Residual current detection system and method based on wireless synchronization and software confluence

Abstract

The invention discloses a residual current detection system and method based on wireless synchronization and software confluence, and relates to the technical field of residual current detection. A host central processing device receives current sampling data with timestamps from a slave central processing device through a signal receiver to complete centralized receiving of multiple paths of current signals; after the host central processing device receives synchronous current sampling data with timestamps transmitted by the slave central processing device, aligning and synthesizing multiple paths of time-synchronized current signals through a software confluence algorithm, carrying out vector summation on the multiple paths of current signals based on a vector operation principle, and calculating the vector sum of residual current; and judging whether a grounding fault or an insulation defect exists according to whether the vector sum is zero, if the vector sum deviates from the zero value, judging that residual current abnormity exists, and giving an alarm or recording fault information. The detection system effectively improves the accuracy, reliability and applicability of residual current detection.

Description

Technical Field

[0001] This invention relates to the field of residual current detection technology, and specifically to a residual current detection system and method based on wireless synchronization and software merging. Background Technology

[0002] In the TN-S grounding system commonly used in substations, grounding faults and insulation defects can be sensitively detected by checking whether the vector sum of the residual current is zero. Its main functions are to prevent electric shock, fire, and equipment damage, and it is an indispensable safety protection measure for low-voltage power distribution systems within substations. Currently, high-precision AC clamp meters are generally used to simultaneously clamp all live and neutral wires of the AC cable for measurement. For long-distance, two-point residual current measurement, instruments such as the Guangzhou Qianshun QAB-50 AC insulation fault finder are used, but this method has the following drawbacks: 1. The cable cores are scattered, and the clamp meter cannot clamp all the live and neutral wires. In some cables, the live and neutral wires are far apart, and in some cables, all three live wires are far apart, making it impossible for the clamp meter to clamp all the live and neutral wires and thus impossible to directly measure the leakage current.

[0003] 2. Measurement is difficult when multiple thick cables are used for power supply. The low-voltage side of the station transformer is generally connected to the low-voltage cabinet through four relatively thick cables. Sometimes it is necessary to measure the current of the four cables at the same time. Therefore, a dual-machine detection mode is adopted, in which a flexible coil is wrapped around each cable at a distance. However, this dual-machine detection mode does not use software current merging. The host central processing unit and the slave central processing unit need to read the current sequentially. This not only makes the calculation process prone to errors, but also affects the work efficiency.

[0004] 3. Flexible coils can measure large currents, but their sensitivity and accuracy for measuring small currents are not high. In practice, the residual current in the four cables A, B, C, and N is very small, usually only a few hundred milliamps, which makes it impossible to measure accurately in actual use and leads to misjudgment. Summary of the Invention

[0005] The purpose of this invention is to provide a residual current detection system and method based on wireless synchronization and software merging. By detecting whether the vector sum of the residual current is zero, grounding faults and insulation defects can be detected sensitively. This not only plays a good role in personal safety protection and electrical fire prevention, but also improves equipment safety and system reliability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a residual current detection method based on wireless synchronization and software merging, the detection method comprising the following steps: The slave central processing unit uses the time reference signal of the GPS / BeiDou synchronization module built into the connected flexible coil detector as the synchronization reference, and uses the current sensor built into the flexible coil detector to perform time-synchronized current sampling of multiple cables to obtain current sampling data with timestamps. The slave central processing unit wirelessly transmits timestamped current sampling data to the master central processing unit via its built-in signal transmitter. The relay module amplifies the signal between the master and slave central processing units. The master central processing unit receives the timestamped current sampling data from the slave central processing unit via its signal receiver, thus completing the centralized reception of multiple current signals. After receiving the timestamped synchronous current sampling data from the slave central processing unit, the host central processing unit aligns and synthesizes the time-synchronized multi-channel current signals using a software current merging algorithm. Based on the principle of vector operation, it performs vector summation on the multi-channel current signals to calculate the vector sum of the residual current. It determines whether there is a grounding fault or insulation defect based on whether the vector sum is zero. If the vector sum deviates from zero, it is determined that there is an abnormal residual current, and an alarm is issued or fault information is recorded.

[0007] Preferably, four flexible coil detectors are provided, with each of the four flexible coil detectors independently fitted onto the phase wire and neutral wire of the low-voltage power distribution system, or one flexible coil detector can be used to cover multiple phase wires of the cable.

