Power transmission project time service fault-tolerant protection method and system based on low earth orbit satellite

Abstract

The invention discloses a power transmission project time service fault-tolerant protection method and system based on a low earth orbit satellite.The method is applied to a double-layer time service device and comprises the steps that multi-source data of multiple signal sources of the double-layer time service device are synchronously obtained for synchronous calibration, and a multi-source state space error model of the double-layer time service device is constructed; the data error state of the multi-path signal source is analyzed through the model, the signal quality is evaluated, the fusion weight is dynamically distributed according to the signal quality evaluation result to obtain a filtering fusion signal, health state evaluation processing is carried out on the multi-path signal source of the double-layer time service device, and then the time bases of the multi-path signal source are correspondingly switched. And performing time service mode switching processing on the double-layer time service device, synchronously distributing the filtering fusion signal to each power transformation point of the power transmission project, and performing round-trip time delay compensation processing on each power transformation point to obtain time service calibration data of the double-layer time service device. The method has the effect of improving the time service fault-tolerant capability of the power transmission project of the low-orbit satellite.

Description

Technical Field

[0001] This invention relates to the technical field of time-to-fault protection in engineering, and in particular to a time-to-fault protection method and system for power transmission projects based on low-Earth orbit satellites. Background Technology

[0002] Currently, key algorithms in power transmission engineering, such as differential protection, power angle control, and fault location, have extremely high requirements for timing accuracy. Generally, the clock deviation needs to be controlled within 5 ns, and the deterministic foldback delay needs to be less than 1 μs, in order to meet the reliability requirements of millisecond-level protection actions.

[0003] Existing timing solutions primarily rely on a combination of Global Navigation Satellite System (GNSS) and a local OCXO (Oven-Controlled Crystal Oscillator). GNSS provides a pulse-per-second output signal to calibrate the OCXO, achieving nanosecond-level synchronization under normal conditions. However, when the GNSS signal is interrupted or lost due to obstruction, smoke, or malicious interference, the OCXO experiences excessive drift within hours, making it difficult to continuously meet the protection system's requirement for a highly stable time base. Furthermore, the GNSS link lacks sufficient anti-interference capabilities in disaster scenarios such as landslides and typhoons, posing safety hazards. Therefore, in extreme post-disaster scenarios such as GNSS signal failure, complete fiber optic cable breakage, or other adverse events, existing timing solutions struggle to simultaneously meet the technical requirements of "nanosecond-level jitter," "millisecond-level response," and "low-cost, large-scale deployment" for low-Earth orbit (LEO) satellites, leaving room for further optimization in fault-tolerant protection for LEO satellite power transmission projects. Summary of the Invention

[0004] To address the problem of insufficient fault tolerance in timing schemes for power transmission projects using low-Earth orbit (LEO) satellites under extreme post-disaster scenarios such as GNSS signal failure, complete fiber optic cable breakage, and GNSS signal failure, this invention provides a fault-tolerant timing protection method and system for power transmission projects based on LEO satellites. This method can improve the fault tolerance of timing in power transmission projects using LEO satellites and provide support for the continuous and reliable operation of power transmission projects in high-rigidity timing scenarios.

[0005] Firstly, the above-mentioned inventive objective of this application is achieved through the following technical solution: A time-synchronous fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites, the method being applied to a two-layer time-synchronous device combining an atomic clock, GNSS, and a low-Earth orbit satellite bidirectional time delay demodulator, the method comprising: The system synchronously acquires multi-source data from multiple signal sources of the dual-layer timing device, performs synchronous calibration on the multi-source data, and constructs a multi-source state-space error model for the dual-layer timing device. The data error state of multiple signal sources is analyzed by the multi-source state-space error model and the signal quality of the corresponding signal sources is evaluated. The fusion weights are dynamically allocated according to the signal quality evaluation results to obtain the filtered and fused signal. The health status assessment of the multiple signal sources of the dual-layer time synchronization device is performed, and the time base of the multiple signal sources is switched according to the signal health assessment results. The time synchronization mode of the dual-layer time synchronization device is then switched. According to the switched time synchronization mode, the filtered and fused signal is synchronously distributed to each substation of the power transmission project, and round-trip delay compensation is performed on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

[0006] In a preferred embodiment, this application can be further configured as follows: synchronously acquiring multi-source data from multiple signal sources of the dual-layer timing device, synchronously calibrating the multi-source data, and constructing a multi-source state-space error model of the dual-layer timing device, specifically including: Simultaneously acquire the GNSS pulse output, low-orbit satellite delay estimate, and atomic clock local oscillator phase corresponding to the multiple signal sources of the dual-layer timing device to obtain multi-source data from the multiple signal sources; Obtain the signal arrival time difference of each signal source at the same sampling time node, perform synchronous calibration on the corresponding multi-source data, and construct the state vector matrix of the multi-source data. The expression of the state vector matrix is ​​as follows: (1) in, express The state vector at each time sampling point Indicates frequency drift. Indicates short-term fluctuations. Indicates a sudden change; Based on the state vector matrix analysis, the drift state vector and the unit observation vector under the drift state are shown in Equation (2) and Equation (3), respectively: (2) (3) in, express The drift state vector at the time sampling point, This represents the state transition matrix under drift conditions. express Observation vector at time sampling point Represents the unit observation matrix. These are the process noise covariance and the observation noise covariance, respectively. The covariance matrix representing the process noise. The covariance matrix representing the observation noise. and These represent Gaussian white noise vectors with zero mean; Calculate the signal time difference sequence within the preset sampling window, estimate the drift rate and jitter variance of the multi-source data respectively, optimize the drift state matrix and unit observation matrix, and construct a multi-source state space error model; The expression for the signal time difference sequence is as follows: (4) (5) in, , , They represent The arrival timestamps of signals from GNSS, low-orbit satellite two-way time delay demodulators, and atomic clocks at the sampling time points.

[0007] In a preferred embodiment, this application can be further configured as follows: the step of analyzing the data error state of multiple signal sources and evaluating the signal quality of the corresponding signal sources through the multi-source state-space error model, and dynamically allocating fusion weights according to the signal quality evaluation results to obtain the filtered fused signal, specifically includes: The multi-source state space error model is used to analyze the data error state of the state vectors corresponding to adjacent sampling times, and the signal quality of the corresponding signal source is evaluated based on the data error state. Based on the signal quality assessment results, Kalman gain is assigned to the corresponding signal sources to create fusion weights, and the state vectors of the corresponding signal sources are updated to obtain the filtered and fused signal. The Kalman gain expression is shown below: (6) in, express Kalman gain at time step To predict covariance, Represents the observation matrix. The table resembles the transpose of the observation matrix. Represents the observation noise covariance matrix; The state update expression for the signal source is as follows: (7) in, express The signal source state vector at time -1.

