An arc light self-testing device and method based on dual optical path isolation and timing embedding

Abstract

This invention discloses an arc light self-testing device and method based on dual-optical-path isolation and timing embedding. The device includes: a passive sensor for receiving external arc light signals and reflecting self-test light; dual-optical-path independent transmission optical fibers, including physically independent transmission and reception channels; a photoelectric conversion module, including a self-test light source driving unit and a photoelectric conversion unit; a main control unit connected to both the self-test light source driving unit and the photoelectric conversion unit; the transmission channel connects the self-test light source driving unit and the passive sensor, and the reception channel connects the passive sensor and the photoelectric conversion unit; the main control unit controls the transmission of self-test light pulses within the interval between two adjacent arc light samplings and performs one sampling to acquire the signal output by the photoelectric conversion unit. Compared with the prior art, this invention, through the collaborative design of dual-optical-path physical isolation and self-test pulse timing embedding, eliminates optical path crosstalk and protection blind spots without interrupting arc light detection, achieving highly reliable, blind-spot-free arc light self-testing.

Description

Technical Field

[0001] This invention relates to the field of arc flash protection technology in power systems, and in particular to an arc flash self-testing device and method based on dual optical path isolation and timing embedding. Background Technology

[0002] Arc flash protection is a critical safety measure in medium- and low-voltage power distribution systems. Its core principle is to detect the intense ultraviolet and visible light signals generated by arc faults within the switchgear and, combined with current criteria, quickly trigger the circuit breaker to trip, preventing the accumulation of arc energy that could lead to major accidents such as cabinet combustion or explosion. Studies have shown that if an arc fault cannot be cleared within 35ms, the released energy will increase exponentially, causing equipment damage and even personal injury within a short period. Therefore, the real-time performance and reliability of arc flash protection devices are crucial to the safety of power distribution systems.

[0003] To prevent protection devices from failing to operate at critical moments due to sensor malfunction, fiber optic link abnormalities, probe contamination, or light source aging, existing arc flash protection devices typically possess self-testing functions. Currently, the mainstream self-testing technologies used in engineering applications mainly fall into the following two categories: One is a single-fiber time-division multiplexing scheme. Application publication number CN120978690A discloses a self-test circuit and method for arc light channel of an arc light protection device. This scheme uses a control unit to trigger the light source driving module at regular intervals to emit self-test light with stepped intensity. The light is transmitted through a single optical fiber to the remote probe and reflected, and then transmitted back to the photoelectric detection circuit through the same optical fiber. The system determines whether the channel is normal by comparing the returned voltage signal with a preset threshold.

[0004] The second is a single-fiber structure isolation scheme. Application publication number CN117977483A discloses an arc light protection device with fiber optic self-diagnosis function. This scheme uses Y-shaped light guide pillars in conjunction with optical structures such as partitions and filters to suppress crosstalk and realize arc light self-test function.

[0005] Although the aforementioned existing technologies have achieved basic condition monitoring to a certain extent, they still have inherent shortcomings that are difficult to overcome when facing the requirements of modern power distribution systems with high reliability, fast response, and complex electromagnetic environments. These shortcomings are as follows: (1) Self-testing and detection compete for resources, resulting in both protection blind spots and the risk of false tripping: The core pain point of existing single-fiber or pseudo-dual-fiber solutions lies in the shared nature of optical path resources and the mutual exclusion of timing logic. Traditional solutions mostly use timed interrupt mode for self-testing, that is, pausing arc light sampling within a specific time window and instead transmitting self-test light. This time-slice polling mechanism results in the device being blind to real arc faults during self-testing. If an arc fault happens to occur within this millisecond window, the system will not be able to respond in time, forming a fatal detection blind spot. At the same time, in the single-fiber transmission architecture, the transmitter and receiver share the physical channel, and Fresnel reflections on the connector end face and inside the coupler can easily cause high-intensity self-test light to leak directly to the receiver, forming near-end crosstalk. In order to prevent the self-test light from causing false tripping, system designers are forced to significantly reduce the transmission power of the self-test light, resulting in the system being insensitive to early faults such as weak fiber cracks and slight contamination, falling into a contradiction between self-test sensitivity and the risk of false tripping, and failing to take into account both early fault detection and protection reliability.

[0006] (2) The fault diagnosis granularity is coarse and lacks refined health assessment capabilities: The existing self-test logic is mostly based on a simple threshold comparison method, that is, it only judges whether the returned signal is lower than a certain fixed threshold, and the output result is either on or off. This binary judgment mechanism has obvious shortcomings: First, it cannot distinguish between different types of faults such as light source failure, complete fiber breakage, connector detachment, severe probe contamination, and slow fiber aging, so maintenance personnel cannot formulate targeted maintenance strategies accordingly; Second, the threshold setting does not fully consider the comprehensive influence of multiple factors such as fiber length difference, connector batch loss, sensor reflectivity dispersion, and ambient temperature drift. Fixed thresholds often lead to a high false alarm rate for newly installed equipment and a high false alarm rate for old equipment, lacking an adaptive adjustment mechanism.