[0008] Preferably, if the effective vector sum of the current flowing into the closed surface S1 of any flexible coil detector is equal to zero, then IA+IB+IC+IN=0, where IA, IB, and IC are phase currents, IN is the neutral current, S1 is any closed surface, and the vector sum of the three-phase currents enclosed by the flexible coil detector is equal in magnitude, opposite in direction, and cancels each other out.

[0009] Preferably, each of the flexible coil detectors is connected to the side interface of the slave central processing unit via a connecting line, for transmitting measurement data to the slave central processing unit in real time, and performing initial current synthesis on the data transmitted by all connecting lines.

[0010] Preferably, the host central processing unit and the slave central processing unit synchronously trigger the acquisition signal during operation, and then send the timestamped sampled data from the slave central processing unit to the host central processing unit through a signal transmitter.

[0011] Preferably, after receiving the residual current from the slave central processing unit, the host central processing unit performs final software current merging processing and displays the vector sum of the residual current values ​​on the display screen in real time. The software current merging results of the residual current on the display screens of the host central processing unit and the slave central processing unit are synchronized in real time.

[0012] Preferably, the display screen of the host central processing unit automatically determines the level based on the magnitude of the displayed residual current vector sum. If the residual current vector sum synthesized by the software is less than 2 amps, it automatically switches to the 25x gain level for amplification; if the residual current vector sum synthesized by the software is greater than or equal to 2 amps, it automatically switches to the 0.5x gain level for amplification.

[0013] This application also provides a residual current detection system based on wireless synchronization and software confluence, including a relay module, a flexible coil detector, and a central processing unit. The central processing unit includes a master central processing unit and a slave central processing unit. The relay module is used to establish a wireless communication connection between the master central processing unit and the slave central processing unit. The flexible coil detector is connected to the slave central processing unit via a connecting line. The slave central processing unit performs time-synchronized current sampling using the current sensor built into the connected flexible coil detector and the GPS / BeiDou synchronization module. The timestamped sampling data is sent to the master central processing unit through the signal transmitter of the slave central processing unit. The master central processing unit performs vector summation on the synchronized multi-channel current data, calculates whether the vector sum of the residual current is zero, and determines whether there is a grounding fault or insulation defect.

[0014] The technical effects and advantages provided by the present invention in the above technical solution are as follows: The central processing unit of this invention employs a software current merging algorithm to accurately align and synthesize multiple synchronous current signals, and performs vector summation based on the principle of vector operation to calculate the vector sum of the system's residual current. By judging whether it approaches zero, it can sensitively identify grounding faults or insulation defects. It has particularly high detection sensitivity for small current anomalies, effectively solving the problem that traditional detection methods are difficult to accurately measure residual current due to the dispersion of cable cores, the coexistence of multiple thick cables, and the insufficient sensitivity of flexible coils to small currents.

[0015] This invention employs a GPS / BeiDou synchronization module to achieve high-precision time synchronization among all flexible coil detectors. Under strict synchronization control, the current signals collected by each flexible coil detector are sampled synchronously to ensure that the multiple current data are strictly aligned in the time dimension. This fundamentally solves the problem of residual current vector synthesis error caused by asynchronous sampling in traditional detection methods, laying the foundation for subsequent accurate vector summation calculations.

[0016] This invention wirelessly transmits current sampling data with precise timestamps to the host central processing unit via a slave central processing unit, and uses a relay module to enhance the signal in environments with long distances or weak signals. This not only overcomes the limitations of traditional wired connection methods, such as difficult construction and poor flexibility in complex wiring environments, but also ensures the stability and integrity of multiple current signals during wireless transmission, achieving centralized and efficient reception of multi-node, distributed current data. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 This is a schematic diagram of the overall structure of the detection system of the present invention; Figure 2 This is a flowchart of the detection method of the present invention; Figure 3 This is a schematic diagram of the residual current measurement of the detection system of the present invention; Figure 4 The circuit diagrams for different gain levels of the detection system of this invention are shown below; Figure 5 This is a schematic diagram of the grounding fault location detection system of the present invention.