[0008] In a preferred embodiment, this application can be further configured as follows: performing a health status assessment on the multiple signal sources of the dual-layer time synchronization device, switching the time base of the multiple signal sources according to the signal health assessment result, and performing a time synchronization mode switching on the dual-layer time synchronization device, specifically including: The observation residual vector after filtering and fusion is calculated based on the fused filtered signal, and the timing quality of the dual-layer timing device is analyzed based on the observation residual vector. The expression for the observation residual vector is as follows: (8) The expression for timing quality is as follows: (9) in, This indicates the time difference between GNSS and LEO observations. For the observation matrix, This indicates updating the state vector of the corresponding signal source. This represents the measurement noise covariance. express The observed residual vector at time t, This represents the transpose of the residual vector; The health status of multiple signal sources is assessed based on the time synchronization quality analysis results. The time base of the multiple signal sources is switched based on the signal health assessment results. The time synchronization mode of the dual-layer time synchronization device is switched.

[0009] In a preferred embodiment, this application can be further configured as follows: The filtered and fused signal is synchronously distributed to each substation of the power transmission project according to the switched time synchronization mode, and round-trip delay compensation is performed on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device, specifically including: Through a preset data distribution mechanism, the time base of the switched time synchronization mode is synchronized to each substation of the power transmission project, and the clock deviation of each substation is adjusted accordingly. According to the adjusted substation clock, the filtered and fused signal is synchronously distributed to each substation, and the round-trip delay of signal reception and feedback at each substation is calculated. Calculate the round-trip delay compensation coefficient for each substation point, perform round-trip delay compensation processing on the corresponding substation points, and obtain the timing calibration data of the dual-layer timing device; The expression for the round-trip delay compensation coefficient is as follows: (10) in, , These represent the signal transmission timestamp of the dual-layer time synchronization device and the signal reception timestamp of the substation, respectively. , These represent the timestamps of the delay signals transmitted by the dual-layer time synchronization device and the timestamps of the delay signals received by the substation, respectively.

[0010] In a preferred embodiment, this application may be further configured as follows: the step of calculating the round-trip delay compensation coefficient for each substation point, performing round-trip delay compensation processing on the corresponding substation points, and obtaining the timing calibration data of the dual-layer timing device further includes: According to the round-trip compensation coefficient, the local clock of each substation is calibrated, and the clock difference between the calibrated substation clock and the master station clock of the dual-layer time synchronization device is evaluated to see if it is within a preset range. When the clock difference exceeds the preset range, the local clock of the corresponding substation point is subjected to cyclic clock calibration to obtain the timing calibration data after the substation point clock is calibrated. The local clock calibration expression for the substation is shown below: (11) in, This indicates the local clock calibration compensation amount at the substation point. The local clock indicating the substation point This represents the round-trip compensation coefficient.

[0011] In a preferred embodiment, this application can be further configured such that the method also includes: Real-time operation monitoring data of the dual-layer time synchronization device is acquired, and the operation monitoring data is compared with the corresponding operation safety thresholds to analyze the operation safety performance of the power transmission project. Based on the results of the operational safety performance analysis, fault analysis and location are performed on the local alarm data, and corresponding maintenance instructions are generated and sent synchronously to the faulty substation.

[0012] Secondly, the above-mentioned inventive objective of this application is achieved through the following technical solutions: A fault-tolerant protection system for power transmission projects based on low-Earth orbit satellites, the system being applied to the aforementioned time-synchronization fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites, the system comprising: The model building module is used to synchronously acquire multi-source data from multiple signal sources of the dual-layer timing device, synchronously calibrate the multi-source data, and build a multi-source state space error model of the dual-layer timing device. The data processing module is used to analyze the data error state of multiple signal sources and evaluate the signal quality of the corresponding signal sources through the multi-source state space error model, and dynamically allocate fusion weights according to the signal quality evaluation results to obtain the filtered fused signal. The mode switching module is used to perform health status assessment processing on the multiple signal sources of the dual-layer time synchronization device, and switch the time base of the multiple signal sources according to the signal health assessment results, and perform time synchronization mode switching processing on the dual-layer time synchronization device. The data calibration module is used to synchronously distribute the filtered and fused signal to each substation of the power transmission project according to the switched time synchronization mode, and perform round-trip delay compensation processing on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

[0013] Thirdly, the above-mentioned objectives of this application are achieved through the following technical solutions: A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the above-described time-to-fault protection method for power transmission projects based on low-Earth orbit satellites.

[0014] Fourthly, the above-mentioned objectives of this application are achieved through the following technical solutions: A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described time-compensated fault protection method for power transmission projects based on low-Earth orbit satellites.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. This application incorporates three time base sources—GNSS, LEO-TWTT, and a micro atomic clock—into the same error state extended Kalman filter (ESAKF multi-strategy Kalman filter algorithm) framework. It evaluates the jitter and drift characteristics of each source in real time and dynamically allocates fusion weights, outputting a 1-pulse-per-second output reference signal with nanosecond-level jitter. This application balances the low short-term jitter of GNSS, the disaster tolerance of the LEO link, and the long-term timekeeping characteristics of the atomic clock. Even in extreme scenarios such as GNSS lockout or complete fiber optic cable failure, it maintains a high-precision time base, improving the system's robustness and reliability. 2. Under normal operating conditions, GNSS is used as the primary time base, with LEO-TWTT and local OCXO in parallel for backup. The three time base data are fused in real time through the Error State Extended Kalman Filter (ESAKF multi-strategy Kalman filter algorithm) algorithm to estimate and compensate for jitter, drift and abrupt changes online, achieving 1 pulse output per second and nanosecond-level jitter (σ≤2 ns) and microsecond-level delay determinism for 10 MHz signal. When GNSS is lost or the ground fiber is completely broken, it automatically switches to the micro rubidium atomic clock timekeeping mode and adaptively increases the weight of LEO-TWTT to try to ensure that the time base deviation is ≤30 ns within 72 hours without manual intervention.

