A method and system for detecting leakage of a power distribution cabinet

Abstract

The application provides a power distribution cabinet leakage detection method and system, comprising continuously collecting initial electric field signals outside the power distribution cabinet, continuously removing non-power frequency interference and burst interference in the initial electric field signals based on a filtering strategy to generate effective electric field signals, comparing the effective electric field signals with an electric field threshold to determine whether there is leakage, and the filtering strategy comprising: time-frequency converting the initial electric field signals, removing interference frequencies outside the working frequency band of the power distribution cabinet to form effective power frequency signals, iteratively predicting theoretical effective power frequency signals in future time periods based on the obtained effective power frequency signals, and replacing actual effective power frequency signals whose difference from the actual signals at the corresponding time is greater than a threshold to generate continuous effective electric field signals. The application can adapt to different voltage levels, determine the electric field threshold for the materials of the power distribution cabinet, collect initial electric field signals, and effectively remove continuous non-power frequency interference signals and short burst interference signals in the initial electric field signals.

Description

Technical Field

[0001] This invention relates to the field of leakage current detection technology for power distribution cabinets, and specifically to a leakage current detection method and system for power distribution cabinets. Background Technology

[0002] Currently, voltage testing of the casings of 10 kV and below ring main units and distribution cabinets in power systems mainly relies on traditional voltage detectors (such as voltage testers and handheld voltage detectors) and ordinary portable voltage testing modules. Their core function is to detect whether the cabinet casing is live, assisting maintenance personnel in determining the safety boundaries of operations and preventing electric shock accidents. With the improvement of the intelligent operation and maintenance level of distribution networks, the demand for batch inspection of outdoor multi-ring main units and multi-distribution cabinets in distribution rooms is becoming increasingly urgent. Existing voltage testing equipment is gradually revealing many compatibility defects and can no longer meet the needs of efficient, safe, and convenient operation and maintenance.

[0003] Existing voltage testing equipment is mainly divided into two categories: one is the traditional voltage tester, which is small in size but has a single function. It can only indicate the live status through sound and light alarms, without display function or voice feedback. The accuracy of voltage testing is greatly affected by environmental interference, and it requires manual continuous pressing and contact with the cabinet shell. Hand shaking can easily lead to detection errors, and it is not suitable for rapid troubleshooting of multiple cabinets. The other category is portable voltage testing modules, some of which have display and alarm functions, but they generally have problems such as large size, cumbersome operation, poor adaptability, insufficient battery life, and inconvenient charging. In addition, they are not specifically designed for the special characteristics of voltage testing of ring main unit distribution cabinet shells (weak electric field, multi-material shell, and operation in confined space).

[0004] Defects and shortcomings of existing technology: (1) Contact-type voltage testing is cumbersome and has poor adaptability: Existing equipment with contact-type voltage testing function requires manual continuous pressing of the contacts to fit against the cabinet shell. Operators are prone to fatigue from holding the device for a long time, and hand shaking can easily lead to poor contact and detection errors. The device does not have magnetic contacts, so it cannot be quickly attached to the metal shell, which is not suitable for the rapid deployment requirements when multiple cabinets are inspected in batches. At the same time, it is difficult to adapt to contact-type testing in narrow spaces such as gaps in ring network cabinet doors and corners of distribution cabinets.

[0005] (2) Large size and insufficient portability: Existing portable voltage testing modules mostly adopt a distributed layout, with low integration of internal components, large size and weight, which is not convenient to carry by hand. In particular, they are not suitable for mobile inspection operations of multi-ring network boxes and multi-distribution cabinets in outdoor power distribution rooms. They cannot flexibly adapt to operation in narrow spaces, reducing the efficiency of multi-cabinet inspection.

[0006] (3) Poor display effect and insufficient ease of operation: Some voltage testing modules do not have a display interface, or the display interface layout is unreasonable and the brightness is insufficient, making it impossible to clearly view the test parameters under strong outdoor light; although some modules have display functions, they do not take into account the small size design, resulting in a display interface that is too small or a complicated layout of operation buttons. Maintenance personnel need to look down carefully to obtain test information, which makes it impossible to "use both hands and eyes", affecting the efficiency of multi-cabinet inspection.

[0007] (4) Lack of voice broadcast function and insufficient safety warnings: Existing power testing equipment mainly relies on sound and light alarms to indicate the energized status. When operators are in noisy outdoor environments or are focused on operation, they may easily ignore the alarm signals, which poses a safety hazard. At the same time, it is impossible to detect key information such as status, fault information, and charging status through voice feedback. Maintenance personnel need to frequently check the display interface, which is cumbersome and further reduces work efficiency.

[0008] (5) Inconvenient charging method and poor battery life adaptability: Most existing voltage testing modules use traditional charging interfaces (such as MicroUSB), which have poor universality and some do not support fast charging. It is difficult to replenish the power conveniently through power banks or ordinary charging heads when working outdoors. The charging time is long and the standby time is short. Frequent charging seriously affects the continuity of batch inspection of multiple cabinets and cannot meet the needs of long-term independent voltage testing outdoors.

