CN117834077A

CN117834077A - Time synchronization system and method

Info

Publication number: CN117834077A
Application number: CN202410101621.2A
Authority: CN
Inventors: 季建峰; 郑栩展; 霍煜红; 赵军
Original assignee: Beijing Zhixiang Technology Co Ltd
Current assignee: Beijing Zhixiang Technology Co Ltd
Priority date: 2024-01-24
Filing date: 2024-01-24
Publication date: 2024-04-05

Abstract

The invention provides a time synchronization system and a method, which relate to the technical field of metering, and the system comprises: the master clock calibrates the current time information of the master clock according to the second pulse signal and the time code signal to obtain first time information; under the condition that the boundary clock is not in a self-time keeping state, updating the current time information of the boundary clock according to the first time information to obtain second time information; correcting the current time information of the boundary clock according to the first temperature compensation coefficient under the condition of being in a self-time keeping state to obtain third time information; under the condition that the slave clock is not in the self-keeping state, updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock to obtain fourth time information; and correcting the current time information of the slave clock according to the second temperature compensation coefficient under the condition of being in a self-time keeping state to obtain fifth time information. The system effectively solves the requirement of high-precision time synchronization and has strong applicability.

Description

Time synchronization system and method

Technical Field

The invention relates to the technical field of metering, in particular to a time synchronization system and a method.

Background

With the development of informatization and digitalization of a power grid, a large number of metering devices are connected into the power distribution network, so that the topology structure of the power distribution network is increasingly complex, and the requirement for realizing data synchronous acquisition at each metering device in the power distribution network is increasingly urgent. Nodes serving different functions in the whole power distribution network also correspond to the level requirements of different time synchronization precision. For example, the time synchronization accuracy required by power consumption management, load monitoring, electric quantity collection and the like is 1 second; the time synchronization accuracy of the data acquisition and monitoring control system (Supervisory Control and Data Acquisition, SCADA) is 10 milliseconds (ms); the time synchronization accuracy of the event sequence records (Sequence of Events, soE) is 1ms; and the time synchronization accuracy of the synchrophasor measurement unit (Phasor Measurement Unit, PMU) is 1 microsecond (μs).

The existing time synchronization system can be a power time-frequency value transmission and time synchronization system applying a power carrier or a high-precision double-redundancy time synchronization system based on Ethernet and second pulse. The time synchronization system of the self-adaptive networking utilizes a digital-analog converter and a voltage-controlled oscillator to perform time-frequency synchronization and self-adaptive timekeeping based on a power carrier technology, but for metering equipment of a national network, the volume, the power consumption and the cost cannot be satisfied, so that the precision of time synchronization of the metering equipment is lower; the latter device comprises: a time system station, a management unit and a plurality of control units; the management unit and each control unit receive the time code message of the time system station, the output of the time system station is connected with the input received by the double-redundancy receiving module of the management unit and is used for receiving the double-redundancy second pulse information of the time system station, the output of the double-redundancy second pulse forwarding module in the management unit is connected with the input of the double-redundancy second pulse receiving module in each control unit and forwards the second pulse information received by the management unit from the time system station to each control unit, so that the latter can perform double-layer time synchronization through the second pulse and the time code information, and system time offset caused by single-line faults such as second pulse offset, time code message interruption and the like is prevented, but the system needs to be based on an Ethernet and second pulse signal mode and cannot perform time synchronization in a power carrier network with low precision.

In summary, any existing time synchronization system has certain limitations, so that the accuracy of time synchronization is low, and the requirements of the smart grid cannot be met.

Disclosure of Invention

The invention provides a time synchronization system and a method, which are used for solving the defect that the existing time synchronization system has certain limitation and lower precision in time synchronization, solving the requirements of high-precision time synchronization and low-cost compatibility which are needed by digital informatization of a power grid, meeting the application requirements of various power scenes, having strong applicability and laying a foundation for the popularization of carrier time-frequency value transmission and self-adaptive time keeping technology in a whole-network metering device.

The invention provides a time synchronization system, comprising: a master clock, a boundary clock, and a slave clock;

the master clock is used for calibrating the current time information of the master clock according to the second pulse signal and the time code signal to obtain first time information;

the boundary clock is used for updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information;

The slave clock is configured to update current time information of the slave clock according to the first time information or updated time information corresponding to the boundary clock when the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state, so as to obtain fifth time information.

According to the time synchronization system provided by the invention, the boundary clock is used for correcting the current time information of the boundary clock according to the first temperature compensation coefficient to obtain the third time information, and comprises the following steps: the boundary clock is specifically configured to determine the first temperature compensation coefficient when it is determined that the power carrier network where the time synchronization system is located is in an on-line state; and under the condition that the power carrier network is in an offline state, if the boundary clock is in a self-timekeeping state, correcting the current time information of the boundary clock according to the first temperature compensation coefficient to obtain the third time information.

According to the time synchronization system provided by the invention, the boundary clock comprises an all-digital time-frequency compensation adjustment module, and the all-digital time-frequency compensation adjustment module is in open loop control under the condition that the power carrier network is in an offline state; the all-digital time-frequency compensation adjustment module comprises: the device comprises a decoding unit, a time-frequency calibration parameter estimation unit and a temperature compensation parameter estimation unit; the boundary clock is specifically configured to determine the first temperature compensation coefficient, and includes: the decoding unit is used for completing the function of obtaining the remote synchronous time from the carrier signal; the time-frequency calibration parameter estimation unit is used for completing the difference comparison between the synchronous time and the current output time under different temperature conditions and converting the synchronous time and the current output time into digital correction compensation parameters under the different temperature conditions; the temperature compensation parameter estimation unit is used for analyzing and determining a first temperature compensation coefficient of the crystal oscillator under different temperature conditions according to the digital correction compensation parameters under different temperature conditions.