[0019] In the diagram: 1A, main unit central processing unit; 1B, slave unit central processing unit; 101, battery; 102A, signal receiver; 102B, signal transmitter; 103, display screen; 104, gear position; 2, flexible coil detector; 201, connecting cable; 3, relay module. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 embodiments of the present invention, 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.

[0021] Example 1: Please refer to Figure 1As shown, this embodiment provides a residual current detection system based on wireless synchronization and software merging, comprising a relay module 3, four flexible coil detectors 2, and two central processing units (master central processing unit 1A and slave central processing unit 1B). When the master central processing unit 1A and slave central processing unit 1B are far apart, the relay module 3 needs to amplify the signal at a position between them to ensure successful wireless communication. The four flexible coil detectors 2 can be independently fitted onto each phase line and neutral line of the low-voltage power distribution system, or, when the cable diameter is small, one coil can be used to fit multiple cable phase lines. Each flexible coil detector 2 is connected to the slave central processing unit 1B via a connecting line 201. The slave central processing unit 1B transmits the signal to the connected flexible coil detectors. The high-precision current sensor and GPS / BeiDou synchronization module built into the detector 2 perform high-precision time-synchronized current sampling. The time-stamped sampling data is sent to the host central processing unit 1A via the signal transmitter 102B of the slave central processing unit 1B. The host central processing unit 1A receives the time-stamped current sampling data from the slave central processing unit 1B via the signal receiver 102A. A software current-merging algorithm is used to perform vector summation on the strictly synchronized multi-channel current data, calculating whether the vector sum of the residual current is zero. This allows for sensitive determination of the presence of grounding faults and insulation defects. This invention effectively solves the problem of inaccurate residual current measurement caused by dispersed cable cores, the coexistence of multiple thick cables, and insufficient sensitivity of flexible coils to small currents, achieving high-precision and reliable detection of milliampere-level residual current in complex wiring scenarios.

[0022] like Figure 1 As shown, the shaded area in the flexible coil detector 2 is the optimal measurement area. When the flexible coil detector 2 is working, it can be independently fitted onto each phase line and neutral line of the low-voltage power distribution system. If the phase lines are concentrated, they can be fitted onto each phase line at the same time; if the phase lines are scattered, each phase line can be independently fitted onto the flexible coil detector 2 and connected to the side interface of the slave central processing device 1B through the connecting line 201.

[0023] The flexible coil detector 2 is connected to the side interface of the slave central processing device 1B via the connecting line 201, which facilitates the real-time uploading of measurement data to the slave central processing device 1B, and performs initial current synthesis on the data sent by all connecting lines 201.

[0024] Both central processing units have rechargeable batteries 101 to provide power to the units.

[0025] When the host central processing unit 1A and the slave central processing unit 1B are working, they synchronously trigger the acquisition signal and then send the timestamped sampled data from the slave central processing unit 1B to the host central processing unit 1A via wireless communication.

[0026] Either of the two central processing units can be the host, and the choice can be made flexibly according to the actual situation on site. However, the software results of the residual current on the host and slave display screens 103 are synchronized in real time.

[0027] If the master and slave devices are far apart, the relay module 3 needs to amplify the signal at the midpoint between the master and slave devices to ensure successful wireless communication.

[0028] The host central processing unit 1A performs final software current combining processing on the residual current received from the slave central processing unit 1B, and displays the vector sum of the residual current values ​​on the display screen 103 in real time, unaffected by direction.

[0029] The display screen 103 of the host central processing unit automatically determines the range based on the magnitude of the displayed residual current vector sum. If the residual current vector sum synthesized by the software is less than 2 amps, it automatically switches to the 25x gain range for amplification. If the residual current vector sum synthesized by the software is greater than or equal to 2 amps, it automatically switches to the 0.5x gain range for amplification. This will completely solve the problem of inaccurate measurement of residual current caused by insufficient sensitivity of flexible coils to small currents.

[0030] Example 2: This example provides a residual current detection method based on wireless synchronization and software merging. Please refer to [link / reference]. Figure 2 As shown, the detection method includes the following steps: Four flexible coil detectors are installed independently or in combination (for cases with multiple small-diameter cables) on each phase line and neutral line of the low-voltage power distribution. Each flexible coil detector is connected to the slave central processing unit via a connecting line. The slave central processing unit uses the time reference signal of the GPS / BeiDou synchronization module built into the connected flexible coil detector as the synchronization reference, and uses the current sensor built into the flexible coil detector to perform time-synchronized current sampling of multiple cables to obtain current sampling data with precise timestamps.

