An emergency self-healing networking method for power well lid based on mirror backup communication mode

Abstract

This invention discloses an emergency self-healing networking method for power manhole covers based on a mirrored backup communication mode, specifically relating to the field of power manhole cover technology. The method includes the following steps: Step 1: Deploying a first communication module and a second communication module within each smart manhole cover, wherein the first communication module is a wireless communication module and the second communication module is a wired carrier communication module; Step 2: A controllable electronic switch is installed in the power supply circuit of the second communication module. Under normal conditions, the controllable electronic switch is in an open state, and the second communication module is in a zero-power standby state. This invention proposes the concept of mirrored backup. The LoRa and card-mounted PLC communication modes are logically completely equivalent, forming a mirrored symmetrical relationship of mutual backup. Each mode can independently complete the complete communication function. When one communication mode fails, the other mode can seamlessly take over the communication task, realizing a self-healing mechanism of mutual backup and dynamic switching.

Description

Technical Field

[0001] This invention relates to the field of power manhole cover technology, and more specifically, to a method for emergency self-healing networking of power manhole covers based on mirror backup communication mode. Background Technology

[0002] Numerous smart manhole covers are densely deployed along cable trenches and tunnels of power cable corridors. These covers monitor the tilt angle, displacement, and damage status of the covers, as well as the water level, temperature, and gas concentration environment underground. They also serve to prevent theft and vandalism. Current communication solutions for smart manhole covers generally employ 4G and NB-IoT. The core flaw of single public network communication modules such as IoT is that in the event of natural disasters such as typhoons, earthquakes, and floods, or in the event of base station power outages or communication line failures, all manhole covers will be completely disconnected. At this time, the sensors underground may still be working, but emergency alarm information such as fire, flooding, and excessive gas levels cannot be transmitted, potentially leading to a major safety accident.

[0003] A few solutions attempt to address reliability issues by introducing dual-mode communication technology. For example, patents such as an HPLC+HRF dual-mode communication system and its power consumption optimization method propose a dual-mode coexistence scheme. However, these solutions are all based on a dual-mode simultaneous online or simple master-slave switching architecture, primarily applied to electricity meter collection and reading scenarios where nodes have continuous power supply and do not involve low-power battery-powered equipment. Specifically, existing technologies mainly suffer from the following problems: 1. The dual-mode solution has too high power consumption and does not meet the battery life requirements of smart manhole covers: The working current of the snap-on PLC module is much greater than that of the LoRa module. If the snap-on PLC and LoRa are kept on at the same time, the battery life will be greatly shortened, which seriously contradicts the constraint of a sleep current of <60μA and a 5-year battery life. The existing dual-mode solution is mainly used for active power supply concentrators and meters, and does not consider the application scenarios of low power battery-powered equipment. 2. Manhole cover communication is completely paralyzed when the public network is interrupted: Existing smart manhole covers rely too much on the 4G / LoRa public network. Once the base station loses power or communication is interrupted, all manhole covers will lose connection at the same time. Although the manhole covers have communication capabilities, they lack a cross-media emergency self-healing networking mechanism. 3. Wireless signals are severely attenuated in underground spaces: The instruction manual clearly states that the effective immersion depth is <0.4M. When the manhole cover is submerged in water, wireless communication such as LoRa completely fails and data cannot be transmitted. This is precisely the emergency moment when communication is most needed. 4. The existing dual-mode solution has rigid primary and backup roles: In the existing solution, once the primary communication mode is determined, the backup mode is in a hibernation-wake-up subordinate position. The two modes do not have a true mirror symmetry relationship, making it difficult to achieve dynamic self-healing between multiple communication media. 5. Complex routing calculations and high resource consumption: Existing solutions require nodes to maintain routing tables and periodically exchange neighbor information, which places high demands on the storage and computing capabilities of the MCU and is not suitable for resource-constrained manhole cover equipment. 6. The communication distance of the existing snap-fit ​​inductive coupling method is limited: When a single section of power cable uses snap-fit ​​inductive coupling, the signal attenuation is large, and the typical reliable communication distance is generally no more than 5km. When the length of the buried cable exceeds this threshold, if there is no relay measure, the end manhole cover will not be able to connect to the cascaded network, which limits the coverage radius of the emergency communication system.

[0004] Therefore, there is an urgent need for an emergency self-healing networking method for power manhole covers based on a mirror backup communication mode to solve the above problems. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide an emergency self-healing networking method for power manhole covers based on mirror backup communication mode, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an emergency self-healing networking method for power manhole covers based on mirror backup communication mode, comprising the following steps: Step 1: Deploy a first communication module and a second communication module inside each smart manhole cover, wherein the first communication module is a wireless communication module and the second communication module is a wired carrier communication module; Step 2: A controllable electronic switch is installed in the power supply circuit of the second communication module. Under normal conditions, the controllable electronic switch is in the off state, and the second communication module is in the zero-power standby state. Step 3: The first communication module continuously monitors the connection status with the base station and evaluates the current link quality; Step 4: When a base station connection failure is detected and a preset high-risk alarm event exists locally, the second communication module is woken up by closing the controllable electronic switch. The alarm levels include Emergency Level I, Important Level II, and Normal Level III. Step 5: After being woken up, the second communication module of each manhole cover sends a probe frame on the power line to automatically establish a linear chain network, in which each node only stores the upstream neighbor address and the downstream neighbor address, and does not maintain a complete routing table; Step 6: Data is forwarded level by level along a fixed direction. Intermediate nodes only perform signal regeneration and data forwarding. When a node goes offline, the upstream node automatically skips the offline node and sends the data to the downstream node, thus achieving degenerate cascading. Step 7: Use a dynamic channel borrowing mechanism on the linear chain network to obtain transmission permission and perform data transmission; Step 8: Evaluate the link quality of the first and second communication modules in real time, and calculate the comprehensive cost of each communication mode. The comprehensive cost includes the link quality score, energy consumption cost, and transmission delay. Step 9: Dynamically determine the current primary communication mode based on the overall cost, and realize a mirror-symmetric relationship between the two communication modes as primary and backup to each other; Step 10: Role switching adopts a soft switching strategy of "connect first, disconnect later" to ensure uninterrupted data transmission during the switching process; Step 11: Dual-condition triggering mechanism. When the base station loses contact and there is a Level I or Level II alarm event, the second communication module is triggered to wake up and emergency networking is set up. Regular Level III alarms are only uploaded through the first communication module. Step 12: When the length of the power cable trench exceeds the reliable transmission distance of single-segment snap-fit ​​PLC communication, deploy at least one active repeater at the cable joint or appropriate location. The repeater contains two snap-fit ​​inductive couplers and a signal regeneration unit, which is used to receive the PLC signal from the previous cable segment, regenerate it, and couple it to the next cable segment. The repeater is transparent to the upper-layer network, does not participate in routing decisions, and supports the automatic skip function in the degradation cascading mechanism.