According to the time synchronization system provided by the invention, the digital correction compensation parameter is a frequency locking control quantity; the frequency locking control quantity under the different temperature conditions is used for controlling the first temperature compensation coefficient under the different temperature conditions.

According to the time synchronization system provided by the invention, the time-frequency calibration parameter estimation unit comprises a time drift model and a temperature drift model; the time-frequency calibration parameter estimation unit is specifically used for acquiring an external clock control word and the different temperature conditions; inputting the external clock control word into the time drift model to obtain a first parameter; inputting the external clock control word and the different temperature conditions into the temperature drift model to obtain a second parameter; and according to the first parameter and the second parameter, completing the difference comparison between the synchronous time and the current output time under different temperature conditions, and converting the synchronous time and the current output time into digital correction compensation parameters under different temperature conditions.

According to the time synchronization system provided by the invention, the boundary clock is used for updating the current time information of the boundary clock according to the first time information to obtain the second time information, and comprises the following steps: the boundary clock is specifically configured to update current time information of the boundary clock according to the first time information based on a software protocol of carrier communication, so as to obtain the second time information.

According to the time synchronization system provided by the invention, the master clock is specifically used for performing time-frequency calibration parameter estimation operation on the current time information of the master clock according to the second pulse signal and the time code signal by adopting a temperature compensation type crystal oscillator to obtain the first time information.

The time synchronization system provided by the invention further comprises three stages of time nodes; the third-level time node is used for determining sixth time information of a navigation satellite system according to satellite navigation signals; and generating the second pulse signal and the time code signal according to the sixth time information.

According to the time synchronization system provided by the invention, the three-stage time node is configured to generate the second pulse signal and the time code signal according to the sixth time information, and includes: the third-level time node is specifically configured to determine an absolute time of the second-level node by applying a global navigation satellite system GNSS common view principle according to the sixth time information; and generating the second pulse signal and the time code signal according to the absolute time.

The invention also provides a time synchronization method, which is applied to the time synchronization system of any one of the above, and the time synchronization system comprises: a master clock, a boundary clock, and a slave clock; the method comprises the following steps:

Calibrating current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain first time information;

updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state by the boundary clock, so as to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information;

updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock under the condition that the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state to obtain fifth time information.

The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the time synchronization method as described above when executing the program.

The invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements a time synchronization method as described above.

The invention also provides a computer program product comprising a computer program which, when executed by a processor, implements a time synchronization method as described in any of the above.

The invention provides a time synchronization system and a method, wherein the system comprises the following steps: a master clock, a boundary clock, and a slave clock; the master clock is used for calibrating the current time information of the master clock according to the second pulse signal and the time code signal to obtain first time information; the boundary clock is used for updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information; the slave clock is configured to update current time information of the slave clock according to the first time information or updated time information corresponding to the boundary clock when the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state, so as to obtain fifth time information. The system solves the requirements of high-precision time synchronization and low-cost compatibility which are needed in the digital informatization of the power grid, can meet the application requirements of various power scenes, has strong applicability, and lays a foundation for the popularization of carrier time-frequency value transmission and self-adaptive time keeping technology in the whole-grid metering device.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a time synchronization system according to the present invention;

FIG. 2 is a schematic diagram of a time topology corresponding to a time synchronization system according to the present invention;

FIG. 3 is a schematic diagram of a boundary clock according to the present invention;

FIG. 4 is a schematic diagram of an all-digital time-frequency compensation adjustment module according to the present invention;

fig. 5 is a flow chart of a method for maintaining a frequency of a slave node in an offline state according to the present invention;

FIG. 6 is a second schematic diagram of a time synchronization system according to the present invention;

FIG. 7 is a third schematic diagram of a time synchronization system according to the present invention;

FIG. 8 is a flow chart of a time synchronization method provided by the present invention;

fig. 9 is a schematic structural diagram of an electronic device provided by the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, which is a schematic structural diagram of a time synchronization system provided by the present invention, the time synchronization system may include: a Master Clock (T-GM) 101, a Boundary Clock (T-BC) 102, and a slave Clock (T-SC) 103;

a master clock 101 for calibrating current Time information of the master clock 101 according to a Pulse Per Second (PPS) signal and a Time of Day (ToD) signal to obtain first Time information;

the boundary clock 102 is configured to update current time information of the boundary clock 102 according to the first time information to obtain second time information when the boundary clock 102 is not in a self-timekeeping state; correcting the current time information of the boundary clock 102 according to the first temperature compensation coefficient under the condition that the boundary clock 102 is in a self-time keeping state to obtain third time information;

The slave clock 103 is configured to update current time information of the slave clock 103 according to the first time information or updated time information corresponding to the boundary clock 102 when the slave clock 103 is in a self-timekeeping state, so as to obtain fourth time information; when the slave clock 103 is in the self-clocking state, the current time information of the slave clock 103 is corrected based on the second temperature compensation coefficient, and fifth time information is obtained.

Wherein the master clock 101, the boundary clock 102 and the slave clock 103 are all metering devices for time synchronization in the power carrier network. These metering devices play a key role in the time synchronization of the power carrier network, and are important to ensure the time consistency of each metering device in the power carrier network.

The master clock 101 is the primary source of time on the power carrier network to which other metering devices will synchronize. Wherein the master clock 101 may achieve time synchronization by transmitting a time signal (e.g., first time information).

