A quantum time-frequency synchronization method and system for distribution network areas

Abstract

This invention relates to the field of smart grid technology, specifically a method and system for quantum time-frequency synchronization in distribution network areas. The method includes: deploying a master reference unit on the distribution transformer side to generate a high-precision reference time signal and distribute entangled photon pairs within the distribution area; deploying multiple slave node synchronization units on each smart terminal device to receive entangled photon pairs and record photon arrival times; calculating the real-time quantum clock difference between each slave node and the master reference unit using the coincidence counting principle; taming the local CPT atomic clock using an adaptive feedback control module based on the quantum clock difference to achieve time synchronization with the master reference unit; and monitoring the status of the distribution network communication network in real time, automatically switching between closed-loop control mode and open-loop hold mode based on the network status. This invention achieves highly reliable and accurate synchronization of distribution network areas without relying on the public network, possesses anti-spoofing attack capabilities, and provides a secure and accurate time reference for distribution network equipment.

Description

Technical Field

[0001] This invention belongs to the field of smart grid technology, and in particular relates to a quantum time and frequency synchronization method and system for distribution network areas. Background Technology

[0002] As the "last mile" of the smart grid facing users, the operation of distribution network areas directly affects power supply reliability and power quality. With the large-scale integration of distributed photovoltaic, energy storage systems, and electric vehicle charging piles, distribution areas have higher requirements for time synchronization: the intelligent integrated terminals of distribution areas need microsecond-level synchronization to achieve low-voltage topology identification and fault diagnosis; distributed photovoltaic inverters need high-precision time to achieve islanding detection and grid-connected synchronization control; and charging pile clusters need precise timestamps to support orderly charging and V2G (vehicle-to-grid) services.

[0003] Currently, time synchronization in distribution network areas mainly relies on two methods: one is obtaining base station time synchronization through the 4G / 5G public network, and the other is synchronizing between devices through power line carrier (PLC) or low-power wireless communication. However, existing technologies have the following drawbacks: strong dependence on the public network: when the public network is congested or there is a signal blind spot, the timing accuracy of 4G / 5G base stations drops sharply, making it difficult to meet the microsecond-level synchronization requirements; insufficient security: public network time synchronization is not encrypted, making it vulnerable to spoofing attacks and threatening the control security of the distribution area; low synchronization accuracy: power line carrier is affected by channel noise and impedance changes, and the synchronization error can reach the millisecond level, which cannot support high-precision applications such as distribution area fault location; lack of a unified benchmark: the number of devices in the distribution area is large and they are scattered, lacking an effective unified time benchmark and anti-interruption capabilities. Patent CN117376404B discloses a substation communication network architecture based on a wireless public network and quantum encryption. It includes a station control layer switch, a monitoring host, a first time synchronizer, and a wireless quantum security gateway. These components are connected through the station control layer network to exchange data. The wireless quantum security gateway connects to multiple quantum CPEs, which are connected to remote control units (RCUs) via switches and protocol gateways. Each RCU is connected to a second time synchronizer, and the first and second time synchronizers are synchronized using a GPS master clock. The wireless quantum security gateway and the quantum CPEs communicate via a public network remote transmission structure. While this patent involves a time synchronizer and quantum encryption in the substation communication network, it does not optimize the design for the low-cost, high-density characteristics of transformer substation scenarios, exhibiting the same drawbacks as existing technologies.

[0004] Therefore, it is imperative to address the problems of existing distribution network time synchronization, such as strong reliance on the public grid, insufficient security, low accuracy, and lack of a unified benchmark. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a quantum time-frequency synchronization method for distribution network areas, thereby solving the problems of existing distribution network area time synchronization being heavily dependent on the public grid, lacking security, having low accuracy, and lacking a unified benchmark; in addition, this invention also provides a quantum time-frequency synchronization system for distribution network areas.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a quantum time-frequency synchronization method for distribution network areas, comprising the following steps:

[0008] S10. Deploy the main reference unit of the distribution transformer area on the side of the distribution transformer. The main reference unit includes a quantum clock source and a quantum entanglement distribution module, which are used to generate a high-precision reference time signal and distribute entangled photon pairs within the distribution area.

