture of the outer stainless steel mesh layer or the breakdown of the intermediate epoxy resin-based composite material layer.

[0070] In some embodiments, the main control unit is also configured with a fault self-diagnosis and status locking function: it is used to record the time of fault occurrence, fault level, fault circuit location and arc extinguishing process parameters after the fault is handled, and generate a fault event log; it outputs a cabinet interlocking signal to control the electromagnetic lock device set on the cabinet door to operate and maintain the cabinet interlocking state; it detects the status of the quick-break switch, and if it detects that any branch quick-break switch or the main quick-break switch is not in the fully disconnected state, it outputs an emergency alarm signal and triggers the backup trip circuit; it only releases the cabinet interlocking state and allows the system to be re-closed when a manual reset command is received.

[0071] In some embodiments, the fast-disconnecting switch is a vacuum circuit breaker with an energy storage mechanism; the response wavelength range of the arc light sensor is 200-800nm, and the detection sensitivity is ≤100lux; the current sensor has an adjustable current change detection threshold; the composite arc-extinguishing medium is a composite medium of modified quartz sand and magnesium fluoride, wherein the particle size of the modified quartz sand is 0.3mm-1.2mm, and the mass ratio of magnesium fluoride is 5%-15%; the multilayer grid structure is 8-12 layers of copper-tungsten alloy grids, the tungsten content is 25%-35%, the grid spacing gradually decreases from 12mm-15mm to 5mm-8mm along the arc movement direction, and the width of the annular arc-extinguishing groove on the grid surface is 1mm-3mm, and the depth is 0.5mm-1.5mm.

[0072] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes, characterized in that, Includes the following steps: S1. The arc light sensor and current sensor are used to monitor the internal structure of the power distribution equipment in a coordinated manner, and the arc light intensity signal and the loop current change rate are collected in real time. When the arc light intensity signal exceeds the first preset threshold, and the current change rate exceeds the second preset threshold within a time window that is no more than the time when the arc light intensity signal is detected, the main control unit confirms that an internal arc fault has occurred and executes S2. The power distribution equipment includes a distribution box, a cable branch box, and a metering box. S2. The main control unit calculates the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and classifies the arc fault into low energy level or high energy level. S3. Based on the determined fault level, control the corresponding level of fast-disconnect switch to cut off the fault circuit and dynamically adjust the arc-extinguishing intensity, specifically including: If the fault is determined to be of low energy level, the local arc-extinguishing cavity at the corresponding switching element location is activated to maintain the basic effective participation of the composite arc-extinguishing medium for arc extinguishing. If the fault is determined to be of a high energy level, the linkage mechanism is triggered to increase the effective participation of the composite arc-extinguishing medium in the arc-extinguishing cavity and activate the multi-layer grid structure to divide and divert the arc.

2. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, In S1, before confirming the occurrence of an internal arc fault, interference suppression preprocessing of the arc intensity signal is also included, specifically including: Continuously monitor the background light intensity of each arc light sensor and dynamically update the background light intensity reference value; When the current light intensity signal of a certain arc light sensor exceeds a preset multiple of the background light intensity reference value, the light intensity change rate analysis of the area where the arc light sensor is located is initiated; only when the light intensity change rate exceeds the preset light intensity change rate threshold, the current light intensity signal is marked as a valid arc light signal, otherwise it is filtered out as ambient light interference. The current light intensity signal, which is marked as a valid arc light signal, is used as the arc light intensity signal to perform the judgment step that the arc light intensity signal exceeds a first preset threshold.

3. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, S2 specifically includes: The energy characterization value is calculated using the following formula. E : in, The maximum absolute value of the rate of change of current. This is the peak current. The time it takes for the loop current to rise from its initial value to the peak current; , , These are the preset reference current change rate, reference peak current, and reference rise time, respectively. , For the preset weighting coefficients, and + =1; The calculated energy characterization value Compare with a preset energy threshold, when When the energy level is less than the stated energy threshold, it is determined to be a low-energy level fault; when If the energy level is greater than or equal to the energy threshold, it is determined to be a high-energy-level fault.

4. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, Fast disconnect switches at different levels include branch fast disconnect switches installed in each branch circuit and main fast disconnect switches installed in the main circuit; S3 dynamically adjusts the arc extinguishing intensity based on the determined fault level, specifically including the following graded disconnection strategies: When a low-energy level fault is detected, the branch circuit where the fault is located is determined based on the sensor location that detects the effective arc light signal and the current change rate of the corresponding branch circuit. The branch fast disconnect switch of that branch circuit is triggered to maintain the normal operation of the main circuit and other branch circuits, thus forming selective protection. When a high-energy-level fault is detected, the main fast disconnect switch and all branch fast disconnect switches are triggered simultaneously to achieve full circuit disconnection.

5. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, The arc-extinguishing chamber is equipped with multiple independent medium storage chambers, and each medium storage chamber is connected to the main arc-extinguishing chamber by a controllable release channel and a corresponding linkage valve. In S3, when a high-energy-level fault is detected, the steps to trigger the linkage mechanism to increase the effective participation of the composite arc-extinguishing medium in the arc-extinguishing chamber include: The multi-layer grid structure is activated simultaneously, and the first-stage controllable release channel is opened, allowing the first portion of the composite arc-extinguishing medium to enter the main arc-extinguishing chamber. If, after a preset time interval, the real-time monitored rate of change of gas pressure in the arc-extinguishing chamber still exceeds the safety threshold, the subsequent controllable release channels at each level will be opened sequentially, allowing the composite arc-extinguishing medium to be gradually replenished into the main arc-extinguishing chamber until the rate of change of gas pressure drops below the safety threshold, or all the controllable release channels have been opened.

6. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 3, characterized in that, In S3, when a high-energy-level fault is determined, the activation of the multi-layer grid structure to segment and guide the arc specifically includes: The multi-layer grid structure is made of copper-tungsten alloy material, and the grid surface is provided with annular arc-extinguishing grooves, and the grid spacing is distributed in a gradient decreasing distribution along the direction of arc movement; The main control unit controls the electromagnetic current guiding device located at the entrance of the multi-layer grid structure to be energized, generating a directional magnetic field to forcibly guide the electric arc to the central region of the multi-layer grid structure; As the electric arc penetrates deeper into the multi-layer grid structure, it is divided into multiple sub-arcs connected in series by the multi-layer grid, causing the total arc voltage to rise above the system power supply voltage, thereby forcing the arc to extinguish or preventing it from reigniting when the current crosses zero.

7. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, It also includes gradient protection steps for the anti-arc sputtering layer, specifically including: During the process of triggering internal arc protection from S1 to S3, passive protection is provided by using a multi-layer composite anti-arc sputtering layer attached to the inside of the cabinet door panel. The multi-layer composite anti-arc sputtering layer consists of an outer stainless steel mesh layer, a middle epoxy resin-based composite material layer, and an inner ceramic fiber cloth layer, from the outside to the inside. The outer stainless steel mesh layer is used to intercept and break up high-temperature metal particles sputtered by electric arc; the middle epoxy resin-based composite material layer is used to absorb the heat radiated by electric arc and the energy of shock waves through ablation, melting and vaporization processes; the inner ceramic fiber cloth layer is used to form a thermal insulation barrier to control the temperature of the outer surface of the door panel below a safe threshold.

8. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 7, characterized in that, The multi-layer composite anti-arc sputtering layer is also equipped with an integrity monitoring function, specifically including: The impedance changes of each protective layer are monitored in real time by conductive detection circuits connected in series in the outer stainless steel mesh layer and the middle epoxy resin-based composite material layer to determine the integrity status. When a sudden impedance change signal is detected in the conductive detection circuit, a maintenance alarm signal is output.

9. The multi-level protection and rapid arc extinguishing method for internal arc faults in distribution boxes, cable branch boxes, and metering boxes according to claim 1, characterized in that, It also includes post-fault self-diagnosis and status locking steps, specifically including: After S1 to S3 are completed, the main control unit records the time of the fault occurrence, the fault level, the location of the fault circuit and the arc extinguishing process parameters, and generates a fault event log. The main control unit outputs a cabinet locking signal to control the electromagnetic lock device installed on the cabinet door to maintain the cabinet in a locked state. The main control unit detects the status of the quick-break switch. If it detects that any branch quick-break switch or the main quick-break switch is not in the fully disconnected state, it outputs an emergency alarm signal and triggers the backup trip circuit. Only after maintenance personnel complete on-site inspection and input a manual reset command will the main control unit release the cabinet lockout and allow the system to be re-energized.

10. A multi-level protection and rapid arc extinguishing system for internal arc faults in distribution boxes, cable branch boxes, and metering boxes, characterized in that, include: The arc fault rapid detection unit includes at least one arc light sensor installed in a key area inside the power distribution equipment cabinet, and at least one current sensor installed in the main circuit and each branch circuit, for real-time acquisition of arc light intensity signals and circuit current change rate. The main control unit, connected to the arc light sensor and the current sensor, is used to confirm the occurrence of an internal arc fault when the arc light intensity signal exceeds a first preset threshold and the current change rate exceeds a second preset threshold within a time range that is no more than a preset time window away from the detection time of the arc light intensity signal; the main control unit is also used to calculate the energy characterization value of the fault arc based on the amplitude of the current change rate and the peak current, and to classify the arc fault into a low energy level or a high energy level; The graded disconnection unit includes branch quick disconnection switches installed in each branch circuit and a main quick disconnection switch installed in the main circuit. The branch quick disconnection switches and the main quick disconnection switch are electrically connected to the main control unit and are used to perform corresponding level disconnection actions according to the determined fault level. The high-efficiency arc extinguishing unit includes arc extinguishing cavities located inside the cabinet corresponding to the positions of each switching element. Each arc extinguishing cavity is filled with a composite arc extinguishing medium and has a multi-layer grid structure. The arc extinguishing cavity is equipped with a linkage mechanism to dynamically adjust the arc extinguishing intensity according to the fault level determined by the main control unit: when a low-energy fault is determined, the local arc extinguishing cavity at the corresponding switching element position is activated, and the basic effective participation of the composite arc extinguishing medium is maintained; when a high-energy fault is determined, the effective participation of the composite arc extinguishing medium in the arc extinguishing cavity is increased, and the multi-layer grid structure is activated to divide and divert the arc.

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