[0007] (3) Weak electromagnetic interference resistance and difficulty in adapting to complex operating environments: In order to integrate self-testing functions, traditional solutions often use active sensors encapsulated in metal shells or place the photoelectric conversion link in the high-voltage area inside the switch cabinet. In the strong alternating electromagnetic field inside the switch cabinet, metal conductors and long-distance signal lines are prone to eddy current effects and induced electromotive force, resulting in distortion and falsification of the self-testing signal. Relevant tests show that in the power frequency magnetic field interference environment of 30kV / m, the arc protection device using the traditional single-fiber active self-testing solution has a severe distortion of the self-testing signal and a false trip rate as high as 5.2%. This instability makes it difficult for the existing technology to guarantee the reliability of the self-testing function when facing complex electromagnetic transient processes such as DC arcing and switching operations, and it is easy to cause misjudgment or missed judgment of faults due to signal distortion.

[0008] Therefore, how to eliminate resource competition and near-end crosstalk between self-testing and arc detection without interrupting arc detection, and achieve blind-zone-free and highly reliable arc self-testing, is a technical problem that needs to be solved. Summary of the Invention

[0009] The purpose of this invention is to overcome the defects of the prior art and provide an arc light self-testing device and method based on dual optical path isolation and timing embedding.

[0010] The objective of this invention can be achieved through the following technical solutions: According to a first aspect of the present invention, an arc self-testing device based on dual-optical-path isolation and timing embedding is provided, comprising: A passive sensor used to receive external arc light signals and reflect self-test light; Dual-path independent transmission optical fiber, including physically independent transmission and reception channels; The photoelectric conversion module includes a self-testing light source driver unit and a photoelectric conversion unit; The main control unit is connected to both the self-testing light source driving unit and the photoelectric conversion unit. One end of the transmitting channel is connected to the self-testing light source driving unit, and the other end is connected to the passive sensor; one end of the receiving channel is connected to the passive sensor, and the other end is connected to the photoelectric conversion unit. The main control unit is used to control the self-test light source driving unit to emit a self-test light pulse during the time interval between two adjacent arc light sampling moments, and to control the execution of one sampling to collect the signal output by the photoelectric conversion unit.

[0011] As a preferred technical solution, the passive sensor has a dual optical path coupling structure at its tail end. The dual optical path coupling structure adopts a dual-hole positioning design to fix the end faces of the transmitting channel and the receiving channel respectively.

[0012] As a preferred technical solution, the passive sensor has a reflective surface inside, which is shaped like a light bulb and is used to directionally reflect the self-test light transmitted from the transmitting channel to the end face of the receiving channel.

[0013] As a preferred technical solution, the dual-optical-path independent transmission optical fiber is a single-mode dual-core optical fiber or two independent single-core parallel optical fibers. The transmitting channel transmits self-test excitation light in only one direction, and the receiving channel transmits the composite signal of external arc light signal and self-test reflected light in only one direction.

[0014] As a preferred technical solution, the passive sensor is integrally injection molded from a polymer transparent material.

[0015] According to a second aspect of the present invention, an arc self-testing method based on the arc self-testing device is provided, comprising: The main control unit continuously controls the photoelectric conversion unit to perform arc light sampling, and obtains an arc light sampling sequence used to characterize the background light intensity; During the time interval between two adjacent arc light sampling moments, the main control unit controls the self-test light source driving unit to trigger and emit a self-test light pulse. The self-test light pulse enters the receiving channel after being reflected by the transmitting channel and the passive sensor in sequence. After emitting a self-test light pulse, the main control unit controls the execution of a sampling once within the same time interval, and obtains a composite signal value through the photoelectric conversion unit. The composite signal value includes background light and self-test reflected light transmitted through the receiving channel. Based on the composite signal value and the adjacent arc light sampling points, the pure self-test light intensity component is extracted by differential calculation. The health status of the optical path is assessed based on the pure self-test light intensity component.

[0016] As a preferred technical solution, the differential calculation specifically includes: Obtain two adjacent arc light sampling points S at the sampling time. n and S n+1 The theoretical background light intensity S_est=(S) at the sampling time is estimated using linear interpolation. n +S n+1 ) / 2; The composite signal value C n Subtracting the theoretical background light intensity S_est yields the pure self-tested light intensity component J. n =C n -S_est.

[0017] As a preferred technical solution, after obtaining the composite signal value, the method further includes a safety-priority fuse-breaking step: A preset emergency threshold for arc faults is defined, which is greater than the sum of the preset maximum background light and the maximum self-test light. If the composite signal value C n If the value exceeds the emergency threshold for arc fault, a real arc fault is determined to have occurred, the self-test process is immediately terminated, and trip protection is triggered.

[0018] As a preferred technical solution, the assessment of the optical path health status specifically includes: The pure self-test light intensity component calculated from multiple consecutive self-test cycles is subjected to moving average filtering to obtain the self-test light intensity reference value; Based on the length of the dual-path independent transmission optical fiber, connector loss, and sensor reflectivity parameters, the adaptive self-test threshold is dynamically calculated. The self-test light intensity benchmark value is compared with the adaptive self-test threshold at multiple levels, and the corresponding health status is output based on the comparison results.