[0009] S20. Deploy multiple slave node synchronization units on each smart terminal device. Each slave node synchronization unit includes a local CPT atomic clock and a single photon detection module, which are used to receive entangled photon pairs and record the photon arrival time.

[0010] S30. Calculate the real-time quantum clock difference between each slave node and the master reference unit using the coincident counting principle;

[0011] S40. Based on the quantum clock difference, the local CPT atomic clock is tamed by the adaptive feedback control module to achieve time synchronization with the main reference unit;

[0012] S50: Real-time monitoring of the communication network status of the distribution area, and automatic switching of synchronization mode according to the network status: when communication is normal, closed-loop control mode is adopted, and real-time feedback is provided for discipline; when communication is interrupted, open-loop hold mode is adopted, and time accuracy is maintained based on the local temperature compensation model.

[0013] Furthermore, in S10, the main reference unit also includes a GNSS (Global Navigation Satellite System) receiving module and a network status detection module. When the GNSS signal is detected to be normal, the main reference unit tames the local quantum clock source through GNSS. When the GNSS signal is detected to be lost or interfered with, the main reference unit switches to the internal quantum clock holding mode to continue providing a unified time reference for the station area.

[0014] Furthermore, in S50, the open-loop hold mode includes:

[0015] Read local temperature sensor data T;

[0016] Query the pre-stored temperature-frequency compensation table to obtain the frequency offset compensation value. ;

[0017] According to the last recorded clock difference Using a local crystal oscillator drift model, estimate the current time deviation. ;

[0018] Output the compensated local time ;

[0019] in, The local time after compensation. Local time before compensation;

[0020] Periodically attempt to recapture the quantum entanglement signal; if recovered, immediately switch back to closed-loop control mode.

[0021] Furthermore, the closed-loop control mode includes:

[0022] Receive entangled photon pairs and calculate clock bias ;

[0023] The control voltage is generated by a PID controller;

[0024] The control voltage is applied to the voltage control terminal of the CPT atomic clock to adjust the output frequency;

[0025] Repeat the above steps until | | <Preset threshold.

[0026] Furthermore, in S40, the calculation of quantum clock error is achieved through a wavelength division multiplexing quantum entanglement distribution network, which utilizes the existing optical fiber resources in the distribution area to simultaneously transmit entangled photons and classical data in the same optical fiber, thereby eliminating the influence of channel asymmetric delay.

[0027] Furthermore, it also includes quantum encrypted communication steps: the calculation of quantum clock difference is realized through wavelength division multiplexing quantum entanglement distribution network, which utilizes the existing optical fiber resources in the substation area to simultaneously transmit entangled photons and classical data in the same optical fiber, eliminating the influence of channel asymmetric delay.

[0028] Furthermore, it also includes a time synchronization constraint construction step: constructing time synchronization constraints for each node in the distribution network, extracting node feature information for clustering under the condition of satisfying the time synchronization constraints, dividing the distribution network into multiple sub-distribution networks, and optimizing the synchronization network topology.

[0029] Secondly, the present invention also provides a quantum time-frequency synchronization system for distribution network areas, comprising:

[0030] The main reference unit for the distribution area is deployed on the side of the distribution transformer and includes:

[0031] Quantum clock sources, such as CPT atomic clocks or chip-scale atomic clocks, are used to generate high-precision local time;

[0032] The GNSS receiver module is used to receive an external time reference from a tamed quantum clock source.

[0033] The quantum entanglement distribution module generates and distributes entangled photon pairs from nodes within the distribution area. It uses wavelength division multiplexing technology to transmit entangled photons and classical data through different wavelength channels in the fiber optic network of the distribution area, thereby achieving co-fiber transmission.

[0034] The network status detection module is used to monitor the public network connection status in real time.

[0035] ARM / FPGA main controller, used for overall coordination and control;

[0036] The system also includes multiple slave node synchronization units, deployed in various smart terminal devices within the distribution area. Each slave node synchronization unit includes:

[0037] Local CPT atomic clock, used for local timekeeping and frequency output;

[0038] A single-photon detection module is used to receive entangled photons and record their arrival time;

[0039] A time-to-digital converter is used to convert the arrival time of photons into a digital signal;

[0040] Temperature sensor, used to collect local temperature data;

[0041] ARM / FPGA slave controller is used to implement clock difference calculation, PID control and dual-mode switching;

[0042] A quantum-encrypted communication channel connects the master reference unit and the slave node unit, and is used for encrypted transmission of synchronization information.