[0016] 3. This application distributes the fused 1 pulse per second / 10 MHz reference in each substation using the Profile-EHVAC hardware timestamp PTP mechanism, and eliminates path asymmetry through phase FIFO compensation, which can achieve an end-to-end time base deviation of <5 ns for 5 stations or more. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0018] Figure 1 This is a flowchart illustrating the implementation of the time-compensated fault protection method for power transmission projects based on low-Earth orbit satellites in this embodiment.

[0019] Figure 2 This is a flowchart illustrating the implementation of step S10 of the power transmission engineering time synchronization fault-tolerant protection method in this embodiment.

[0020] Figure 3 This is a flowchart illustrating the implementation of step S20 of the power transmission engineering time-compensated fault protection method in this embodiment.

[0021] Figure 4 This is a flowchart illustrating the implementation of step S30 of the power transmission engineering time-compensated fault protection method in this embodiment.

[0022] Figure 5 This is a flowchart illustrating the implementation of step S40 of the power transmission engineering time-compensated fault protection method in this embodiment.

[0023] Figure 6 This is a flowchart illustrating the implementation of round-trip delay compensation in the power transmission engineering timing fault-tolerant protection method of this embodiment.

[0024] Figure 7 This is a flowchart illustrating the implementation of fault alarm in the power transmission engineering time-compensated fault protection method of this embodiment.

[0025] Figure 8 This is a flowchart of the overall data processing of the dual-layer time synchronization device in this embodiment.

[0026] Figure 9 This is a schematic diagram illustrating the application scenario of the dual-layer time synchronization device in this embodiment.

[0027] Figure 10 This is a structural block diagram of the fault-tolerant protection system for power transmission projects based on low-orbit satellites in this embodiment.

[0028] Figure 11This is a schematic diagram of the internal structure of a computer device used to implement a time-compensated fault protection method for power transmission projects. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0031] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0033] In one embodiment, this application discloses a time synchronization fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites. This method is applied to a two-layer time synchronization device combining an atomic clock, GNSS, and a two-way time delay demodulator from a low-Earth orbit satellite. The application scenario of this two-layer time synchronization device is as follows: Figure 9 As shown, the atomic clock in this application is a miniature rubidium atomic clock. The miniature rubidium atomic clock, GNSS receiver, and LEO-TWTT modem are packaged in a 19″ / 3U chassis, completing the power, clock, and data bus connections, constructing a timekeeping-time tracking hardware closed loop, and achieving portable deployment. Specifically, in terms of chassis and volume control, a 19″ / 3U chassis with an internal depth D=45 mm, width W=482.6 mm, and height H=133 mm is selected, meeting the installation requirements of confined spaces on site. In this embodiment, LEO-TWTT represents bidirectional time delay measurement based on low-Earth orbit satellites (such as Starlink, OneWeb reverse ranging) to compensate for LEO link jitter and achieve nanosecond-level time base tracking. GNSS represents the Global Navigation Satellite System. The overall dimensions of the chassis correspond to the volume expression shown below: (12) Specifically, the atomic clock module outputs 1 pulse per second and a 10 MHz reference via an SMA interface. The GNSS receiver and LEO-TWTT modem are each connected to the main clock bus via coaxial cables of equal length (ΔL≤0.2 m). Because the signal propagation speed is approximately... The expression for calculating the maximum time delay difference corresponding to the chassis signal interface is as follows: (13) The timing delay of the chassis's main clock bus is adjusted by using the maximum experimental difference to ensure that the initial time base deviation of the chassis is within the nanosecond range. The power consumption of the entire system consists of a miniature rubidium atomic clock, a GNSS module, and a LEO-TWTT unit, which meets the power supply capacity and heat dissipation limitations of the substation site. After completing the above assembly, a highly stable and low-jitter hardware foundation is laid for subsequent baseline calibration and adaptive filtering.

[0034] In this embodiment, in order to cope with the extreme temperature (-40 ℃ ~ +70 ℃), humidity and mechanical vibration environment that may occur in mountain substations or disaster sites, this step uses a "shallow mist cooling" shell combined with a wide temperature vibration reduction structure to achieve dual isolation of temperature and vibration for the miniature rubidium atomic clock, ensuring a constant internal operating temperature and significantly attenuating external excitation.

[0035] Specifically, the chassis incorporates a Peltier semiconductor cooling unit and a high-precision temperature sensor (resolution 0.01 ℃) to form a PID closed loop, achieving closed-loop temperature control and stabilizing the atomic clock's operating temperature at 20 ± 0.1 ℃. The dynamic characteristics of the temperature control can be described using a first-order inertial model. (14) in, Indicates time The actual operating temperature of the atomic clock; Indicates the set target temperature; It represents thermal time, used to characterize the dynamic response speed of a temperature control system; This represents the rate of change of temperature over time. The thermal stability ensures that the temperature returns to the set temperature within 10 minutes in the event of a sudden change in ambient temperature of ±30 ℃. The frequency drift coefficient caused by temperature sensitivity is ≤1×10⁻¹¹ / ℃, and the corresponding frequency jitter is <1×10⁻¹² under fluctuations of ±0.1 ℃, supporting nanosecond-level stable frequency output.

[0036] The outer shell uses an aluminum alloy main frame and a nanoporous "light mist" heat insulation coating, with a total thermal conductivity coefficient of [missing information]. At an external temperature of -40 °C, the rate of temperature decrease inside the casing is controlled within a certain range. It significantly extends the response time to cold / thermal shocks and reduces the impact on the refrigeration system.

[0037] The atomic clock is "tamed" with GNSS signals, and the delay of the internal coaxial wiring and LEO link is calibrated to provide an accurate initial state for the subsequent ESAKF multi-strategy Kalman filter algorithm fusion with a jitter of <5 ns. LEO represents low Earth orbit satellite.

[0038] Specifically, after the system is powered on, it continuously collects the time difference between the GNSS pulse output per second and the atomic clock pulse output per second. The atomic clock frequency is adjusted using a PI servo controller, and the expression for adjusting the atomic clock frequency is shown below: (15) (16) in, Indicates at time The time difference between GNSS pulse signals and atomic clock pulse signals; This represents the control output of the PI servo controller; This represents the proportional gain, used to quickly correct instantaneous errors; This represents the integral gain, used to eliminate accumulated bias. This represents the local oscillator frequency of the atomic clock during its free-running operation. Indicates at time The atomic clock output frequency after servo adjustment. In this embodiment, by reasonably selecting the gain (K_p,K_i), Δt is made to converge to <2 ns within 1 h, thus completing the first "taming" of the atomic clock.