[0031] The slave central processing unit (CPU) wirelessly transmits current sampling data with precise timestamps to the host CPU located at an appropriate position (or via a relay module to amplify the signal if the distance between the host and slave CPUs is too great). The relay module amplifies the signal between the host and slave CPUs, ensuring stable and reliable wireless communication in long-distance or complex environments, and guaranteeing that the data from the slave CPU is accurately transmitted to the host CPU. The host CPU receives the timestamped current sampling data from the slave CPU via a signal receiver, completing the centralized reception of multiple current signals.

[0032] After receiving the timestamped synchronous current sampling data from the slave central processing unit, the host central processing unit performs precise alignment and synthesis processing on the multiple current signals with strict time synchronization through the built-in software current merging algorithm; based on the principle of vector operation, it performs vector summation on the multiple current signals to calculate the vector sum of the residual current; it judges whether there is a grounding fault or insulation defect based on whether the vector sum approaches zero (theoretically it should be close to zero under normal circumstances); if the vector sum deviates significantly from zero, it is determined that there is an abnormal residual current, and an alarm can be issued or fault information can be recorded, thereby achieving high-precision and high-reliability detection of milliampere-level residual current in low-voltage power distribution systems, effectively dealing with the challenges of complex wiring, multiple coexisting cables, and small current detection.

[0033] The specific operating method will be described in detail below with reference to the accompanying drawings.

[0034] like Figure 3 As shown, in a TN-S grounding configuration of an AC system, IA, IB, and IC are phase currents, IN is the neutral current, and S1 is any enclosed surface. According to Kirchhoff's laws, the effective vector sum of the currents flowing into the enclosed surface S1 of any flexible coil detector is equal to zero, therefore IA + IB + IC + IN = 0. Under normal conditions, the vector sum of the three-phase currents enclosed by the flexible coil detector is equal in magnitude and opposite in direction to the current flowing through the neutral line (N line), thus canceling each other out.

[0035] Before starting the residual current detection, depending on the cable diameter and the distance between each phase, you can flexibly choose to individually attach the flexible coil detector to each phase and neutral wire of the cable. If the phase and neutral wires are concentrated together, you can also use one flexible coil detector to cover all the wires. Neither the dispersed nor concentrated placement will affect the measurement results.

[0036] Each flexible coil detector is connected to the side interface of the slave central processing unit via a connecting cable, which facilitates the real-time transmission of measurement data to the slave central processing unit and performs initial current synthesis on the data transmitted from all connecting cables.

[0037] The host central processing unit and the slave central processing unit synchronously trigger the acquisition signal during operation, and then send the timestamped sampled data from the slave central processing unit to the host central processing unit through the signal transmitter.

[0038] If the host central processing unit and the slave central processing unit are far apart, the relay module needs to amplify the signal at the position between the host central processing unit and the slave central processing unit to ensure successful wireless communication.

[0039] The host central processing unit performs final software current merging processing after receiving the residual current from the slave central processing unit, and displays the vector sum of the residual current values ​​on the display screen in real time. The software current merging results of the residual current on the display screens of the host central processing unit and the slave central processing unit are synchronized in real time.

[0040] The display screen on the central processing unit of the host computer automatically determines the gain setting based on the magnitude of the displayed residual current vector sum. If the residual current vector sum synthesized by the software is less than 2 amps, it automatically switches to the 25x gain setting for amplification. If the residual current vector sum synthesized by the software is greater than or equal to 2 amps, it automatically switches to the 0.5x gain setting for amplification. This will completely solve the problem of inaccurate measurement of residual current caused by insufficient sensitivity of flexible coil detectors to small currents.

[0041] Gain circuit diagrams for different levels are as follows: Figure 4 As shown.

[0042] When the current is greater than or equal to 2 amps, position 1 (low gain) is used: the relay SW contact closes, gain G1 = 0.4902, approximately 0.5 times. This is used to directly measure the current of each phase, and the residual current is synthesized by software to prevent signal saturation.

[0043] ; In the formula, V in V is the input voltage. out For the output voltage, RB_22||RB_2 represents the equivalent resistance value of RB_22 and RB_2 connected in parallel, and RB_1 represents the series resistance value.