The boundary clock 102 is a device with multiple network interfaces that can receive timing messages, adjust the network delay of the power carrier network, and then create a new master time signal (e.g., second time information) to pass down the network. This may reduce the number of devices that communicate directly with the master clock 101 and resist some of the effects of distance degradation.

The slave clock 103 is a metering device synchronized with the master clock 101 or the boundary clock 102, and does not serve as a timing source. The slave clock 103 acquires corresponding time information from the master clock 101 or the boundary clock 102, adjusts to take network delay of the power carrier network into consideration, and synchronizes own time information to the time information corresponding to the master clock 101 or the boundary clock 102.

A pulse-second signal is a periodic signal, the signal period of which is typically 1 second, and which is commonly used for time synchronization and measurement.

A time code signal is a digital signal used for time synchronization and measurement and contains all the information required for time synchronization. The format of the time code signal is generally a B time code format, and is classified into two types, a B (DC) code and a B (AC) code. Among them, the B (DC) code is mainly used for short-distance time transfer, and the B (AC) code is mainly used for long-distance time transfer.

In the self-clocking state means that one boundary clock 102 and the slave clock 103 do not require external inputs to maintain their respective time synchronization.

The temperature compensation coefficient refers to a ratio of a change in the boundary clock 102 or the slave clock 103 output time signal to a temperature change amount when a temperature change occurs in the boundary clock 102 or the slave clock 103. The first temperature compensation coefficient and the second temperature compensation coefficient may be the same or different, and are not particularly limited herein.

The updated time information corresponding to the boundary clock 102 is the second time information or the third time information.

In the embodiment of the present invention, in the process of time synchronization of the master clock 101, the boundary clock 102 and the slave clock 103 in the power carrier network, for the master clock 101, it is not necessary to determine whether the master clock 101 is in a self-time keeping state, and the master clock 101 may first acquire a second pulse signal and a time code signal, and then perform synchronous update calibration on current time information of the master clock 101 according to the two signals, so as to obtain first time information with higher precision, and realize time synchronization with a satellite navigation system.

For the boundary clock 102, whether the boundary clock 102 is in a self-timekeeping state needs to be judged, if not, the current time information of the boundary clock 102 is updated directly according to the first time information transmitted by the master clock 101, and second time information with higher precision is obtained; if so, a first temperature compensation coefficient is acquired first, and then based on the first temperature compensation coefficient, the current time information of the boundary clock 102 is updated and corrected to obtain third time information with higher precision, and time synchronization with the master clock 101 can be achieved no matter the second time information or the third time information.

For the slave clock 103, it is necessary to determine whether the slave clock 103 is in a self-time keeping state, and if not, update the current time information of the slave clock 103 directly according to the first time information transmitted by the master clock 101 or directly according to the second time information or the third time information transmitted by the boundary clock 102 to obtain fourth time information with higher precision; if the clock is in the state, a second temperature compensation coefficient is acquired first, and then based on the second temperature compensation coefficient, the current time information of the slave clock 103 is updated and corrected to obtain fifth time information with higher precision, and time synchronization with the master clock 101 or the boundary clock 102 can be realized whether the fifth time information is fourth time information or fifth time information.

Therefore, the time synchronization process of all the metering devices can effectively meet the requirements of high-precision time synchronization and low-cost compatibility which are needed by the digital informatization of the power grid, can meet the application requirements of various power scenes, has strong applicability, and lays a foundation for the popularization of carrier time-frequency value transmission and self-adaptive time keeping technology in the whole-network metering devices.

Among them, the power carrier network is a technology for transmitting analog signals or digital signals at high speed by a carrier system using an existing power line. The power carrier network can transmit signals only by wires without re-erecting the network.

Optionally, as shown in fig. 2, a schematic structural diagram of a time topology corresponding to the time synchronization system provided by the present invention is shown. As can be seen from fig. 2, the time synchronization system is based on the power carrier network, and according to the master node and the slave node in the time synchronization system, a time topology diagram corresponding to the time synchronization system is constructed, so that a time synchronization system is established in the power carrier network where the time synchronization system is located. That is, the time synchronization system can combine the carrier communication link layer networking process to construct a corresponding time topological graph.

Note that, in the case where the master node is the master clock 101, the slave node is the boundary clock 102 and/or the slave clock 103, where the boundary clock 102 may also be a relay node in the time topology, that is, the boundary clock 102 is a slave node of the master clock 101 and a master node of the slave clock 103; in the case where the master node is the boundary clock 102, the slave node is the slave clock 103, and the slave clock 103 is an end node.

Wherein the number of master clocks 101 is one, and the number of boundary clocks 102 and the number of slave clocks 103 are not limited.

In some embodiments, the boundary clock 102, configured to correct the current time information of the boundary clock 102 according to the first temperature compensation coefficient, to obtain third time information, may include: the boundary clock 102 is specifically configured to determine a first temperature compensation coefficient when it is determined that the power carrier network where the time synchronization system is located is in an on-line state; under the condition that the power carrier network is in an offline state, if the boundary clock 102 is in a self-clocking state, correcting the current time information of the boundary clock 102 according to the first temperature compensation coefficient to obtain third time information.

Wherein, the power carrier network is in an on-line state, which means that the power carrier network is available and stable, and meanwhile, the metering devices can normally perform data transmission and communication.

The power carrier network being offline means that the power carrier network is not available and/or unstable, and at the same time, data transmission and communication between metering devices cannot be performed normally.