[0039] Subsequently, the lengths L_i of the coaxial cables and PCB traces from the atomic clock, GNSS module, and LEO modem to the main clock bus were measured, and the time delay was calculated based on the signal propagation speed v≈2×10^8 m / s: (17) In this embodiment, based on the calculated time delay, phase compensation is performed on the 1 second pulse output signal in the bus access logic to ensure that the initial deviation after each source access is <1 ns.

[0040] Finally, the LEO-TWTT link is initiated. The ground station records the transmission timestamp t_1, the LEO satellite relay timestamp t_2′, and the ground reception timestamp t_3, and calculates the round-trip delay. (18) τ_LEO is then written into the initial state vector x0 of the ESAKF multi-strategy Kalman filter algorithm, providing accurate priors for subsequent filtering. This completes the initialization of the two-layer timing device. This indicates the timestamp sent by the ground station. This indicates the timestamp used by the low-orbit satellite to receive uplink signals from the ground station. This indicates the timestamp used by a low-orbit satellite to relay downlink signals. This indicates the timestamp of the downlink signal received by the ground station.

[0041] This embodiment integrates a GNSS receiver, a LEO-TWTT modem, and a miniature rubidium atomic clock within a 19″ / 3U portable chassis. It employs PID temperature control and vibration damping to ensure temperature fluctuations of ≤0.1℃ under ±30℃ sudden temperature changes. When any time source fails, the system can complete a three-state switch between "time tracking—timekeeping—time tracking" within ≤500 μs. This chassis-based, modular design achieves low cost and portable deployment; the rapid switching capability ensures uninterrupted pulse output at 1 pulse per second, meeting the millisecond-level continuity requirements of differential protection and reducing the frequency of maintenance intervention.

[0042] This embodiment presents a time-synchronous fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites, such as... Figure 1 As shown, the method specifically includes the following steps: S10: Synchronously acquire multi-source data from multiple signal sources of the dual-layer time synchronization device, synchronously calibrate the multi-source data, and construct a multi-source state-space error model of the dual-layer time synchronization device.

[0043] Specifically, such as Figure 2 As shown, step S10 includes: S101: Synchronously acquire GNSS pulse output, low-orbit satellite delay estimate and atomic clock local oscillator phase corresponding to multiple signal sources of the dual-layer timing device to obtain multi-source data of multiple signal sources.

[0044] Specifically, during the operation of the dual-layer timing device after initialization, the corresponding GNSS pulse output, low-orbit satellite delay estimate, and atomic clock local oscillator phase are synchronously acquired to obtain multi-source data. In this embodiment, there are three signal sources: a miniature rubidium atomic clock, a GNSS receiver, and a LEO-TWTT modem.

[0045] S102: Obtain the signal arrival time difference of each signal source at the same sampling time node, perform synchronous calibration on the corresponding multi-source data, and construct the state vector matrix of the multi-source data. The expression of the state vector matrix is ​​as follows: (1) in, express The state vector at each time sampling point Indicates frequency drift. Indicates short-term fluctuations. Indicates a sudden change. k This represents the sampling time number in the discrete-time series, used to identify the first sampling time. k The state of each sampling point.

[0046] Specifically, a time interval counter (TDC) with a resolution of 1 ns is used to simultaneously sample three 1-pulse-per-second output signals and record the arrival timestamp of each signal: It should be noted that the sampling period can be configured to 1 second or shorter to meet the requirements of millisecond-level protection actions, and is not limited to one of the methods in this embodiment.

[0047] The arrival time difference of each signal source at the same sampling time node is calculated based on the arrival timestamp of each signal. The corresponding signal sources are compared with the master clock reference for synchronous clock calibration. Data such as frequency drift, short-term jitter and sudden jump are obtained to construct a state vector matrix.

[0048] S103: Analyze the drift state vector and unit observation vector under the drift state based on the state vector matrix. The expressions for the drift state vector and unit observation vector are shown in Equation (2) and Equation (3), respectively: (2) (3) in, express The drift state vector at the time sampling point, This represents the state transition matrix under drift conditions. express Observation vector at time sampling point Represents the unit observation matrix. These are the process noise covariance and the observation noise covariance, respectively. The covariance matrix, representing process noise, is used to characterize the intensity of random disturbances during system state transitions. The covariance matrix, representing the observation noise, is used to characterize the random errors introduced during the measurement process. and These represent Gaussian white noise vectors with zero mean, reflecting the uncertainties in state evolution and observation.

[0049] S104: Calculate the signal time difference sequence within the preset sampling window, estimate the drift rate and jitter variance of the multi-source data respectively, optimize the drift state matrix and unit observation matrix, and construct a multi-source state space error model.

[0050] The expression for the signal time difference sequence is as follows: (4) (5) in, , , They represent The arrival timestamps of signals from GNSS, low-orbit satellite two-way delay demodulators, and atomic clocks at the sampling time points. Represents the first in a discrete time series Each sampling point is used to identify the signal arrival timestamp at the corresponding time.

[0051] Specifically, the drift rate estimate and jitter variance are used as... , The initial values ​​are used to optimize the drift state matrix and the unit observation matrix by combining formulas (2) and (3), and the state vector matrix is ​​adaptively calibrated according to the optimization results to construct a multi-source state space error model.

[0052] S20: Analyze the data error state of multiple signal sources and evaluate the signal quality of the corresponding signal sources through a multi-source state-space error model. Dynamically allocate fusion weights based on the signal quality evaluation results to obtain the filtered and fused signal.

[0053] Specifically, such as Figure 3 As shown, step S20 includes: S201: Perform data error state analysis on the state vectors corresponding to adjacent sampling times using a multi-source state-space error model, and evaluate the signal quality of the corresponding signal source based on the data error state.

[0054] Specifically, through the state vectors corresponding to adjacent sampling time points , The data is input into a multi-source state-space error model for filtering. The changing trend of the filtered state vector is analyzed to obtain the data error state. The larger the deviation of the state vector, the worse the signal quality. The signal quality of the corresponding signal source is then evaluated based on the error state.

[0055] S202: Based on the signal quality assessment results, assign fusion weights to the corresponding signal sources using Kalman gain and update the state vectors of the corresponding signal sources to obtain the filtered and fused signal.

