Optical fiber bus and multi-mode wireless cooperative power distribution network cable joint intelligent monitoring system

Abstract

The application provides a power distribution network cable joint intelligent monitoring system cooperating with a fiber bus and a multi-mode wireless, and belongs to the technical field of smart grids. The system comprises a temperature measuring unit, a monitoring node and a monitoring host. When receiving data of each byte sent by the monitoring node, the monitoring host is configured to: acquire the state of a timer; if the timer is in a closed state, start the timer, save the data of a single byte to the latest writing position of a first storage space, and write a frame start mark to the latest writing position of a second storage space; if the timer is in an open state, reset the timer, save the data of a single byte to the latest writing position of the first storage space, and write an intra-frame data mark to the latest writing position of the second storage space; and if the timing time of the timer arrives, close the timer, and write a frame end mark to the previous position of the latest writing position of the second storage space. The application can improve the reliability of the monitoring result of the cable joint.

Description

Technical Field

[0001] This application relates to the field of smart grid technology, and in particular to a smart monitoring system for distribution network cable joints that combines fiber optic bus and multimode wireless collaboration. Background Technology

[0002] Underground cable networks are critical infrastructure for power transmission. Cable joints, as the weakest link in cable lines, are frequent points of failure due to factors such as manufacturing processes and aging. Their operational status directly affects the reliability of power supply. Traditional manual inspection methods suffer from drawbacks such as long cycles, low efficiency, and numerous blind spots. Problems cannot be detected in a timely manner, fault location is difficult, and repair cycles are long, seriously affecting the reliability of power supply.

[0003] With the development of industrial-grade wireless communication and multi-dimensional sensing and monitoring technologies, intelligent monitoring systems for cable joints have emerged. By deploying sensing and monitoring equipment at cable joints, the system collects the temperature of the cable joints in real time and transmits the data remotely to the monitoring host via a communication network. This enables all-weather, blind-spot-free online monitoring of the operating status of cable joints, breaking through the time and space limitations of manual inspection.

[0004] In the aforementioned intelligent monitoring system for cable joints, the quality of communication data processing directly determines the validity of the monitoring data. If the data processing mechanism is poorly designed, it can lead to data transmission errors, thereby affecting the reliability of the entire cable joint monitoring results. Summary of the Invention

[0005] This application provides an intelligent monitoring system for power distribution network cable joints that combines fiber optic bus and multimode wireless communication to improve the reliability of cable joint monitoring results.

[0006] This application provides an intelligent monitoring system for power distribution cable joints that utilizes fiber optic bus and multimode wireless collaboration, including a temperature measurement unit, monitoring nodes, and a monitoring host.

[0007] The temperature measuring unit is configured to monitor the temperature of the cable joint, obtain temperature data, and send the temperature data to the monitoring node via a wireless communication unit.

[0008] The monitoring node is configured to send the temperature data to the monitoring host via a fiber optic bus;

[0009] The monitoring host is configured as follows:

[0010] Get the state of the preset first timer;

[0011] Upon receiving each byte of data sent by the monitoring node, if the first timer is off, the first timer is turned on, the single byte of data is saved to the latest write position of the preset first storage space, and a frame start marker is written to the latest write position of the preset second storage space; wherein, the first storage space and the second storage space are of the same size, and there is a fixed position offset between the latest write position of the first storage space and the latest write position of the second storage space;

[0012] Upon receiving each byte of data sent by the monitoring node, if the first timer is enabled, the first timer is reset, and the single byte of data is saved to the latest write position of the first storage space.

[0013] If the timing of the first timer expires, the first timer is turned off, and a frame end marker is written at the position above the latest write position in the second storage space;

[0014] The monitoring host is also configured to:

[0015] The data in the first storage space is parsed based on the frame start marker and the frame end marker, and the parsed data is displayed.

[0016] In one exemplary embodiment of this application, the intelligent monitoring system for power distribution network cable joints that coordinates fiber optic bus and multimode wireless communication further includes:

[0017] If the latest write position is the starting position of the second storage space, then the previous position of the latest write position is the ending position of the second storage space.

[0018] In one exemplary embodiment of this application, there are multiple monitoring nodes. When setting the address of each monitoring node, the multiple monitoring nodes are connected to the monitoring host in a cascaded manner, and a switching circuit is provided between the uplink port and the downlink port of each monitoring node. Before setting the address of each monitoring node, the switching circuit of the monitoring node is in the off state.

[0019] Each of the aforementioned monitoring nodes is configured as follows:

[0020] Receive an address setting instruction carrying a first address identifier sent by the upper-level device; if the monitoring node is a first-level monitoring node, the upper-level device is the monitoring host; if the monitoring node is a monitoring node other than a first-level monitoring node, the upper-level device is the upper-level monitoring node of the monitoring node.

[0021] The address of the monitoring node is set based on the first address identifier, and after the address of the monitoring node is set, the first confirmation information is sent to the next higher level device; the first confirmation information is used to indicate that the address of the monitoring node has been set.

[0022] Send an address setting instruction carrying a second address identifier to the next-level monitoring node, so that the next-level monitoring node sets its own address based on the second address identifier;

[0023] Upon receiving the second confirmation message from the next-level monitoring node, the switching circuit of that monitoring node is closed; the second confirmation message indicates that the address setting of the next-level monitoring node is complete.

[0024] In one exemplary embodiment of this application, each of the monitoring nodes is further configured to:

[0025] If the monitoring node does not receive the second confirmation information from the next-level monitoring node, it resends the address setting instruction carrying the second address identifier to the next-level monitoring node, and accumulates the number of resends to obtain the cumulative resend count.