In the embodiment of the invention, in the process of determining the third time information according to the first temperature compensation coefficient, if the power carrier network where the time synchronization system is located is determined to be in an on-line state, the boundary clock 102 collects temperature data of each node in the power carrier network, and further determines temperature differences among each node in the power carrier network based on a time topological graph corresponding to the time synchronization system, wherein the temperature differences can accurately reflect the actual situation of the power carrier network; determining a first temperature compensation coefficient corresponding to the boundary clock 102 according to all the temperature differences; if the power carrier network is determined to be in an offline state, reading current time information of the boundary clock 102; and correcting the current time information of the boundary clock 102 according to the first temperature compensation coefficient determined previously, and determining the corrected time information as third time information.

In this way, the boundary clock 102 can correct the current time information of the boundary clock 102 when the power carrier network is in an offline state. The whole correction process has the advantages of accuracy, reliability, flexibility, expandability and the like, can ensure the accuracy and consistency of time information, and has important significance for application scenes needing high-precision time synchronization.

It should be noted that, the process of determining the second temperature compensation coefficient from the clock 103 is similar to the process of determining the first temperature compensation coefficient by the boundary clock 102, and the process of determining the fifth time information from the clock 103 is similar to the process of determining the third time information by the boundary clock 102, which is not described in detail herein.

In some embodiments, as shown in fig. 3, which is a schematic structural diagram of a boundary clock provided by the present invention, the boundary clock 102 may include: the full-digital time-frequency compensation adjustment module 1021 is in open loop control under the condition that the power carrier network is in an offline state; the all-digital time-frequency compensation adjustment module 1021 may include: a decoding unit 10211, a time-frequency calibration parameter estimation unit 10212, and a temperature compensation parameter estimation unit 10213;

the boundary clock 102, specifically configured to determine a first temperature compensation coefficient, includes:

A decoding unit 10211 for performing a function of obtaining a remote synchronization time from the carrier signal;

the time-frequency calibration parameter estimation unit 10212 is used for completing the difference comparison between the synchronous time and the current output time under different temperature conditions and converting the synchronous time and the current output time into digital correction compensation parameters under different temperature conditions;

the temperature compensation parameter estimation unit 10213 is configured to analyze and determine a first temperature compensation coefficient of the crystal oscillator at different temperatures according to the digital correction compensation parameters at different temperatures.

The fact that the all-digital time-frequency compensation adjustment module 1021 is in open loop control means that the time synchronization system where the all-digital time-frequency compensation adjustment module 1021 is located does not include a feedback link, and at this time, the time synchronization system is an open loop control system. The output of the open loop control system is only affected by the input control signal, once the input control signal is sent out, the output is output according to a preset functional relation, and the output result cannot be fed back and corrected.

A carrier signal refers to a waveform, typically a sine wave, modulated to transmit a signal.

The digital correction compensation parameter refers to a parameter used to control and adjust a digital system (e.g., a time synchronization system) for the purpose of correcting and optimizing system performance.

In the embodiment of the present invention, in the process of determining the first temperature compensation coefficient, the decoding unit 10211 may first obtain a carrier signal, and decode a remote synchronization time from the carrier signal, which specifically involves performing operations such as demodulation and parsing on the carrier signal to extract a target signal containing time information, and converting the target signal into a usable time format; the time-frequency calibration parameter estimation unit 10212 generates digital correction compensation parameters according to the difference comparison between the synchronous time and the current output time under different temperature conditions, and specifically may include performing operations such as frequency analysis, deviation calculation, etc. on the time signal to determine the digital correction compensation parameters that need to be corrected, such as frequency offset, phase deviation, time deviation, etc.; the temperature compensation parameter estimation unit 10213 may perform temperature correlation analysis on the digitally corrected compensation parameters for different temperature conditions to determine a first temperature compensation coefficient for the crystal oscillator for different temperature conditions.

In this way, the decoding unit 10211, the time-frequency calibration parameter estimation unit 10212 and the temperature compensation parameter estimation unit 10213 cooperate with each other, so that the function of decoding and obtaining the remote synchronization time from the carrier signal can be realized, and the time-frequency calibration and the temperature compensation can be performed under different temperature environments, so as to ensure the accuracy and the stability of the time synchronization.

Alternatively, the slave clock 103 may include: an all digital time frequency compensation adjustment module 1021.

Alternatively, as shown in fig. 4, the structure of the all-digital time-frequency compensation adjustment module provided by the invention is schematically shown. The full digital time-frequency compensation adjustment module 1021 is arranged in the boundary clock 102 or the slave clock 103, and as can be seen from fig. 4, the decoding unit 10211 acquires different temperature conditions after the function of obtaining the remote synchronous time from the carrier signal is completed; the time-frequency calibration parameter estimation unit 10212 completes the difference comparison between the synchronous time and the current output time under different temperature conditions and converts the synchronous time and the current output time into digital correction compensation parameters under different temperature conditions; the temperature compensation parameter estimation unit 10213 performs correction parameter selection according to the digital correction compensation parameters under different temperature conditions, and analyzes and determines a first temperature compensation coefficient of the crystal oscillator under different temperature conditions, where the first temperature compensation coefficient is used for correcting the current time information of the boundary clock 102 or the slave clock 103, obtaining time information with higher accuracy, and outputting the time information.

In some embodiments, the digitally corrected compensation parameter is a frequency locking control quantity; the frequency locking control quantity under different temperature conditions is used for controlling the first temperature compensation coefficient under different temperature conditions.

The frequency locking control quantity is a parameter used for controlling the phase-locked loop and used for determining the response characteristics of the phase-locked loop under different conditions.