[0007] In a preferred embodiment, the dynamic channel borrowing mechanism in step seven is as follows: (a) Set up a virtual token on a linear chain network, where only the node holding the token is allowed to send data; (b) The data sending node appends a forwarding authorization flag to the end of the data frame and passes the token to the receiving node; (c) When a node has no data to send, the token will automatically jump to the next node after a preset timeout.

[0008] In a preferred embodiment, the controllable electronic switch in steps two and four is a MOSFET, whose gate is connected to the GPIO pin of the MCU. Under normal conditions, the MCU outputs a low level to turn off the MOSFET, and when the MCU is woken up, it outputs a high level to turn on the MOSFET and power on the second communication module.

[0009] In a preferred embodiment, the linear chain network does not perform dynamic routing optimization after its establishment, and the nodes do not periodically exchange neighbor information. The upstream and downstream relationships are determined only through neighbor discovery at the time of network entry, and subsequent forwarding is carried out in a fixed direction.

[0010] In a preferred embodiment, the second communication module uses the power cable shield or low-voltage lead as the transmission medium, which is unaffected by water immersion in the manhole cover.

[0011] A system for implementing an emergency self-healing networking method for power manhole covers based on mirror backup communication mode includes a manhole cover sensing layer, a mirror backup communication layer, a self-healing networking layer, and a cloud emergency access layer. The manhole cover sensing layer includes a status monitoring sensor group, a battery management unit, and an MCU microcontroller. The status monitoring sensor group includes a triaxial accelerometer, an inclination sensor, a water level sensor, a temperature sensor, and a gas sensor. Each electric manhole cover integrates the status monitoring sensor group, the battery management unit, and the MCU microcontroller. The mirror backup communication layer includes two types of communication modules: a LoRa wireless communication module and a snap-in PLC communication power line carrier module. Each manhole cover is equipped with these two types of communication modules, which are logically mirror-symmetrical. They are mirror mode A based on the LoRa wireless communication module and mirror mode B based on the snap-in PLC communication power line carrier module. Mirror mode A operates with low power consumption and is the main communication channel during normal periods. It can wake up the snap-in PLC communication power line carrier module. Mirror mode B is in zero-power standby mode. It is activated in an emergency when there is a physical power failure and uses power line cables for backup transmission. The snap-in PLC communication power line carrier module uses the power cable shielding layer or low-voltage lead wire in the cable channel as the transmission medium. The two communication modes are mutually primary and backup, and their roles are dynamically switched according to the environment to achieve mirror backup. The self-healing networking layer is deployed on the manhole cover MCU and regional edge gateway. It includes a link quality dual-dimensional evaluation module, a mirror role decision module, a degradation cascade routing module, a dynamic channel borrowing module, and a zero-power wake-up module. The link quality dual-dimensional evaluation module evaluates the signal-to-noise ratio of the LoRa channel and the physical layer rate and noise level of the power line of the card-mount PLC in real time. The mirror role decision module dynamically determines the primary and backup roles of the two communication modes based on the link quality score and energy consumption cost. The degradation cascade routing module realizes linear forwarding without a routing table. Nodes only know their upstream and downstream neighbors. Data is forwarded step by step along a fixed direction. When a node is offline, it automatically degrades to a downstream node. The dynamic channel borrowing module uses a token passing and tail-following response mechanism to obtain sending permissions without the need for pre-allocation of time slots. The zero-power wake-up module realizes physical power-off and on-demand wake-up of the card-mount PLC module through a controllable electronic switch. The cloud-based emergency access layer is deployed in substations or operation and maintenance centers. As the aggregation node of the card-connected PLC cascade network, it is responsible for receiving emergency data uploaded from the cascaded links and forwarding it to the operation and maintenance platform.

[0012] A long-distance repeater for an emergency self-healing networking method for power manhole covers based on mirror backup communication mode includes a first snap-fit ​​inductive coupler, a second snap-fit ​​inductive coupler, a signal regeneration unit, a power supply unit, and a zero-power wake-up interface. The first snap-fit ​​inductive coupler is used to couple a PLC signal on a first segment of power cable, and the second snap-fit ​​inductive coupler is used to couple a second segment of power cable. The signal regeneration unit is connected between the first and second snap-fit ​​inductive couplers and is used to amplify, filter, shape, and forward the received PLC signal. The power supply unit is used to power the signal regeneration unit, and the zero-power wake-up interface is used to receive a wake-up signal from the manhole cover or an upstream repeater.

[0013] The technical effects and advantages of this invention are as follows: 1. This invention includes a mirror backup communication mode. Unlike the master-slave architecture in the existing dual-mode solution, this solution designs LoRa and card-mounted PLC as mirror symmetric relationships with each other as master and backup. The roles switch dynamically according to the environment, and the switching decision is based on a two-dimensional evaluation of link quality and a comprehensive cost calculation. 2. This invention features a degenerate cascading routing algorithm. Unlike existing solutions that require maintaining complex routing tables, this solution adopts a routing table-free design. Each node only knows its upstream and downstream neighbors. Data is forwarded level by level along a fixed direction. When a node goes offline, it automatically degenerates to a downstream node to continue forwarding, which greatly reduces computation and storage overhead. 3. This invention features a dynamic channel borrowing mechanism, which differs from the existing TDMA fixed time slot allocation scheme. This scheme uses a token passing mechanism to obtain transmission rights and combines it with tail-following acknowledgment technology to realize a serial transmission chain, thus efficiently utilizing the channel without the need for pre-allocation of time slots. 4. This invention features a zero-power standby architecture, which differs from the power consumption optimization methods of existing dual-mode solutions (which mostly adjust power consumption levels within the module). This solution sets a controllable electronic switch (MOSFET) in the power supply circuit of the snap-in PLC module. Under normal conditions, the snap-in PLC module is completely physically powered off, and the standby power consumption is zero. 5. This invention proposes the concept of mirror backup. The two communication modes, LoRa and card-mount PLC, are logically completely equivalent, forming a mirror symmetric relationship of mutual backup. Each mode can independently complete the complete communication function. When one communication mode fails, the other mode can seamlessly take over the communication task, realizing a self-healing mechanism of mutual backup and dynamic switching. Attached Figure Description

[0014] Figure 1 This is a diagram of the overall system architecture of the present invention.