[0056] The Kalman gain expression is shown below: (6) in, express The Kalman gain at time step 1 is used to determine the weighting ratio of predicted and observed values ​​in the state update. To predict covariance, The observation matrix represents the system state and is used to map it to the observation space. The table resembles the transpose of the observation matrix. This represents the observation noise covariance matrix, used to characterize the uncertainty in the observation process.

[0057] The state update expression for the signal source is as follows: (7) in, express The signal source state vector at time -1.

[0058] S30: Perform health status assessment on the multiple signal sources of the dual-layer time synchronization device, switch the time base of the multiple signal sources according to the signal health assessment results, and perform time synchronization mode switching on the dual-layer time synchronization device.

[0059] Specifically, such as Figure 4 As shown, step S30 includes: S301: Calculate the observation residual vector after filtering and fusion based on the fused filtered signal, and analyze the timing quality of the dual-layer timing device based on the observation residual vector.

[0060] The expression for the observation residual vector is as follows: (8) The expression for timing quality is as follows: (9) in, This indicates the time difference between GNSS and LEO observations. For the observation matrix, This indicates updating the state vector of the corresponding signal source. This represents the measurement noise covariance. express The observation residual vector at time step is used to measure the difference between the predicted state and the actual observation. This represents the transpose of the residual vector, used to construct the residual sum of squares to quantify the timekeeping quality.

[0061] Specifically, when The smaller the value, the closer the residual is to the expected noise level, and the higher the time synchronization quality; conversely, the larger the value, the lower the residual is to the expected noise level. An increase indicates a possible signal abnormality or environmental interference. Finally, adjust according to the preset threshold. Mapped to A–E levels: (19) When the classification result is C, D or E (i.e. When the time exceeds 1.5), the system immediately records the anomaly and reports it in the BMS / SCADA system. At the same time, it suppresses the differential protection action to ensure the safe operation of the power grid during periods of declining time synchronization quality.

[0062] S302: Evaluate the health status of multiple signal sources based on the time synchronization quality analysis results, switch the time base of multiple signal sources based on the signal health assessment results, and perform time synchronization mode switching processing on the dual-layer time synchronization device.

[0063] Specifically, the lower the timing quality of the corresponding signal source, the worse its health status. When the health status falls below a preset threshold, the time base of the corresponding signal source is switched, thereby adjusting the timing mode. Specifically, based on the preset threshold and Q-Index quality level, seamless switching is completed between three modes: "normal time tracking," "timekeeping maintenance," and "time tracking recovery," ensuring that the continuity of 1 pulse per second output is not interrupted by any single path failure. The switching process is controlled within 500 µs, requires no manual intervention, and can maintain time base timekeeping for 72 hours under extreme conditions.

[0064] This embodiment includes three time synchronization modes: Normal time tracking mode: When both GNSS and LEO-TWTT are available and Q-Index ≤ B level, the system uses the synthesized signal fused by the ESAKF multi-strategy Kalman filter algorithm as the main time base, and the atomic clock is in the following state and continuously receives GNSS frequency correction.

[0065] Timekeeping mode: If a GNSS or LEO link loss of lock (Q-Index>C level) is detected or both channels experience jitter abnormalities simultaneously, the system switches to atomic clock timekeeping mode within ≤500 µs. At this time, all external correction inputs are isolated, and the output uses the local atomic clock as the sole time base to ensure continuous output of 1 pulse per second.

[0066] Recovery of time tracking mode: When the failed path is recovered and the Q-Index rises to ≤B level within 3 seconds of continuous monitoring, the system starts the smooth discipline process, gradually introduces the GNSS / LEO signal into the ESAKF multi-strategy Kalman filter algorithm fusion according to the preset gain, and completes the time base switching without introducing phase jump, thus restoring the fused output.

[0067] S40: According to the switched time synchronization mode, the filtered and fused signal is synchronously distributed to each substation of the power transmission project, and round-trip time delay compensation is performed on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

[0068] Specifically, such as Figure 5As shown, step S40 includes: S401: Through a preset data distribution mechanism, the time base of the switched time synchronization mode is synchronized to each substation of the power transmission project, and the clock deviation of each substation is adjusted accordingly.

[0069] Specifically, the data distribution mechanism in this embodiment is the PTP (Precision Time Protocol) Profile-EHVAC method with hardware timestamps. According to the switched time synchronization mode, the time base is synchronized to each substation of the power transmission project, and the clock deviation of each substation is adjusted accordingly to ensure that the clock deviation of 5 terminals and above substations is <5ns, thereby preventing the differential protection from tripping falsely due to inconsistent time bases within the network.

[0070] S402: According to the adjusted substation clock, the filtered and fused signal is synchronously distributed to each substation, and the round-trip delay of signal reception and feedback at each substation is calculated.

[0071] Specifically, according to the adjusted substation clock, the filtered and fused signal is synchronously distributed to each substation, and the round-trip delay of signal reception and feedback at each substation is calculated. Specifically, the master station sends a Sync message and records the sending timestamp t1 in hardware, the slave station records the receiving Sync timestamp t2 in hardware, the slave station sends a Delay_Req message and records the sending timestamp t3, and the master station receives the Delay_Req message and records the receiving timestamp t4 in hardware.

[0072] S403: Calculate the round-trip delay compensation coefficient for each substation point, perform round-trip delay compensation processing on the corresponding substation points, and obtain the timing calibration data of the dual-layer timing device.

[0073] The expression for the round-trip delay compensation coefficient is as follows: (10) in, , These represent the signal transmission timestamp of the dual-layer time synchronization device and the signal reception timestamp of the substation, respectively. , These represent the timestamps of the delay signals transmitted by the dual-layer time synchronization device and the timestamps of the delay signals received by the substation, respectively.

[0074] In this embodiment, round-trip delay compensation is performed on the corresponding substation points according to the round-trip delay compensation coefficient, such as... Figure 6 As shown, it specifically includes: S4031: Based on the round-trip compensation coefficient, calibrate the local clock of each substation point and evaluate whether the clock difference between the calibrated substation point clock and the master station clock of the dual-layer time synchronization device is within the preset range.

[0075] Specifically, the local clock of each substation is calibrated according to the round-trip delay compensation coefficient, the clock difference between the calibrated substation clock and the master station clock is calculated, and the clock difference is evaluated to see if it is within the preset range.