[0043] Furthermore, it also includes a time synchronization constraint construction module, which is used to construct time synchronization constraints for each node in the distribution network and perform cluster analysis based on node characteristic information to optimize the synchronization network topology.

[0044] Furthermore, the slave node synchronization unit also includes a PLC, a PLC+RF and an RF wireless communication module, which are used as backup communication channels to transmit classical synchronization information when quantum communication is interrupted.

[0045] Compared with existing technologies, the quantum time-frequency synchronization method and system for distribution network areas provided by this invention have at least the following advantages:

[0046] The existing time synchronization of distribution network areas suffers from problems such as strong dependence on the public network, insufficient security, low accuracy, and lack of a unified benchmark. This invention provides a unified time reference for the entire distribution area even when the public network is interrupted, thanks to a master quantum clock for the distribution area, thus solving the problem of excessive reliance on the public network in traditional solutions. It utilizes the strong correlation characteristics of quantum entanglement to achieve picosecond-level clock difference measurement, combined with local CPT atomic clock discipline, ensuring synchronization errors between devices within the distribution area are better than 1μs, meeting the requirements for distributed photovoltaic island detection and distribution area fault location. Furthermore, it employs quantum encrypted communication to transmit synchronization auxiliary information, preventing spoofing attacks and man-in-the-middle tampering, ensuring distribution area control security, and improving the overall security of the distribution area. The wavelength division multiplexing technology reuses existing fiber optic resources, and the slave nodes use low-cost CPT atomic clocks, making it suitable for large-scale deployment in distribution areas. The invention intelligently switches between closed-loop and open-loop modes based on network status, maintaining accuracy through local timekeeping during communication interruptions, improving system robustness and time synchronization accuracy. In summary, this invention achieves highly reliable, low-cost microsecond-level synchronization without relying on the public network by constructing a hierarchical synchronization system of "distribution area master quantum clock + slave node atomic clock discipline + quantum encrypted communication". Attached Figure Description

[0047] To more clearly illustrate the solution of the present invention, a brief introduction will be given to the drawings used in the description of the embodiments below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0048] Figure 1 A flowchart of a quantum time-frequency synchronization method for distribution network areas provided in an embodiment of the present invention;

[0049] Figure 2 This is a flowchart illustrating a dual-mode synchronization control method for quantum time-frequency synchronization in a distribution network area, provided in an embodiment of the present invention.

[0050] Figure 3 This is a schematic diagram of the structure of a quantum time-frequency synchronization system for a power distribution network area, provided in an embodiment of the present invention.

[0051] Figure 4 A schematic diagram of the main reference unit of a quantum time-frequency synchronization system for a distribution network area provided in an embodiment of the present invention;

[0052] Figure 5 This is a block diagram illustrating the principle of a slave node synchronization unit in a quantum time-frequency synchronization system for a power distribution network, provided as an embodiment of the present invention. Detailed Implementation

[0053] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0055] This invention provides a quantum time-frequency synchronization method for distribution network substations, applicable to synchronization scenarios involving distribution network equipment (including but not limited to smart converged terminals, metering equipment, measuring equipment, control equipment, charging equipment, and distributed photovoltaic equipment) that face communication interruption risks, complex electromagnetic environments, and cost sensitivity. The quantum time-frequency synchronization method for distribution network substations includes the following steps:

[0056] S10. Deploy the main reference unit of the distribution transformer area on the distribution transformer side. The main reference unit includes a quantum clock source and a quantum entanglement distribution module, which are used to generate a high-precision reference time signal and distribute entangled photon pairs within the distribution area. S20. Deploy multiple slave node synchronization units on each smart terminal device. Each slave node synchronization unit includes a local CPT atomic clock and a single-photon detection module, which are used to receive entangled photon pairs and record photon arrival times. S30. Calculate the real-time quantum clock difference between each slave node and the main reference unit using the coincidence counting principle. S4. Based on the quantum clock difference, tame the local CPT atomic clock through an adaptive feedback control module to achieve time synchronization with the main reference unit. S5. Monitor the status of the distribution area's communication network in real time and automatically switch the synchronization mode according to the network status: when communication is normal, a closed-loop control mode is used with real-time feedback taming; when communication is interrupted, an open-loop hold mode is used, maintaining time accuracy based on a local temperature compensation model.