[0015] Figure 2 This is a data flow diagram of the normal mirror mode of the present invention.

[0016] Figure 3 This is a flowchart of the emergency self-healing mode of the present invention.

[0017] Figure 4 This is a flowchart of the recovery mode of the present invention.

[0018] Figure 5 This is a degenerate cascaded network topology diagram of the present invention.

[0019] Figure 6 This is a timing diagram for the dynamic channel borrowing of the present invention.

[0020] Figure 7 This is a schematic diagram of the zero-power wake-up circuit of the present invention. Detailed Implementation

[0021] 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, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] As attached Figure 1 Appendix Figure 2 Appendix Figure 3 Appendix Figure 4 Appendix Figure 5 Appendix Figure 6 and attached Figure 7 As shown, this invention provides an emergency self-healing networking method for power manhole covers based on a mirror backup communication mode, comprising the following steps: Step 1: Deploy a first communication module and a second communication module inside each smart manhole cover, wherein the first communication module is a wireless communication module and the second communication module is a wired carrier communication module; Step 2: A controllable electronic switch is installed in the power supply circuit of the second communication module. Under normal conditions, the controllable electronic switch is in the off state, and the second communication module is in the zero-power standby state. Step 3: The first communication module continuously monitors the connection status with the base station and evaluates the current link quality; Step 4: When a base station connection failure is detected and a preset high-risk alarm event exists locally, the second communication module is woken up by closing the controllable electronic switch. The alarm levels include Emergency Level I, Important Level II, and Normal Level III. Step 5: After being woken up, the second communication module of each manhole cover sends a probe frame on the power line to automatically establish a linear chain network, in which each node only stores the upstream neighbor address and the downstream neighbor address, and does not maintain a complete routing table; Step 6: Data is forwarded level by level along a fixed direction. Intermediate nodes only perform signal regeneration and data forwarding. When a node goes offline, the upstream node automatically skips the offline node and sends the data to the downstream node, thus achieving degenerate cascading. Step 7: Use a dynamic channel borrowing mechanism on the linear chain network to obtain transmission permission and perform data transmission; Step 8: Evaluate the link quality of the first and second communication modules in real time, and calculate the comprehensive cost of each communication mode. The comprehensive cost includes the link quality score, energy consumption cost, and transmission delay. Step 9: Dynamically determine the current primary communication mode based on the overall cost, and realize a mirror-symmetric relationship between the two communication modes as primary and backup to each other; Step 10: Role switching adopts a soft switching strategy of "connect first, disconnect later" to ensure uninterrupted data transmission during the switching process; Step 11: Dual-condition triggering mechanism. When the base station loses contact and there is a Level I or Level II alarm event, the second communication module is triggered to wake up and emergency networking is set up. Regular Level III alarms are only uploaded through the first communication module. Step 12: When the length of the power cable trench exceeds the reliable transmission distance of single-segment snap-fit ​​PLC communication, deploy at least one active repeater at the cable joint or appropriate location. The repeater contains two snap-fit ​​inductive couplers and a signal regeneration unit, which is used to receive the PLC signal from the previous cable segment, regenerate it, and couple it to the next cable segment. The repeater is transparent to the upper-layer network, does not participate in routing decisions, and supports the automatic skip function in the degradation cascading mechanism.

[0023] In a preferred embodiment, the dynamic channel borrowing mechanism in step seven is as follows: (a) Set up a virtual token on a linear chain network, where only the node holding the token is allowed to send data; (b) The data sending node appends a forwarding authorization flag to the end of the data frame and passes the token to the receiving node; (c) When a node has no data to send, the token will automatically jump to the next node after a preset timeout.

[0024] In a preferred embodiment, the controllable electronic switch in steps two and four is a MOSFET, whose gate is connected to the GPIO pin of the MCU. Under normal conditions, the MCU outputs a low level to turn off the MOSFET, and when the MCU is woken up, it outputs a high level to turn on the MOSFET and power on the second communication module.

[0025] In a preferred embodiment, the linear chain network does not perform dynamic routing optimization after its establishment, and the nodes do not periodically exchange neighbor information. The upstream and downstream relationships are determined only through neighbor discovery at the time of network entry, and subsequent forwarding is carried out in a fixed direction.

[0026] In a preferred embodiment, the second communication module uses the power cable shield or low-voltage lead as the transmission medium, which is unaffected by water immersion in the manhole cover.