[0076] S4032: When the clock difference exceeds the preset range, perform cyclic clock calibration on the local clock of the corresponding substation point to obtain the timing calibration data after the substation point calibrates the clock.

[0077] The local clock calibration expression for the substation is shown below: (11) in, This indicates the local clock calibration compensation amount at the substation point. The local clock indicating the substation point This represents the round-trip compensation coefficient.

[0078] Specifically, local clock calibration ensures that the calibrated clocks of all substations are synchronized. Difference from the main station clock The time base deviation is strictly controlled within 5 ns. This embodiment distributes the fused 1 pulse per second / 10 MHz reference within each substation using the Profile-EHVAC hardware timestamp PTP mechanism, and eliminates paphylsymmetry through phase FIFO compensation, achieving an end-to-end time base deviation of <5 ns for 5 or more substations. This ensures a consistent clock across all substations in the system, eliminates the impact of source switching transients on differential protection, and prevents the risk of cascading tripping due to time base inconsistency.

[0079] In this embodiment, as Figure 7 As shown, the method also includes: S50: Real-time acquisition of operation monitoring data from the dual-layer time synchronization device, comparison of the operation monitoring data with the corresponding operation safety thresholds, and analysis of the operation safety performance of the power transmission project.

[0080] Specifically, the timing consistency, link jitter, atomic clock drift, and environmental parameters (temperature, vibration, etc.) of the dual-layer timing device are monitored online 24 / 7 to obtain operational monitoring data. The operational monitoring data is then compared with the corresponding operational safety thresholds. When the operational monitoring data is within the operational safety threshold, it indicates that the current operational safety performance is high. When any parameter in the operational monitoring data exceeds the preset safety threshold, it indicates that the operational safety performance is reduced.

[0081] S60: Based on the results of the operational safety performance analysis, perform fault analysis and location on the local alarm data, and generate corresponding maintenance instructions to be sent synchronously to the faulty substation.

[0082] Specifically, based on the operational safety performance analysis results, local alarms are triggered promptly when safe operating thresholds are exceeded. For example, if jitter σ > 5 ns, Q-Index > C level, or temperature / vibration exceeds limits, a local alarm flag is immediately triggered. The alarm information, after being uplinked via LEO-TWTT or encapsulated using IEC 61850 MMS, is transmitted back to the dispatch center via a satellite-to-ground link or SCADA network, along with the most recent 3 seconds of time base quality history to quickly pinpoint the cause of the fault. Upon receiving the alarm, the dispatch center automatically issues remote reset or on-site maintenance commands. Alarm data and processing results are simultaneously transmitted to the device for subsequent error model and threshold self-learning updates, ensuring continuous optimization and reliable operation of the dual-layer time synchronization device. The overall data processing flowchart of the dual-layer time synchronization device in this embodiment is shown below. Figure 8 As shown.

[0083] This embodiment adds a Q-Index quality score to the synthesized 1 second pulse output signal and classifies it in real time according to five levels: A–E. When the quality is lower than level B, an automatic "prohibit tripping" command is issued to the differential protection device; at the same time, level C–E anomalies are alarmed through the LEO uplink or SCADA channel. In this way, the timing quality is quantified in real time and linked with the protection action, avoiding malfunctions caused by time base jitter or link anomalies, and improving the safety of power grid operation.

[0084] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0085] In one embodiment, a fault-tolerant protection system for power transmission projects based on low-Earth orbit (LEO) satellites is provided. This LEO satellite-based fault-tolerant protection system corresponds one-to-one with the LEO satellite-based time-synchronization fault-tolerant protection method for power transmission projects described in the previous embodiments. For example... Figure 10 As shown, the fault-tolerant protection system for power transmission projects based on low-Earth orbit satellites includes a model building module, a data processing module, a mode switching module, and a data calibration module. Detailed descriptions of each functional module are as follows: The model building module is used to synchronously acquire multi-source data from multiple signal sources of the dual-layer timing device, synchronously calibrate the multi-source data, and construct a multi-source state-space error model of the dual-layer timing device.

[0086] The data processing module is used to analyze the data error status of multiple signal sources and evaluate the signal quality of the corresponding signal sources through a multi-source state-space error model. Based on the signal quality evaluation results, it dynamically allocates fusion weights to obtain a filtered and fused signal.

[0087] The mode switching module is used to perform health status assessment on the multiple signal sources of the dual-layer time synchronization device, and switch the time base of the multiple signal sources according to the signal health assessment results, and perform time synchronization mode switching on the dual-layer time synchronization device.

[0088] The data calibration module is used to synchronously distribute the filtered and fused signal to each substation of the power transmission project according to the switched time synchronization mode, and to perform round-trip delay compensation processing on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

[0089] Preferably, the model building module specifically includes: The data acquisition submodule is used to synchronously acquire the GNSS pulse output, low-orbit satellite delay estimate, and atomic clock local oscillator phase corresponding to the multiple signal sources of the dual-layer timing device, thereby obtaining multi-source data from the multiple signal sources.

[0090] The state matrix construction submodule is used to obtain the signal arrival time difference of each signal source at the same sampling time node, perform synchronous calibration on the corresponding multi-source data, and construct the state vector matrix of the multi-source data. The expression of the state vector matrix is ​​as follows: (1) in, express The state vector at each time sampling point Indicates frequency drift. Indicates short-term fluctuations. It indicates a sudden change.

[0091] The drift state analysis submodule is used to analyze the drift state vector and unit observation vector under the drift state based on the state vector matrix. The expressions for the drift state vector and unit observation vector are shown in Equation (2) and Equation (3), respectively: (2) (3) in, express The drift state vector at the time sampling point, This represents the state transition matrix under drift conditions. express Observation vector at time sampling point Represents the unit observation matrix. These are the process noise covariance and the observation noise covariance, respectively. The covariance matrix representing the process noise. The covariance matrix representing the observation noise. and These represent Gaussian white noise vectors with a mean of zero.

[0092] The model building submodule is used to calculate the signal time difference sequence within a preset sampling window, estimate the drift rate and jitter variance of multi-source data respectively, optimize the drift state matrix and unit observation matrix, and construct a multi-source state space error model.

[0093] The expression for the signal time difference sequence is as follows: (4) (5) in, , , They represent The arrival timestamps of signals from GNSS, low-orbit satellite two-way time delay demodulators, and atomic clocks at the sampling time points.