In the embodiment of the present invention, the time-frequency calibration parameter estimation unit 10212 may also be referred to as a frequency digital learning device, which may complete recording and learning of different frequency locking control amounts under different temperature conditions of the frequency amount, as a first temperature compensation coefficient under different temperature conditions for offline open-loop control.

Under the condition that the power carrier network is determined to be in an offline state, the frequency digital learning device can be switched from real-time synchronous time to open-loop control self-maintenance, and the temperature compensation control of time information is carried out by utilizing a first temperature compensation coefficient obtained by online operation, so that the self-maintenance of the slave node in a short time and high precision time under the offline state is realized at lower cost.

In addition, the process of determining the temperature compensation coefficient by using the all-digital time-frequency compensation adjustment module 1021 eliminates the links of the existing digital-analog converter and voltage-controlled oscillator, further reduces the links and hardware component modules of the time synchronization system, improves the stability and reliability of the time synchronization system, and simultaneously reduces the power consumption and cost of the time synchronization system.

In some embodiments, the time-frequency calibration parameter estimation unit 10212 may include: a time drift model and a temperature drift model;

the time-frequency calibration parameter estimation unit 10212 is specifically configured to obtain an external clock control word and different temperature conditions; inputting an external clock control word into a time drift model to obtain a first parameter; inputting the external clock control word and different temperature conditions into a temperature drift model to obtain a second parameter; and according to the first parameter and the second parameter, the difference comparison between the synchronous time and the current output time under different temperature conditions is completed, and the digital correction compensation parameters under different temperature conditions are converted.

The time drift model refers to a model that time information of a time synchronization system naturally changes with time under the condition of no external interference.

The temperature drift model refers to a model in which time information of a time synchronization system changes with ambient temperature.

In the embodiment of the invention, the time-frequency calibration parameter estimation unit 10212 can firstly acquire an external clock control word and acquire different temperature conditions through a temperature sensor after finishing the difference comparison between the synchronous time and the current output time under different temperature conditions and converting the synchronous time and the current output time into the digital correction compensation parameters under different temperature conditions; then, inputting an external clock control word into the time drift model to obtain a time related parameter, namely a first parameter; inputting the external clock control word and different temperature conditions into a temperature drift model to obtain a temperature related parameter, namely a second parameter; and then combining the first parameter and the second parameter, completing the difference comparison between the synchronous time and the current output time under different temperature conditions, and converting the synchronous time and the current output time into digital correction compensation parameters under different temperature conditions. In this way, the whole process can more accurately estimate the difference between the synchronous time and the current output time at different temperatures by using the external clock control word, the temperature drift model and the time drift model, thereby obtaining the digital correction compensation parameter with higher accuracy.

Exemplary, as shown in fig. 5, a flow chart of a method for maintaining the frequency of a slave clock in an offline state is provided in the present invention. As can be seen from fig. 5, the slave clock 103 is started after the time service signal is captured and locked by the built-in frequency digital adjusting device, and the adaptive prediction of the temperature drift model and the time drift model is performed. This is because the temperature drift model and the time drift model are trained on the course of the loop response, not the drift behavior of the clock crystal, if the capture loop of the master clock 101 has not yet locked steadily at the beginning of the training. If the master clock 101 is locked and lost, the system automatically switches to a drift correction compensation mode, and performs open loop time-keeping compensation processing by using the trained temperature drift model and time drift model. The output process of the time keeping compensation is treated differently according to the temperature drift model and the degree of sufficiency of the time drift model training. If the external clock (such as the boundary clock 102 or the slave clock 103) is stable for a long enough time, the temperature drift model and the time drift model are sufficiently trained, the timekeeping output is the output of the prediction model before the external clock disappears; on the contrary, the state before the external clock disappears is simply processed by low-pass smoothing and then is output as the time keeping.

The self-adaptive time drift model can be used for predicting the temperature drift model in a linear Kalman filtering mode, and based on the assumption that the temperature stability and the temperature change of an external clock are in a linear relation, the time drift is predicted in the linear Kalman filtering mode, and the short-time aging characteristic of the clock crystal oscillator is also in a linear relation with time. The transient response time of the time drift model to the temperature drift model is long, and the transient response time can reach hours to days by modifying the pre-filter parameters and/or the Kalman filtering parameters according to the clock timekeeping level requirements of the slave nodes. Generally, the longer the transient response time, the smaller the filtering bandwidth of the time drift model to the temperature drift model, the more sufficiently the clock noise is suppressed, and the better the final time keeping performance, but the longer the convergence time required for the time drift model to train the temperature drift model.

In order to accelerate the convergence time of the model training amount, the state setting of various model bandwidths can be carried out, specifically, the large bandwidth is adopted for rapid convergence in the initial stage, and then the small bandwidth is used for finer model convergence. The transient response time of different pre-filters is different, and the compensation processing of the filtering delay amount needs to be performed before the temperature drift predicted amount and the time drift predicted amount are combined, so that the predicted amounts of the two clock drift are aligned.

The above method for maintaining the frequency of the slave clock in the off-line state, i.e. the self-adaptive timekeeping scheme, can utilize the low-level precision temperature-controlled crystal oscillator (Oven Controlled Crystal Oscillator, OCXO)/TCXO to realize high-level timekeeping stability. In addition, the cost and power consumption can be greatly reduced by adopting the OCXO with high-grade requirements relatively directly.

Optionally, the slave clock 103 may also include an all-digital time-frequency compensation adjustment module 1021 for determining the second temperature compensation coefficient. The specific process is similar to the process of determining the first temperature compensation coefficient, and is not specifically limited herein.