[0027] A system for implementing an emergency self-healing networking method for power manhole covers based on mirror backup communication mode includes a manhole cover sensing layer, a mirror backup communication layer, a self-healing networking layer, and a cloud emergency access layer. The manhole cover sensing layer includes a status monitoring sensor group, a battery management unit, and an MCU microcontroller. The status monitoring sensor group includes a triaxial accelerometer, an inclination sensor, a water level sensor, a temperature sensor, and a gas sensor. Each electric manhole cover integrates the status monitoring sensor group, the battery management unit, and the MCU microcontroller. The mirror backup communication layer includes two types of communication modules: a LoRa wireless communication module and a snap-in PLC communication power line carrier module. Each manhole cover is equipped with these two types of communication modules, which are logically mirror-symmetrical. They are mirror mode A based on the LoRa wireless communication module and mirror mode B based on the snap-in PLC communication power line carrier module. Mirror mode A operates with low power consumption and is the main communication channel during normal periods. It can wake up the snap-in PLC communication power line carrier module. Mirror mode B is in zero-power standby mode. It is activated in an emergency when there is a physical power failure and uses power line cables for backup transmission. The snap-in PLC communication power line carrier module uses the power cable shielding layer or low-voltage lead wire in the cable channel as the transmission medium. The two communication modes are mutually primary and backup, and their roles are dynamically switched according to the environment to achieve mirror backup. The self-healing networking layer is deployed on the manhole cover MCU and regional edge gateway. It includes a link quality dual-dimensional evaluation module, a mirror role decision module, a degradation cascade routing module, a dynamic channel borrowing module, and a zero-power wake-up module. The link quality dual-dimensional evaluation module evaluates the signal-to-noise ratio of the LoRa channel and the physical layer rate and noise level of the power line of the card-mount PLC in real time. The mirror role decision module dynamically determines the primary and backup roles of the two communication modes based on the link quality score and energy consumption cost. The degradation cascade routing module realizes linear forwarding without a routing table. Nodes only know their upstream and downstream neighbors. Data is forwarded step by step along a fixed direction. When a node is offline, it automatically degrades to a downstream node. The dynamic channel borrowing module uses a token passing and tail-following response mechanism to obtain sending permissions without the need for pre-allocation of time slots. The zero-power wake-up module realizes physical power-off and on-demand wake-up of the card-mount PLC module through a controllable electronic switch. The cloud-based emergency access layer is deployed in substations or operation and maintenance centers. As the aggregation node of the card-connected PLC cascade network, it is responsible for receiving emergency data uploaded from the cascaded links and forwarding it to the operation and maintenance platform.

[0028] A long-distance repeater for an emergency self-healing networking method for power manhole covers based on mirror backup communication mode includes a first snap-fit ​​inductive coupler, a second snap-fit ​​inductive coupler, a signal regeneration unit, a power supply unit, and a zero-power wake-up interface. The first snap-fit ​​inductive coupler is used to couple a PLC signal on a first segment of power cable, and the second snap-fit ​​inductive coupler is used to couple a second segment of power cable. The signal regeneration unit is connected between the first and second snap-fit ​​inductive couplers and is used to amplify, filter, shape, and forward the received PLC signal. The power supply unit is used to power the signal regeneration unit, and the zero-power wake-up interface is used to receive a wake-up signal from the manhole cover or an upstream repeater.

[0029] This invention Figure 1 The deployment locations and interaction methods of the manhole cover sensing layer, mirror backup communication layer, self-healing networking layer, and cloud emergency access layer are demonstrated. (1) Manhole cover sensing layer Each power manhole cover integrates the following sensors and modules: Condition monitoring sensor group: triaxial accelerometer, tilt sensor, water level sensor, temperature sensor, gas sensor; Battery Management Unit: Monitors battery voltage and remaining capacity; Microcontroller (MCU): Responsible for data acquisition, local preprocessing, and communication mode decision-making; (2) Mirroring backup communication layer This layer is one of the core advantages. Each manhole cover is equipped with the following two communication modules, which are logically mirror-symmetric:

[0030] Among them, the card-type PLC module uses the power cable shielding layer or low-voltage lead wire in the cable channel as the transmission medium. The two communication modes are mutually primary and backup, and the roles are dynamically switched according to the environment to achieve mirror backup.

[0031] (3) Self-healing networking layer (core algorithm layer) Deployed in manhole cover MCUs and regional edge gateways, it includes the following algorithm modules: Link quality dual-dimensional evaluation module: Real-time evaluation of the signal-to-noise ratio (SNR) of the LoRa channel and the physical layer rate and noise level of the plug-in PLC power line; Mirror Role Decision Module: Dynamically determines the primary / backup role for two communication modes based on link quality score and energy consumption cost; Degenerate cascaded routing module: Implements linear forwarding without a routing table. Nodes only know their upstream and downstream neighbors. Data is forwarded step by step in a fixed direction. When a node goes offline, it automatically degenerates to a downstream node. Dynamic channel borrowing module: It uses a token passing + tail acknowledgment mechanism to obtain sending permission, without the need for pre-allocation of time slots; Zero-power wake-up module: Enables physical power-off and on-demand wake-up of the card-mount PLC module via a controllable electronic switch; (4) Cloud-based emergency access layer Deployed in substations or operation and maintenance centers, it serves as the aggregation node of a card-connected PLC cascade network, responsible for receiving emergency data uploaded from the cascaded links and forwarding it to the operation and maintenance platform.

[0032] The operation of the system of this invention is divided into three stages: normal mirror mode, emergency self-healing mode, and recovery mode; Phase 1: Normal Image Mode (Low Power Operation) Under normal operating conditions, the system operates with minimal power consumption, ensuring a 5-year battery life requirement. This section describes the working mechanism of the LoRa main channel and the zero-power standby management of the card-mount PLC module. Figure 2 This demonstrates the data flow and power consumption status under normal mode; Step 1: Mirror Mode A (LoRa) Operation During normal operation, the LoRa module of the manhole cover maintains a low-power operation state. The MCU wakes up according to a preset cycle (such as every 15 minutes), collects sensor data, and uploads it to a nearby base station or gateway via LoRa. At this time, the card-type PLC module is in a zero-power standby state, and the controllable electronic switch (MOSFET) in its power supply circuit is in the open state. The module is completely physically powered off, and the power consumption is zero.

[0033] Step 2: Base station status monitoring and alarm level determination The MCU continuously monitors the connection status with the base station. The monitoring methods include: (1) Heartbeat confirmation: periodically sending heartbeat packets to the base station. If no response is received for N consecutive times, the base station is judged to be disconnected; (2) RSSI detection: monitoring the received signal strength indication of LoRa signal. If it is lower than the preset threshold (such as -110dBm), the communication quality is judged to be degraded.

[0034] When the sensor detects an abnormal event, the MCU determines the alarm level based on the event type and severity:

[0035] Step 3: Mirror Character Maintenance In normal mirror mode, LoRa is used as the main communication mode, and the card-mounted PLC is in a zero-power standby state. The MCU continuously evaluates the LoRa link quality. When the link quality is detected to be lower than the preset threshold, it makes a prediction in advance and prepares for possible mode switching.