[0044] When the current is less than 2 amps, use setting 2 (high gain): the relay SW contact is open, and the gain G2 = 25. The coil is directly wrapped around each phase conductor for high-sensitivity measurement of minute leakage currents.

[0045] ; In the formula, V in V is the input voltage. out RB_1 represents the series resistance value, and RB_2 represents the feedback resistance value of the high-gain branch.

[0046] like Figure 5 As shown, when the combined residual current of the software displayed on the main unit's central processing unit and the slave unit's central processing unit is large and exceeds 300mA (e.g., Figure 5 If the S1 closed surface is not found, then troubleshooting needs to be performed along that branch. When troubleshooting the flexible coil detector at the lower end of the branch, it is necessary to continue troubleshooting along the branch until the residual current disappears or until the load end is reached. If the residual current does not disappear before reaching the load end (e.g. Figure 5In the S2 closed surface), the insulation fault point is at the front end of the residual current disappearance point (e.g. Figure 5 (point a in the middle).

[0047] Example 3: This example provides a detailed description of each operational process of the detection system of this application, as follows: Based on the actual wiring characteristics of the low-voltage power distribution system, four flexible coil detectors are installed independently or in combination on each phase line (e.g., phase A, phase B, and phase C) and the neutral line (N line). For scenarios with small cable diameters and multiple cables laid in parallel (e.g., multiple thin-diameter phase lines closely arranged), to avoid magnetic leakage due to a single coil not being able to completely cover multiple cables, a combined deployment method of a single flexible coil simultaneously wrapping around multiple cable phase lines can be used to ensure effective coupling of the current and magnetic field of the target conductor. For scenarios with larger cable diameters or single cables laid independently, an independent deployment method is used, with a single flexible coil independently installed on the corresponding phase line or neutral line. Each flexible coil detector is physically connected to the slave central processing unit via a dedicated connecting cable (e.g., shielded twisted pair cable).

[0048] The flexible coil detector has a built-in high-precision current sensor (usually a sensor based on the Rogowski coil or fluxgate principle, with small current detection capability from nanoampere to milliampere) that senses the current signal flowing through the corresponding flexible coil in real time.

[0049] Specifically, when an alternating current flows through the conductor being measured, an alternating magnetic field related to the magnitude and phase of the current is generated around it. The flexible coil converts this magnetic field into a weak voltage signal (proportional to the rate of change of the current) through the principle of electromagnetic induction. This signal is initially processed by the signal conditioning circuit (such as amplification and filtering) inside the slave central processing unit, and then digitally acquired by a high-precision analog-to-digital converter (ADC) at a fixed sampling rate (such as 10kHz or higher). At the same time, the GPS / BeiDou synchronization module built into the flexible coil detector continuously receives a unified time reference signal from the BeiDou satellite (with time accuracy up to the nanosecond level), and synchronizes and calibrates the local clock with the BeiDou time reference through an internal clock discipline algorithm (such as frequency / phase tracking technology based on phase-locked loop). Ultimately, all the local clocks of the flexible coil detectors (regardless of their physical location) are strictly aligned to the same time reference (such as UTC time or the synchronization start time defined by the system).

[0050] After time base synchronization is completed, the central processing unit (such as an embedded microcontroller or DSP chip) of the slave central processing unit, based on the synchronized local clock, initiates synchronous sampling of the current signals of all connected flexible coils at strictly aligned time points according to a preset synchronization triggering mechanism (e.g., by receiving the synchronization pulse signal output by the GPS / BeiDou synchronization module or a software trigger command based on a unified timestamp). During the sampling process, the slave central processing unit performs parallel acquisition of the current signals of all the flexible coil detectors (which may be one or more coils in combination) under its responsibility. Each sampling records the precise timestamp of the current moment (e.g., identified by UTC time or the counter value of the slave's local synchronization clock) and converts the original analog signal into a digital quantity (e.g., a 16-bit or 24-bit resolution digital signal).