In some embodiments, the boundary clock 102, configured to update the current time information of the boundary clock 102 according to the first time information, to obtain the second time information, may include: the boundary clock 102 is specifically configured to update the current time information of the boundary clock 102 according to the first time information based on a software protocol of carrier communication, so as to obtain the second time information.

The software protocol of carrier communication is generally a specification and standard, and is used to define a data transmission format, a communication rule, a data packet structure, etc. in the carrier communication process. The software protocols for carrier communication are typically formulated by an associated standardization organization or industry association to ensure interoperability between different vendors and devices.

In the field of power carrier communication, common software protocols may include: power line communication (Power Line Communication, PLC) protocol. The PLC protocol is a standard for power line communication, and defines a data transmission format, a communication rule, a data packet structure, and the like on a power line. Different PLC protocols may have different characteristics and application ranges, but all follow the same communication principles and specifications.

In the embodiment of the present invention, the boundary clock 102 may update the current time information of the boundary clock 102 according to the first time information through a software protocol based on carrier communication, so as to obtain the second time information, thereby ensuring the accuracy and consistency of time in the whole time synchronization system.

Optionally, the slave clock 103 is configured to update the current time information of the slave clock 103 according to the first time information or the updated time information corresponding to the boundary clock, to obtain fourth time information, which may include: the slave clock 103 is specifically configured to update the current time information of the slave clock 103 according to the first time information or the updated time information corresponding to the boundary clock based on a software protocol of the carrier communication, so as to obtain fourth time information.

It should be noted that, the process of determining the second time information by the boundary clock 102 based on the software protocol of the carrier communication is similar to the process of determining the fourth time information by the slave clock 103 based on the software protocol of the carrier communication, which is not described in detail herein.

In some embodiments, the master clock 101 is specifically configured to perform a time-frequency calibration parameter estimation operation on current time information of the master clock according to a second pulse signal and a time code signal by using a temperature compensated crystal oscillator (Temperature Compensated Crystal Oscillator, TCXO), so as to obtain first time information.

Among them, TCXOs are a high-precision, high-stability crystal oscillator that is commonly used to provide a high-precision time reference for a master clock. The TCXO corrects the frequency of the crystal oscillator by means of temperature compensation to reduce the influence of temperature change on the frequency stability.

In the embodiment of the invention, the TCXO is adopted by the master clock 101 to perform time-frequency calibration parameter estimation operation on the current time information of the master clock according to the second pulse signal and the time code signal, and parameters such as frequency and phase to be adjusted are calculated by comparing the difference between the current time information of the master clock 101 and the received time information (such as the time information of the navigation satellite system), so as to obtain high-precision time information transmitted by the magnitude, namely, first time information, so that the first time information is consistent with the time information of the navigation satellite system, and further, the accuracy and consistency of time in the whole time synchronization system are improved.

In some embodiments, as shown in fig. 6, which is a schematic structural diagram of a time synchronization system provided by the present invention, the time synchronization system may further include a three-level time node 104; a third-level time node 104, configured to determine sixth time information of the navigation satellite system according to the satellite navigation signal; based on the sixth time information, a second pulse signal and a time code signal are generated.

The satellite navigation signal, which may also be referred to as a global navigation satellite system (Global Navigation Satellite System, GNSS) satellite navigation signal, refers to a radio broadcast signal broadcast by a space segment navigation satellite system, and is the only signal capable of establishing a core link for connection in a space segment, a ground segment and a user segment at the same time.

The navigation satellite system is a system for autonomous geographic positioning by utilizing satellites, and has time information with higher accuracy, namely sixth time information.

In the embodiment of the present invention, the three-stage time node 104 may first acquire a satellite navigation signal issued by a navigation satellite system; analyzing the satellite navigation signal to obtain sixth time information of the navigation satellite system; then, the third-stage time node 104 identifies the sixth time information, and generates a corresponding second pulse signal and a corresponding time code signal, so as to provide data support for subsequently updating the current time information of the master clock 101.

In some embodiments, the third stage time node 104, configured to generate the second pulse signal and the time code signal according to the sixth time information, may include: the third-level time node 104 is specifically configured to determine, according to the sixth time information, an absolute time of the second-level node by applying a global navigation satellite system GNSS common view principle; based on the absolute time, a pulse-per-second signal and a time code signal are generated.

The GNSS common view principle refers to that two or more receivers simultaneously receive and measure satellite navigation signals of the same navigation satellite system, and the receivers may be located at different positions and at different times, but can all locate the same satellite.

In the embodiment of the invention, the three-stage time node 104 captures and tracks satellite navigation signals through the common view unit, and then recovers sixth time information of a navigation satellite system based on the satellite navigation information, and then obtains absolute time of the two-stage node by applying a GNSS common view principle, outputs a second pulse signal and a time code signal with higher accuracy, and provides data support for subsequently updating current time information of the main clock 101.

Exemplary, as shown in fig. 7, a schematic structural diagram of the time synchronization system provided by the present invention is shown. As can be seen from fig. 7, the standard time node in the three-stage time node performs time synchronization with the upper time node through a satellite sharing mode, and performs time-frequency synchronization with the master clock 101 through a 1PPS interface and a ToD interface, and performs time-frequency synchronization through a carrier mode when the boundary clock 102 and the slave clock 103 are online, so that each metering device in the whole power electric wave network completes online time-frequency quantity transmission. The whole process solves the demands of high-precision time synchronization and low-cost compatibility which are needed by the digital informatization of the power grid, can meet the application demands of various power scenes, has strong applicability, and lays a foundation for the popularization of carrier time-frequency value transmission and self-adaptive time keeping technology in the whole-network metering device.