[0026] If the cumulative number of retransmissions exceeds the preset number, the monitoring node is designated as the last-level monitoring node, its switching circuit is kept open, and a prompt message is sent to the next higher-level monitoring node; the prompt message indicates that the address settings of all monitoring nodes are complete.

[0027] In one exemplary embodiment of this application, for each monitoring node, the switching circuit of the monitoring node includes a tri-state gate and a pull-up resistor.

[0028] The enable terminal of the tri-state gate is connected to the control signal output terminal of the monitoring node, the first terminal of the tri-state gate is connected to the uplink port of the monitoring node, and the second terminal of the tri-state gate is connected to the downlink port of the monitoring node.

[0029] The enable terminal of the tri-state gate is connected to the power supply through the pull-up resistor.

[0030] In one exemplary embodiment of this application, the wireless communication unit is configured with a 2.4G protocol stack and a Bluetooth protocol stack, and each monitoring node is configured as follows:

[0031] After power-on, the priority of the 2.4G protocol stack is set higher than that of the Bluetooth protocol stack, and the second timer is started;

[0032] During the active period of the 2.4G protocol stack, the temperature data reported by the temperature measuring unit through the 2.4G protocol stack is received, and the second timer is reset after each receipt of the temperature data; when the communication channel of the 2.4G protocol stack is idle, if a Bluetooth connection request information sent by the terminal device is received, a connection is established with the terminal device based on the Bluetooth protocol stack after a set delay time.

[0033] In one exemplary embodiment of this application, each of the monitoring nodes is further configured to:

[0034] During the active period of the 2.4G protocol stack, when the temperature data is received, if Bluetooth communication based on the Bluetooth protocol stack is already connected, the temperature data is sent to the terminal device through the Bluetooth protocol stack.

[0035] In one exemplary embodiment of this application, each of the monitoring nodes is further configured to:

[0036] If no Bluetooth connection request information is received and no established Bluetooth communication connection is found when the second timer expires, the wireless communication unit is controlled to enter a low-power listening mode.

[0037] In one exemplary embodiment of this application, each monitoring node is further provided with a first current monitoring unit and a second current monitoring unit. The first current monitoring unit is configured to monitor the first current at the cable connector inlet end, and the second current monitoring unit is configured to monitor the second current at the cable connector outlet end.

[0038] Each of the aforementioned monitoring nodes is configured as follows:

[0039] Calculate the difference between the first current and the second current at the monitoring node to obtain the leakage current;

[0040] When the leakage current exceeds a preset leakage current threshold, leakage current fault information is sent to the monitoring host.

[0041] In one exemplary embodiment of this application, both the first current monitoring unit and the second current monitoring unit are Rogowski coils.

[0042] The beneficial effects of the intelligent monitoring system for power distribution network cable joints that combines fiber optic bus and multimode wireless collaboration provided in this application embodiment are as follows:

[0043] This embodiment designs a dual-structure storage space (first storage space and second storage space) with a marked area, and combines it with a timer timeout mechanism to define the data frame boundary, so as to realize the automatic capture, storage and isolation of complete data frames, thereby avoiding communication data parsing errors and improving the reliability of cable joint monitoring results.

[0044] The specific processing procedure is as follows: When the monitoring host receives each byte of data sent by the monitoring node, it first obtains the status of the first timer. If the first timer is off, it indicates that the currently received byte is the first byte of a new data frame. At this time, the first timer is turned on, and the currently received single byte of data is saved to the latest write position of the preset first storage space. At the same time, the preset second storage space is used as the marking area corresponding to the first storage space, and the frame start mark is written at the latest write position of the second storage space.

[0045] After receiving the first byte of data, each subsequent byte of data received is intra-frame data. Simultaneously, each received byte of data triggers a receive interrupt. After each interrupt, the interrupt service routine saves the received single byte of data to the latest write position in the first memory space and immediately resets the first timer to restart the timing.

[0046] After the last byte is received, since no new data is received, the first timer is no longer reset and continues to count down. When the countdown reaches the preset timeout period, the first timer interrupt is triggered. In the interrupt service routine of the first timer, since the latest write position in the second memory space already points to the next byte, it is necessary to backtrack to the previous position (i.e., the mark position corresponding to the last byte of data) and write the frame end mark to ensure that the frame end mark corresponds precisely to the last byte of data, thus guaranteeing the accuracy of frame boundary identification. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the structure of the intelligent monitoring system for power distribution cable joints that combines fiber optic bus and multimode wireless collaboration provided in this application embodiment;

[0049] Figure 2 This is a schematic diagram of a dual-structure storage space with a marked area provided in an embodiment of this application;

[0050] Figure 3 This is a schematic diagram illustrating the cascaded relationship of multiple monitoring nodes provided in the embodiments of this application;

[0051] Figure 4 This is a schematic diagram of the switching circuit provided in the embodiments of this application. Detailed Implementation

[0052] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this solution. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0053] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0054] The implementation of this application will be described in detail below with reference to the specific accompanying drawings:

[0055] Figure 1 This is a schematic diagram of a smart monitoring system for power distribution network cable joints that combines fiber optic bus and multimode wireless communication, provided as an embodiment of this application. (Refer to...) Figure 1 This intelligent monitoring system for power distribution network cable joints, which integrates fiber optic bus and multi-mode wireless communication, includes temperature measurement units (specifically, wireless temperature sensors), monitoring nodes, and a monitoring host. Multiple wireless temperature sensors are distributed across each phase cable joint. The monitoring nodes integrate a 2.4G wireless module (i.e., a wireless communication unit), enabling synchronous acquisition of temperature sensor data from each phase cable joint via a proprietary 2.4G protocol. Simultaneously, each monitoring node has dual 10M fiber optic interfaces, connected to the fiber optic bus via optical modules (i.e., fiber optic transceiver modules), transmitting the collected temperature data to the monitoring host. The monitoring host can be located in a back-end management center, where it displays the received data. This allows staff to monitor the cable joint status in real time from the back-end management center.