[0019] As a preferred technical solution, the multi-level comparison specifically includes: If the self-test light intensity reference value is greater than or equal to the first threshold, it is determined to be in a normal state; If the self-test light intensity reference value is less than the first threshold and greater than or equal to the second threshold, it is determined to be a mild abnormal state; If the self-test light intensity reference value is less than the second threshold, it is determined to be a severe fault state; Wherein, both the first threshold and the second threshold are preset multiples of the adaptive self-test threshold, and the first threshold is greater than the second threshold.

[0020] Compared with the prior art, the present invention has the following advantages: 1. This invention uses physically independent transmission and reception channels to form a dual-optical-path independent transmission optical fiber. The self-test light is completely separated from the external arc light signal and the self-test reflected light on the optical path, which eliminates near-end crosstalk and resource contention at the physical level. At the same time, the main control unit emits a self-test light pulse and performs sampling within the time interval between two adjacent arc light sampling times. The self-test operation is embedded in the normal sampling gap, thereby achieving blind-zone-free and highly reliable arc light self-test without interrupting arc light detection.

[0021] 2. This invention collects external arc light signals and reflects self-test light through a passive sensor. The passive sensor has no metal parts inside and is integrally injection molded from a high-molecular light-transmitting material. Combined with a photoelectric conversion module with dual-path independent transmission optical fibers, the device has strong anti-electromagnetic interference capabilities and can work stably in harsh environments such as strong electromagnetic fields, high temperature and high humidity inside the switch cabinet, avoiding misjudgment or missed judgment caused by signal distortion.

[0022] 3. After acquiring the composite signal, this invention uses linear interpolation between two adjacent arc light sampling points to estimate the theoretical background light intensity at the current moment, and extracts the pure self-test light intensity component through differential calculation, which can effectively eliminate the influence of ambient light fluctuations and electromagnetic noise on the self-test results.

[0023] 4. This invention performs moving average filtering on the pure self-test light intensity components of multiple consecutive self-test cycles, and dynamically calculates the adaptive self-test threshold based on parameters such as fiber length, connector loss, and sensor reflectivity. Furthermore, through multi-level comparison, the health status is subdivided into multiple levels such as normal, slightly abnormal, and severely faulty, which realizes fine differentiation of fault types and early warning, and improves operation and maintenance efficiency.

[0024] 5. The present invention presets an emergency threshold for arc faults. When the composite signal value exceeds the emergency threshold, the self-test process is immediately terminated and the trip protection is triggered. This ensures that the priority of arc detection is always higher than that of the self-test function. While achieving blind-zone-free self-testing, it also ensures that the arc protection device can respond quickly when a real fault occurs, effectively reducing the harm of arc faults. Attached Figure Description

[0025] Figure 1 This is an overall structural diagram of the arc self-testing device of the present invention; Figure 2 This is a hardware structure block diagram of the arc self-testing device of the present invention; Figure 3 This is a flowchart of the arc self-testing method of the present invention; Figure 4 This is a schematic diagram of the timing logic flow of the arc self-test method in an embodiment of the present invention; Figure 1 The reference numerals indicate: 100, passive sensor; 101, acquisition surface; 102, reflective surface; 103, dual-optical-path coupling mechanism; 200, dual-optical-path independent transmission optical fiber; 201, transmitting channel; 202, receiving channel; 300, photoelectric conversion module; 301, dual-optical-path receiving structure; 302, self-testing light source driving unit; 303, photoelectric conversion unit. Figure 2 The components are labeled as follows: 1. LCD panel; 11. LCD screen; 12. Operation buttons; 13. Indicator light; 2. Power supply board; 21. Current transformer; 22. Voltage transformer; 3. Bus board; 31. Input unit; 32. Output unit; 33. RS485 communication circuit; 34. GPS time synchronization circuit; 35. Watchdog circuit; 4. Core board; 41. MCU unit; 42. Flash unit; 43. SDRAM unit; 5. Arc light acquisition board. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] Example 1: This invention provides an arc light self-testing device based on dual-optical-path isolation and timing embedding. For example... Figure 1 As shown, the device includes: a passive sensor 100, a dual-optical-path independent transmission optical fiber 200, a photoelectric conversion module 300, and a main control unit. The various components are interconnected using standardized interfaces to achieve modular assembly and flexible adaptation.

[0028] Passive sensor 100: The passive sensor 100 is an integrated passive structure with no internal metal parts. It is made of a high-voltage, arc-resistant, light-transmitting polymer material (such as polymethyl methacrylate PMMA) through one-piece injection molding. The material has a voltage resistance rating of ≥35kV, a flame retardant rating of VW-1, and an operating temperature range of -40℃ to 85℃. It can be adapted to the harsh operating environment of high voltage, strong electromagnetic fields, high and low temperatures, and high humidity in switch cabinets.