The time synchronization method provided by the invention is described below, and the time synchronization method described below and the time synchronization system described above can be referred to correspondingly.

Fig. 8 is a schematic flow chart of a time synchronization method according to the present invention, where the method is applied to the time synchronization system according to any one of fig. 1 to 7, and the time synchronization system includes: a master clock, a boundary clock, and a slave clock; the method may include:

801. and calibrating the current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain first time information.

Optionally, calibrating the current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain the first time information includes: and performing time-frequency calibration parameter estimation operation on the current time information of the main clock according to the second pulse signal and the time code signal by using a temperature compensation type crystal oscillator through the main clock to obtain first time information.

Optionally, the time synchronization system further comprises three levels of time nodes; the method further comprises the steps of: determining sixth time information of a navigation satellite system according to the satellite navigation signals through the three-level time nodes; based on the sixth time information, a second pulse signal and a time code signal are generated.

Optionally, generating, by the third-stage time node, a second pulse signal and a time code signal according to the sixth time information, including: determining the absolute time of the secondary node by using the global navigation satellite system GNSS common view principle according to the sixth time information through the tertiary time node; based on the absolute time, a pulse-per-second signal and a time code signal are generated.

802. Updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-time keeping state by the boundary clock, so as to obtain second time information; and correcting the current time information of the boundary clock according to the first temperature compensation coefficient under the condition that the boundary clock is in a self-time keeping state to obtain third time information.

Optionally, updating, by the boundary clock, current time information of the boundary clock according to the first time information to obtain second time information, including: and updating the current time information of the boundary clock according to the first time information by using the boundary clock, and obtaining second time information, wherein the software protocol is specifically used for carrier communication.

Optionally, correcting, by the boundary clock, current time information of the boundary clock according to the first temperature compensation coefficient to obtain third time information, including: determining a first temperature compensation coefficient by a boundary clock under the condition that the power carrier network where the time synchronization system is located is in an on-line state; and under the condition that the power carrier network is in an offline state, if the boundary clock is in a self-timekeeping state, correcting the current time information of the boundary clock according to the first temperature compensation coefficient to obtain third time information.

Optionally, the boundary clock includes an all-digital time-frequency compensation adjustment module, and the all-digital time-frequency compensation adjustment module is in open loop control under the condition that the power carrier network is in an offline state; the full digital time-frequency compensation adjustment module comprises: the device comprises a decoding unit, a time-frequency calibration parameter estimation unit and a temperature compensation parameter estimation unit; determining a first temperature compensation coefficient by a boundary clock, comprising: the function of obtaining the remote synchronous time from the carrier signal is completed through the decoding unit; the difference comparison of the synchronous time and the current output time under different temperature conditions is completed through a time-frequency calibration parameter estimation unit, and the synchronous time and the current output time are converted into digital correction compensation parameters under different temperature conditions; and the temperature compensation parameter estimation unit is used for analyzing and determining a first temperature compensation coefficient of the crystal oscillator under different temperature conditions according to the digital correction compensation parameters under different temperature conditions.

Optionally, the digital correction compensation parameter is a frequency locking control quantity; the frequency locking control quantity under different temperature conditions is used for controlling the first temperature compensation coefficient under different temperature conditions.

Optionally, the time-frequency calibration parameter estimation unit includes a time drift model and a temperature drift model; the difference comparison of the synchronous time and the current output time under different temperature conditions is completed through the time-frequency calibration parameter estimation unit, and the digital correction compensation parameters under different temperature conditions are converted, and the method comprises the following steps: acquiring an external clock control word and different temperature conditions through a time-frequency calibration parameter estimation unit; inputting an external clock control word into a time drift model to obtain a first parameter; inputting the external clock control word and different temperature conditions into a temperature drift model to obtain a second parameter; and according to the first parameter and the second parameter, the difference comparison between the synchronous time and the current output time under different temperature conditions is completed, and the digital correction compensation parameters under different temperature conditions are converted.

803. Under the condition that the slave clock is in a self-timekeeping state, updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock to obtain fourth time information; and correcting the current time information of the slave clock according to the second temperature compensation coefficient under the condition that the slave clock is in a self-time keeping state to obtain fifth time information.

In the embodiment of the invention, the current time information of the master clock is calibrated according to the second pulse signal and the time code signal by the master clock to obtain the first time information; updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-time keeping state by the boundary clock, so as to obtain second time information; correcting the current time information of the boundary clock according to the first temperature compensation coefficient under the condition that the boundary clock is in a self-time keeping state to obtain third time information; under the condition that the slave clock is in a self-timekeeping state, updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock to obtain fourth time information; and correcting the current time information of the slave clock according to the second temperature compensation coefficient under the condition that the slave clock is in a self-time keeping state to obtain fifth time information. The method solves the requirements of high-precision time synchronization and low-cost compatibility which are needed in the digital informatization of the power grid, can meet the application requirements of various power scenes, and has strong applicability; laying a foundation for the carrier time-frequency value transmission and the self-adaptive time keeping technology popularization in the whole network metering device.

In addition, the method can be widely applied to various links such as power monitoring, metering management, power data analysis and the like, is used for time quantity transmission and self-adaptive timekeeping of the platform metering device from the platform three-level clock node, realizes accurate clock management of various links of the whole power topology, and overcomes the defect of high technical cost of a hardware phase-locked loop commonly used for current time-frequency value transmission.