[0057] This invention achieves highly reliable and accurate synchronization of distribution network areas without relying on the public network, possesses anti-spoofing attack capabilities, and provides a safe and accurate time reference for distribution network equipment.

[0058] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0059] This invention provides a quantum time-frequency synchronization method for distribution network areas, applicable to synchronization scenarios involving distribution network equipment (including but not limited to smart converged terminals, metering equipment, measuring equipment, control equipment, charging equipment, and distributed photovoltaic equipment) where communication interruption risks exist, electromagnetic environments are complex, and costs are sensitive. Figures 1 to 5 In this embodiment, the quantum time-frequency synchronization method for distribution network areas includes the following steps:

[0060] S10. Deploy the main reference unit of the distribution transformer on the side of the distribution transformer. The main reference unit includes a quantum clock source and a quantum entanglement distribution module, which are used to generate a high-precision reference time signal and distribute entangled photon pairs within the distribution area.

[0061] Specifically, in this embodiment, the main reference unit also includes a GNSS receiving module and a network status detection module. When the GNSS signal is detected to be normal, the main reference unit tames the local quantum clock source through GNSS. When the GNSS signal is detected to be lost or interfered with, the main reference unit switches to the internal quantum clock hold mode to continue providing a unified time reference for the station area.

[0062] S20. Deploy multiple slave node synchronization units on each smart terminal device. Each slave node synchronization unit includes a local CPT atomic clock and a single photon detection module, which are used to receive entangled photon pairs and record the photon arrival time.

[0063] S30. Calculate the real-time quantum clock difference between each slave node and the master reference unit by using the coincidence counting principle.

[0064] Specifically, in this embodiment, the calculation of quantum clock bias is achieved through a wavelength division multiplexing quantum entanglement distribution network, which utilizes the existing optical fiber resources in the distribution area to simultaneously transmit entangled photons and classical data in the same optical fiber, thereby eliminating the effects of channel asymmetric delay.

[0065] S40. Based on the quantum clock difference, the local CPT atomic clock is tamed through the adaptive feedback control module to achieve time synchronization with the main reference unit.

[0066] S50: Real-time monitoring of the communication network status of the distribution area, and automatic switching of synchronization mode according to the network status: when communication is normal, closed-loop control mode is adopted, and real-time feedback is provided for discipline; when communication is interrupted, open-loop hold mode is adopted, and time accuracy is maintained based on the local temperature compensation model.

[0067] Specifically, in this embodiment, the open-loop hold mode (network status offline) includes:

[0068] Read local temperature sensor data T;

[0069] Query the pre-stored temperature-frequency compensation table to obtain the frequency offset compensation value. ;

[0070] According to the last recorded clock difference Using a local crystal oscillator drift model, estimate the current time deviation. ;

[0071] Output the compensated local time ;

[0072] Where t_local is the compensated local time, and t_counter is the local time before compensation;

[0073] Periodically attempt to recapture the quantum entanglement signal; if recovered, immediately switch back to closed-loop control mode.

[0074] Closed-loop control modes (network status online) include:

[0075] Receive entangled photon pairs and calculate clock bias ;

[0076] The control voltage is generated by a PID controller;

[0077]

[0078] in, This is the proportional gain, with a value ranging from 0.1 to 5. This is the integral gain, with a value ranging from 0.01 to 0.5. This is the differential gain, with a value ranging from 0.001 to 0.1.

[0079] The control voltage is applied to the voltage control terminal of the CPT atomic clock to adjust the output frequency;

[0080] Repeat the above steps until | | <Preset threshold (e.g., 100ns).

[0081] Furthermore, this embodiment also includes a quantum encrypted communication step: generating a shared key through quantum key distribution technology to encrypt and transmit clock feedback information and synchronization control commands, preventing spoofing attacks and man-in-the-middle tampering.