[0056] In addition, the monitoring node uses a high-performance microcontroller based on the ARM Cortex-M4 core as the main controller (Microcontroller Unit, MCU), runs a real-time operating system (embedded system), and is responsible for data acquisition, calculation, communication scheduling and protocol processing.

[0057] In this embodiment, the inventors of this application, through extensive experimental research, discovered that a significant reason for data transmission errors in existing intelligent cable connector monitoring systems is that, in traditional embedded communication, a common practice is to use standard drivers such as the Cortex Microcontroller Software Interface Standard Driver (CMSIS-Driver). The advantage of this method is that it reduces the CPU load during data transfer. However, this method has a significant drawback: the application layer is responsible for identifying and parsing a complete data frame from a continuous byte stream. This increases the complexity of the application logic, and when the data flow rate is high or the frame structure is irregular, improper parsing logic can easily lead to incomplete frames, packet fragmentation, and other problems, affecting the reliability of communication.

[0058] Therefore, this embodiment abandons the original receiving mode that relies on application layer parsing and designs a dual-structure storage space (first storage space and second storage space) with a marked area. It also combines a timer timeout mechanism to define the data frame boundary, so as to realize the automatic capture, storage and isolation of complete data frames, thereby avoiding data parsing errors and improving the reliability of cable joint monitoring results.

[0059] Specifically, when transmitting temperature data, the monitoring node can encapsulate the temperature data into data frames for transmission. The monitoring host is configured to perform the following operations (steps S101-S104):

[0060] S101, Obtain the state of the preset first timer.

[0061] In this embodiment, the MCU of the monitoring node is connected to the optical module via a serial port (Universal Asynchronous Receiver / Transmitter, UART) to achieve fiber optic communication between the monitoring node and the monitoring host. For example, the UART can be configured to a single-byte receive interrupt mode, meaning that a UART interrupt is triggered once for each byte of data received. Simultaneously, a first timer is configured to operate in interrupt mode, and the timeout period of the first timer is based on the current communication baud rate and a preset timeout value. Value calculation settings, where, This indicates the maximum number of idle bytes. When receiving the same frame of data continuously, the idle time between bytes is extremely short, while the idle time between two frames of data becomes significantly longer. The purpose of a value is to define continuity. The time required for one byte to be transmitted is used as the timeout threshold, that is, when the interval between receiving two bytes exceeds [a certain value], the timeout is determined. The time required for the transmission of one byte is considered as the completion of receiving one frame of data.

[0062] For example, the formula for calculating the timeout period is as follows:

[0063] ;

[0064] in, This indicates the timeout period of the first timer. The transmission time per byte can be determined based on the UART's baud rate. For example, with a baud rate of 9600bps (1 bit transmission time ≈ 104μs), and assuming a single byte has 10 bits (1 start + 8 data + 1 stop), the transmission time per byte is approximately 1040μs. In this case, if n=3 is set, then... .

[0065] Simultaneously, during the initialization configuration, a first storage space and a second storage space can be predefined. The first and second storage spaces are of the same size, and there is a fixed offset between the latest write position of the first and second storage spaces. For example, the first storage space has a starting address of 0x20001000, an ending address of 0x20001FFF, and a size of 4096 bytes; the second storage space has a starting address of 0x20002000, an ending address of 0x20002FFF, and a size of 4096 bytes. The first byte of the first storage space has a fixed offset of 0x1000 (4096 decimal) bytes from the first byte of the second storage space, the second byte of the first storage space has a fixed offset of 0x1000 bytes from the second byte of the second storage space, and so on. Each byte of the first storage space has a fixed offset of 0x1000 bytes from its corresponding byte in the second storage space.

[0066] S102. When receiving each byte of data sent by the monitoring node, if the first timer is off, turn on the first timer, save the single byte of data to the latest write position of the preset first storage space, and write the frame start mark at the latest write position of the preset second storage space.

[0067] In this embodiment, within the UART interrupt service routine, if the first timer is off, it indicates that the first timer was turned off after the last data frame reception ended, and the currently received byte is the first byte of the new data frame. At this time, the first timer can be turned on, and the currently received single byte of data can be saved to the latest write position of a preset first storage space. Simultaneously, a preset second storage space can be used as the marker area corresponding to the first storage space, and a frame start marker, such as 0xAA, is written to the latest write position of the second storage space. Figure 2As shown, the first byte of the data frame can be Addr (i.e., the address identifier of the monitoring node).

[0068] S103. When receiving each byte of data sent by the monitoring node, if the first timer is in the enabled state, reset the first timer and save the single byte of data to the latest write position of the first storage space.

[0069] In this embodiment, after receiving the first byte of data, each subsequent byte of data received is intra-frame data. Simultaneously, each received byte of data triggers a UART receive interrupt. After each interrupt, the interrupt service routine saves the received single byte of data to the latest write position in the first memory space and immediately resets the first timer to restart the timing.