[0036] Phase Two: Emergency Self-Healing Mode (Mirror Mode B Activated) When a base station is detected to be out of service and a high-risk alarm is detected, the system automatically activates mirror mode B and triggers the cross-media networking emergency communication mechanism. This stage describes in detail the complete process of zero-power wake-up of the card-mounted PLC module, degradation cascading networking, dynamic channel borrowing, and mirror role switching. Figure 3 This demonstrates the emergency self-healing process from the failure of mirror mode A to the activation of mirror mode B.

[0037] Step 1: Zero-power wake-up in mirror mode B The MCU activates mirror mode B when it detects the following dual conditions: Condition A: Base station disconnection (N consecutive heartbeat timeouts) or LoRa link quality is lower than a preset threshold; Condition B: A Level I or Level II alarm event exists (fire, flooding, unauthorized opening, etc.); When conditions A and B are met simultaneously, the algorithm determines that emergency communication is required. The MCU outputs a high-level signal via GPIO, closing the controllable electronic switch (MOSFET) in the power supply circuit of the snap-in PLC module, thus powering on and starting the snap-in PLC module. Simultaneously, a wake-up command is broadcast via LoRa to activate the snap-in PLC modules of adjacent manhole covers. This method achieves power-level wake-up rather than state-level wake-up, resulting in truly zero standby power consumption.

[0038] Step 2: Establishing the Degenerate Cascade Network After activation, the snap-on PLC modules of each manhole cover begin sending probe frames on the power lines, automatically discovering adjacent nodes and forming a linear chain topology. Unlike traditional networking schemes, this scheme employs a degenerate cascading routing algorithm, which has the following characteristics: No routing table design: Each node does not store a complete network routing table, but only knows a unique upper-level neighbor (towards the sink node) and a unique lower-level neighbor (away from the sink node).

[0039] Fixed-direction forwarding: Data is forwarded step by step along a fixed physical direction. Intermediate nodes only perform signal regeneration and data forwarding, without parsing the data content or performing routing calculations.

[0040] Self-healing capability: When a node goes offline (battery depleted or malfunctions), the upstream node automatically degrades after a preset timeout, skips the offline node, and directly sends the data to the downstream node (i.e., the downstream node of the original downstream node), without needing to recalculate the route.

[0041] Detailed network setup process: The substation-side convergence node serves as the root node (direction starting point), and the upstream and downstream relationships are determined step by step along the cable trench direction.

[0042] When a new node joins the network, it determines its upstream and downstream neighbors by receiving probe frames from neighboring nodes, without maintaining information about other nodes.

[0043] Trigger link health checks periodically (e.g., every 24 hours). If an upstream node is found to be offline, automatically switch to a backup upstream node (if any).

[0044] Step 3: Deployment and cross-segment forwarding of cascaded repeaters When the length of the power cable trench exceeds the reliable transmission distance of a single-segment snap-fit ​​PLC communication (e.g., 5 km), an active repeater should be deployed at an appropriate location (e.g., at a cable joint). This repeater consists of two snap-fit ​​inductive couplers and a signal regeneration unit.

[0045] One end of the repeater couples the PLC signal from the previous cable segment, which is then amplified, shaped, and regenerated before being coupled to the next cable segment through the other end.

[0046] The repeater is transparent to the upper network layer, meaning that no routing relationship is maintained between the manhole cover node and the repeater; the repeater only performs physical layer or link layer forwarding.

[0047] In the degenerate cascading logic, the repeater is regarded as a transparent forwarding node. When it is offline, it also supports the upstream node to automatically jump to the downstream repeater or manhole cover to maintain the continuity of the cascading network.

[0048] Step 4: Dynamic Channel Borrowing Mechanism Unlike existing TDMA fixed time slot allocation schemes, this scheme adopts a token passing + tail acknowledgment mechanism to achieve efficient channel utilization: Token passing: A virtual token is set on the transmission link, and only the node holding the token is allowed to send data on the card-to-card PLC channel. The token is passed downstream along the chain topology, starting from the root node.

[0049] Tail-following acknowledgment: When node A sends data to node B, node B, while acknowledging receipt, appends a forwarding authorization flag to the end of the data frame, passing the token to node B. This design allows token passing to be completed synchronously with data forwarding, eliminating the need for a separate token management frame, thereby reducing channel occupancy.

[0050] Channel borrowing: When a node has no data to send, the token will automatically jump to the next node after a preset timeout to avoid channel idleness and waste.

[0051] This dynamic channel borrowing mechanism does not require pre-allocation of time slots, can flexibly adapt to the differences in data volume among nodes, and has a high channel utilization rate.

[0052] Step 5: Dynamically switch between mirrored characters One of the core advantages of this invention is mirrored role decision-making, with two communication modes acting as primary and backup to each other, and roles dynamically switching according to the environment. The decision-making process is as follows: Link quality is evaluated in two dimensions: real-time assessment of the signal-to-noise ratio (SNR) of the LoRa channel and the physical layer rate and noise level of the plug-in PLC power line.

[0053] Overall Cost Calculation: For each communication mode, calculate the overall cost C:

[0054] in: Link quality normalization score (comprehensive evaluation based on indicators such as SNR, RSSI, and bit error rate); Energy consumption cost (reflecting the level of communication power consumption); Transmission delay (including frame interval and forwarding delay); , , Configurable weights (adaptively adjusted according to operational needs).

[0055] Mirror role decision-making: The main control MCU (microprocessor) dynamically determines the optimal main communication mode based on the overall cost C: like Select mirror mode A (LoRa) as the primary mode; like Switch to mirror mode B (card-mounted PLC communication) as the main mode; If both are unavailable, enter "orphan mode" and local cached data awaits recovery; Soft handover mechanism: The mirror role switching adopts a soft switching strategy of "connect first, disconnect later" to ensure that data is not interrupted during the switching process: First, activate the target communication mode; First, start the card-mounted PLC (or LoRa) module, establish a new link, and complete the handshake confirmation.

[0056] Link availability verification; Confirm that the SNR / RSSI / latency of the new link meet the service requirements.

[0057] Downgrade to the original communication mode again; Once the new link is stable, the original backup communication mode will be shut down.

[0058] Step 6: Emergency Data Degradation Cascading Transmission Once mirror mode B is activated and the network is established, each node sends emergency data under the dynamic channel borrowing mechanism: The node that possesses the token sends data on the channel; The data is forwarded to downstream nodes level by level, eventually reaching the substation aggregation point; The aggregation point forwards the data to the operations and maintenance center; When an intermediate node in a cascaded link goes offline, the upstream node automatically degrades after detecting a timeout and sends the data directly to the downstream node, thus achieving self-healing.

[0059] Phase 3: Recovery Mode Once base station communication is restored, the system needs to smoothly exit emergency mode and resume low-power operation. This stage describes the recovery detection and mode rollback process. Figure 4 It demonstrates the process of restoring from emergency mode to normal mirror mode.

[0060] Step 1: Base station status recovery detection In emergency mode, each node periodically (e.g., every 30 seconds) attempts to check the base station status via mirror mode A. Once the base station is detected to have restored connection, a recovery notification is sent to the aggregation point.

[0061] Step 2: Exit Mirror Mode B Once the aggregation point receives recovery notifications or confirmations from all nodes that all emergency data has been transmitted, it broadcasts a sleep command via the card-mounted PLC. Upon receiving the command, each node's MCU outputs a low-level signal via GPIO, disconnecting the controllable electronic switch in the power supply circuit of the card-mounted PLC module. The module is then completely physically powered off, returning to zero-power standby mode. Simultaneously, the system switches the main communication mode back to mirror mode A (LoRa).

[0062] 3.3 Key Algorithms and Data Models This section details the implementation of core algorithms such as dual-dimensional link quality assessment and mirror role decision-making, degradation cascade routing, dynamic channel borrowing, and zero-power wake-up.

[0063] (1) Two-dimensional assessment of link quality and decision-making on mirror role:

[0064] Among them: The coupled signal power, Background noise power; RSSI measured directly (unit: dBm).

[0065] LoRa wireless channel: For received signal power; Background noise power; RSSI is measured directly by the LoRa module hardware, and its unit is dBm. It is used to characterize the link signal strength.

[0066] SIM-connect PLC communication power line channel: Physical layer rate: determined by modulation method (such as OFDM), bandwidth, and coding rate; 1. Multipath channel transfer function The inherent impedance of the cable shield / armor layer determines the signal coupling efficiency:

[0067] : Number of effective propagation paths (formed by reflections from cable joints, branches, and nodes); : Coupling and reflection gain of the i-th path (clamp coupling efficiency); : The physical length of the i-th path; Signal propagation delay (v is the signal propagation speed in the cable); 2. Card-coupled channel model

[0068] : Mutual inductance between the clamping coil and the cable shielding layer; : PLC module input impedance; The equivalent impedance of the cable shield at the coupling point; 3. Link attenuation calculation (used for channel quality assessment)

[0069] Total attenuation (dB) is positively correlated with frequency and distance; It can be directly used for the quantitative calculation of link quality scores in MCUs; 4. Degraded cascaded transmission model (adapted to patented networking) In a linear chain topology, the total transfer function after M nodes are cascaded is:

[0070] : The transfer function between the k-th cable segment and the node; When a node is offline, the degradation model is as follows: (Skip the i-th faulty node and directly cascade the upstream and downstream links); 5. Noise and Signal-to-Noise Ratio Model In a card-mount PLC channel, the formula for calculating the signal-to-noise ratio (SNR) at the receiver is as follows:

[0071] Module transmit power; : Cable channel noise power (background noise + impulse noise); It can be directly used for link quality assessment in mirror role decision-making; Link quality score The mirror role decision algorithm, obtained through weighted normalization, dynamically switches between primary and backup roles based on the comprehensive cost C, which differs from the rigid primary-backup relationship in existing schemes.

[0072] (2) Degenerate cascaded routing algorithm For details on the algorithm's topology and node forwarding logic, please refer to [link / details]. Figure 5 Degenerate cascaded network topology, distinguishing it from existing routing schemes by the following key features: ① No routing table storage: Each node only stores two addresses, the upstream neighbor address and the downstream neighbor address, and does not store a complete routing table. The storage cost is fixed at O(1).

[0073] ② Fixed-direction forwarding: Data is forwarded step by step along a fixed direction. Intermediate nodes do not parse the data content, but only regenerate the signal.

[0074] ③ Automatic degradation mechanism: When a node detects that a downstream node is offline, it automatically skips the offline node and sends the data to the downstream node's downstream node.

[0075] ④ Path length: In the worst case, the number of transmission hops is equal to the number of nodes N, but since the nodes only forward the data and do not perform calculations, the single-hop processing latency is extremely low (<10ms).

[0076] ⑤ Path length and delay analysis in repeater scenarios: After adding repeaters, the maximum number of transmission hops = number of manhole cover nodes + number of repeaters. Since repeaters only regenerate signals and do not parse data content, the single-hop processing delay can still be controlled within 10 ms. By cascading multiple repeaters (e.g., 10 levels), the total communication distance can be extended to tens of kilometers, while maintaining the original fixed-direction forwarding without routing tables and automatic degradation mechanism.

[0077] (3) Dynamic channel borrowing mechanism A token passing + trailing acknowledgment mechanism is adopted. For details on the timing coordination of token passing, data transmission, and acknowledgment, please refer to [link / reference needed]. Figure 6 Dynamic channel borrowing timing diagram; virtual tokens are passed along the chain topology, timeout jump when no data is sent, efficient channel multiplexing: ① Token holding rights: Only the node holding the token can send data on the card-type PLC communication channel, while other nodes can only receive.

[0078] ② Token initialization: The root node (substation convergence point) initiates a token at startup and passes it downstream.

[0079] ③ Token passing rule: After node A sends data to node B, node B, upon confirming receipt, appends a forwarding authorization flag to the end of the data frame and passes the token to node B.

[0080] ④ Timeout handling: If a node does not send data within a preset timeout (e.g., 50ms), the token will automatically jump to the next node.

[0081] (4) Zero-power wake-up mechanism One of the key advantages of this invention is its zero-power standby architecture, which differs from existing power consumption optimization methods in dual-mode solutions. The power supply control circuit principle is detailed in [link to relevant documentation]. Figure 7 Zero-power wake-up circuit diagram; by connecting an N-channel MOSFET in series in the power supply circuit, true zero power consumption is achieved by normally turning off the circuit, and wake-up is achieved by a high-level output from the GPIO. The hardware is extremely simple and reliable. 1) Hardware Design: An N-channel MOSFET is connected in series as an electronic switch in the power supply circuit of the card-mount PLC communication module. The gate of the MOSFET is connected to the GPIO pin of the MCU.

[0082] Zero-power standby: Under normal conditions, the MCU outputs a low level, the MOSFET is turned off, the power supply circuit of the card-type PLC communication module is disconnected, the module is completely physically powered off, and the power consumption is zero.

[0083] Wake-up trigger: When the wake-up condition is met, the MCU outputs a high level, the MOSFET turns on, and the card-mounted PLC communication module powers on and starts. The module takes approximately 100ms to complete initialization after wake-up.

[0084] Emergency Broadcast Wake-up: When this manhole cover detects an emergency, it sends a wake-up command via LoRa broadcast. Upon receiving the command, the MCU of the adjacent manhole cover also closes its MOSFET to wake up the card-mounted PLC module.

[0085] Example 1 Taking a real cable tunnel scenario as an example, the deployment method and operational effect of the present invention are explained.

[0086] Taking a cable trench in a development zone as an example: the trench is 2 kilometers long, with 25 smart manhole covers deployed along the route, with an average spacing of about 80 meters. Each manhole cover is equipped with a LoRa module and a snap-on PLC communication module, and a convergence node is set up on the substation side.

[0087] Normal scenario: The daily status is normal. The manhole cover uploads data periodically via LoRa. The card-mounted PLC module is in zero-power standby mode (MOSFET off), with zero power consumption, and the overall battery life meets the 5-year requirement.

[0088] Emergency Scenario: During a heavy rainstorm, water accumulated to a depth of over 0.5 meters at manhole cover #12 in a low-lying area, triggering a Level I alarm from the water level sensor. Simultaneously, the heavy rain caused a power outage at a nearby base station, disrupting LoRa communication.

[0089] The MCU of manhole cover #12 detected two conditions (base station disconnection + Level I alarm) and triggered emergency mode: The MCU outputs a high level to close the MOSFET, enabling the card-mounted PLC module to power on and start (zero-power wake-up). The PLC modules of adjacent manhole covers #11 and #13 are woken up via LoRa broadcast; Each manhole cover snap-fit ​​PLC module sends detection frames on the power line to establish a degradation cascade network; The token is passed from the root node. After obtaining the token, manhole cover #12 forwards the data of water level exceeding limit + coordinate position + timestamp to the downstream level level by level. The data eventually reaches the substation's aggregation point, and the operation and maintenance center receives the alarm and immediately dispatches personnel to handle it; Throughout the process, the card-mount PLC module only operates during the alarm period (approximately 30 seconds), and the increase in power consumption is negligible; in the event of a public network outage, emergency data is successfully transmitted to the maintenance center via the power line as a backup.

[0090] Example 2 Long-distance deployment example including repeaters Taking a cross-regional power tunnel as an example, with a total length of 15 km and 60 smart manhole covers deployed along the route, tests showed that the reliable communication distance of a single-section snap-on PLC was 4.5 km.

[0091] An active repeater was deployed at distances of 4 km, 8 km, and 12 km from the starting point.

[0092] Does the repeater use the same zero-power wake-up mechanism as the manhole cover? Repeaters are typically powered by an active power source and can be normally open, but they can also be designed to start after receiving a wake-up signal from the first cable segment.

[0093] When a section of cable fails or a repeater fails, the PLC module of the upstream manhole cover automatically attempts to communicate directly with the next repeater (degradation cascading), which still ensures the uploading of emergency data for most manhole covers.

[0094] This solution extends the emergency communication coverage distance from 5 km to over 15 km without requiring modifications to the routing logic of the manhole cover nodes.

[0095] This invention includes a mirrored backup communication mode. Unlike the master-slave architecture in existing dual-mode solutions, this solution designs LoRa and the card-mounted PLC as mirrored symmetric entities, with roles dynamically switching according to the environment. The switching decision is based on a two-dimensional evaluation of link quality and a comprehensive cost calculation. This invention also features a degradation cascading routing algorithm. Unlike existing solutions that require maintaining complex routing tables, this solution uses a table-free design. Each node only knows its upstream and downstream neighbors, and data is forwarded sequentially along a fixed direction. When a node goes offline, it automatically degrades to a downstream node to continue forwarding, significantly reducing computational and storage overhead. This invention also features a dynamic channel borrowing mechanism. Unlike existing TDMA fixed time slot allocation schemes, this solution uses a token passing mechanism to obtain sending permissions. By employing tail-follower response technology to achieve a serial transmission chain, this invention can efficiently utilize the channel without pre-allocating time slots. It features a zero-power standby architecture, unlike existing dual-mode solutions that optimize power consumption (often by adjusting power levels within the module). This solution incorporates a controllable electronic switch (MOSFET) in the power supply circuit of the card-mount PLC module. Under normal conditions, the card-mount PLC module is completely physically powered off, resulting in zero standby power consumption. This invention also proposes a mirror backup concept, where LoRa and card-mount PLC communication modes are logically equivalent, forming a mirror-symmetric relationship of mutual backup. Each mode can independently complete the full communication function. When one communication mode fails, the other can seamlessly take over the communication task, achieving a self-healing mechanism of mutual backup and dynamic switching.

[0096] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power well lid emergency self-healing networking method based on a mirror backup communication mode, characterized in that, Includes the following steps: Step 1: Deploy a first communication module and a second communication module inside each smart manhole cover, wherein the first communication module is a wireless communication module and the second communication module is a wired carrier communication module; Step 2: A controllable electronic switch is installed in the power supply circuit of the second communication module. Under normal conditions, the controllable electronic switch is in the off state, and the second communication module is in the zero-power standby state. Step 3: The first communication module continuously monitors the connection status with the base station and evaluates the current link quality; Step 4: When a base station connection failure is detected and a preset high-risk alarm event exists locally, the second communication module is woken up by closing the controllable electronic switch. The alarm levels include Emergency Level I, Important Level II, and Normal Level III. Step 5: After being woken up, the second communication module of each manhole cover sends a probe frame on the power line to automatically establish a linear chain network, in which each node only stores the upstream neighbor address and the downstream neighbor address, and does not maintain a complete routing table; Step 6: Data is forwarded level by level along a fixed direction. Intermediate nodes only perform signal regeneration and data forwarding. When a node goes offline, the upstream node automatically skips the offline node and sends the data to the downstream node, thus achieving degenerate cascading. Step 7: Use a dynamic channel borrowing mechanism on the linear chain network to obtain transmission permission and perform data transmission; Step 8: Evaluate the link quality of the first and second communication modules in real time, and calculate the comprehensive cost of each communication mode. The comprehensive cost includes the link quality score, energy consumption cost, and transmission delay. Step 9: Dynamically determine the current primary communication mode based on the overall cost, and realize a mirror-symmetric relationship between the two communication modes as primary and backup to each other; Step 10: Role switching adopts a soft switching strategy of "connect first, disconnect later" to ensure uninterrupted data transmission during the switching process; Step 11: Dual-condition triggering mechanism. When the base station loses contact and there is a Level I or Level II alarm event, the second communication module is triggered to wake up and emergency networking is set up. Regular Level III alarms are only uploaded through the first communication module. Step 12: When the length of the power cable trench exceeds the reliable transmission distance of single-segment snap-fit ​​PLC communication, deploy at least one active repeater at the cable joint or appropriate location. The repeater contains two snap-fit ​​inductive couplers and a signal regeneration unit, which is used to receive the PLC signal from the previous cable segment, regenerate it, and couple it to the next cable segment. The repeater is transparent to the upper-layer network, does not participate in routing decisions, and supports the automatic skip function in the degradation cascading mechanism.

2. The power well lid emergency self-healing networking method based on the mirror backup communication mode according to claim 1, characterized in that: The dynamic channel borrowing mechanism in step seven is as follows: (a) Set up a virtual token on a linear chain network, where only the node holding the token is allowed to send data; (b) The data sending node appends a forwarding authorization flag to the end of the data frame and passes the token to the receiving node; (c) When a node has no data to send, the token will automatically jump to the next node after a preset timeout.

3. The power well lid emergency self-healing networking method based on the mirror backup communication mode according to claim 1, characterized in that: The controllable electronic switch in steps two and four is a MOSFET, whose gate is connected to the GPIO pin of the MCU. Under normal conditions, the MCU outputs a low level to turn off the MOSFET, and when the MCU is woken up, it outputs a high level to turn on the MOSFET and power on the second communication module.

4. The power well lid emergency self-healing networking method based on the mirror backup communication mode according to claim 1, characterized in that: After the linear chain network is established, no dynamic routing optimization is performed, and the nodes do not periodically exchange neighbor information. The upstream and downstream relationships are determined only through neighbor discovery at the time of network entry, and subsequent forwarding is carried out in a fixed direction.

5. The power well lid emergency self-healing networking method based on mirror backup communication mode according to claim 1, characterized in that: The second communication module uses the power cable shielding layer or low-voltage lead wire as the transmission medium, and is not affected by water immersion in the manhole cover.

6. A system for implementing a power well lid emergency self-healing networking method based on a mirror backup communication mode, characterized in that, It includes a manhole cover sensing layer, a mirror backup communication layer, a self-healing networking layer, and a cloud emergency access layer; The manhole cover sensing layer includes a status monitoring sensor group, a battery management unit, and an MCU microcontroller. The status monitoring sensor group includes a triaxial accelerometer, an inclination sensor, a water level sensor, a temperature sensor, and a gas sensor. Each electric manhole cover integrates the status monitoring sensor group, the battery management unit, and the MCU microcontroller. The mirror backup communication layer includes two types of communication modules: a LoRa wireless communication module and a snap-in PLC communication power line carrier module. Each manhole cover is equipped with these two types of communication modules, which are logically mirror-symmetrical. They are mirror mode A based on the LoRa wireless communication module and mirror mode B based on the snap-in PLC communication power line carrier module. Mirror mode A operates with low power consumption and is the main communication channel during normal periods. It can wake up the snap-in PLC communication power line carrier module. Mirror mode B is in zero-power standby mode. It is activated in an emergency when there is a physical power failure and uses power line cables for backup transmission. The snap-in PLC communication power line carrier module uses the power cable shielding layer or low-voltage lead wire in the cable channel as the transmission medium. The two communication modes are mutually primary and backup, and their roles are dynamically switched according to the environment to achieve mirror backup. The self-healing networking layer is deployed on the manhole cover MCU and regional edge gateway. It includes a link quality dual-dimensional evaluation module, a mirror role decision module, a degradation cascade routing module, a dynamic channel borrowing module, and a zero-power wake-up module. The link quality dual-dimensional evaluation module evaluates the signal-to-noise ratio of the LoRa channel and the physical layer rate and noise level of the power line of the card-mount PLC in real time. The mirror role decision module dynamically determines the primary and backup roles of the two communication modes based on the link quality score and energy consumption cost. The degradation cascade routing module realizes linear forwarding without a routing table. Nodes only know their upstream and downstream neighbors. Data is forwarded step by step along a fixed direction. When a node is offline, it automatically degrades to a downstream node. The dynamic channel borrowing module uses a token passing and tail-following response mechanism to obtain sending permissions without pre-allocating time slots. The zero-power wake-up module realizes physical power-off and on-demand wake-up of the card-mount PLC module through a controllable electronic switch. The cloud-based emergency access layer is deployed in substations or operation and maintenance centers. As the aggregation node of the card-connected PLC cascade network, it is responsible for receiving emergency data uploaded from the cascaded links and forwarding it to the operation and maintenance platform.

7. A long-distance repeater for an emergency self-healing networking method of a power well lid based on a mirror backup communication mode, characterized in that, The system includes a first snap-fit ​​inductive coupler, a second snap-fit ​​inductive coupler, a signal regeneration unit, a power supply unit, and a zero-power wake-up interface. The first snap-fit ​​inductive coupler is used to couple PLC signals on a first segment of power cable, and the second snap-fit ​​inductive coupler is used to couple a second segment of power cable. The signal regeneration unit is connected between the first and second snap-fit ​​inductive couplers and is used to amplify, filter, shape, and forward the received PLC signals. The power supply unit is used to power the signal regeneration unit, and the zero-power wake-up interface is used to receive wake-up signals from a manhole cover or an upstream repeater.

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