[0082] Furthermore, this embodiment also includes a time synchronization constraint construction step: constructing time synchronization constraints for each node in the distribution network, extracting node feature information for clustering under the condition of satisfying the time synchronization constraints, dividing the distribution network into multiple sub-distribution networks, and optimizing the synchronization network topology.

[0083] This invention also provides a quantum time-frequency synchronization system for distribution network areas, which employs the quantum time-frequency synchronization method for distribution network areas described in the above embodiments, combined with... Figures 1 to 5In this embodiment, the distribution network area quantum time and frequency synchronization system includes:

[0084] The main reference unit for the distribution area is deployed on the side of the distribution transformer and includes:

[0085] Quantum clock sources, such as CPT atomic clocks or chip-scale atomic clocks, are used to generate high-precision local time;

[0086] The GNSS receiver module is used to receive an external time reference from a tamed quantum clock source.

[0087] The quantum entanglement distribution module generates and distributes entangled photon pairs from nodes within the distribution area. It uses wavelength division multiplexing technology to transmit entangled photons and classical data through different wavelength channels in the fiber optic network of the distribution area, thereby achieving co-fiber transmission.

[0088] The network status detection module is used to monitor the public network connection status in real time. When the public network is detected to be normal, the main reference unit obtains the external time reference through the GNSS dual-mode (GPS / BeiDou) receiver and synchronizes it to each slave node through the quantum entanglement distribution network. When the public network is detected to be interrupted or the GNSS is interfered with, the main reference unit switches to the internal quantum clock holding mode to continue to provide a unified time reference for the station area.

[0089] ARM / FPGA main controller, used for overall coordination and control;

[0090] The system also includes multiple slave node synchronization units, deployed in various smart terminal devices (including converged terminals, PMUs, and edge computing gateways) within the distribution area. Each slave node synchronization unit includes:

[0091] Local CPT atomic clock, used for local timekeeping and frequency output;

[0092] A single-photon detection module is used to receive entangled photons and record their arrival time;

[0093] A time-to-digital converter, connected to a single-photon detection module, is used to convert photon arrival time into a digital signal;

[0094] A temperature sensor, connected to the ARM / FPGA slave controller, is used to acquire local temperature data for temperature compensation in open-loop hold mode;

[0095] The ARM / FPGA slave controller is connected to the time-to-digital converter and the local CPT atomic clock. It is used to calculate the quantum clock difference with the main reference unit based on the photon arrival time, generate PID control voltage to discipline the local CPT atomic clock based on the quantum clock difference, monitor the communication network status in real time, and automatically switch between closed-loop control mode and open-loop hold mode according to the network status.

[0096] A quantum encrypted communication channel connects the master reference unit and the slave node unit, and is used to encrypt the transmission of synchronization information. Classical synchronization auxiliary information is transmitted in encrypted form through quantum key distribution (QKD) technology.

[0097] An adaptive feedback control module, embedded in the ARM / FPGA of the master reference unit and slave node unit, is used to dynamically adjust the local clock based on the clock difference information of quantum entanglement measurement.

[0098] Furthermore, this embodiment also includes a time synchronization constraint construction module, which is used to construct time synchronization constraints for each node in the distribution network and perform cluster analysis based on node characteristic information to optimize the synchronization network topology.

[0099] Furthermore, in this embodiment, the slave node synchronization unit also includes various communication modules such as PLC, PLC+RF, and RF wireless, which are used as backup communication channels to transmit classical synchronization information when quantum communication is interrupted.

[0100] Furthermore, in this embodiment, the slave node synchronization unit includes a dual-mode synchronization mode: when communication is normal, a closed-loop control mode is adopted, which calculates the clock difference by receiving quantum entanglement signals in real time and feeds back to tame the local CPT atomic clock; when communication is interrupted, an open-loop hold mode is adopted, which uses the temperature compensation model of the local CPT atomic clock and pre-stored frequency control parameters to maintain time accuracy.