[0051] Strict synchronization here does not require absolute zero latency, but rather uses BeiDou time reference and local clock discipline technology to control the sampling time deviation between each flexible coil detector within a tolerable range (for example, industrial applications typically require less than 10 microseconds, which can be further optimized to within 1 microsecond using a high-precision synchronization module). Timestamps are marked using continuous counting or absolute time encoding (such as Unix timestamps or custom synchronization clock counting) to ensure the host can accurately identify the sampling time of each signal and perform alignment processing. For combined flexible coil deployments (i.e., a single coil wrapping around multiple cables), the actual conductor object corresponding to each sampling data point must be clearly identified through preset topology configuration information (such as pre-stored information on which conductors correspond to the flexible coil detector), so that the host can perform targeted vector calculations subsequently.

[0052] After completing synchronous sampling and generating a set of current sampling data with precise timestamps, the slave central processing unit first preprocesses and encapsulates the raw data. Preprocessing operations include data format standardization (e.g., converting timestamps to a system-standard time encoding format, such as UTC timestamps or high-precision counter values ​​from the slave's local synchronous clock), data integrity verification (e.g., detecting potential errors in the sampled data before local storage or transmission using CRC checksums or parity bits), and data packetization (if the amount of data sampled in a single instance is large, it is split into multiple data packets according to a preset communication frame length, with each data packet containing a portion of the sampling points and their corresponding timestamps).

[0053] The slave central processing unit transmits encapsulated data as radio waves to the space channel via a built-in signal transmitter (typically a low-power, high-interference-resistance wireless communication module, such as a LoRa, ZigBee, or proprietary frequency band FSK modulation wireless module). During transmission, the slave central processing unit sends data packets in an orderly manner according to a preset communication protocol (such as a custom timestamp-data-point pairing transmission protocol) and may employ a retransmission mechanism (e.g., automatically retransmitting specific data packets when the signal strength is detected to be below a threshold or when the receiver does not return an acknowledgment) to improve transmission reliability.

[0054] When the straight-line distance between the host central processing unit and the slave central processing unit is large (e.g., exceeding the standard communication distance of the wireless module, typically several hundred meters to several kilometers, depending on module performance and environmental interference), or when the deployment environment has complex interference factors (such as metal structure shielding in power distribution rooms, signal attenuation due to multipath reflection, electromagnetic noise interference from high-voltage equipment, etc.), a relay module is introduced as a relay node for wireless communication. A relay module is essentially a wireless signal forwarding device with bidirectional communication capabilities. Its working logic is based on a signal strength detection-path selection-data forwarding processing flow. The relay module continuously monitors the wireless signal strength from the slave central processing unit (assessed by Received Signal Strength Indicator (RSSI) or Signal-to-Noise Ratio (SNR)) and the signal reachability from the master unit (determined through active detection or historical communication quality records). If the quality of the direct communication link between the slave and master central processing units is detected to be below a preset threshold (e.g., RSSI < -85dBm or packet loss rate > 5%), the relay module automatically activates its signal relay function. It receives and demodulates the wireless signal transmitted from the slave central processing unit into digital data, performs internal buffering and format preservation (ensuring no modification to the original timestamp and sampled data content), remodulates and transmits it to the master central processing unit. The relay module is typically deployed in the area between the master and slave central processing units (e.g., the middle layer of a power distribution cabinet in a power distribution system or an open area). Optimizing its physical location reduces path loss during signal transmission, and its anti-interference design (e.g., metal shielding housing, narrowband filtering circuit) reduces the distortion caused by environmental noise, thus ensuring the stability and reliability of wireless communication over long distances or in complex environments.

[0055] The host central processing unit continuously monitors wireless signals from the slave central processing unit (or relayed via a relay module) through its built-in signal receiver (a wireless communication module matching the slave transmitter's frequency band, supporting the same modulation method and communication protocol). During reception, the host central processing unit first demodulates the captured radio electromagnetic wave signal (restoring the RF signal to a baseband digital signal), then parses the data packets according to a preset communication protocol, extracts the timestamp and current sampling data key fields, and performs data verification at the receiving end (such as recalculating the CRC checksum and comparing it with the received check bits; if they do not match, the data packet is marked as suspicious and a retransmission request mechanism is triggered). For valid data packets that pass the verification, the host central processing unit stores them in a local cache (such as a RAM buffer) or non-volatile memory (such as Flash), and simultaneously classifies and manages multiple data streams according to timestamp order, ultimately forming a multi-channel synchronous current sampling data set. This set contains all current signal samples with precise timestamps uploaded by the slave, and the time deviation of each sample is controlled within the allowable range of synchronization error (e.g., less than 1 microsecond).