[0070] like Figure 2 As shown, after saving the received single byte of data to the latest write position of the first storage space, the intra-frame data marker, such as 0x00, can be written to the latest write position of the second storage space; alternatively, all data in the second storage space can be initialized to 0x00 during power-on initialization, in which case the marker area data corresponding to the intra-frame data is 0x00 by default.

[0071] S104. If the timing of the first timer expires, turn off the first timer and write the end-of-frame marker at the position above the latest write position in the second storage space.

[0072] After the last byte is received, since no new data is received, the first timer is no longer reset and continues counting. When the countdown reaches the preset timeout, the first timer interrupt is triggered. In the interrupt service routine of the first timer, since the latest write position already points to the next byte, it is necessary to backtrack to the previous position (i.e., the marker position corresponding to the last data byte) and write the end-of-frame marker, for example, 0x55, to ensure that the end-of-frame marker corresponds precisely to the last data byte, guaranteeing the accuracy of frame boundary identification. Figure 2 As shown, the last byte of the data frame can be a CRC (checksum). Meanwhile, since the current data frame has been completely received, the first timer can be turned off. At this point, a complete data frame is marked in the second storage space.

[0073] Based on the above steps S101-S104, the monitoring host is further configured as follows:

[0074] The data in the first storage space is parsed based on the start-of-frame and end-of-frame markers, and the parsed data is then displayed.

[0075] In this embodiment, when the monitoring host processes the data in the first storage space, it can query the second storage space (marked area) to find the data between 0xAA and 0x55 as a complete data frame.

[0076] As can be seen from the above, in this embodiment, when the monitoring host receives each byte sent by the monitoring node, it first obtains the status of the first timer. If the first timer is off, it indicates that the currently received byte is the first byte of a new data frame. At this time, the first timer is turned on, and the data of the currently received single byte is saved to the latest write position of the preset first storage space. At the same time, the preset second storage space is used as the marking area corresponding to the first storage space, and the frame start mark is written at the latest write position of the second storage space.

[0077] After receiving the first byte of data, each subsequent byte of data received is intra-frame data. Simultaneously, each received byte of data triggers a UART receive interrupt. After each interrupt, the interrupt service routine saves the received single byte of data to the latest write position in the first memory space and immediately resets the first timer to restart the timing.

[0078] After the last byte is received, since no new data is received, the first timer is no longer reset and continues to count down. When the countdown reaches the preset timeout period, the first timer interrupt is triggered. In the interrupt service routine of the first timer, since the latest write position already points to the next byte, it is necessary to backtrack to the previous position (i.e., the mark position corresponding to the last data byte) and write the end-of-frame marker to ensure that the end-of-frame marker corresponds precisely to the last data byte, thus guaranteeing the accuracy of frame boundary identification.

[0079] In one exemplary embodiment of this application, the intelligent monitoring system for power distribution network cable joints that combines fiber optic bus and multimode wireless communication further includes:

[0080] If the latest write position is the starting position of the second storage space, the position preceding the latest write position is the ending position of the second storage space.

[0081] In this embodiment, the second storage space can be set as a circular storage area. That is, after data is written to the end position of the second storage space, if there is new data to be written, the new data can be written from the beginning position of the second storage space. Therefore, if the latest written position is the beginning position of the second storage space, the position before the latest written position is the end position of the second storage space.

[0082] Similarly, the first storage space can also be set as a ring storage area. This storage method can realize the cyclic reuse of limited storage space and avoid interruption of temperature measurement data reception due to the storage space being full.

[0083] Reference Figure 3 In one exemplary embodiment of this application, there are multiple monitoring nodes. When setting the address of each monitoring node, the multiple monitoring nodes are connected to the monitoring host in a cascade manner, and a switch circuit is provided between the uplink port and the downlink port of each monitoring node. Before setting the address of each monitoring node, the switch circuit of the monitoring node is in the off state.

[0084] Each monitoring node is configured as follows:

[0085] Receives an address setting instruction carrying a first address identifier sent by the upper-level device; if the monitoring node is a first-level monitoring node, the upper-level device is a monitoring host; if the monitoring node is a monitoring node other than a first-level monitoring node, the upper-level device is the upper-level monitoring node of the monitoring node.

[0086] The address of the monitoring node is set based on the first address identifier, and after the address of the monitoring node is set, the first confirmation message is sent to the next higher level device; the first confirmation message is used to indicate that the address of the monitoring node has been set.

[0087] Send an address setting command carrying a second address identifier to the next-level monitoring node so that the next-level monitoring node can set its own address based on the second address identifier;

[0088] After receiving the second confirmation message from the next-level monitoring node, the switching circuit of that monitoring node is closed; the second confirmation message is used to indicate that the address setting of the next-level monitoring node is complete.

[0089] In addition, each monitoring node is configured as follows:

[0090] If the monitoring node does not receive the second confirmation information from the next-level monitoring node, it resends the address setting instruction carrying the second address identifier to the next-level monitoring node, and accumulates the number of resends to obtain the cumulative resend count.

[0091] If the cumulative number of retransmissions exceeds the preset number, the monitoring node is designated as the last-level monitoring node, its switching circuit is kept open, and a prompt message is sent to the next higher-level monitoring node. The prompt message indicates that the address settings for all monitoring nodes are complete.

[0092] In this embodiment, the uplink port of each monitoring node is a communication port pointing to the monitoring host / upper-level monitoring node, used to realize cascading with the monitoring host / upper-level monitoring node; the downlink port of each monitoring node is a communication port pointing to the next-level monitoring node, used to realize cascading with the next-level monitoring node.