[0094] Preferably, the data processing module specifically includes: The quality assessment submodule is used to perform data error state analysis on the state vectors corresponding to adjacent sampling times using a multi-source state-space error model, and to assess the signal quality of the corresponding signal source based on the data error state.

[0095] The filtering submodule is used to assign fusion weights to the corresponding signal sources according to the signal quality assessment results, and update the state vector of the corresponding signal sources to obtain the filtered and fused signal.

[0096] The Kalman gain expression is shown below: (6) in, express Kalman gain at time step To predict covariance, Represents the observation matrix. The table resembles the transpose of the observation matrix. This represents the observation noise covariance matrix.

[0097] The state update expression for the signal source is as follows: (7) in, express The signal source state vector at time -1.

[0098] Preferably, the mode switching module specifically includes: The timing quality analysis submodule is used to calculate the observation residual vector after filtering and fusion based on the fused filtered signal, and to analyze the timing quality of the dual-layer timing device based on the observation residual vector.

[0099] The expression for the observation residual vector is as follows: (8) The expression for timing quality is as follows: (9) in, This indicates the time difference between GNSS and LEO observations. For the observation matrix, This indicates updating the state vector of the corresponding signal source. This represents the measurement noise covariance. express The observed residual vector at time t, This represents the transpose of the residual vector.

[0100] The mode switching submodule is used to evaluate the health status of multiple signal sources based on the time synchronization quality analysis results, perform time base switching on multiple signal sources based on the signal health assessment results, and perform time synchronization mode switching processing on the dual-layer time synchronization device.

[0101] Preferably, the data calibration module specifically includes: The deviation adjustment submodule is used to synchronize the time base of the switched time mode to each substation of the power transmission project through a preset data distribution mechanism, and to adjust the clock deviation of each substation accordingly.

[0102] The delay statistics submodule is used to synchronously distribute the filtered and fused signal to each substation according to the adjusted substation clock, and to calculate the round-trip delay of signal reception and feedback at each substation.

[0103] The time delay compensation submodule is used to calculate the round-trip time delay compensation coefficient for each substation point, perform round-trip time delay compensation processing on the corresponding substation points, and obtain the time synchronization calibration data of the dual-layer time synchronization device.

[0104] The expression for the round-trip delay compensation coefficient is as follows: (10) in, , These represent the signal transmission timestamp of the dual-layer time synchronization device and the signal reception timestamp of the substation, respectively. , These represent the timestamps of the delay signals transmitted by the dual-layer time synchronization device and the timestamps of the delay signals received by the substation, respectively.

[0105] Preferably, the data calibration module further includes: The clock calibration submodule is used to calibrate the local clock of each substation according to the round-trip compensation coefficient, and to evaluate whether the clock difference between the calibrated substation clock and the master station clock of the dual-layer time synchronization device is within the preset range.

[0106] The cyclic calibration submodule is used to perform cyclic clock calibration on the local clock of the corresponding substation when the clock difference exceeds the preset range, so as to obtain the timing calibration data after the substation clock is calibrated.

[0107] The local clock calibration expression for the substation is shown below: (11) in, This indicates the local clock calibration compensation amount at the substation point. The local clock indicating the substation point This represents the round-trip compensation coefficient.

[0108] Preferably, the time-compensated fault protection method for power transmission projects also includes: The operation monitoring module is used to acquire the operation monitoring data of the dual-layer time synchronization device in real time, compare the operation monitoring data with the corresponding operation safety thresholds, and analyze the operation safety performance of the power transmission project.

[0109] The fault analysis module is used to analyze and locate faults in local alarm data based on the results of operational safety performance analysis, and generate corresponding maintenance instructions to be sent synchronously to the faulty substation.

[0110] Specific limitations regarding the fault-tolerant protection system for power transmission projects based on low-Earth orbit (LEO) satellites can be found in the above section on the limitations of the time-synchronization fault-tolerant protection method for power transmission projects based on LEO satellites, and will not be repeated here. Each module in the aforementioned fault-tolerant protection system for power transmission projects based on LEO satellites can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0111] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 11As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores fault-tolerant protection data for low-Earth orbit satellite power transmission projects. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements a time-synchronization fault-tolerant protection method for low-Earth orbit satellite power transmission projects.

[0112] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of a time-to-fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites.

[0113] Those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.

[0114] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical functional division. In actual implementation, there may be other division methods, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored.

[0115] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0116] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A time-synchronous fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites, characterized in that, The method is applied to a two-layer timing device combining an atomic clock, GNSS, and a low-Earth orbit satellite two-way time delay demodulator. The method includes: The system synchronously acquires multi-source data from multiple signal sources of the dual-layer timing device, performs synchronous calibration on the multi-source data, and constructs a multi-source state-space error model for the dual-layer timing device. The data error state of multiple signal sources is analyzed by the multi-source state-space error model and the signal quality of the corresponding signal sources is evaluated. The fusion weights are dynamically allocated according to the signal quality evaluation results to obtain the filtered and fused signal. The health status assessment of the multiple signal sources of the dual-layer time synchronization device is performed, and the time base of the multiple signal sources is switched according to the signal health assessment results. The time synchronization mode of the dual-layer time synchronization device is then switched. According to the switched time synchronization mode, the filtered and fused signal is synchronously distributed to each substation of the power transmission project, and round-trip delay compensation is performed on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

2. The time-synchronous fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites according to claim 1, characterized in that, The process of synchronously acquiring multi-source data from multiple signal sources of the dual-layer timing device, synchronously calibrating the multi-source data, and constructing a multi-source state-space error model for the dual-layer timing device specifically includes: Simultaneously acquire the GNSS pulse output, low-orbit satellite delay estimate, and atomic clock local oscillator phase corresponding to the multiple signal sources of the dual-layer timing device to obtain multi-source data from the multiple signal sources; Obtain the signal arrival time difference of each signal source at the same sampling time node, perform synchronous calibration on the corresponding multi-source data, and construct the state vector matrix of the multi-source data. The expression of the state vector matrix is ​​as follows: （1） in, express The state vector at each time sampling point Indicates frequency drift. Indicates short-term fluctuations. Indicates a sudden change; Based on the state vector matrix analysis, the drift state vector and the unit observation vector under the drift state are shown in Equation (2) and Equation (3), respectively: （2） （3） in, express The drift state vector at the time sampling point, This represents the state transition matrix under drift conditions. express Observation vector at time sampling point Represents the unit observation matrix. These are the process noise covariance and the observation noise covariance, respectively. The covariance matrix representing the process noise. The covariance matrix representing the observation noise. and These represent Gaussian white noise vectors with zero mean; Calculate the signal time difference sequence within the preset sampling window, estimate the drift rate and jitter variance of the multi-source data respectively, optimize the drift state matrix and unit observation matrix, and construct a multi-source state space error model; The expression for the signal time difference sequence is as follows: （4） （5） in, , , They represent The arrival timestamps of signals from GNSS, low-orbit satellite two-way time delay demodulators, and atomic clocks at the sampling time points.