[0101] Furthermore, in this embodiment, the system adopts a hierarchical synchronization architecture, including multiple relay synchronization nodes. Each relay node synchronizes with the main reference unit through quantum entanglement, and then broadcasts the time synchronization signal to a large number of low-cost terminal devices in its jurisdiction via power line carrier or wireless means.

[0102] Furthermore, in this embodiment, the time-to-digital converter (TDC) of the slave node synchronization unit has a resolution better than 10 ps, ​​which is used to accurately record the arrival time of entangled photons and realize picosecond-level clock difference measurement.

[0103] The working principle of the quantum time-frequency system for the distribution network area provided in this embodiment is as follows:

[0104] During normal system operation, the main reference unit in the distribution area acquires Coordinated Universal Time (UTC) via GNSS as an external reference, while an internal quantum clock source generates a highly stable local time. The main reference unit sends entangled photon pairs to each slave node within the distribution area via a quantum entanglement distribution module. Each slave node records the photon arrival time using a single-photon detector and compares it with its local CPT atomic clock time to calculate the real-time clock difference with the main reference. This clock difference information is fed back to the ARM / FPGA control module of the slave node via a quantum encrypted channel. A PID algorithm is then used to generate a control voltage to discipline the local CPT atomic clock, achieving synchronization with the main reference.

[0105] When the public network is interrupted or the GNSS signal is interfered with, the master reference unit automatically switches to the internal quantum clock hold mode, using a highly stable CPT atomic clock to continue providing a time reference for the station area. If each slave node simultaneously detects a communication interruption, it switches to open-loop hold mode, maintaining accuracy based on a local temperature compensation model. Once communication is restored, it re-acquires the quantum entangled signal for synchronization correction.

[0106] Example 1

[0107] Quantum synchronization system for converged smart terminals in distribution areas

[0108] like Figure 3 As shown, this embodiment provides a quantum time-frequency synchronization system for a distribution network area, including:

[0109] The main reference unit for the distribution transformer area, deployed on the side of the distribution transformer, includes a dual-mode GNSS receiver (supporting GPS and BeiDou), a CPT atomic clock (frequency stability better than 5×10^-11 / s), a quantum entangled light source (based on spontaneous parametric down-conversion of PPKTP crystal, brightness 10^6 pairs / second), a wavelength division multiplexing module, and an ARM / FPGA main controller.

[0110] The slave node synchronization unit is deployed in 20 intelligent fusion terminals within the distribution area. Each unit includes a CPT atomic clock, a single-photon detector (detection efficiency 80%, dark count 100 cps), a time-to-digital converter (resolution 5 ps), an ARM / FPGA slave controller and PLC, PLC+RF and RF communication modules;

[0111] The quantum encrypted communication channel utilizes the existing fiber optic network in the distribution area and employs the BB84 protocol to implement quantum key distribution for encrypted transmission of clock feedback information.

[0112] The system workflow is as follows:

[0113] Step 1: Master Reference Unit Initialization: After the master reference unit is powered on, the dual-mode GNSS receiver acquires satellite signals, obtains UTC time, and tames the local CPT atomic clock to establish the station area time reference. Simultaneously, the quantum entangled light source is activated, generating entangled photon pairs and transmitting them to each slave node via the wavelength division multiplexing module.

[0114] Step 2: Acquiring entangled signals from the slave node synchronization unit: Each slave node receives entangled photons through a single-photon detector and records the photon arrival time τ_i (i=1,...,20). Since entangled photon pairs are time-correlated, the effect of fiber transmission delay can be eliminated by coincidence counting, and the clock difference ∆τ_i between slave node i and the master reference can be calculated.

[0115] Step 3: Clock Difference Feedback and Closed-Loop Discipline: The slave nodes upload ∆τ_i to the master reference unit via a quantum-encrypted channel. The ARM / FPGA controller of the master reference unit calculates the PID control input based on the clock difference information of each slave node and sends it to the corresponding slave node. The slave nodes adjust the voltage-controlled voltage of their local CPT atomic clocks according to the control inputs, thus achieving closed-loop discipline.

[0116] Step 4: Dual-mode switching mechanism: The network status detection module of the main reference unit monitors the public network connection status in real time. For example... Figure 4 As shown, when a GNSS signal loss or public network interruption is detected, the master reference unit automatically switches to internal quantum clock hold mode, utilizing the short-term high stability characteristics of the CPT atomic clock to continue outputting reference time. Simultaneously, a switching command is broadcast to each slave node. Upon receiving the command, if the slave node's communication is normal (it can still receive entangled photons), it continues closed-loop synchronization; if communication is also interrupted, it switches to open-loop hold mode, maintaining local time accuracy based on a pre-stored temperature-frequency compensation table.

[0117] Step 5: Recovery and Resynchronization: Once the public network is restored or the GNSS signal is reacquired, the master reference unit re-tames the external reference and initiates a resynchronization process to each slave node to gradually correct the time deviation accumulated during the open loop.

[0118] Example 2

[0119] Detailed implementation of quantum cryptographic synchronization

[0120] This embodiment, based on Embodiment 1, further details the implementation of quantum encrypted communication. A shared key is generated between the master reference unit and the slave node via quantum key distribution (QKD) to encrypt the transmission of clock difference feedback information and synchronization control commands. Specific steps include:

[0121] The master reference unit prepares a decoy state quantum signal using a weakly coherent light source and transmits it to the slave node via optical fiber;

[0122] The basis vector information and photon arrival time are measured and recorded from the node using a single-photon detector;

[0123] Both parties perform basis comparison, key screening, and error correction through a classic authentication channel to generate a secure key;

[0124] The clock feedback information is encrypted using a one-time pad using this key to ensure the security of the synchronization process.

[0125] Compared with existing technologies, the quantum time and frequency synchronization method and system for distribution network areas described in the above embodiments have problems such as strong dependence on the public network, insufficient security, low accuracy and lack of a unified benchmark. This invention provides a unified time reference for the entire distribution area even when the public network is interrupted, thanks to a master quantum clock for the distribution area, thus solving the problem of excessive reliance on the public network in traditional solutions. It utilizes the strong correlation characteristics of quantum entanglement to achieve picosecond-level clock difference measurement, combined with local CPT atomic clock discipline, ensuring synchronization errors between devices within the distribution area are better than 1μs, meeting the requirements for distributed photovoltaic island detection and distribution area fault location. Furthermore, it employs quantum encrypted communication to transmit synchronization auxiliary information, preventing spoofing attacks and man-in-the-middle tampering, ensuring distribution area control security, and improving the overall security of the distribution area. The wavelength division multiplexing technology reuses existing fiber optic resources, and the slave nodes use low-cost CPT atomic clocks, making it suitable for large-scale deployment in distribution areas. The invention intelligently switches between closed-loop and open-loop modes based on network status, maintaining accuracy through local timekeeping during communication interruptions, improving system robustness and time synchronization accuracy. In summary, this invention achieves highly reliable, low-cost microsecond-level synchronization without relying on the public network by constructing a hierarchical synchronization system of "distribution area master quantum clock + slave node atomic clock discipline + quantum encrypted communication".

[0126] Obviously, the embodiments described above are merely preferred embodiments of the present invention, and not all embodiments. The accompanying drawings illustrate preferred embodiments of the present invention, but do not limit the scope of the patent. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this invention.

Claims

1. A quantum time-frequency synchronization method for distribution network areas, characterized in that, Includes the following steps: S10. Deploy the main reference unit of the distribution transformer area on the side of the distribution transformer. The main reference unit includes a quantum clock source and a quantum entanglement distribution module, which are used to generate a high-precision reference time signal and distribute entangled photon pairs within the distribution area. S20. Deploy multiple slave node synchronization units on each smart terminal device. Each slave node synchronization unit includes a local CPT atomic clock and a single photon detection module, which are used to receive entangled photon pairs and record the photon arrival time. S30. Calculate the real-time quantum clock difference between each slave node and the master reference unit using the coincident counting principle; S40. Based on the quantum clock difference, the local CPT atomic clock is tamed by the adaptive feedback control module to achieve time synchronization with the main reference unit; S50: Real-time monitoring of the communication network status of the distribution area, and automatic switching of synchronization mode according to the network status: when communication is normal, closed-loop control mode is adopted, and real-time feedback is provided for discipline; when communication is interrupted, open-loop hold mode is adopted, and time accuracy is maintained based on the local temperature compensation model.

2. The quantum time-frequency synchronization method for distribution network areas according to claim 1, characterized in that, In S10, the main reference unit also includes a GNSS receiving module and a network status detection module. When the GNSS signal is detected to be normal, the main reference unit tames the local quantum clock source through GNSS. When GNSS signal loss or interference is detected, the main reference unit switches to internal quantum clock hold mode to continue providing a unified time reference for the station area.

3. The quantum time-frequency synchronization method for distribution network areas according to claim 1, characterized in that, In S50, the open-loop hold mode includes: Read local temperature sensor data T; Query the pre-stored temperature-frequency compensation table to obtain the frequency offset compensation value. ; According to the last recorded clock difference Using a local crystal oscillator drift model, estimate the current time deviation. ; Output the compensated local time ; in, The local time after compensation. Local time before compensation; Periodically attempt to recapture the quantum entanglement signal; if recovered, immediately switch back to closed-loop control mode.

4. The quantum time-frequency synchronization method for distribution network areas according to claim 3, characterized in that, The closed-loop control modes include: Receive entangled photon pairs and calculate clock bias ; The control voltage is generated by a PID controller; The control voltage is applied to the voltage control terminal of the CPT atomic clock to adjust the output frequency; Repeat the above steps until | | <Preset threshold.

5. The quantum time-frequency synchronization method for distribution network areas according to claim 1, characterized in that, In S40, the calculation of quantum clock error is realized through wavelength division multiplexing quantum entanglement distribution network, which utilizes the existing optical fiber resources in the substation area to simultaneously transmit entangled photons and classical data in the same optical fiber, thereby eliminating the influence of channel asymmetric delay.

6. The quantum time-frequency synchronization method for distribution network areas according to claim 1, characterized in that, It also includes quantum encrypted communication steps: the calculation of quantum clock difference is realized through wavelength division multiplexing quantum entanglement distribution network, which utilizes the existing optical fiber resources in the substation area to transmit entangled photons and classical data simultaneously in the same optical fiber, eliminating the effects of channel asymmetric delay.

7. The quantum time-frequency synchronization method for distribution network areas according to claim 6, characterized in that, It also includes a time synchronization constraint construction step: constructing time synchronization constraints for each node in the distribution network, extracting node feature information for clustering under the condition that the time synchronization constraints are met, dividing the distribution network into multiple sub-distribution networks, and optimizing the synchronization network topology.

8. A system employing the method as described in any one of claims 1 to 7, characterized in that, include: The main reference unit for the distribution area is deployed on the side of the distribution transformer and includes: Quantum clock sources, such as CPT atomic clocks or chip-scale atomic clocks, are used to generate high-precision local time; The receiving module is used to receive an external time reference tamed quantum clock source; The quantum entanglement distribution module generates and distributes entangled photon pairs from nodes within the distribution area. It uses wavelength division multiplexing technology to transmit entangled photons and classical data through different wavelength channels in the fiber optic network of the distribution area, thereby achieving co-fiber transmission. The network status detection module is used to monitor the public network connection status in real time. ARM / FPGA main controller, used for overall coordination and control; The system also includes multiple slave node synchronization units, deployed in various smart terminal devices within the distribution area. Each slave node synchronization unit includes: Local CPT atomic clock, used for local timekeeping and frequency output; A single-photon detection module is used to receive entangled photons and record their arrival time; A time-to-digital converter is used to convert the arrival time of photons into a digital signal; An ARM / FPGA slave controller is used to implement clock difference calculation, PID control, and dual-mode switching.

9. The system according to claim 8, characterized in that, It also includes a time synchronization constraint construction module, which is used to construct time synchronization constraints for each node in the distribution network and perform cluster analysis based on node characteristic information to optimize the synchronization network topology.

10. The system according to claim 8, characterized in that, The slave node synchronization unit also includes a PLC, a PLC+RF and an RF wireless communication module, used as a backup communication channel to transmit classical synchronization information when quantum communication is interrupted; and a quantum encrypted communication channel, connecting the master reference unit and the slave node unit, used for encrypted transmission of synchronization information.

Images