[0093] Multiple monitoring nodes communicate with the monitoring host via a fiber optic bus. Before normal communication, each monitoring node needs to be assigned a unique address identifier. This address identifier is the identification of the monitoring node. The monitoring host sends instructions to the designated monitoring node through the address identifier. Each monitoring node only receives data packets that match its own address identifier. At the same time, when the monitoring node uploads temperature measurement data, it will carry its own address identifier, allowing the monitoring host to accurately identify the location of the cable connector to which the temperature measurement data belongs.

[0094] This embodiment uses a recursive automatic address allocation method based on fiber optic bus to set an address identifier for each monitoring node (hereinafter referred to as slave). The specific steps are as follows:

[0095] Step 1: All slave devices power on and close their switching circuits by default, ensuring physical connectivity of the fiber optic bus. The monitoring host (hereinafter referred to as the host) broadcasts a "disconnect switching circuit" command. Upon receiving this command, all slave devices immediately disconnect their own switching circuits to achieve logical isolation.

[0096] Step 2: The host sends the first address identifier (e.g., address 1) to the fiber optic module 1 of the first slave. Since the switching circuit of the first slave is not closed, the second slave cannot receive the command. After the first slave successfully sets the address, it replies with the first confirmation message.

[0097] Step 3: After the first slave device successfully sets its address, it actively sets the address of the second slave device through its downlink port. During this process, the master device remains in a waiting state and does not need to send commands to downstream devices. At this time, the switching circuit of the first slave device is not yet closed, and the master device cannot receive the address setting command sent by the slave device, thus preventing the address setting command of the second slave device from occupying the bus. After the second slave device replies with a second confirmation message, the first slave device closes its own switching circuit.

[0098] Using the same method, the above process is carried out in succession. After each slave device completes its own address setting, it assumes the responsibility of setting the address for the next slave device. For each slave device, the switching circuit of the slave device is not closed until the address setting of the next-level slave device is completed. The slave device that has completed synchronization with the upper level cannot receive the address setting command sent by the slave device, thus avoiding interference with the slave device that has completed synchronization with the upper level.

[0099] Step 4: When a slave node (e.g., the Nth slave node) attempts to set an address for a downstream device but does not receive a second confirmation message from the downstream device, it will repeatedly send the address setting command. A preset number of resends can be defined (e.g., 3 times). If the number of resends (i.e., the cumulative number of resends) exceeds the preset number and still does not receive a second confirmation message from the downstream device, it determines itself to be the end node. This end node keeps its switching circuit open and broadcasts an "Address setting complete" frame (i.e., a notification message) upstream. The notification message carries its own address N. Since all upstream slave nodes have closed their switching circuits, meaning the entire upstream fiber optic bus is connected, the notification message is sent directly to the host via the fiber optic bus. The host thus learns that the total number of slave nodes is N, completing network discovery.

[0100] As can be seen from the above, this embodiment adopts the method of setting the address of the previous slave to the next slave, which can reduce the communication load of the master. The master only initiates the initial command, and the subsequent address setting is completed autonomously by the slave, without the master continuously participating in downstream interaction. At the same time, the address setting command is only transmitted between adjacent slaves and will not occupy the backbone fiber optic bus, thereby avoiding bus congestion and interference caused by the simultaneous transmission of multiple commands.

[0101] Furthermore, the design of the slave device having a closed switch circuit in the default power-on state ensures that if a slave device unexpectedly restarts during automatic addressing, its default state is a closed switch circuit, which will not cause bus communication interruption and greatly enhances the fault tolerance of the system.

[0102] In one exemplary embodiment of this application, for each monitoring node, the switching circuit of the monitoring node includes a tri-state gate and a pull-up resistor.

[0103] The enable terminal of the tri-state gate is connected to the control signal output terminal of the monitoring node, the first terminal of the tri-state gate is connected to the uplink port of the monitoring node, and the second terminal of the tri-state gate is connected to the downlink port of the monitoring node.

[0104] The enable pin of a tri-state gate is connected to the power supply via a pull-up resistor.

[0105] In this embodiment, the switching circuit is implemented using a tri-state gate and a pull-up resistor. The tri-state gate features fast turn-on speed and low voltage drop, which is beneficial for achieving high-speed and stable communication on the fiber optic bus. The control terminal of the tri-state gate is controlled by the control signal output terminal of the MCU (e.g., an I / O port of the MCU). When the control signal output terminal of the MCU is high, the tri-state gate is enabled, and the first and second terminals of the tri-state gate are at the same level, i.e., the switching circuit is on. When the control signal output terminal of the MCU is low, the tri-state gate is disabled, and the output terminal of the tri-state gate is always in a high-impedance state, i.e., the switching circuit is off. Through the above process, the control of the monitoring node's access to or disconnection from the bus is logically realized. Specifically, the tri-state gate can be implemented using a tri-state bus transceiver SN74HC245.

[0106] The control terminal of the tri-state gate is pulled up to a high level by a pull-up resistor. This ensures that when a monitoring node fails, the tri-state gate is enabled and the switching circuit of that monitoring node is in a conducting state, thus preventing the failure of one monitoring node from affecting the communication of other normal monitoring nodes.

[0107] Specifically, in this embodiment, the MCU of the monitoring node is connected to the optical module via a serial port, as shown in the following example. Figure 4 Each monitoring node has two optical modules (optical module 1 and optical module 2), which are connected to the two UARTs (UART1 and UART2) of the MCU, respectively. Correspondingly, there are two switching circuits. The first switching circuit includes a tri-state gate U1B, a diode D2, and a pull-up resistor R3. The second switching circuit includes a tri-state gate U1A, a diode D3, and a pull-up resistor R1. Among them, diodes D2 and D3 play a unidirectional conduction role.

[0108] The TTL-side pin TX of optical module 1 and the TTL-side pin RX of optical module 2 are connected through a first switching circuit, and the TTL-side pin TX of optical module 2 and the TTL-side pin RX of optical module 1 are connected through a second switching circuit, forming a bidirectional controllable cascaded path. UART1 is used for data communication, and UART2 is used to send address setting commands to the next-level monitoring node when synchronizing addresses.

[0109] When setting the address, both switch circuits are disconnected. The monitoring nodes are cascaded through the fiber optic bus. When the host sends data, the fiber optic side of optical module 1 of the monitoring node receives the optical signal, the TTL side pin TX level goes low, and UART1 receives the data sent by the host. At the same time, the TTL side pin RX level of optical module 2 goes low, and the fiber optic side of optical module 2 sends data to the next level monitoring node, realizing bus cascading.

[0110] When the monitoring host and monitoring nodes are communicating normally, both switching circuits are on, and each monitoring node communicates with the monitoring host via the bus. By default, the TTL-side pin RX of optical module 1 is set to a high level through pull-up resistor R4, and the TTL-side pin RX of optical module 2 is set to a high level through pull-up resistor R2. This monitoring node does not send data to the fiber optic bus. When the MCU of each monitoring node sends data to the next-level device, the TX1 pin of the MCU is pulled low, the TTL-side pin RX of optical module 1 goes low, and the optical module sends uplink data; when the MCU of each monitoring node sends data to the next-level monitoring node, the TX2 pin of the MCU is pulled low, the TTL-side pin RX of optical module 2 goes low, and the optical module sends downlink data.

[0111] As can be seen from the above, this embodiment realizes the cascading of each monitoring node (slave) through a switching circuit. In cascading mode, the slave sets the address of the next adjacent slave through the slave, avoiding address setting on the fiber optic bus and reducing the probability of address setting failure.

[0112] In one exemplary embodiment of this application, the wireless communication unit is configured with a 2.4G protocol stack and a Bluetooth protocol stack, and the monitoring node is configured as follows:

[0113] After power-on, the 2.4G protocol stack is set to have higher priority than the Bluetooth protocol stack.

[0114] After power-on, the priority of the 2.4G protocol stack is set higher than that of the Bluetooth protocol stack, and the second timer is started;

[0115] During the active period of the 2.4G protocol stack, the system receives temperature data reported by the wireless temperature measurement unit through the 2.4G protocol stack and resets the second timer after each temperature data is received. When the communication channel of the 2.4G protocol stack is idle, if a Bluetooth connection request message is received from the terminal device, a connection is established with the terminal device based on the Bluetooth protocol stack after a set delay.

[0116] Furthermore, the monitoring nodes are also configured as follows:

[0117] During the active period of the 2.4G protocol stack, when temperature data is received, if Bluetooth communication based on the Bluetooth protocol stack is already connected, the temperature data will be sent to the terminal device through the Bluetooth protocol stack.

[0118] Furthermore, the monitoring nodes are also configured as follows:

[0119] The monitoring node is also configured as follows:

[0120] If no Bluetooth connection request is received and no established Bluetooth communication connection is found when the second timer expires, the wireless communication unit is controlled to enter a low-power listening mode.

[0121] In this embodiment, the wireless communication unit adopts a System on Chip (SoC) chip with multiple protocols coexisting. It integrates an independently running Bluetooth (BLE) protocol stack and a 2.4G proprietary protocol stack. Through the 2.4G proprietary protocol stack, the monitoring node can communicate with the wireless temperature sensor. Through the BLE protocol stack, the monitoring node can communicate with the Bluetooth maintenance software of the field terminal device (such as a mobile phone). Field maintenance personnel can connect to the monitoring node via Bluetooth on their mobile phones to perform operations such as parameter setting, real-time data viewing, and log reading, which is convenient and efficient.

[0122] Each protocol stack independently maintains its MAC layer queue. The Bluetooth (BLE) protocol stack and the 2.4G proprietary protocol stack share the radio frequency resources of the wireless communication unit, with radio frequency control switching by an intelligent scheduler within the monitoring node at microsecond precision. When neither the Bluetooth (BLE) protocol stack nor the 2.4G proprietary protocol stack receives data, the intelligent scheduler controls the radio frequency front-end to enter a listening mode, waking only the reference clock circuit (the most basic clock source circuit), reducing power consumption to 1 / 5 of the normal mode. The 2.4G proprietary protocol stack uses periodic wake-up (the period is configurable), while the BLE protocol stack uses connection event wake-up.

[0123] Meanwhile, this embodiment incorporates an optimized anti-collision mechanism. The private protocol stack uses 26 non-BLE broadcast channels within the 2.405-2.480GHz band, and the sensor reporting period is increased by ±5ms random jitter to avoid multi-node synchronization conflicts. The specific working process is as follows:

[0124] Step 1. Initialization state:

[0125] The device powers on and starts up, completing the initialization of the dual protocol stacks (2.4G proprietary protocol stack and BLE protocol stack). Control of radio frequency resources is preferentially allocated to the 2.4G proprietary protocol stack, laying the foundation for monitoring sensor data. Proceed to step 2.