[0009] (6) Slow response speed, not suitable for rapid troubleshooting of multiple cabinets: The existing voltage detection module has a slow induction response and alarm response speed, and the voltage detection time of a single cabinet is long. It also requires repeated manual start and stop operations, which cannot realize continuous autonomous detection of multiple cabinets and cannot meet the high-efficiency requirements of batch voltage detection. At the same time, it has weak anti-interference ability and is easily affected by outdoor electromagnetic radiation, power frequency harmonics in power distribution rooms, etc., which leads to inaccurate detection and the risk of misjudgment.

[0010] (7) Low degree of autonomy and high labor intensity: Existing voltage detection modules mostly require manual operation throughout the entire process (start-up, data collection, judgment, and recording), which cannot achieve autonomous operation of autonomous start-up, autonomous data collection, autonomous judgment, autonomous alarm, and autonomous storage. The labor intensity of maintenance personnel is high, and human error can easily lead to detection omissions and data loss, which is not suitable for the digital maintenance and archiving requirements of multi-cabinet systems.

[0011] (8) Poor versatility and maintainability: The detection threshold of the existing voltage detection module is fixed and cannot be adapted to the voltage detection requirements of ring network distribution cabinets with different voltage levels and different materials (metal, composite insulation) of 10 kV and below; some modules adopt an integrated design, the core components cannot be replaced independently, the maintenance cost is high, and the operation is complicated, requiring professional skills to master, resulting in insufficient adaptability. Summary of the Invention

[0012] In view of this, the problem to be solved by the present invention is to provide a leakage current detection method for power distribution cabinets, which can be adapted to different voltage levels, determine the electric field threshold for power distribution cabinet materials, collect the initial electric field signal, and effectively remove non-power frequency continuous interference signals and short-term sudden interference signals in the initial electric field signal, so as to more accurately detect the leakage current of the power distribution cabinet.

[0013] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A leakage current detection method for a power distribution cabinet includes continuously acquiring an initial electric field signal from the outside of the power distribution cabinet, continuously removing non-power frequency interference and sudden interference from the initial electric field signal based on a filtering strategy to generate an effective electric field signal, and comparing the effective electric field signal with an electric field threshold to determine whether there is leakage current. The filtering strategy includes: converting the initial electric field signal to a time frequency and removing interference frequencies from the non-distribution cabinet's operating frequency band to form an effective power frequency signal; iteratively predicting the theoretical effective power frequency signal in future time periods based on the obtained effective power frequency signal; and replacing the actual effective power frequency signal whose difference from its actual signal at the corresponding time is greater than a threshold, so as to generate a continuous effective electric field signal.

[0014] Furthermore, before performing the "comparison of effective electric field signal with electric field threshold to determine whether there is leakage", the process includes: determining whether the power distribution cabinet is made of metal or non-metal based on the effective electric field signal and material matching strategy, and switching to contact sampling mode and non-contact sampling mode to reacquire the initial electric field signal, and then obtaining the optimized effective electric field signal based on the filtering strategy.

[0015] Furthermore, the material matching strategy includes: extracting feature information from the effective electric field signal, including waveform abrupt changes and abrupt change time intervals, and determining the material of the distribution cabinet by comparing the feature information.

[0016] Furthermore, optimizing the effective electric field signal also includes: determining the actual signal interval based on the peak and valley values ​​of the effective electric field signal, calculating the interval scaling ratio between the preset standard maximum signal interval and the actual signal interval, and scaling the effective electric field signal and the corresponding electric field threshold based on the interval scaling ratio.

[0017] Furthermore, before performing the "comparison of effective electric field signal and electric field threshold to determine whether there is leakage", the following steps are taken: real-time acquisition of the operating voltage signal of the corresponding bus of the distribution cabinet to determine the voltage level of the current operating condition of the distribution cabinet, and obtaining the electric field threshold of the corresponding voltage through a pre-built voltage-leakage parameter correlation model.

[0018] A leakage current detection system for a power distribution cabinet includes a main control module that controls the operation of the system and generates detection results. The main control module is electrically connected to an induction acquisition module that can acquire the initial electric field signal outside the power distribution cabinet through a signal processing module that can remove interference from the initial electric field signal. The sensing acquisition module includes a sensing probe that converts the electric field into an initial electric field signal and a signal conditioning unit that amplifies the initial electric field signal. The sensing probe includes a dual-channel redundant sensing probe that collects the main electric field signal and the reference electric field signal respectively, a magnetic contact to improve contact stability, and a signal conditioning unit that amplifies and filters interference.

[0019] Furthermore, the signal processing module includes an analog-to-digital converter unit that converts the initial electric field signal in analog form into a digital form, and a filter unit that removes non-power frequency interference and random burst interference from the digital signal.

[0020] Furthermore, the leakage current detection system includes an autonomous power supply module for power supply. The autonomous power supply module includes a lithium battery for storing electrical energy. The lithium battery is electrically connected to a Type-C port through a charging management unit. The charging management unit is electrically connected to the main control module through a charging status detection unit. The lithium battery is electrically connected to the main control module through a power level detection unit. Both the lithium battery and the Type-C port are connected to the input terminal of a power protection unit through a power switching module. The output terminal of the power protection unit is electrically connected to each power-consuming module within the leakage current detection system.

[0021] Furthermore, the main control module is electrically connected to the human-machine interaction module, which includes a display screen and operation buttons.

[0022] Furthermore, the main control module is electrically connected to a storage module, a data export interface, a voice broadcast module, and an alarm indication module.

[0023] The beneficial effects of this invention are: By setting filtering and material matching strategies, the filtering strategy can effectively remove continuous non-power frequency interference signals and discontinuous burst interference signals in the digital electric field signal. By switching the contact mode for acquiring the initial electric field signal in conjunction with the material matching strategy, interference from the material of the distribution cabinet shell and signal strength can be removed during the data acquisition process, so as to more accurately detect the energization status of the distribution cabinet. It can adapt to different distribution cabinet materials to acquire the initial electric field signal in a targeted manner, and effectively remove continuous non-power frequency interference signals and short-term burst interference signals in the initial electric field signal, so as to more accurately detect the leakage of the distribution cabinet.

[0024] During the leakage current detection process of the distribution cabinet, the operating voltage signal of the corresponding bus of the distribution cabinet is collected in real time to determine the voltage level of the current operating condition of the distribution cabinet, and then the electric field threshold is determined accordingly. This can adapt to the electric field threshold of different voltage levels, thereby improving the accuracy and applicability of leakage current detection. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a structural diagram of a leakage current detection system for a power distribution cabinet according to the present invention; Figure 2 This is a structural diagram of the self-powered module in a leakage current detection system for a power distribution cabinet according to the present invention. Detailed Implementation

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

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein 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. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed terms.

[0028] This invention provides a leakage current detection method for power distribution cabinets, such as... Figure 1 As shown, the process includes continuously acquiring the initial electric field signal outside the distribution cabinet, continuously removing non-power frequency interference and sudden interference from the initial electric field signal based on a filtering strategy to generate an effective electric field signal, and comparing the effective electric field signal with the electric field threshold to determine whether there is leakage.

[0029] The filtering strategy includes: converting the initial electric field signal to a time frequency and removing interference frequencies from the non-distribution cabinet's operating frequency band to form an effective power frequency signal; iteratively predicting the theoretical effective power frequency signal in future time periods based on the acquired effective power frequency signal; and replacing the actual effective power frequency signal whose difference from its actual signal at the corresponding time is greater than a threshold, so as to generate a continuous effective electric field signal.

[0030] The specific process of filtering to remove continuous non-power frequency interference is as follows: When there is leakage in the distribution cabinet, the frequency of the electric field signal related to the degree of leakage is the standard power frequency of the power distribution network, concentrated in the 50Hz power frequency band. The initial electric field signal collected usually also includes non-power frequency continuous interference generated by the operating harmonics of the switching power supply in the distribution cabinet, electromagnetic radiation from radio transmitting equipment, and induced disturbances in the material of the distribution cabinet shell. The leakage situation of the distribution cabinet cannot be effectively determined based solely on the initial electric field signal.

[0031] To effectively remove non-power frequency interference signals, the initial electric field signal in the time domain is converted to the frequency domain. The frequency component distribution within the initial electric field signal is analyzed, and continuous non-power frequency interference signals that are persistent and periodically superimposed in the initial electric field signal are accurately suppressed (removed). Then, the initial electric field signal in the frequency domain is restored to the time domain to generate an effective power frequency signal. The effective power frequency signal accurately retains the effective leakage current signal at the 50Hz power frequency, avoiding the signal submersion and detection distortion caused by continuous fixed interference. This can compensate for the deficiency of subsequent Kalman filtering in filtering out continuous interference at steady-state fixed frequency points.

[0032] The filtering strategy includes Kalman filtering to remove sudden short-term interference: Since the grid current has AC characteristics, based on the time-series iterative prediction logic, relying on the real-time generated effective power frequency signal, the predicted effective power frequency signal without interference in the future period is iteratively predicted. By quantifying and comparing the deviation difference between the theoretically predicted effective power frequency signal and the actual generated effective power frequency signal, and judging whether the deviation difference exceeds the threshold, the short-term sudden interference can be accurately identified.

[0033] The future time period can be several future power frequency cycles (the cycle of a 50Hz power frequency is 0.02s), for example, a future time period of 0.1s. The deviation difference is calculated by calculating the difference between the predicted effective power frequency signal and the corresponding actual effective power frequency signal at each moment in the future time period and summing them up to generate the deviation difference.

[0034] When the difference between the two signals exceeds a preset difference threshold, it is determined that there is a short-term burst interference in the current actual effective power frequency signal. The abnormal actual effective power frequency signal is replaced by a predicted effective power frequency signal with higher fitting degree and no abrupt deviation. When the predicted effective power frequency signal is within the threshold range, the actual effective power frequency signal is retained to generate an effective electric field signal. This method can efficiently and quickly eliminate sudden short-term interference signals such as instantaneous pulse interference, short-term electromagnetic disturbances during equipment start-up and shutdown, and instantaneous voltage jumps generated during power distribution operation. It effectively preserves the gradual and steady-state change characteristics of the real leakage current signal, making up for the shortcomings of conventional filtering strategies in filtering out non-periodic and sudden short-term interference, and further improving the purity and detection stability of leakage current signal acquisition.

[0035] Before performing the "comparison of effective electric field signal and electric field threshold to determine whether there is leakage", the process includes assigning the power cabinet to metal or non-metal material based on the effective electric field signal and material matching strategy, and switching to the corresponding contact sampling mode or non-contact sampling mode to reacquire the initial electric field signal, and then obtaining the optimized effective electric field signal based on the filtering strategy.

[0036] Existing power distribution cabinets include those made of metal and those made of non-metal. Metal materials have good conductivity; when a metal cabinet leaks current, the current quickly flows through the metal to form a circuit. Due to the conductivity of the metal, the current diffuses rapidly, reducing localized electric field concentration. Therefore, the electric field signal waveform generated by a power distribution cabinet leaking current is usually smooth, without obvious peaks or abrupt changes. Non-metal materials have good insulation; when a non-metal cabinet leaks current, the current does not easily flow through the cabinet to form a circuit. The electric field concentrates near the leakage point, forming a localized high electric field region. Therefore, the electric field signal waveform generated by a power distribution cabinet leaking current is usually sharper, with obvious peaks or abrupt changes.

[0037] The material matching strategy includes extracting feature information from the effective electric field signal, including waveform abrupt changes and the time interval between these changes, and then determining the material of the distribution cabinet based on this feature information. Specifically, non-metallic distribution cabinets exhibit waveform abrupt changes with a fixed time interval between these changes (periodic abrupt changes).

[0038] When the distribution cabinet is made of non-metallic material, if the detection equipment uses a contact sampling mode and comes into contact with the leakage point, the leakage point will form a current loop through the detection equipment and the testing personnel, affecting the safety of the detection. For distribution cabinets made of metallic material, using a contact-sampling mode can increase the strength of the initial electric field signal, further improving the accuracy of leakage detection.

[0039] Optimizing the effective electric field signal also includes: determining the actual signal range based on the peak and valley values ​​of the effective electric field signal, calculating the interval scaling ratio between the preset standard maximum signal range and the actual signal range, and scaling the effective electric field signal and the corresponding electric field threshold based on the interval scaling ratio. This optimization method can dynamically adapt to fluctuations in the strength of the electric field signal, effectively solving the problems of signal processing errors and judgment failures caused by oversaturation distortion of the effective electric field signal and insufficient signal-to-noise ratio due to low signal amplitude. This allows for precise adaptation to the needs of weak leakage electric field signal acquisition and accurate processing under different grid voltage levels and transformer operating conditions with different casing and core materials, greatly expanding the adaptability range of leakage detection scenarios and improving leakage detection accuracy.

[0040] Constructing the standard maximum signal range involves: determining the theoretical maximum and minimum values ​​of the effective electric field signal based on the rated operating parameters of various detectable distribution cabinets and transformers, and constructing the standard maximum signal range of the electric field signal.

[0041] Before performing the "comparison of effective electric field signal and electric field threshold to determine whether leakage occurs," the operating voltage signal of the corresponding bus of the distribution cabinet is collected in real time to determine the voltage level of the distribution cabinet under the current operating condition. The electric field threshold under the voltage level is matched by a pre-built voltage-leakage parameter correlation model. It can dynamically and adaptively calibrate the electric field threshold according to the actual voltage level of the distribution cabinet, effectively avoiding the detection threshold mismatch problem caused by grid voltage fluctuations and load switching voltage regulation, adapting to the leakage detection needs of different voltage conditions, and ensuring the accuracy and stability of leakage determination across the entire voltage range.

[0042] The process of "comparing the effective electric field signal with the electric field threshold to determine whether there is leakage" specifically includes: receiving the optimized effective electric field signal and quickly comparing it with the corresponding electric field threshold; if it is determined to be in a charged state, immediately provide alarm feedback and voice broadcast feedback, the voice broadcast content can be "The casing is charged, please pay attention to safety"; if it is determined to be in a de-charged state, continuously acquire the effective electric field signal and perform cyclic detection, the interval time can be set through the human-machine interaction module (adjustable from 1 to 10 seconds); if the result is always de-charged, provide voice broadcast feedback, the voice broadcast content is "The casing is not charged, normal operation is possible"; if the result is partially charged, provide voice broadcast feedback, the voice broadcast content is "The result of the casing being charged is abnormal, re-determine the electric field threshold". It can adapt to the rapid voltage testing needs of multiple cabinets in different scenarios.

[0043] A leakage current detection system for a power distribution cabinet, such as Figure 1 As shown, the system includes a main control module that controls the operation of the system and generates detection results. The main control module is electrically connected to a sensing acquisition module that can collect the initial electric field signal outside the power distribution cabinet through a signal processing module that can remove interference in the initial electric field signal. The main control module gives the detection result based on the effective electric field signal output by the signal processing module. The main control module is electrically connected to an alarm indication module and a voice broadcasting module to comprehensively display the detection results and system operating status.

[0044] The sensing and acquisition module includes a sensing probe that converts the electric field into an electric field signal and a signal conditioning unit that amplifies the electric field signal. The sensing probe senses the magnitude of the electric field on the surface of the distribution cabinet by approaching or maintaining stable contact with it, and converts it into an electric field signal. Since the electric field on the surface of the distribution cabinet is relatively weak, the acquired electric field signal is also very weak. To avoid distortion of the digital electric field signal during subsequent transmission and processing, the signal conditioning unit amplifies the digital electric field signal, preventing data distortion during subsequent filtering.

[0045] Specifically, the sensing probe includes a dual-channel redundant sensing probe that collects the main electric field signal and the reference electric field signal respectively, a magnetic contact to improve contact stability, and a signal conditioning unit that amplifies and filters interference.

[0046] The signal conditioning unit includes an amplifier circuit for amplifying the digital electric field signal and a filter circuit for filtering out noise within the digital electric field signal. The amplifier circuit uses a high-input-impedance JFET operational amplifier (model: JFET 2N5485), with an input impedance ≥10Ω. 12 Ω, drain-source current IDSS: 1-5mA, enabling high-precision amplification of electric field signals. The filter circuit includes several filter capacitors and filter resistors, which remove noise from the digital electric field signal through hardware circuitry.

[0047] One embodiment of this application is: the signal conditioning unit includes a temperature-compensated reference source that stably provides a reference voltage unaffected by ambient temperature, so as to ensure the performance reliability of the signal conditioning unit over a wide temperature range.

[0048] One embodiment of this application is that a copper foil shielding layer is installed on the outside of the signal conditioning unit, which can improve the anti-interference capability of the signal conditioning unit.

[0049] The signal processing module includes an analog-to-digital converter (ADC) that converts the electric field signal into a digital signal, and a filter unit that removes non-power frequency interference and random burst noise from the digital signal. The ADC converts the initial electric field signal output from the sensing acquisition module from an analog signal to a digital signal. The filter unit converts the initial electric field signal in digital form from the time domain to the frequency domain, analyzes the frequency distribution, and selectively filters continuous non-power frequency interference signals to generate a valid power frequency signal. The filter unit then uses Kalman filtering to remove short-term high-frequency interference and random noise signals from the valid power frequency signal and outputs the valid electric field signal, improving the accuracy of the valid electric field signal.

[0050] Specifically, the analog-to-digital conversion unit uses a 16-bit high-precision, small-size converter (model: ADS1115), which has the advantages of high sampling rate and fast conversion speed. It can quickly convert weak electric field signals into digital electric field signals, ensuring the accuracy and speed of the conversion.

[0051] The filtering unit includes a small-sized ARM Cortex-M0+ core chip (model: LPC1114). The filtering unit incorporates an FFT digital spectrum analysis algorithm to convert the initial electric field signal in the time domain to the frequency domain. The standard frequency of mains power is 50Hz, and the unit removes non-power frequency signals that do not fall within 50Hz. It can effectively remove non-power frequency signals caused by non-power frequency interference sources such as switching power supplies, radio transmitting equipment, and casing materials.

[0052] The filtering unit is also equipped with a Kalman filter algorithm. Based on the Kalman filter algorithm, the predicted value of the effective power frequency signal in the future period is determined and compared with the actual value of the effective power frequency signal. The actual effective power frequency signal with sudden high-frequency interference signal and random noise signal is identified and replaced with the predicted effective power frequency signal. This can effectively remove sudden high-frequency interference signal and random noise signal in the digital electric field signal.

[0053] One embodiment of this application is that a copper foil shielding layer is installed on the outside of the signal processing module, which can improve the anti-interference capability of the signal processing module.

[0054] The alarm indicator module includes an audible and visual alarm unit and a vibration alarm unit, both directly controlled by the main control unit. They display the operating status and detection results of the leakage current detection system through light indicators, audible prompts, or vibration alerts. Specifically, the audible and visual alarm unit includes several high-brightness, small-volume LED indicator lights and a small-volume buzzer connected to the main control module. The vibration alarm unit includes a miniature vibration motor connected to the main control module.

[0055] The voice broadcast module includes a voice control unit, a small voice chip, and a miniature speaker. The main control module controls the voice chip to play voice through the voice control unit, and the miniature speaker is used to amplify the voice playback so as to broadcast key information in the test results in real time, helping operators to quickly understand the test status of the power distribution cabinet.

[0056] Specifically, the voice chip uses a small-size, low-cost voice synthesis chip (model: SYN6288), which has the advantages of small size, low power consumption, and clear voice, and supports multiple voice broadcast modes; the miniature speaker uses a small-size waterproof speaker (model: 8Ω 0.5W miniature waterproof speaker), with a waterproof rating of IP67, suitable for outdoor high humidity, rain and fog environments, and the volume is adjustable. The voice control unit controls the voice chip to perform voice broadcast according to the control commands output from the main control module, and the miniature speaker amplifies the content of the voice broadcast.

[0057] like Figure 2 As shown, the leakage current detection system also includes an autonomous power supply module for power generation. This module includes a lithium battery that stores electrical energy. The lithium battery is electrically connected to a Type-C port via a charging management unit to control its charging. The charging management unit is electrically connected to the main control module via a charging status detection unit, which transmits the lithium battery's charging status (charging, fully charged, low charge, charging abnormality) to the main control module. The lithium battery is also electrically connected to the main control module via a power detection unit, which continuously monitors the remaining electrical energy within the battery and transmits this information to the main control module.

[0058] Both the lithium battery and the Type-C port are connected to the input of the power protection unit via a power switching module. The output of the power protection unit is electrically connected to each module in the leakage current detection system to provide a stable power supply to each module. When the Type-C port is not connected to an external power source, the power switching module controls the lithium battery to power the system. When the Type-C port is connected to an external power source, the power switching module controls the external power source to power the system (while also charging the lithium battery).

[0059] Specifically, the lithium battery uses a 3.7V rechargeable small-volume lithium thionyl chloride battery (model: ER14505, capacity: 2000mAh), which has the advantages of small size, high energy density, and support for up to 14.7 months of standby time; the charging management unit uses a dedicated small-volume charging chip (model: TP4056-C, compatible with Type-C interface), which can be used with ordinary USB charging heads and external power banks; the power protection unit includes a fuse (model: 0402 1A / 32V surface mount fuse) and a low dropout small-volume regulator (model: AMS1117-3.3, output voltage: 3.3V); the charging status detection unit uses a current, voltage, and power consumption monitoring chip (model: INA219); the Type-C port uses a Type-C 2.0 waterproof interface, and the interface is equipped with a silicone rubber sealing plug (model: SR-01C).

[0060] The main control module has a built-in leakage detection program for determining leakage current in the distribution cabinet. The leakage detection program integrates multi-dimensional monitoring and control functions, which can identify the leakage current operation status of the distribution cabinet in real time and simultaneously inspect the working conditions of each functional module of the entire detection system. It can accurately identify the material type of the distribution cabinet shell and automatically match the voltage level of the distribution cabinet. It can monitor the output voltage, remaining power and other power supply parameters of the self-powered module in real time. It has mode switching control logic, which can control the system to switch to low-power sleep mode according to operation commands or standby time. It can also trigger the batch detection mode of the equipment to complete the continuous leakage current collection and analysis of multiple distribution cabinets in batches.

[0061] Specifically, the main control module is a small-sized microcontroller (model: STM32L431RCT6, ARM Cortex-M4 core), which has the advantages of small size and fast processing speed.

[0062] The batch testing mode includes: setting the batch testing quantity and testing interval based on the human-computer interaction module, automatically recording the electrical testing data of each cabinet and storing it in categories, supporting batch export, and adapting to the scenario of centralized inspection of multiple cabinets.

[0063] The sleep mode includes: automatically switching to sleep mode when the system is idle (after 30 seconds without voltage testing), with sleep power consumption ≤5μA. The system is immediately woken up after the voltage testing operation is restarted or the magnetic attachment is performed, which can further extend the system's standby time.

[0064] The main control module is electrically connected to a storage module and a data export interface. The storage module records cabinet-related data and categorizes and stores cabinet-related test data. The data export interface is used to export the cabinet's test data. The storage module connects to the main control module via an SPI communication interface for rapid communication between them. The main control module connects to external devices (computers, mobile phones) via the data export interface, enabling rapid data querying, exporting, and deletion.

[0065] Specifically, the storage module uses a small-sized Flash memory chip (model: W25Q128JV), which has the advantages of small size, fast storage speed, and support for cyclic storage, and can store at least 10,000 test results. The data export interface adopts a Type-C 3.0 waterproof interface for rapid export of test results. The interface is equipped with a waterproof and dustproof silicone rubber seal, which can be connected to computers and mobile phones to realize data query, export, and backup.

[0066] One embodiment of this application is as follows: the detection results include the distribution cabinet number, detection time, voltage level of the distribution cabinet, detection conclusion of the distribution cabinet (energized / non-energized), alarm status of the alarm indicator module, power supply information of the power supply module, identification result of the material of the distribution cabinet shell, detection mode (contact / non-contact), contact status of the magnetic contact, charging status of the Type-C interface, voice broadcast setting status, and other information.

[0067] The main control module is electrically connected to the human-machine interface module, which includes a display screen and operation buttons. By using the display screen and operation buttons in conjunction, the operating parameters and working status of each module in the leakage current detection system can be viewed and adjusted, and the detection results of the distribution cabinet can be displayed, which can improve the flexibility of the leakage current detection system.

[0068] Specifically, the display screen uses a small-volume, narrow-bezel OLED high-definition, high-brightness display (model: SSD1306 1.3), which has the advantages of being compact and displaying clearly. The operation buttons include a power button, mode button, setting button, confirmation button, and adjustment button. The power button is used to quickly start and stop the module. The mode button is used to quickly switch between voltage detection modes (autonomous / manual), alarm modes (audible / visual alarm / vibration alarm / silent), shell material adaptation modes (automatic / manual), voltage detection methods (contact / non-contact), and voice broadcast modes (on / silent). The setting button is used to quickly enter the parameter setting interface, where parameters such as detection interval, alarm volume, voltage threshold, date and time, cabinet number, and voice broadcast volume can be quickly set (to categorize and store various types of distribution cabinet detection data and voice requirements under different environments). The confirmation button is used to confirm operation commands. The adjustment button is used to adjust the alarm volume, detection threshold, display brightness, and voice broadcast volume.

[0069] The specific workflow of the leakage current detection system is as follows: Startup Phase: Operators start the module by pressing and holding the power button (≥2 seconds) or by waking it up via voice wake-up. The main control module immediately starts the autonomous initialization program, performing a comprehensive self-test on the sensing and acquisition module, signal processing module, alarm indication module, voice broadcast module, storage module, human-machine interaction module, and autonomous power supply module. The self-test time is ≤1 second. After the self-test is normal, the voice broadcast module announces "Module normal, power testing can begin," the display of the human-machine interaction module shows "Standby Status" and "Current Power Level," and the autonomous power supply module synchronously provides feedback on the power supply status. The module then enters the standby power testing mode. If a fault is detected during the self-test (such as probe failure, abnormal charging of the Type-C port, or storage abnormality), the alarm indication module immediately triggers a flashing red light and vibration alarm. The voice broadcast module synchronously broadcasts the corresponding fault information, and the display shows the fault details, reminding the operator to handle the issue. The module cannot enter the power testing mode until the fault is resolved.

[0070] During the voltage testing mode switching phase: The main control module automatically identifies the material of the cabinet shell under test (metal / composite insulation) through a material matching strategy. If it is identified as a metal shell, it automatically switches to contact voltage testing mode and announces "Switched to contact voltage testing mode, please contact the magnetic contact"; if it is identified as a composite insulation shell, it automatically switches to non-contact voltage testing mode and announces "Switched to non-contact voltage testing mode, please approach the cabinet shell"; the operator can also manually switch the voltage testing mode through the mode key of the human-machine interaction module. After switching, the voice broadcast module synchronously provides feedback on the switching result, and the display shows the current voltage testing mode.

[0071] Signal Acquisition and Processing Stage: In contact-type voltage testing mode, the operator attaches the magnetic contact in the induction acquisition module to the metal shell. The magnetic contact quickly adheres (attachment time ≤ 0.3 seconds). After good contact, a voice announcement reads "Good magnetic contact, voltage testing in progress." The induction acquisition module quickly acquires the weak electric field signal of the cabinet shell through the dual-channel induction probe and magnetic contact. The signal conditioning unit amplifies, rectifies, and filters the signal before transmitting it to the signal processing module. In non-contact voltage testing mode, the operator brings the induction probe close to the cabinet shell (distance 5-30mm). The induction acquisition module directly acquires the weak electric field signal of the shell. After conditioning by the signal conditioning unit, it is transmitted to the signal processing module. The signal processing module converts the electric field signal into a digital electric field signal through the analog-to-digital conversion unit. After FFT spectrum analysis and Kalman filtering algorithm processing, non-power frequency interference, high-frequency interference, and random noise interference are eliminated, and the effective digital electric field signal is extracted and transmitted to the main control module. The entire signal acquisition and processing process takes ≤ 0.5 seconds, ensuring rapid response.

[0072] Autonomous Judgment and Feedback Phase: The main control module receives the digital electric field signal transmitted by the signal processing module and quickly compares it with the preset electric field threshold (adjustable via the human-machine interaction module) (judgment time ≤ 10ms) to complete the live state judgment: ① If the judgment is live, the alarm indicator module immediately triggers a solid red light + buzzer alarm (volume adjustable) + vibration alarm, the voice broadcast module repeatedly broadcasts "The casing is live, please pay attention to safety", the display shows "Live State", "Detected Voltage Value", and "Voltage Level", and the storage module synchronously stores the voltage detection data (cabinet number, detection time, voltage level, voltage detection mode, live state); ② If the judgment is de-energized, the alarm indicator module has a solid green light, the voice broadcast module broadcasts "The casing is not live, normal operation is possible", the display shows "De-energized State" and "Detected Voltage Value", and the storage module synchronously stores the voltage detection data; ③ If an abnormal signal is detected (such as poor contact or weak signal), a voice prompt will announce "Electrical test abnormal, please try again," and the display will show "Signal abnormal." The main control module will control the sensing and acquisition module to reacquire the signal. After three consecutive abnormalities, the alarm indicator module will be triggered to provide a prompt and avoid misjudgment.

[0073] Multi-cabinet batch power testing phase: If the operator starts the batch testing mode, after completing the power testing of a single cabinet, the main control module automatically records the data and announces "Power testing complete, you can proceed to the next cabinet for power testing" in voice. The display shows "Batch testing in progress, XX units completed". There is no need to manually restart the module. The module can be moved directly to the next cabinet and the above power testing process can be repeated. After the batch testing is completed, all power testing data can be exported in batches via the data export interface or Bluetooth to meet the needs of digital operation and maintenance archiving of multiple cabinets.

[0074] Charging Phase: When the autonomous power supply module detects that the lithium battery level is below 10%, the alarm indicator module flashes red, and a voice announcement says "Insufficient power, please charge via Type-C." The display shows "Low power, charging required." When the operator inserts the Type-C charging cable into the Type-C port, the autonomous power supply module immediately starts fast charging mode. The charging management unit performs constant current and constant voltage charging, and the charging status detection unit monitors the charging current and voltage in real time and transmits the data to the main control module. The human-machine interface module displays "Charging in progress" and "Current charging progress (percentage)" in real time, and the voice announcement module announces the charging progress every 30 seconds (e.g., "Type-C charging in progress, current power level 30%"). After charging is complete, the autonomous power supply module automatically cuts off the charging circuit, announces "Charging complete, please disconnect the Type-C power supply," the display shows "Charging complete," and the alarm indicator module's green light remains on. If there is a Type-C charging abnormality (e.g., poor interface contact, incompatible charging equipment), the voice announcement says "Type-C charging abnormality, please check the interface," the display shows "Charging abnormality," and the alarm indicator module's red light flashes.