[0029] The passive sensor's acquisition surface 101 has a 180° wide viewing angle structure, ensuring a high capture rate for arc light generated at any angle inside the switch cabinet and avoiding missed detection of arc light due to blind spots. The acquisition surface adopts a dirt-resistant and sealed structure to reduce the impact of environmental dust on detection accuracy.

[0030] The passive sensor has a dual optical path coupling structure 103 at its tail end, which adopts a precision dual-hole positioning design to fix the end faces of the transmitting channel (Tx) and the receiving channel (Rx) respectively, thereby achieving physical isolation between the self-test optical path and the arc light detection optical path and avoiding crosstalk between the two signals.

[0031] The passive sensor has a reflective surface 102 inside, which is bulb-shaped. Through optical simulation optimization, it can ensure that the self-test light energy transmitted from the transmitting fiber is directionally reflected to the receiving fiber end face with a reflectivity of ≥90%, forming a stable self-test circuit.

[0032] Dual-path independent transmission fiber optic cable 200: The dual-path independent transmission fiber optic 200 uses single-mode dual-core fiber or two independent parallel single-core fibers as the transmission medium, and is divided into a transmitting channel 201 (Tx) and a receiving channel 202 (Rx). The two optical paths are completely physically independent and have no shared components, which fundamentally cuts off the path of the transmitted light directly leaking to the receiving end and eliminates near-end crosstalk.

[0033] The transmitting channel (Tx) is dedicated to unidirectionally transmitting the self-test excitation light generated by the photoelectric conversion module controlled by the main control unit to the passive sensor. The transmission direction is unique, avoiding optical signal backflow interference. The receiving channel (Rx) is dedicated to unidirectionally transmitting the composite signal of the external arc light signal and the self-test reflected light signal back to the photoelectric conversion module, realizing complete physical isolation between the self-test light and the arc light signal, eliminating the need for time-division multiplexing of optical paths, and solving the resource competition problem of existing technologies.

[0034] The attenuation coefficient of the transmission optical fiber is ≤0.16dB / m. Under typical switch cabinet wiring distance (e.g., 5 meters), the total transmission loss is controlled within 0.8dB. Its short-term bending radius can reach 25mm, and its long-term tensile load can withstand 1N. It can withstand more than 1000 repeated bends without breaking, making it suitable for wiring installation scenarios of different switch cabinets.

[0035] Photoelectric conversion module 300: The photoelectric conversion module 300 is integrated on the arc light acquisition board and includes a dual-optical-path receiving structure 301, a photoelectric conversion unit 303, a self-testing light source driving unit 302, and a noise suppression unit. Each unit is connected to the main control unit through a standardized interface, enabling modular plug-in and maintenance.

[0036] The dual-optical-path receiving structure 301 is located at the front of the photoelectric conversion module. It adopts a precision dual-hole positioning design to fix the end faces of the transmitting fiber (Tx) and the receiving fiber (Rx) respectively, thereby achieving physical isolation between the self-testing light source driving unit and the photoelectric conversion unit and avoiding crosstalk between the two signals.

[0037] The photoelectric conversion unit 303 incorporates a high-sensitivity photodiode (PD) and a transimpedance amplifier (TIA), which can efficiently convert the weak composite optical signal transmitted through the receiving channel (Rx) into a voltage signal. The conversion efficiency is high and the distortion is low, ensuring accurate signal transmission and subsequent processing.

[0038] The self-test light source driving unit 302 integrates a standard self-test light source and a high-speed driving circuit. The self-test light source preferably uses an 850nm infrared LED, a wavelength invisible to the human eye and separated from the main visible and ultraviolet spectra of the arc light, avoiding spectral aliasing interference. The high-speed driving circuit employs a high-speed MOSFET design with a response time ≤2μs, supporting microsecond-level precise pulse control. It can emit short, high-intensity self-test light pulses with adjustable width according to the instructions of the main control unit.

[0039] The noise suppression unit includes a multi-stage RC filter circuit and a circuit board shielding structure. The RC filter circuit consists of a precision current-limiting resistor and a low leakage capacitor, which can effectively filter out high-frequency switching noise and power frequency interference. The circuit board adopts a multi-layer board design, with analog ground and digital ground strictly separated. Protective rings are set around key signal traces to further suppress electromagnetic interference and improve the purity of signal acquisition.

[0040] Main control unit: like Figure 2 As shown, the main control unit is the core control hub of the device, including LCD panel 1, power board 2, bus board 3, core board 4 and arc light acquisition board 5. All boards are integrated and installed in the housing, with a compact structure that is suitable for narrow installation spaces.

[0041] The core board 4 includes an MCU unit 41, a Flash unit 42, and an SDRAM unit 43. The MCU unit 41 is a high-performance microcontroller with a main frequency of ≥500MHz. It has powerful computing capabilities and real-time response capabilities, and can quickly process sampling signals, execute diagnostic algorithms, and trigger control commands to meet the requirement of clearing arc faults within 35ms. The external storage includes the Flash unit 42, SPI Flash, and SDRAM unit 43, which are used to store historical fault data, calibration parameters, and diagnostic algorithms. The stored data is not lost when power is off, which facilitates subsequent operation and maintenance queries and fault tracing.

[0042] The arc light acquisition board 5 is used to carry the photoelectric conversion module 300 and is connected to the built-in ADC module of the core board to realize the real-time acquisition and calculation of arc light background signal and composite light signal. The photoelectric conversion process is completed inside the device, avoiding external wiring interference.

[0043] The high-performance microcontroller features a built-in ADC with a resolution of 16-bit or higher, a sampling rate of ≥2.4 MSPS, and supports multi-channel synchronous sampling. The entire ADC conversion process is managed by hardware DMA, with a single conversion time of ≤15μs, without consuming CPU resources, ensuring that the main control chip has sufficient computing power to handle complex algorithms.

[0044] The bus board 3 includes 8-channel digital input acquisition circuits and 5-channel passive relay output circuits. The digital input acquisition circuits are compatible with multiple voltage levels, including AC / DC 110V, AC / DC 220V, and DC 24V / 48V signals, adapting to the signal output requirements of different external devices. The passive relay output circuits can be freely configured with outputs through the protection logic of the core control module, enabling rapid tripping, alarm, and other protective actions based on the arc flash protection fault determination results. The bus board also integrates an RS485 communication circuit 33 (compatible with IEC60870-5-103 and Modbus-RTU communication protocols) and a GPS time synchronization circuit 34 (supporting IRIG-B time synchronization), enabling data interaction and accurate time synchronization between the device and external terminals.

[0045] The LCD panel 1 includes an LCD screen 11, seven operation buttons 12 and six status indicator lights 13. The indicator lights use red, green and yellow colors to correspond to different equipment states such as fault, operation, tripping and closing, so as to realize the visual display of the device's operating status and local manual operation.

[0046] The power board 2 includes an electrical parameter acquisition module and a power supply module. The electrical parameter acquisition module contains a voltage transformer 22 and a current transformer 21, which can acquire basic voltage and current electrical parameters in real time. These parameters, together with the arc flash analog quantity obtained from the arc flash acquisition board, participate in the arc flash protection logic. The power supply module supports AC / DC universal 110V / 220V or 48V / 24V power supply, adapting to the power supply needs of different small and medium-sized power scenarios.

[0047] The housing is made of thermoplastic plastic, which is flame-retardant, insulating, and lightweight. The housing has a miniaturized, sealed structure and uses an embedded installation method with clips for fixation. It can be directly installed in confined spaces such as household distribution boxes and small generator control cabinets, making installation convenient and providing good protection.

[0048] This invention discloses an arc flash self-testing device based on dual-optical-path isolation and timing embedding, comprising a passive sensor, dual-optical-path independent transmission optical fibers, a photoelectric conversion module, and a main control unit. The transmitting and receiving channels are physically independent, and the main control unit controls the transmission of self-testing light pulses and performs sampling within the interval between two adjacent arc flash samplings. This device eliminates crosstalk between the self-testing light and the arc flash signal through physical isolation, allowing self-testing to be completed without interrupting arc flash detection, thereby eliminating protection blind spots and adapting to harsh environments such as strong electromagnetic fields, thus improving the reliability of arc flash protection.

[0049] Example 2: like Figure 3 As shown, this invention provides an arc light self-testing method based on dual-optical-path isolation and temporal embedding. The core of this method is to implicitly embed the self-testing process into the normal arc light sampling stream, eliminate crosstalk through physical dual-optical-path isolation, and eliminate environmental interference by combining a differential background removal algorithm, thus achieving conflict-free collaboration between self-testing and arc light detection. Specifically, it includes the following steps: Step S1: The main control unit continuously controls the photoelectric conversion unit to perform arc light sampling to obtain an arc light sampling sequence, which is used to characterize the background light intensity; Step S2: At the center of the time interval between two adjacent arc light sampling moments, control the self-test light source driving unit to trigger and emit a self-test light pulse. The self-test light pulse enters the receiving channel after being reflected by the transmitting channel and the passive sensor in sequence. Step S3: After emitting the self-test light pulse, the main control unit controls the execution of one sampling within the same time interval, and obtains the composite signal value through the photoelectric conversion unit. The composite signal value includes the background light and the self-test reflected light transmitted through the receiving channel. Step S4: Determine whether the composite signal value exceeds the preset emergency threshold for arc fault; if so, determine that a real arc fault has occurred, immediately terminate the self-test process and trigger the trip protection; otherwise, continue to execute the subsequent steps. Step S5: Based on the composite signal value and its adjacent arc sampling points, extract the pure self-test light intensity component through differential calculation; Step S6: Perform a moving average filter on the pure self-test light intensity component calculated from multiple consecutive self-test cycles to obtain the self-test light intensity reference value, and dynamically calculate the adaptive self-test threshold based on the fiber length, connector loss and sensor reflectivity.