[0126] Step 2. Private protocol stack active state:

[0127] The system continuously monitors data reported by wireless temperature sensors via a 2.4G proprietary protocol stack, initiating an adaptive timeout second timer. The timeout period t2 is not fixed but dynamically calculated: t2 = basic monitoring period + random backoff value. This design adapts to the random wake-up mechanism of multiple wireless temperature sensors, avoiding communication conflicts caused by simultaneous reporting from multiple sensors. The basic monitoring period can be determined based on the periodic wake-up interval of the 2.4G proprietary protocol stack to match the sensor reporting period (e.g., 5~30s), balancing monitoring efficiency and power consumption. The random backoff value is a random number in the millisecond range (Tb) (Tb ≤ 1 / 10 of the basic period), dynamically adjusted according to the number of wireless temperature sensors to avoid conflicts.

[0128] Step 2.1: When private protocol stack data arrives, if BLE is already connected, immediately jump to the data coordination state in step 4; otherwise, maintain this state and continue receiving.

[0129] Step 2.2: When a BLE connection request arrives, if the private protocol stack channel is idle, switch to step 3 after a set delay; otherwise, do not respond to the BLE connection request.

[0130] The set duration is a preset constant. Those skilled in the art can set the specific value of the set duration according to actual needs, such as 200μs. This duration can ensure that the private protocol stack completes the confirmation of the channel idle state and releases the radio frequency control right, while keeping the response delay of the BLE connection request within an acceptable range to avoid request timeout, and at the same time not affecting the scheduling stability of the dual protocol stack.

[0131] Step 2.3: When the second timer times out, if there is no need for BLE communication, enter low-power listening mode; otherwise, prepare to switch to step 3.

[0132] Step 3. BLE Service State:

[0133] When the monitoring center needs to interact with the terminal equipment on site, the radio frequency resources switch to the BLE protocol stack, and the device begins BLE broadcasting or attempts to establish a connection with the terminal equipment. A third connection protection timer (default 3 seconds) is started to ensure the stable completion of the connection process within this window.

[0134] Step 3.1: When the BLE connection is successfully established, remain in the connection state. If data arrives at the private protocol stack at this time, proceed to step 4, the data coordination state.

[0135] Step 3.2: When the third timer times out or the connection is broken, the system will return to a low-power state or the private protocol stack active state as determined by the scheduling logic.

[0136] Step 4. Data Co-state:

[0137] While maintaining the BLE connection, when data arrives at the private protocol stack, the device does not disconnect the BLE connection. Instead, it forwards the sensor data received by the private protocol stack directly and in real time to the terminal devices in the field, such as the connected mobile maintenance software, via BLE notification.

[0138] Reference Figure 1 In an exemplary embodiment of this application, each monitoring node is further provided with a first current monitoring unit and a second current monitoring unit. The first current monitoring unit is configured to monitor the first current at the cable connector inlet end, and the second current monitoring unit is configured to monitor the second current at the cable connector outlet end.

[0139] Each monitoring node is configured as follows:

[0140] Calculate the difference between the first current and the second current at the monitoring node to obtain the leakage current;

[0141] When the leakage current exceeds the preset leakage current threshold, a leakage current fault message is sent to the monitoring host.

[0142] In this embodiment, a first current monitoring unit and a second current monitoring unit can be set up to measure the incoming phase current (first current) and outgoing phase current (second current) of the cable joint, respectively. The monitoring node collects the first current and the second current in real time through the sampling circuit and calculates the difference between the two as the leakage current. When the leakage current exceeds the preset leakage current threshold (e.g., 100mA), it is determined that a leakage fault has occurred and is reported to the monitoring center.

[0143] In one exemplary embodiment of this application, both the first current monitoring unit and the second current monitoring unit are Rogowski coils.

[0144] In this embodiment, two external flexible Rogowski coils can be used as the first current monitoring unit and the second current monitoring unit, respectively, to measure the incoming phase current and the outgoing phase current of the cable joint. The Rogowski coils can achieve wide-range current measurement and maintain high-precision measurement over a long period of time.

[0145] In summary, this embodiment integrates multi-parameter sensing and intelligent edge computing functions. It achieves wide-range current measurement through a high-precision Rogowski coil and realizes real-time diagnosis of leakage faults based on a differential algorithm for the combined current of the incoming / outgoing lines. Simultaneously, the monitoring node integrates a 2.4G wireless module, synchronously collecting data from the wireless temperature sensor of each phase cable joint via a proprietary 2.4G protocol. The 2.4G wireless module also supports Bluetooth, enabling communication with near-field mobile phone Bluetooth maintenance software. The monitoring node also has dual 10M fiber optic interfaces, uploading diagnostic results and raw data to the monitoring host via a fiber optic bus.

[0146] The intelligent monitoring system for cable joints in this embodiment can achieve comprehensive perception, intelligent diagnosis, and data fusion of the operating status of cable joints, thereby significantly improving the safety operation level and the intelligence level of operation and maintenance of underground cable joints.

[0147] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A smart monitoring system for power distribution network cable joints that integrates fiber optic bus and multimode wireless communication, characterized in that, Includes temperature measurement units, monitoring nodes, and monitoring hosts; The temperature measuring unit is configured to monitor the temperature of the cable joint, obtain temperature data, and send the temperature data to the monitoring node via a wireless communication unit. The monitoring node is configured to send the temperature data to the monitoring host via a fiber optic bus; The monitoring host is configured as follows: Get the state of the preset first timer; Upon receiving each byte of data sent by the monitoring node, if the first timer is off, the first timer is turned on, the single byte of data is saved to the latest write position of the preset first storage space, and a frame start marker is written to the latest write position of the preset second storage space; wherein, the first storage space and the second storage space are of the same size, and there is a fixed position offset between the latest write position of the first storage space and the latest write position of the second storage space; Upon receiving each byte of data sent by the monitoring node, if the first timer is enabled, the first timer is reset, and the single byte of data is saved to the latest write position of the first storage space. If the timing of the first timer expires, the first timer is turned off, and a frame end marker is written at the position above the latest write position in the second storage space; The monitoring host is also configured as follows: The data in the first storage space is parsed based on the frame start marker and the frame end marker, and the parsed data is displayed. There are multiple monitoring nodes. When setting the address of each monitoring node, the multiple monitoring nodes are connected to the monitoring host in a cascade manner, and a switch circuit is set between the uplink port and the downlink port of each monitoring node. Before setting the address of each monitoring node, the switch circuit of the monitoring node is in the off state. Each of the aforementioned monitoring nodes is configured as follows: Receive an address setting instruction carrying a first address identifier sent by the upper-level device; if the monitoring node is a first-level monitoring node, the upper-level device is the monitoring host; if the monitoring node is a monitoring node other than a first-level monitoring node, the upper-level device is the upper-level monitoring node of the monitoring node. The address of the monitoring node is set based on the first address identifier, and after the address of the monitoring node is set, the first confirmation information is sent to the next higher level device; the first confirmation information is used to indicate that the address of the monitoring node has been set. Send an address setting instruction carrying a second address identifier to the next-level monitoring node, so that the next-level monitoring node sets its own address based on the second address identifier; Upon receiving the second confirmation message from the next-level monitoring node, the switching circuit of that monitoring node is closed; the second confirmation message indicates that the address setting of the next-level monitoring node is complete.

2. The intelligent monitoring system for power distribution network cable joints using fiber optic bus and multimode wireless collaboration as described in claim 1, characterized in that, Also includes: If the latest write position is the starting position of the second storage space, then the previous position of the latest write position is the ending position of the second storage space.

3. The intelligent monitoring system for power distribution network cable joints using fiber optic bus and multimode wireless collaboration as described in claim 1, characterized in that, Each of the aforementioned monitoring nodes is further configured as follows: If the monitoring node does not receive the second confirmation information from the next-level monitoring node, it resends the address setting instruction carrying the second address identifier to the next-level monitoring node, and accumulates the number of resends to obtain the cumulative resend count. If the cumulative number of retransmissions exceeds the preset number, the monitoring node is designated as the last-level monitoring node, its switching circuit is kept open, and a prompt message is sent to the next higher-level monitoring node; the prompt message indicates that the address settings of all monitoring nodes are complete.

4. The intelligent monitoring system for distribution network cable joints co-operated by fiber optic bus and multimode wireless as described in claim 1 or 3, characterized in that, For each monitoring node, the switching circuit of that monitoring node includes a tri-state gate and a pull-up resistor. The enable terminal of the tri-state gate is connected to the control signal output terminal of the monitoring node, the first terminal of the tri-state gate is connected to the uplink port of the monitoring node, and the second terminal of the tri-state gate is connected to the downlink port of the monitoring node. The enable terminal of the tri-state gate is connected to the power supply through the pull-up resistor.

5. The intelligent monitoring system for power distribution network cable joints using fiber optic bus and multimode wireless collaboration as described in claim 1, characterized in that, The wireless communication unit is configured with a 2.4G protocol stack and a Bluetooth protocol stack, and each monitoring node is configured as follows: After power-on, the priority of the 2.4G protocol stack is set higher than that of the Bluetooth protocol stack, and the second timer is started; During the active period of the 2.4G protocol stack, the temperature data reported by the temperature measuring unit through the 2.4G protocol stack is received, and the second timer is reset after each receipt of the temperature data; when the communication channel of the 2.4G protocol stack is idle, if a Bluetooth connection request information sent by the terminal device is received, a connection is established with the terminal device based on the Bluetooth protocol stack after a set delay time.

6. The intelligent monitoring system for power distribution network cable joints co-operated by fiber optic bus and multimode wireless as described in claim 5, characterized in that, Each of the aforementioned monitoring nodes is further configured as follows: During the active period of the 2.4G protocol stack, when the temperature data is received, if Bluetooth communication based on the Bluetooth protocol stack is already connected, the temperature data is sent to the terminal device through the Bluetooth protocol stack.

7. The intelligent monitoring system for power distribution network cable joints using fiber optic bus and multimode wireless collaboration as described in claim 5, characterized in that, Each of the aforementioned monitoring nodes is further configured as follows: If no Bluetooth connection request information is received and no established Bluetooth communication connection is found when the second timer expires, the wireless communication unit is controlled to enter a low-power listening mode.

8. The intelligent monitoring system for power distribution network cable joints using fiber optic bus and multimode wireless collaboration as described in claim 1, characterized in that, Each monitoring node is also equipped with a first current monitoring unit and a second current monitoring unit. The first current monitoring unit is configured to monitor the first current at the cable connector inlet end, and the second current monitoring unit is configured to monitor the second current at the cable connector outlet end. Each of the aforementioned monitoring nodes is configured as follows: Calculate the difference between the first current and the second current at the monitoring node to obtain the leakage current; When the leakage current exceeds a preset leakage current threshold, leakage current fault information is sent to the monitoring host.

9. The intelligent monitoring system for distribution network cable joints co-operated by fiber optic bus and multimode wireless as described in claim 8, characterized in that, Both the first current monitoring unit and the second current monitoring unit are Rogowski coils.

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