[0075] Standby and Sleep Phases: After the voltage testing operation is paused, the module enters sleep mode. If there is no operation for 30 seconds, the main control module automatically starts low-power sleep mode, shutting down unnecessary module components and only keeping the main control module and power detection module running at low power. Sleep power consumption is ≤5μA. If the voltage testing operation is triggered again (magnetic bonding, voice wake-up, manual button press), the module will wake up immediately and quickly enter the voltage testing mode without re-initialization. Press and hold the power button for ≥3 seconds to shut down the module. The voice will announce "Module has been shut down". All components will stop working, and the self-powered module will enter low-power protection state.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for detecting leakage current in a power distribution cabinet, characterized in that, This includes continuously collecting the initial electric field signal outside the distribution cabinet, continuously removing non-power frequency interference and sudden interference from the initial electric field signal based on a filtering strategy to generate an effective electric field signal, and comparing the effective electric field signal with the electric field threshold to determine whether there is leakage. The filtering strategy includes: converting the initial electric field signal to a time frequency and removing interference frequencies from the non-distribution cabinet's operating frequency band to form an effective power frequency signal; iteratively predicting the theoretical effective power frequency signal in future time periods based on the obtained effective power frequency signal; and replacing the actual effective power frequency signal whose difference from its actual signal at the corresponding time is greater than a threshold, so as to generate a continuous effective electric field signal.

2. The leakage current detection method for a distribution cabinet according to claim 1, characterized in that, Before performing the "comparison of effective electric field signal and electric field threshold to determine whether there is leakage", the process includes: determining whether the power distribution cabinet is made of metal or non-metal based on the effective electric field signal and material matching strategy, switching to contact sampling mode and non-contact sampling mode to reacquire the initial electric field signal, and then obtaining the optimized effective electric field signal based on the filtering strategy.

3. The leakage current detection method for a distribution cabinet according to claim 2, characterized in that, The material matching strategy includes: extracting feature information from the effective electric field signal, including waveform abrupt changes and abrupt change time intervals, and determining the material of the distribution cabinet by comparing the feature information.

4. The leakage current detection method for a distribution cabinet according to claim 3, characterized in that, Optimizing the effective electric field signal further includes: determining the actual signal range based on the peak and valley values ​​of the effective electric field signal, calculating the interval scaling ratio between the preset standard maximum signal range and the actual signal range, and scaling the effective electric field signal and the corresponding electric field threshold based on the interval scaling ratio.

5. The leakage current detection method for a distribution cabinet according to claim 1, characterized in that, Before performing the "comparison of effective electric field signal and electric field threshold to determine whether there is leakage", the following steps are taken: real-time acquisition of the operating voltage signal of the corresponding bus of the distribution cabinet to determine the voltage level of the current operating condition of the distribution cabinet, and obtaining the electric field threshold of the corresponding voltage through a pre-built voltage-leakage parameter correlation model.

6. A leakage current detection system for a distribution cabinet, used to implement the leakage current detection method for a distribution cabinet as described in any one of claims 1-5, characterized in that, The system includes a main control module that controls the operation of the system and generates detection results. The main control module is electrically connected to an induction acquisition module that can acquire the initial electric field signal outside the distribution cabinet through a signal processing module that can remove interference from the initial electric field signal. The sensing acquisition module includes a sensing probe that converts the electric field into an initial electric field signal and a signal conditioning unit that amplifies the initial electric field signal. The sensing probe includes a dual-channel redundant sensing probe that collects the main electric field signal and the reference electric field signal respectively, a magnetic contact to improve contact stability, and a signal conditioning unit that amplifies and filters interference.

7. The leakage current detection system for a distribution cabinet according to claim 6, characterized in that, The signal processing module includes an analog-to-digital converter unit that converts the initial electric field signal in analog form into a digital form, and a filtering unit that removes non-power frequency interference and random burst interference from the digital signal.

8. The leakage current detection system for a distribution cabinet according to claim 6, characterized in that, The leakage current detection system includes an autonomous power supply module for power supply. The autonomous power supply module includes a lithium battery for storing electrical energy. The lithium battery is electrically connected to a Type-C port through a charging management unit. The charging management unit is electrically connected to a main control module through a charging status detection unit. The lithium battery is electrically connected to the main control module through a power level detection unit. Both the lithium battery and the Type-C port are connected to the input terminal of a power protection unit through a power switching module. The output terminal of the power protection unit is electrically connected to each power-consuming module within the leakage current detection system.

9. A leakage current detection system for a power distribution cabinet according to claim 6, characterized in that, The main control module is electrically connected to the human-computer interaction module, which includes a display screen and operation buttons.

10. A leakage current detection system for a power distribution cabinet according to claim 6, characterized in that, The main control module is electrically connected to a storage module, a data export interface, a voice broadcast module, and an alarm indication module.

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