As shown in fig. 9, a schematic structural diagram of an electronic device provided by the present invention may include: processor 910, communication interface (Communications Interface), memory 930, and communication bus 940, wherein processor 910, communication interface 920, and memory 930 communicate with each other via communication bus 940. Processor 910 may invoke logic instructions in memory 930 to perform a time synchronization method that is applied to a time synchronization system as described in any of fig. 1-7, including: a master clock, a boundary clock, and a slave clock; the method comprises the following steps: calibrating current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain first time information; updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state by the boundary clock, so as to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information; updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock under the condition that the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state to obtain fifth time information.

Further, the logic instructions in the memory 930 described above may be implemented in the form of software functional units and may be stored in a computer-readable storage medium when sold or used as a stand-alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

In another aspect, the present invention also provides a computer program product comprising a computer program storable on a non-transitory computer readable storage medium, the computer program, when executed by a processor, is capable of performing a time synchronization method that is applied to a time synchronization system as described in any one of fig. 1 to 7, the time synchronization system comprising: a master clock, a boundary clock, and a slave clock; the method comprises the following steps: calibrating current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain first time information; updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state by the boundary clock, so as to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information; updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock under the condition that the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state to obtain fifth time information.

In yet another aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform a time synchronization method, the method being applied to a time synchronization system as described in any of fig. 1-7, the time synchronization system comprising: a master clock, a boundary clock, and a slave clock; the method comprises the following steps: calibrating current time information of the master clock according to the second pulse signal and the time code signal by the master clock to obtain first time information; updating the current time information of the boundary clock according to the first time information under the condition that the boundary clock is not in a self-timekeeping state by the boundary clock, so as to obtain second time information; correcting the current time information of the boundary clock according to a first temperature compensation coefficient under the condition that the boundary clock is in the self-timekeeping state to obtain third time information; updating the current time information of the slave clock according to the first time information or the updated time information corresponding to the boundary clock under the condition that the slave clock is in a self-keeping state, so as to obtain fourth time information; and correcting the current time information of the slave clock according to a second temperature compensation coefficient under the condition that the slave clock is in the self-timekeeping state to obtain fifth time information.

The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.

From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A time synchronization system, comprising: a master clock, a boundary clock, and a slave clock;

2. The system of claim 1, wherein the boundary clock for correcting current time information of the boundary clock according to the first temperature compensation coefficient to obtain third time information comprises:

the boundary clock is specifically configured to determine the first temperature compensation coefficient when it is determined that the power carrier network where the time synchronization system is located is in an on-line state; and under the condition that the power carrier network is in an offline state, if the boundary clock is in a self-timekeeping state, correcting the current time information of the boundary clock according to the first temperature compensation coefficient to obtain the third time information.

3. The system of claim 2, wherein the boundary clock comprises an all-digital time-frequency compensation adjustment module that is in open loop control with the power carrier network in an offline state; the all-digital time-frequency compensation adjustment module comprises: the device comprises a decoding unit, a time-frequency calibration parameter estimation unit and a temperature compensation parameter estimation unit;

The boundary clock is specifically configured to determine the first temperature compensation coefficient, and includes:

the decoding unit is used for completing the function of obtaining the remote synchronous time from the carrier signal;

the time-frequency calibration parameter estimation unit is used for completing the difference comparison between the synchronous time and the current output time under different temperature conditions and converting the synchronous time and the current output time into digital correction compensation parameters under the different temperature conditions;

the temperature compensation parameter estimation unit is used for analyzing and determining a first temperature compensation coefficient of the crystal oscillator under different temperature conditions according to the digital correction compensation parameters under different temperature conditions.

4. The system of claim 3, wherein the digitally corrected compensation parameter is a frequency locking control quantity; the frequency locking control quantity under the different temperature conditions is used for controlling the first temperature compensation coefficient under the different temperature conditions.

5. A system according to claim 3, wherein the time-frequency calibration parameter estimation unit comprises a time drift model and a temperature drift model;

the time-frequency calibration parameter estimation unit is specifically used for acquiring an external clock control word and the different temperature conditions; inputting the external clock control word into the time drift model to obtain a first parameter; inputting the external clock control word and the different temperature conditions into the temperature drift model to obtain a second parameter; and according to the first parameter and the second parameter, completing the difference comparison between the synchronous time and the current output time under different temperature conditions, and converting the synchronous time and the current output time into digital correction compensation parameters under different temperature conditions.

6. The system of any of claims 1-5, wherein the boundary clock is configured to update current time information of the boundary clock according to the first time information to obtain second time information, and the method includes:

the boundary clock is specifically configured to update current time information of the boundary clock according to the first time information based on a software protocol of carrier communication, so as to obtain the second time information.

7. The system of any one of claims 1-5, wherein,

the master clock is specifically configured to perform time-frequency calibration parameter estimation operation on current time information of the master clock according to the second pulse signal and the time code signal by using a temperature compensated crystal oscillator, so as to obtain the first time information.

8. The system of any of claims 1-5, further comprising a tertiary time node;

the third-level time node is used for determining sixth time information of a navigation satellite system according to satellite navigation signals; and generating the second pulse signal and the time code signal according to the sixth time information.

9. The system of claim 8, wherein the tertiary time node for generating the second pulse signal and the time code signal from the sixth time information comprises:

The third-level time node is specifically configured to determine an absolute time of the second-level node by applying a global navigation satellite system GNSS common view principle according to the sixth time information; and generating the second pulse signal and the time code signal according to the absolute time.

10. A time synchronization method, characterized by being applied to a time synchronization system according to any one of claims 1-9, the time synchronization system comprising: a master clock, a boundary clock, and a slave clock; the method comprises the following steps: