Remote meter high-precision synchronization method and system

Abstract

The invention relates to a high-precision synchronization method and system for a remote meter, which are used for sensor time synchronization of a wireless network special for a transformer substation and comprise internal synchronization and external synchronization, and the external synchronization is carried out only when an internal synchronization error exceeds a preset threshold value, the internal synchronization comprises the following steps: synchronizing different sensors accessed to the same node by adopting a time delay error deduction method, and synchronizing different sensors accessed to different nodes by adopting a dynamic master-slave and mutual synchronization hybrid mechanism; initial transmission delay reference values of the merging units are obtained, in the operation process of the transformer substation, delay verification and sampling time unification are carried out on the merging units regularly, and sampling frequency stability correction is carried out; tPSN is optimized through dynamic main node election, FTSP is optimized through hop count error compensation, network layer synchronization is conducted by combining the TPSN and the FTSP, and on-demand broadcasting and time keeping are conducted in a two-way mixed synchronization mode. Compared with the prior art, time synchronization can be stably realized in various complex environments of the transformer substation.

Description

Technical Field

[0001] This invention relates to the field of intelligent power system technology, and in particular to a high-precision synchronization method and system for remote meters. Background Technology

[0002] The safe and reliable operation of power systems relies on real-time monitoring of the generation, transmission, and distribution processes. High-precision time synchronization is a core prerequisite for ensuring the accuracy of monitoring data, which is crucial for advanced metering systems that depend on massive amounts of meter data for accurate billing and analysis. Currently, domestic and international sensor time synchronization technologies mainly include external time synchronization technology and internal time synchronization technology.

[0003] Currently, mainstream external time synchronization technologies primarily rely on satellite time synchronization. For example, Chinese patent CN112367138A discloses a CAN bus device synchronization method and system based on a time synchronization system. This method sets up a synchronization master node and slave nodes on the CAN bus, connects to the master node through a time synchronization system, sends synchronization messages and records the transmission and reception times, calculates the time deviation, and sends a message to the slave node for correction. The slave node adjusts its own time to match the master node's time, ensuring system time synchronization. However, additional satellite time synchronization modules increase sensor power consumption and cost, and place higher demands on sensor reliability and stability control, making them unsuitable for ultra-low power sensor networks in substations.

[0004] Existing classic internal time synchronization algorithms are commonly based on the TPSN or FTSP protocols. For example, Chinese patent CN120640391A discloses a sensor network time synchronization method that uses a clustered topology. It dynamically calibrates the clock frequency offset between the master control clock signal and the cluster head node by quantifying the offset. It also calibrates the logical clock of the cluster head node using an improved TPSN protocol, and performs calibration within the cluster using the clock drift and offset between the cluster head node and its child nodes. Combining the clock mapping relationship of the FTSP protocol, it uses the least squares method to determine the clock drift and offset, implementing dynamic frequency compensation and abnormal data filtering. However, the construction process of the TPSN hierarchical tree increases energy consumption and affects time synchronization accuracy. Flooding time synchronization (FTSP), for large-scale wireless network time synchronization, exhibits problems such as long flooding time and severe error accumulation between nodes. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a high-precision synchronization method and system for remote meters.

[0006] The objective of this invention can be achieved through the following technical solutions: According to a first aspect of the present invention, a high-precision synchronization method for remote meters is provided. This method is used for sensor time synchronization in a dedicated wireless network for substations, including internal synchronization and external synchronization. An external time synchronization module is activated only when the internal synchronization error exceeds a preset threshold. The internal synchronization includes the following steps: Device layer synchronization: For different sensors connected to the same node, a time delay error subtraction method is used for synchronization; for different sensors connected to different nodes, a hybrid mechanism of dynamic master-slave and mutual synchronization is used for synchronization. Synchronization of merging units: Obtain the initial transmission delay reference value of the merging units, and periodically perform delay verification on each merging unit during substation operation, unify the sampling time, and perform sampling frequency stabilization correction. Network layer synchronization: Dynamic master node election is used to optimize TPSN, hop count error compensation is used to optimize FTSP, and TPSN and FTSP algorithms are combined for network layer synchronization. A bidirectional hybrid synchronization method is used for on-demand broadcasting and timekeeping.

[0007] As a preferred technical solution, the time delay error subtraction method is specifically as follows: For different sensors connected to the same node, when performing time calibration with the node device, five types of synchronization error sources are deducted: data transmission delay, access delay, propagation delay, reception delay, and reception processing delay, in order to ensure that the sensor acquisition time is consistent with the node time.

[0008] As a preferred technical solution, the hybrid mechanism of dynamic master-slave and mutual synchronization is specifically as follows: For different sensors connected to different nodes, the clock stability, message transmission and reception success rate, and link quality of each node are periodically evaluated to determine the comprehensive index. The node with the best comprehensive index is selected as the master node, and the remaining nodes periodically request calibration from the master node. When the clock accuracy of the master node decreases or the link becomes unstable, it is automatically re-evaluated, and a slave node that meets the conditions is selected to replace the original master node based on the comprehensive index. If there is no slave node that meets the conditions to replace the master node in a short period of time, the neighboring nodes compare their times and temporarily keep them consistent to avoid synchronization interruption caused by single point of failure.

[0009] As a preferred technical solution, the merging unit includes a data acquisition unit and a data processing unit. The data acquisition unit is responsible for analog sampling, A / D conversion, and raw data packaging. The initial transmission delay reference value of the merging unit includes the data acquisition unit processing delay, the data acquisition unit data transmission delay, the merging unit internal buffer waiting delay, and the data processing delay.

[0010] As a preferred technical solution, the method of periodically performing delay verification on each merging unit and standardizing the sampling time during substation operation specifically includes: During substation operation, the main control device sends a time identifier message to the merging unit. The merging unit returns the time information of the sampling point according to the current sampling rhythm. The main control device then calculates the actual transmission delay on site and compares it with the reference value. If the comparison deviation exceeds the set threshold, the sampling trigger parameters of the merging unit are automatically adjusted based on the deviation through the synchronization algorithm, thereby correcting the sampling time and making its sampling output consistent with other merging units.

[0011] As a preferred technical solution, the sampling frequency stabilization correction specifically includes: Using a high-precision internal crystal oscillator as the sampling frequency reference for the merging unit, environmental parameters are monitored in real time to address frequency drift caused by temperature and humidity. Based on the linear or second-order relationship between the crystal oscillator frequency and temperature and the humidity influence coefficient, the frequency offset is estimated. The crystal oscillator output frequency is dynamically corrected based on the estimation results to ensure that the sampling interval discrete value is stable within 10ps.

[0012] As a preferred technical solution, in the network layer synchronization, for the TPSN protocol, each node reports its own operating indicators at fixed intervals. The operating indicators include clock drift rate, synchronization message success rate, and number of neighboring nodes. The operating indicators are linearly weighted according to preset weights to calculate a comprehensive score, and the node with the highest comprehensive score is selected as the master node. During operation, the heartbeat and drift status of the master node are monitored in real time. Once a heartbeat timeout or drift rate exceeds the limit, the slave nodes are immediately reordered according to the latest comprehensive score, and the node with the highest ranking automatically takes over as the master node.

[0013] As a preferred technical solution, in the network layer synchronization, for the FTSP protocol, during its linear regression correction process, a hop count marker is added to the one-way flooding synchronization message, and a fixed compensation value is preset based on the measured average error per hop. The receiving node automatically adds compensation according to the hop count marker and the fixed compensation value.

[0014] As a preferred technical solution, the network layer synchronization employs a bidirectional hybrid synchronization method for on-demand broadcasting and timekeeping, specifically as follows: Both access nodes and terminal nodes decide whether to broadcast based on their own clock status: when a local clock offset exceeds a threshold or a neighbor synchronization request is received, the node actively broadcasts a synchronization message, which includes a timestamp and the current drift estimate; if the node clock is stable, it only receives and does not send, thereby reducing air interface occupation; the receiving node corrects its local clock based on the synchronization message to keep the time of each node consistent.

[0015] According to a second aspect of the present invention, a high-precision synchronization system for remote meters is provided. This system is used for sensor time synchronization in a substation dedicated wireless network, including an internal synchronization module and an external time synchronization module. The external time synchronization module is activated for external synchronization only when the error after synchronization by the internal synchronization module exceeds a preset threshold. The internal synchronization module includes: The device layer synchronization module is used to: synchronize different sensors connected to the same node using a time delay error subtraction method, and synchronize different sensors connected to different nodes using a hybrid mechanism of dynamic master-slave and mutual synchronization. The merging unit synchronization module is used to: obtain the initial transmission delay reference value of the merging unit, periodically verify the delay of each merging unit during substation operation, unify the sampling time, and perform sampling frequency stabilization correction. The network layer synchronization module is used to: optimize TPSN using dynamic master node election, optimize FTSP using hop count error compensation, perform network layer synchronization by combining TPSN and FTSP algorithms, and use a bidirectional hybrid synchronization method for on-demand broadcasting and timekeeping.

[0016] According to a third aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the program to implement the method described thereon.

[0017] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention eliminates the dependence on satellite time synchronization and is not affected by weather or terrain factors such as rain, tunnels, and pipe corridors. It can stably achieve time synchronization in various complex environments in substations, thus solving the limitations of existing satellite time synchronization scenarios.

[0019] (2) This invention eliminates the problem of asynchronous sampling caused by the inherent delay difference between meter acquisition units by merging unit delay dynamic compensation; the discrete value of sampling frequency is controlled within 10ps, and combined with jump number error compensation and multiple error source deduction, it meets the high-precision acquisition requirements of time-correlated features.

[0020] (3) This invention does not require an additional satellite timing module to operate for a long time. It reduces message interaction and external module power consumption through on-demand broadcasting and timekeeping technology, thereby extending the lifespan of the sensor. Based on the existing substation wireless sensor network architecture, it does not require large-scale hardware modification, thus reducing deployment costs.

[0021] (4) The dynamic master node management of the present invention avoids synchronization interruption caused by root node failure, and the hybrid synchronization mechanism of dynamic master-slave and mutual synchronization is adapted to the mobile multi-hop and dynamic topology change scenarios of substation wireless network. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0025] Example 1 This embodiment provides a high-precision synchronization method for remote meters, used for sensor time synchronization in a dedicated wireless network for substations. The method includes internal synchronization and external synchronization, wherein internal synchronization includes device layer synchronization, merging unit synchronization and network layer synchronization.

[0026] like Figure 1As shown, this method employs a design combining hierarchical synchronization, dynamic compensation, and algorithm optimization, and specifically includes the following steps: Step 1, Device Layer Synchronization: For different sensors connected to the same node, a time delay error subtraction method is used for synchronization. For different sensors connected to different nodes, a hybrid mechanism of dynamic master-slave and mutual synchronization is used for synchronization.

[0027] Step 11: For different sensors connected to the same node, during time calibration with the node device, five types of synchronization error sources—data transmission delay, access delay, propagation delay, reception delay, and reception processing delay—are deducted to ensure that the sensor acquisition time is consistent with the node time. Data transmission delay, reception delay, and propagation delay are calibrated at the factory using a high-precision oscilloscope or logic analyzer, and the measurement results are embedded in the device firmware. Fine-tuning is performed during operation using a temperature compensation table. Access delay is recorded in real-time by the wireless MAC layer, representing the waiting time from data readiness to actual transmission. Reception processing delay is calculated by the receiving node, representing the interval between the RF interrupt trigger and the software capture timestamp. During synchronization, all calibration values, real-time measurement values, and hop count compensation values ​​are deducted, thereby achieving high-precision consistency between the sensor acquisition time and the node's local time.

[0028] Step 12: For different sensors connected to different nodes, a hybrid mechanism of "dynamic master-slave + mutual synchronization" is adopted during the internal time parsing and synchronization process to achieve network-wide time unification. Specifically, the clock stability, message transmission and reception success rate, and link quality of each node are periodically evaluated to determine the comprehensive index. The node with the best comprehensive index is selected as the master node, and the remaining nodes periodically request calibration from the master node. When the clock accuracy of the master node decreases or the link becomes unstable, it is automatically re-evaluated, and a slave node that meets the conditions is selected to replace the original master node based on the comprehensive index. The conditions can be set according to the actual situation. If there is no slave node that meets the conditions to replace the master node in a short period of time, the neighboring nodes compare their times and temporarily keep them consistent to avoid synchronization interruption caused by single point of failure.

[0029] In this embodiment, the comprehensive indicators are determined by a weighted comprehensive evaluation method, with the following weight allocation: clock stability accounts for 40%, as it directly determines the long-term accuracy of the network's time reference, and crystal oscillator drift is a cumulative error with the highest priority; message transmission and reception success rate accounts for 25%, link quality indicators account for 15%, and the number of one-hop neighbor nodes and remaining power each account for 10%. The node with the highest score is selected as the master node.

[0030] The following are some of the situations that trigger a master node re-election: 1) No heartbeat message was received for three consecutive times (approximately 2 minutes, which is close to the substation's tolerance limit). 2) The timekeeping error in the last 10 minutes exceeds 2μs (the process layer synchronization requirement is ≤4μs, and half of it is taken as a warning); 3) The message success rate in the last 5 minutes is less than 75%; 4) Any slave node's overall score is more than 5 points higher than the current master node's score.

[0031] Step 2, Synchronization of Merging Units: Obtain the initial transmission delay reference value of the merging units. During the operation of the substation, periodically perform delay verification on each merging unit, unify the sampling time, and perform sampling frequency stabilization correction.

[0032] After unifying the benchmarks among nodes, the inherent delay differences in the acquisition links of different merging units are further addressed.

[0033] First, the composition of the acquisition link within the merging unit is clarified. The merging unit typically consists of a data acquisition unit and a data processing unit. The data acquisition unit is responsible for analog signal sampling, A / D conversion, and raw data packaging, and is the most critical front-end sampling module in the entire link. During the factory testing phase, the manufacturer will measure and provide the data acquisition unit processing delay, data acquisition unit data transmission delay, merging unit internal buffer waiting delay, and data processing delay. These four delays constitute the initial transmission delay baseline value of the merging unit.

[0034] During substation operation, according to power system regulations, the main control device must periodically perform delay verification on each merging unit. Specifically: The main control unit sends a time identifier message to the merging unit. The merging unit returns the time information of the sampling point according to the current sampling rhythm. The main control unit then calculates the actual transmission delay on site and compares it with the reference value. If the comparison deviation exceeds the set threshold, the sampling trigger parameters of the merging unit are automatically adjusted based on the deviation using a synchronization algorithm (such as linear compensation algorithm, synchronous interpolation algorithm, etc.). This is done by adjusting the sampling phase compensation register or the sampling start threshold to correct the sampling time and make its sampling output consistent with other merging units.

[0035] Based on a unified sampling time, to ensure long-term stability of the sampling frequency, a high-precision internal crystal oscillator is used as the sampling frequency reference for the merging unit, ensuring that the initial sampling interval dispersion is ≤10ps. However, high-precision crystal oscillators are significantly affected by temperature and humidity. Therefore, this embodiment addresses frequency drift caused by temperature and humidity by real-time monitoring of environmental parameters and introducing temperature and humidity compensation algorithms to correct the crystal oscillator output frequency. Specifically, the integrated temperature and humidity sensor can monitor environmental changes in real time. Based on the linear or second-order relationship between frequency and temperature provided by the crystal oscillator manufacturer and the humidity influence coefficient, the frequency offset is estimated. The estimation result is used to dynamically correct the sampling timer loading value, maintaining the sampling interval dispersion within 10ps.

[0036] Step 3, Network Layer Synchronization: TPSN is optimized by dynamic master node election, FTSP is optimized by hop count error compensation, and network layer synchronization is performed by combining TPSN and FTSP algorithms. A bidirectional hybrid synchronization method is used for on-demand broadcasting and timekeeping.

[0037] In the network layer synchronization between the sampling time and frequency stabilization on the merging unit side, the existing TPSN and FTSP algorithms are co-optimized. TPSN is responsible for establishing the basic point-to-point synchronization relationship to accurately measure the actual delay between nodes; FTSP is used to uniformly distribute synchronization parameters when the network scale is large, thereby improving the synchronization convergence speed.

[0038] For the TPSN protocol, a dynamic master node management mechanism is adopted. Each node reports its own operating indicators at fixed intervals. These operating indicators include clock drift rate, synchronization message success rate, and number of neighboring nodes. The operating indicators are linearly weighted according to preset weights to calculate a comprehensive score, and the node with the highest comprehensive score is selected as the master node. During operation, the heartbeat and drift status of the master node are monitored in real time. Once a heartbeat timeout or drift rate exceeds the limit, the slave nodes are immediately reordered according to the latest comprehensive score, and the node with the highest ranking automatically takes over as the master node. This achieves rapid switching without rebuilding the tree topology, thereby reducing energy consumption and avoiding synchronization interruptions.

[0039] The device-level dynamic master-slave mechanism and the network-level TPSN dynamic master node management adopt the same core idea (comprehensive scoring for master selection + immediate succession + mutual synchronization as a fallback), forming a hierarchical and progressive relationship only in terms of application scope: the former is responsible for the micro-robust synchronization within a single-hop cluster, while the latter extends the same mechanism to multi-hop across the entire network to achieve macro-unification, thus forming a fault-tolerant time synchronization system that converges step by step from local to global.

[0040] For the FTSP protocol, during its linear regression correction process, a hop count marker is added to the one-way flooding synchronization message, and a fixed compensation value is preset based on the measured average error per hop. The receiving node automatically adds compensation according to the hop count marker and the fixed compensation value, thereby effectively suppressing error accumulation in large-scale multi-hop networks. At the same time, the synchronization response speed can be further improved by shortening the flooding period.

[0041] After establishing a unified benchmark across the entire network, a bidirectional hybrid synchronization method is adopted to maintain system synchronization. Both access nodes and terminal nodes can broadcast time information, but nodes do not broadcast at fixed intervals; instead, they decide whether to send based on their own clock state. A node will only actively broadcast a synchronization message when it detects that its local clock offset exceeds a threshold or receives a synchronization request from a neighbor. If the node's clock is stable, it will only receive and not send, thereby reducing air interface usage. The synchronization message includes a timestamp and a current drift estimate, which the receiving node uses to correct its local clock and maintain time consistency across all nodes. When the network is idle, terminal nodes integrate high-precision crystal oscillators and employ a "self-timing + compensation optimization" timekeeping mechanism. When environmental temperature and humidity change, a compensation algorithm corrects the self-timing deviation, maintaining synchronization accuracy while reducing power consumption.

[0042] In this embodiment, "receiving node" is a functional term referring to a node that is receiving synchronization messages. Both access nodes and terminal nodes can be receiving nodes; terminal nodes are attached to access nodes.

[0043] Step 4, External Synchronization: The external time synchronization module is activated only when the internal synchronization error exceeds the preset threshold.

[0044] If an external time synchronization source needs to be retained as an emergency backup, the quality of GPS and BD signals, such as the signal-to-noise ratio, should be monitored in real time, and the time synchronization source should be dynamically switched according to the signal quality, rather than always prioritizing GPS. Furthermore, to reduce module runtime and power consumption, this embodiment only activates the external time synchronization module for calibration when the internal synchronization error is too large, and shuts down the module after calibration is complete.

[0045] Example 2 The above is an introduction to the method embodiments. The following system embodiments will further illustrate the solution of the present invention.

[0046] A high-precision synchronization system for remote meters is provided for sensor time synchronization in a substation dedicated wireless network. The system includes an internal synchronization module and an external time synchronization module. The external time synchronization module is activated for external synchronization only when the error after synchronization by the internal synchronization module exceeds a preset threshold. The internal synchronization module includes: The device layer synchronization module is used to: synchronize different sensors connected to the same node using a time delay error subtraction method, and synchronize different sensors connected to different nodes using a hybrid mechanism of dynamic master-slave and mutual synchronization. The merging unit synchronization module is used to: obtain the initial transmission delay reference value of the merging unit, periodically verify the delay of each merging unit during substation operation, unify the sampling time, and perform sampling frequency stabilization correction. The network layer synchronization module is used to: optimize TPSN using dynamic master node election, optimize FTSP using hop count error compensation, perform network layer synchronization by combining TPSN and FTSP algorithms, and use a bidirectional hybrid synchronization method for on-demand broadcasting and timekeeping.

[0047] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0048] Example 3 The electronic device of this invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0049] Multiple components in the device are connected to the I / O interface, including: input units such as keyboards and mice; output units such as various types of displays and speakers; storage units such as disks and optical discs; and communication units such as network interface cards (NICs), modems, and wireless transceivers. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0050] The processing unit executes the various methods and processes described above, such as method steps 1 through 4. For example, in some embodiments, method steps 1 through 4 may be implemented as a computer software program tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of method steps 1 through 4 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute method steps 1 through 4 by any other suitable means (e.g., by means of firmware).

[0051] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0052] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0053] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-precision synchronization method for remote meters, characterized in that, This method is used for sensor time synchronization in a substation dedicated wireless network, including internal synchronization and external synchronization. External synchronization is only activated when the internal synchronization error exceeds a preset threshold. The internal synchronization includes the following steps: Device layer synchronization: For different sensors connected to the same node, a time delay error subtraction method is used for synchronization; for different sensors connected to different nodes, a hybrid mechanism of dynamic master-slave and mutual synchronization is used for synchronization. Synchronization of merging units: Obtain the initial transmission delay reference value of the merging units, and periodically perform delay verification on each merging unit during substation operation, unify the sampling time, and perform sampling frequency stabilization correction. Network layer synchronization: Dynamic master node election is used to optimize TPSN, hop count error compensation is used to optimize FTSP, and TPSN and FTSP algorithms are combined for network layer synchronization. A bidirectional hybrid synchronization method is used for on-demand broadcasting and timekeeping.

2. The high-precision synchronization method for remote meters according to claim 1, characterized in that, The aforementioned time delay error subtraction method is specifically as follows: For different sensors connected to the same node, when performing time calibration with the node device, five types of synchronization error sources are deducted: data transmission delay, access delay, propagation delay, reception delay, and reception processing delay, in order to ensure that the sensor acquisition time is consistent with the node time.

3. The high-precision synchronization method for remote meters according to claim 1, characterized in that, The aforementioned hybrid mechanism of dynamic master-slave and mutual synchronization is as follows: For different sensors connected to different nodes, the clock stability, message transmission and reception success rate and link quality of each node are periodically evaluated to determine the comprehensive index. The node with the best comprehensive index is selected as the master node, and the other nodes periodically request calibration from the master node. When the clock accuracy of the master node decreases or the link becomes unstable, it will automatically re-evaluate and select a suitable slave node to replace the original master node based on comprehensive indicators. If no suitable slave node can replace the master node in a short period of time, the neighboring nodes will compare their times and temporarily keep them consistent to avoid synchronization interruption caused by single point of failure.

4. The high-precision synchronization method for remote meters according to claim 1, characterized in that, The merging unit includes a data acquisition unit and a data processing unit. The data acquisition unit is responsible for analog sampling, A / D conversion, and raw data packaging. The initial transmission delay reference value of the merging unit includes the data acquisition unit processing delay, the data acquisition unit data transmission delay, the merging unit internal buffer waiting delay, and the data processing delay.

5. The high-precision synchronization method for remote meters according to claim 1, characterized in that, The aforementioned method of periodically performing delay verification on each merging unit during substation operation and standardizing sampling times specifically includes: During substation operation, the main control device sends a time identifier message to the merging unit. The merging unit returns the time information of the sampling point according to the current sampling rhythm. The main control device then calculates the actual transmission delay on site and compares it with the reference value. If the comparison deviation exceeds the set threshold, the sampling trigger parameters of the merging unit are automatically adjusted based on the deviation through the synchronization algorithm, thereby correcting the sampling time and making its sampling output consistent with other merging units.

6. The high-precision synchronization method for remote meters according to claim 1, characterized in that, The sampling frequency stabilization correction specifically refers to: Using a high-precision internal crystal oscillator as the sampling frequency reference for the merging unit, environmental parameters are monitored in real time to address frequency drift caused by temperature and humidity. Based on the linear or second-order relationship between the crystal oscillator frequency and temperature and the humidity influence coefficient, the frequency offset is estimated. The crystal oscillator output frequency is dynamically corrected based on the estimation results to ensure that the sampling interval discrete value is stable within 10ps.

7. The high-precision synchronization method for remote meters according to claim 1, characterized in that, In the network layer synchronization described above, for the TPSN protocol, each node reports its own operating indicators at fixed intervals. These operating indicators include clock drift rate, synchronization message success rate, and number of neighboring nodes. The operating indicators are linearly weighted according to preset weights to calculate a comprehensive score, and the node with the highest comprehensive score is selected as the master node. During operation, the heartbeat and drift status of the master node are monitored in real time. Once a heartbeat timeout or drift rate exceeds the limit, the slave nodes are immediately reordered according to the latest comprehensive score, and the node with the highest ranking automatically takes over as the master node.

8. The high-precision synchronization method for remote meters according to claim 1, characterized in that, In the network layer synchronization described above, for the FTSP protocol, during its linear regression correction process, a hop count marker is added to the one-way flooding synchronization message, and a fixed compensation value is preset based on the measured average error per hop. The receiving node automatically adds compensation according to the hop count marker and the fixed compensation value.

9. The high-precision synchronization method for remote meters according to claim 1, characterized in that, In the aforementioned network layer synchronization, the bidirectional hybrid synchronization method employs on-demand broadcasting and timekeeping, specifically as follows: Both access nodes and terminal nodes decide whether to broadcast based on their own clock status: when a local clock offset exceeds a threshold or a neighbor synchronization request is received, the node actively broadcasts a synchronization message, which includes a timestamp and the current drift estimate. If the node clock is stable, it will only receive and not send, thereby reducing air interface usage. The receiving node corrects its local clock based on the synchronization message to keep the time consistent across all nodes.

10. A high-precision synchronization system for remote meters, characterized in that, This system is used for sensor time synchronization in a substation's dedicated wireless network. It includes an internal synchronization module and an external time synchronization module. The external time synchronization module is activated only when the error after synchronization by the internal synchronization module exceeds a preset threshold. The internal synchronization module includes: The device layer synchronization module is used to: synchronize different sensors connected to the same node using a time delay error subtraction method, and synchronize different sensors connected to different nodes using a hybrid mechanism of dynamic master-slave and mutual synchronization. The merging unit synchronization module is used to: obtain the initial transmission delay reference value of the merging unit, periodically verify the delay of each merging unit during substation operation, unify the sampling time, and perform sampling frequency stabilization correction. The network layer synchronization module is used to: optimize TPSN using dynamic master node election, optimize FTSP using hop count error compensation, perform network layer synchronization by combining TPSN and FTSP algorithms, and use a bidirectional hybrid synchronization method for on-demand broadcasting and timekeeping.

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