[0050] Step S7: Compare the self-test light intensity reference value with the adaptive self-test threshold at multiple levels, output the corresponding health status (normal status, mild abnormal status or severe fault status) based on the comparison results, and provide feedback through indicator lights or communication interface.

[0051] The following combination Figure 4 Each step is explained in detail: Step S101: Normal arc light sampling with power frequency synchronization.

[0052] The core board of the main control unit continuously controls the photoelectric conversion unit to perform arc light sampling, obtaining an arc light sampling sequence {S1, S2, …, S} to characterize the background light intensity. n , S n+1 , …}, where S n This represents the ambient background light intensity at time n. As a preferred method, the main control unit uses the power grid's zero-crossing point as the reference trigger point and locks the phase error within ±0.1° using a phase tracking algorithm within the high-performance microcontroller, ensuring that the sampling is synchronized with the power grid's operating status. The ADC module built into the core board synchronously acquires the arc light intensity signal in real time at a frequency of 48 points per cycle (corresponding to a 50Hz system, with a sampling interval of approximately 0.416ms). The entire ADC conversion is managed by hardware DMA, with a single conversion time ≤15μs, without consuming CPU resources, ensuring the real-time computing power of the arc protection logic. The sampled data is synchronously stored in external storage, providing basic data for subsequent background estimation.

[0053] Step S201: Self-test optical pulse injection.

[0054] The core board of the main control unit is in S n After sampling is completed, at any two adjacent arc sampling times (S n With S n+1Within the time interval between the specified points, the self-test light source driving unit triggers and emits a CHK_EN self-test light pulse. Preferably, the emission time is located at the center of this time interval, i.e., at a phase offset of approximately 180°. The self-test light source driving unit triggers an 850nm infrared LED light source to emit a high-intensity pulse with a response speed of ≤2μs. This self-test light pulse is transmitted to the passive sensor via the transmission channel (Tx) of the dual-path independent transmission optical fiber. After directional reflection (reflectivity ≥90%) by the bulb-shaped reflective surface inside the sensor, it is transmitted back to the photoelectric conversion unit along the receiving channel (Rx). This process does not require switching optical paths; the transmission and receiving channels remain uninterrupted, arc light sampling is not interrupted, resource competition between self-test and arc light detection is avoided, and blind spots in protection are eliminated.

[0055] Step S301: Composite signal sampling.

[0056] After emitting a self-test light pulse, the main control unit controls the execution of a sampling process within the same time interval, and obtains the composite signal value C through the photoelectric conversion unit. n The composite signal includes background light and self-test reflected light transmitted through the receiving channel. As a preferred method, the main control unit triggers the sampling after a precise delay of half a sampling interval (e.g., 0.208ms) using a high-precision timer. After sampling, the main control unit immediately shuts off the self-test light source to avoid pulse tail interference with the next normal sampling point S. n+1 .

[0057] Step S401: Safety priority circuit breaker determination.

[0058] After sampling, the main control unit core board first performs a safety-priority fuse triggering judgment to ensure that arc flash protection has higher priority than the self-test function. Specifically, a preset arc flash fault emergency threshold Threshold_trip is set, which is greater than the theoretical sum of the maximum background light and the maximum self-test light. If C n If `Threshold_trip` is reached, a real strong arc fault is determined to have occurred. All self-test calculations are immediately terminated, subsequent differential calculations are skipped, the "arc fault flag" is directly set, and the circuit breaker is driven to trip within 35ms via the passive relay output circuit of the bus board, minimizing the damage caused by the fault. If C... n If the value is less than or equal to Threshold_trip, then it is determined that there is no arc fault, and the process proceeds to the subsequent self-test signal calculation process.

[0059] Step S501: Differential calculation to extract pure self-test light.

[0060] The main control unit core board calls two adjacent arc light sampling points S stored in the external storage. n and S n+1 C is estimated using a linear interpolation algorithm. nThe theoretical background light intensity S_est at time t is calculated using the formula: S_est = (S n +S n+1 ) / 2. Since the sampling frequency is much higher than the change frequency of the background light, it can be assumed that the background light changes linearly within a very short time window, ensuring the accuracy of the estimation results.

[0061] The main control unit core board will combine the composite signal value C n Subtracting the estimated background value S_est yields the pure self-examined light intensity component J. n The calculation formula is: J n =C n -S_est, this step can eliminate the interference of ambient light fluctuations (such as fluorescent light flickering, sunlight changes) and electromagnetic noise on the self-test results, ensuring that the self-test results remain stable even in complete darkness or strong light environments, adapting to different lighting environments.

[0062] Step S601: Filtering and adaptive thresholding.

[0063] The core board of the main control unit calculates the pure self-test light intensity component J for multiple consecutive cycles (e.g., 24 consecutive cycles, corresponding to a time window of approximately 10ms). n After performing moving average filtering to eliminate random noise, a stable self-test light intensity reference value J_avg is obtained. The calculation formula is as follows: Where N is the length of the sliding window, and in this embodiment N=24; J k This represents the pure self-test light intensity component calculated in the k-th self-test cycle, where n is the current self-test cycle number. The filtered data is synchronously stored in external storage for subsequent trend analysis.

[0064] The core board of the main control unit dynamically calculates the adaptive self-test threshold A_threshold based on parameters such as the length of the dual-optical-path independent transmission optical fibers, connector loss, and sensor reflectivity. This threshold setting strictly adheres to international standards such as IEC 60793-2-40 and IEC 61753-C6, adapting to different installation scenarios. Specifically, based on pre-configured and stored link parameters in the main control unit, such as fiber length, fiber attenuation coefficient, number of connectors, typical insertion loss of a single connector, and nominal reflectivity of the passive sensor reflective surface, combined with the standard transmitted optical power of the self-test light source driver unit, the theoretical value of the desired received self-test light intensity is estimated through theoretical link loss. Upon initial power-on of the device or after manual confirmation that the optical path is in good condition, the main control unit continuously executes... Multiple self-test cycles are performed to collect and record the actual received self-test light intensity values, and the average value is calculated as the actual reference value on site. The theoretical self-test light intensity value and the actual reference value on site are weighted and fused, and multiplied by a safety margin coefficient of less than 1 to obtain the final adaptive self-test threshold. During the long-term operation of the device, the main control unit periodically records the changing trend of the self-test light intensity reference value. If the reference value shows a slow decay, the adaptive self-test threshold is dynamically adjusted accordingly to ensure that it always adapts to the actual aging or contamination state of the current optical path, avoiding abnormal false alarms or missed faults caused by a fixed threshold.

[0065] At the same time, the main control unit core board automatically learns the current J avg As a temporary benchmark J base It also records the long-term trend of changes, which makes it easier to detect potential faults such as light source aging and fiber optic attenuation in advance, and to achieve preventive maintenance.

[0066] Step S701: Multi-level fault diagnosis and status feedback.

[0067] The main control unit core board will self-test the light intensity reference value J. avg The system performs multi-level comparisons with the adaptive self-test threshold A_threshold to achieve refined fault classification, and simultaneously outputs status feedback via the LCD status indicator and RS485 communication circuit. Specific criteria are as follows: Normal state: When J_avg≥α·A_threshold (α is a first preset multiple, such as 0.8), the passive sensor, dual-path optical fiber, and photoelectric conversion module are determined to be operating normally. The green operation indicator light on the LCD panel remains constantly lit, and the device continuously performs arc light monitoring and self-test. The core board synchronously records the self-test log to external storage. At this time, the sampling points increase, and the next self-test is executed synchronously, repeating steps S1 to S6.

[0068] Mild anomaly (warning level): When β·A_threshold ≤ J_avg < α·A_threshold (β is the second preset multiple, for example, 0.3), it is diagnosed that the probe is slightly contaminated, the optical fiber has a slight macro-bend, or the connector has poor contact. The yellow warning indicator light on the liquid crystal panel is lit, and the remote signal warning signal is uploaded through the RS485 communication circuit. The core board records the fault event log, does not block the protection function, ensures that the system can still provide arc protection in the degraded state, and reminds the operation and maintenance personnel to perform maintenance in a timely manner.

[0069] Severe fault (critical level): When 0 < J_avg < β·A_threshold, it is diagnosed that the optical fiber is broken, the connector is detached, or the sensor is damaged. The core board immediately blocks the protection output (to prevent misoperation or refusal to operate caused by sensor failure). The red fault indicator light on the liquid crystal panel is always on, and the emergency fault signal is uploaded through RS485, forcing the device to enter the maintenance mode, and reminding the operation and maintenance personnel to handle it immediately.

[0070] Self-check light source failure (source level): When it is detected that J avg is less than the preset minimum threshold value (that is, J_avg ≈ 0) and the background light S n is normal in multiple consecutive self-check cycles (for example, 5 consecutive cycles), it is diagnosed that the self-check light source is damaged or the drive circuit fails. The core board immediately blocks the protection, the red fault indicator light on the liquid crystal panel flashes, reports an error "light source failure" and uploads it to the external terminal, prohibits the device from running without the self-check ability, and avoids the risk of protection refusal to operate.

[0071] After the fault is processed, the operation and maintenance personnel can send a reset command through the operation button on the liquid crystal panel or remotely through RS485. After the main control unit receives the command, it clears the fault alarm flag, re-executes steps S1 to S6, completes the self-check reset, and the device resumes normal operation mode. If it is a mild anomaly, the system automatically records the fault trend, does not require manual reset, and only requires regular maintenance, reducing the operation and maintenance workload.

[0072] An arc self-check method based on double-light-path isolation and timing embedding in the present invention obtains the background light intensity through continuous arc sampling, emits a self-check light pulse and synchronously samples the composite signal within adjacent sampling intervals, extracts the pure self-check light intensity component through differential calculation, and then combines the dynamic adaptive threshold to achieve multi-level health status evaluation. This method realizes parallel operation of self-check and detection without interrupting arc detection, effectively suppresses environmental light interference, and can finely distinguish different types and degrees of faults, effectively improving the accuracy of self-check and the overall credibility of the protection system.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An arc light self-testing device based on dual-optical-path isolation and timing embedding, characterized in that, include: A passive sensor (100) is used to receive external arc light signals and reflect self-test light; Dual-path independent transmission optical fiber (200), including physically independent transmission channel (201) and receiving channel (202); The photoelectric conversion module (300) includes a self-testing light source driving unit (302) and a photoelectric conversion unit (303). The main control unit is connected to the self-testing light source driving unit (302) and the photoelectric conversion unit (303), respectively; One end of the transmitting channel (201) is connected to the self-testing light source driving unit (302), and the other end is connected to the passive sensor (100); one end of the receiving channel (202) is connected to the passive sensor (100), and the other end is connected to the photoelectric conversion unit (303). The main control unit is used to control the self-test light source driving unit (302) to emit a self-test light pulse during the time interval between two adjacent arc light sampling times, and to control the execution of one sampling to collect the signal output by the photoelectric conversion unit (303).

2. The arc light self-testing device based on dual optical path isolation and timing embedding according to claim 1, characterized in that, The passive sensor (100) has a dual optical path coupling structure (103) at its tail. The dual optical path coupling structure (103) adopts a dual-hole positioning design to fix the end faces of the transmitting channel (201) and the receiving channel (202) respectively.

3. The arc light self-testing device based on dual optical path isolation and timing embedding according to claim 2, characterized in that, The passive sensor (100) has a reflective surface (102) inside. The reflective surface (102) is in the shape of a light bulb and is used to reflect the self-test light transmitted from the transmitting channel (201) to the end face of the receiving channel (202).

4. The arc light self-testing device based on dual optical path isolation and timing embedding according to claim 1, characterized in that, The dual-path independent transmission fiber (200) is a single-mode dual-core fiber or two independent single-core parallel cables. The transmitting channel (201) transmits self-test excitation light in only one direction, and the receiving channel (202) transmits the composite signal of external arc light signal and self-test reflected light in only one direction.

5. The arc light self-testing device based on dual optical path isolation and timing embedding according to claim 1, characterized in that, The passive sensor (100) is integrally injection molded from a high-molecular light-transmitting material.

6. An arc light self-testing method based on the arc light self-testing device based on dual optical path isolation and timing embedding as described in any one of claims 1-5, characterized in that, include: The main control unit continuously controls the photoelectric conversion unit to perform arc light sampling, and obtains an arc light sampling sequence used to characterize the background light intensity; During the time interval between two adjacent arc light sampling moments, the main control unit controls the self-test light source driving unit to trigger and emit a self-test light pulse. The self-test light pulse enters the receiving channel after being reflected by the transmitting channel and the passive sensor in sequence. After emitting a self-test light pulse, the main control unit controls the execution of a sampling once within the same time interval, and obtains a composite signal value through the photoelectric conversion unit. The composite signal value includes background light and self-test reflected light transmitted through the receiving channel. Based on the composite signal value and the adjacent arc light sampling points, the pure self-test light intensity component is extracted by differential calculation. The health status of the optical path is assessed based on the pure self-test light intensity component.

7. The arc self-testing method according to claim 6, characterized in that, The difference calculation specifically includes: Obtain two adjacent arc light sampling points S at the sampling time. n and S n+1 The theoretical background light intensity S_est=(S) at the sampling time is estimated using linear interpolation. n +S n+1 ) / 2; The composite signal value C n Subtracting the theoretical background light intensity S_est yields the pure self-tested light intensity component J. n =C n -Sest.

8. The arc self-testing method according to claim 6, characterized in that, After acquiring the composite signal value, the method further includes a safety-priority circuit breaker step: A preset emergency threshold for arc faults is defined, which is greater than the sum of the preset maximum background light and the maximum self-test light. If the composite signal value C n If the value exceeds the emergency threshold for arc fault, a real arc fault is determined to have occurred, the self-test process is immediately terminated, and trip protection is triggered.

9. The arc self-testing method according to claim 6, characterized in that, The assessment of the optical path health status specifically includes: The pure self-test light intensity component calculated from multiple consecutive self-test cycles is subjected to moving average filtering to obtain the self-test light intensity reference value; Based on the length of the dual-path independent transmission optical fiber, connector loss, and sensor reflectivity parameters, the adaptive self-test threshold is dynamically calculated. The self-test light intensity benchmark value is compared with the adaptive self-test threshold at multiple levels, and the corresponding health status is output based on the comparison results.

10. The arc self-testing method according to claim 9, characterized in that, The multi-level comparison specifically includes: If the self-test light intensity reference value is greater than or equal to the first threshold, it is determined to be in a normal state; If the self-test light intensity reference value is less than the first threshold and greater than or equal to the second threshold, it is determined to be a mild abnormal state; If the self-test light intensity reference value is less than the second threshold, it is determined to be a severe fault state; Wherein, both the first threshold and the second threshold are preset multiples of the adaptive self-test threshold, and the first threshold is greater than the second threshold.

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