3. The time-compensated fault protection method for power transmission projects based on low-orbit satellites according to claim 2, characterized in that, The step of analyzing the data error state of multiple signal sources and evaluating the signal quality of corresponding signal sources through the multi-source state-space error model, and dynamically allocating fusion weights based on the signal quality evaluation results to obtain the filtered and fused signal, specifically includes: The multi-source state space error model is used to analyze the data error state of the state vectors corresponding to adjacent sampling times, and the signal quality of the corresponding signal source is evaluated based on the data error state. Based on the signal quality assessment results, Kalman gain is assigned to the corresponding signal sources to create fusion weights, and the state vectors of the corresponding signal sources are updated to obtain the filtered and fused signal. The Kalman gain expression is shown below: （6） in, express Kalman gain at time step To predict covariance, Represents the observation matrix. The table resembles the transpose of the observation matrix. Represents the observation noise covariance matrix; The state update expression for the signal source is as follows: （7） in, express The signal source state vector at time -1.

4. The time-compensated fault protection method for power transmission projects based on low-orbit satellites according to claim 3, characterized in that, The process of performing a health status assessment on the multiple signal sources of the dual-layer time synchronization device, switching the time base of the multiple signal sources according to the signal health assessment results, and performing a time synchronization mode switching process on the dual-layer time synchronization device specifically includes: The observation residual vector after filtering and fusion is calculated based on the fused filtered signal, and the timing quality of the dual-layer timing device is analyzed based on the observation residual vector. The expression for the observation residual vector is as follows: （8） The expression for timing quality is as follows: （9） in, This indicates the time difference between GNSS and LEO observations. For the observation matrix, This indicates updating the state vector of the corresponding signal source. This represents the measurement noise covariance. express The observed residual vector at time t, This represents the transpose of the residual vector; The health status of multiple signal sources is assessed based on the time synchronization quality analysis results. The time base of the multiple signal sources is switched based on the signal health assessment results. The time synchronization mode of the dual-layer time synchronization device is switched.

5. The time-synchronized fault-tolerant protection method for power transmission projects based on low-Earth orbit satellites according to claim 1, characterized in that, The process involves synchronously distributing the filtered and fused signal to each substation of the power transmission project according to the switched time synchronization mode, and performing round-trip delay compensation processing on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device. Specifically, this includes: Through a preset data distribution mechanism, the time base of the switched time synchronization mode is synchronized to each substation of the power transmission project, and the clock deviation of each substation is adjusted accordingly. According to the adjusted substation clock, the filtered and fused signal is synchronously distributed to each substation, and the round-trip delay of signal reception and feedback at each substation is calculated. Calculate the round-trip delay compensation coefficient for each substation point, perform round-trip delay compensation processing on the corresponding substation points, and obtain the timing calibration data of the dual-layer timing device; The expression for the round-trip delay compensation coefficient is as follows: （10） in, , These represent the signal transmission timestamp of the dual-layer time synchronization device and the signal reception timestamp of the substation, respectively. , These represent the timestamps of the delay signals transmitted by the dual-layer time synchronization device and the timestamps of the delay signals received by the substation, respectively.

6. The time-compensated fault protection method for power transmission projects based on low-Earth orbit satellites according to claim 5, characterized in that, The step of calculating the round-trip delay compensation coefficient for each substation point, performing round-trip delay compensation processing on the corresponding substation points, and obtaining the timing calibration data of the dual-layer timing device further includes: According to the round-trip compensation coefficient, the local clock of each substation is calibrated, and the clock difference between the calibrated substation clock and the master station clock of the dual-layer time synchronization device is evaluated to see if it is within a preset range. When the clock difference exceeds the preset range, the local clock of the corresponding substation point is subjected to cyclic clock calibration to obtain the timing calibration data after the substation point clock is calibrated. The local clock calibration expression for the substation is shown below: （11） in, This indicates the local clock calibration compensation amount at the substation point. The local clock indicating the substation point This represents the round-trip compensation coefficient.

7. The time-compensated fault protection method for power transmission projects based on low-orbit satellites according to claim 1, characterized in that, The method further includes: Real-time operation monitoring data of the dual-layer time synchronization device is acquired, and the operation monitoring data is compared with the corresponding operation safety thresholds to analyze the operation safety performance of the power transmission project. Based on the results of the operational safety performance analysis, fault analysis and location are performed on the local alarm data, and corresponding maintenance instructions are generated and sent synchronously to the faulty substation.

8. A fault-tolerant protection system for power transmission projects based on low-Earth orbit satellites, characterized in that, The system is applied to the time-compensated fault protection method for power transmission projects based on low-Earth orbit satellites as described in any one of claims 1-7, and the system comprises: The model building module is used to synchronously acquire multi-source data from multiple signal sources of the dual-layer timing device, synchronously calibrate the multi-source data, and build a multi-source state-space error model of the dual-layer timing device. The data processing module is used to analyze the data error state of multiple signal sources and evaluate the signal quality of the corresponding signal sources through the multi-source state space error model, and dynamically allocate fusion weights according to the signal quality evaluation results to obtain the filtered fused signal. The mode switching module is used to perform health status assessment processing on the multiple signal sources of the dual-layer time synchronization device, and switch the time base of the multiple signal sources according to the signal health assessment results, and perform time synchronization mode switching processing on the dual-layer time synchronization device. The data calibration module is used to synchronously distribute the filtered and fused signal to each substation of the power transmission project according to the switched time synchronization mode, and to perform round-trip delay compensation processing on each substation to obtain the time synchronization calibration data of the dual-layer time synchronization device.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the time-to-fault protection method for power transmission projects based on low-orbit satellites as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the time-to-fault protection method for power transmission projects based on low-orbit satellites as described in any one of claims 1 to 7.

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