[0056] After receiving the timestamped synchronous current sampling data uploaded by the slave device, the host central processing unit first performs time axis alignment of the multiple signals. Since the slave device achieves nanosecond-level time reference synchronization based on the GPS / BeiDou synchronization module, and the sampling time deviation is controlled within an extremely small range (e.g., ≤1 microsecond), theoretically, the current sampling data of each channel already has a strict basis for synchronization in the time dimension. However, in actual transmission, factors such as wireless signal propagation delay, relay module forwarding delay, or slight drift of the slave device's local clock may cause a small time stamp offset (usually sub-millisecond). Therefore, the host needs to perform dynamic alignment processing on the multiple sampling data based on the timestamp field. The processing logic is as follows: Select the smallest timestamp (t) from the slave sampled data. min A unified time coordinate system can be established using either the global reference start time or the slave device's timestamp as a benchmark. Iterate through each time point t (divided according to a fixed sampling interval Δt, such as Δt=0.1ms corresponding to a sampling rate of 10kHz), and extract the sampling point closest to t from the sampling data set of the slave device (if there are multiple sampling points whose time difference with t is less than a preset threshold, such as ±0.05ms, then take the point with the smallest time difference; if there is no perfectly matching point, then estimate the current value at time t by linear interpolation). Remove sampling points whose timestamp deviation exceeds the system's allowable range (e.g., >1ms) (such data may be out of sync due to communication anomalies or clock drift, and should be recorded in the anomaly log but not included in subsequent synthesis).

[0057] Through the above logic, the host converts the current sampling sequences of the slave (corresponding to different phase lines or neutral lines) into synchronous sampling sequences on the same time axis, ensuring that the multiple current data at each time t reflect the current state of the conductor at the same physical moment.

[0058] After completing the time alignment of multiple signals, the host performs vector summation on the synchronized current signals based on the principle of vector operation, and calculates the vector sum of the remaining current.

[0059] In a low-voltage power distribution system, the vector sum of the current in each phase (A / B / C phases) and the current in the neutral line (N phase) should theoretically approach zero during normal operation (i.e., ,in The sum of the instantaneous current vectors of each phase line or neutral line will significantly deviate from zero if there is a grounding fault (such as single-phase grounding) or insulation defect (such as cable insulation aging and leakage). If the current sensor output is a scalar (amplitude only), and the phase relationship of each phase line is known (e.g., phases A / B / C are distributed at 120° electrical angles), then the scalar current of each phase line needs to be converted into a vector form (e.g., phase A current). Phase B current C-phase current N-phase current If the sensor directly outputs a vector (such as an AC signal containing phase information obtained through a Rogowski coil), then the raw vector data can be used directly. Synchronous current vector at each time t (n is the number of flexible coil detectors, usually 4 channels corresponding to 4 wires), perform vector superposition operation (i.e., add the real and imaginary parts of each vector separately, or through complex number operations). Calculate the vector sum; Steady-state and transient processing: For steady-state conditions (such as normal load operation), calculate the mean vector sum over a time window (such as 10 sampling periods). For transient operating conditions (such as the moment of sudden failure), directly analyze the moment of failure. instantaneous vector and .

[0060] Based on the vector summation result, the host central processing unit executes the residual current anomaly detection logic, the core criterion of which is whether the vector sum approaches zero: Based on the system accuracy requirements and the field environment (such as the sensitivity requirements for low current detection), set the alarm threshold for residual current. (e.g., 10mA, 30mA, or 100mA, corresponding to different protection levels); calculate the absolute value of the vector sum. Or the root mean square (RMS) value, and compared with the threshold. Compare; if If the instantaneous value at a transient moment exceeds the dynamic threshold, it is determined to be an abnormal residual current. By combining the direction (e.g., polarity) and magnitude of the vector sum, the fault type can be preliminarily inferred (e.g., small, continuous deviations may indicate insulation aging and leakage, while large, instantaneous changes may indicate a single-phase grounding fault). This triggers the alarm mechanism on the host side (e.g., audible and visual alarms, communication reporting to the monitoring platform) and records the fault information (including the abnormal time t, vector sum magnitude). The system collects sampled current values ​​of each phase line, environmental parameters, etc., to form a traceable fault log. For serious faults (such as vector sums exceeding dangerous values), the system can further link the circuit breaker to trip or activate the backup protection strategy.

[0061] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A residual current detection method based on wireless synchronization and software merging, characterized in that: The detection method includes the following steps: The slave central processing unit uses the time reference signal of the GPS / BeiDou synchronization module built into the connected flexible coil detector as the synchronization reference, and uses the current sensor built into the flexible coil detector to perform time-synchronized current sampling of multiple cables to obtain current sampling data with timestamps. The slave central processing unit wirelessly transmits timestamped current sampling data to the master central processing unit via its built-in signal transmitter. The relay module amplifies the signal between the master and slave central processing units. The master central processing unit receives the timestamped current sampling data from the slave central processing unit via its signal receiver, thus completing the centralized reception of multiple current signals. After receiving the timestamped synchronous current sampling data from the slave central processing unit, the host central processing unit aligns and synthesizes the time-synchronized multi-channel current signals using a software current merging algorithm. Based on the principle of vector operation, it performs vector summation on the multi-channel current signals to calculate the vector sum of the residual current. It determines whether there is a grounding fault or insulation defect based on whether the vector sum is zero. If the vector sum deviates from zero, it is determined that there is an abnormal residual current, and an alarm is issued or fault information is recorded.

2. The residual current detection method based on wireless synchronization and software confluence according to claim 1, characterized in that: The flexible coil detector is configured as four, with each of the four flexible coil detectors independently fitted onto the phase line and neutral line of the cable in the low-voltage power distribution system, or one flexible coil detector can be used to fit onto multiple phase lines of the cable.

3. The residual current detection method based on wireless synchronization and software confluence according to claim 2, characterized in that: If the effective vector sum of the current flowing into the closed surface S1 of any flexible coil detector is equal to zero, then IA+IB+IC+IN=0, where IA, IB, and IC are phase currents, IN is the neutral current, and S1 is any closed surface. The vector sum of the three-phase currents enclosed by the flexible coil detector is equal in magnitude to the current flowing through the neutral line, but opposite in direction and cancels each other out.

4. The residual current detection method based on wireless synchronization and software confluence according to claim 3, characterized in that: Each of the flexible coil detectors is connected to the side interface of the slave central processing unit via a connecting line, for transmitting measurement data to the slave central processing unit in real time, and performing initial current synthesis on the data transmitted by all connecting lines.

5. The residual current detection method based on wireless synchronization and software confluence according to claim 1, characterized in that: The host central processing unit and the slave central processing unit synchronously trigger the acquisition signal during operation, and then send the timestamped sampled data from the slave central processing unit to the host central processing unit through the signal transmitter.

6. The residual current detection method based on wireless synchronization and software confluence according to claim 5, characterized in that: After receiving the residual current from the slave central processing unit, the host central processing unit performs final software current merging processing and displays the vector sum of the residual current values ​​on the display screen in real time. The software current merging results of the residual current on the display screens of the host central processing unit and the slave central processing unit are synchronized in real time.

7. The residual current detection method based on wireless synchronization and software confluence according to claim 6, characterized in that: The display screen of the host central processing unit automatically determines the level based on the magnitude of the displayed residual current vector sum. If the residual current vector sum synthesized by the software is less than 2 amps, it automatically switches to the 25x gain level for amplification; if the residual current vector sum synthesized by the software is greater than or equal to 2 amps, it automatically switches to the 0.5x gain level for amplification.

8. A residual current detection system based on wireless synchronization and software current convergence, used to implement the detection method according to any one of claims 1-7, characterized in that: The system includes a relay module, a flexible coil detector, and a central processing unit. The central processing unit comprises a master central processing unit and a slave central processing unit. The relay module is used to establish a wireless communication connection between the master and slave central processing units. The flexible coil detector is connected to the slave central processing unit via a connecting line. The slave central processing unit performs time-synchronized current sampling using the current sensor and GPS / BeiDou synchronization module built into the connected flexible coil detector. The timestamped sampled data is sent to the master central processing unit via the signal transmitter of the slave central processing unit. The master central processing unit performs vector summation on the synchronized multi-channel current data, calculates whether the vector sum of the remaining current is zero, and determines whether there is a grounding fault or insulation defect.

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