Method and System for Establishing Unified Time for the Whole Power Grid Based on Beidou Satellites

Abstract

The present invention discloses a method and system for establishing a unified time for the entire power grid based on Beidou satellites; it relates to the technical field of synchronous timekeeping; different levels of time reference sources are respectively deployed at the dispatching centers of the entire power grid; the common view data of the visible Beidou satellites corresponding to each time reference source is calculated, the time deviation between each time reference source is calculated, and the time deviation is estimated; according to the estimated time deviation, the time of each time reference source is calculated, the weights of each time reference source participating in the unified time calculation of the entire power grid are determined, and the unified time of the entire power grid is calculated; finally, the frequency and phase of the time reference source are adjusted according to the clock difference between each time reference source and the unified time of the entire power grid, so that the time reference source is synchronized with the unified time of the entire power grid. The present invention enables the establishment of the unified time for the entire power grid not to depend on the operating conditions of individual time reference sources, and at the same time, the widely distributed primary and secondary time reference sources can be used as the common view time reference sources for other common view time synchronization devices, realizing true network-wide time synchronization.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous time service, and particularly to a method and system for establishing a unified time for the entire power grid based on Beidou satellites. Background Art

[0002] Currently, time synchronization systems have been configured in each dispatching center, centralized control station, substation, and power plant of the entire power grid, and initially have the function of regional synchronization. Their time sources mainly come from satellite time service, which is non-traceable unidirectional time service. If there is a deviation during the conversion process of time, neither the local nor the remote end can perceive it, nor can it be traced and corrected. The time service application of the entire power grid only realizes regional time synchronization within the site, and has not established a wide-area time synchronization network across power plants and regions. The time service of the entire power grid acts independently, without a unified and traceable reference time source, which is not conducive to the realization of time synchronization of the entire power grid. Summary of the Invention

[0003] The technical problem to be solved by the present invention is that the time service of the entire power grid acts independently, without a unified and traceable reference time source, which is not conducive to the realization of time synchronization of the entire power grid. The purpose of the present invention is to provide a method and system for establishing a unified time for the entire power grid based on Beidou satellites, calculate the time deviation between time reference sources through visible Beidou satellites among them, estimate it, establish a unified time for the entire power grid, calculate the time deviation between each time reference source and the unified time of the entire power grid, and adjust the time of each time reference source in sequence to achieve time synchronization of each time reference source in the entire power grid.

[0004] The present invention is realized through the following technical solutions:

[0005] This solution provides a method for establishing a unified time for the entire power grid based on Beidou satellites, including:

[0006] Step 1: Deploy time reference sources of different levels in the dispatching centers of the entire power grid; the time reference sources have the co-visibility function;

[0007] Step 2: Calculate the co-visibility data of the corresponding visible Beidou satellites according to each time reference source;

[0008] Step 3: Calculate the time deviation between each time reference source based on the co-visibility data of each Beidou satellite, and estimate the time deviation;

[0009] Step 4: Calculate the time of each time reference source, the unified time of the entire power grid, and the weight of each time reference source participating in the calculation of the unified time of the entire power grid based on the estimated time deviation;

[0010] Step 5: Calculate the clock difference between each time reference source and the unified time of the entire power grid based on Step 4, and adjust the frequency and phase of the time reference source according to the clock difference to synchronize the time reference source with the unified time of the entire power grid.

[0011] A further optimization solution is that different levels of time reference sources are respectively deployed in the control centers of the entire power grid, including the method:

[0012] Classify the control centers of the entire power grid;

[0013] Deploy different levels of time reference sources in control centers of different levels; among them, the higher the level of the control center, the higher the level of the deployed time reference source; the higher the accuracy and stability of the time reference source, the higher the corresponding level of the time reference source.

[0014] A further optimization solution is that the common-view data includes satellite-ground clock difference and elevation angle;

[0015] The method for obtaining the satellite-ground clock difference includes:

[0016] Calculate the satellite-ground clock difference between the i-th time reference source and the k-th visible Beidou satellite according to the following formula

[0017]

[0018] Where: is the satellite-ground clock difference between the k-th visible Beidou satellite and the i-th time reference source, is the pseudo-range between the k-th visible Beidou satellite and the i-th time reference source, is the true range between the k-th visible Beidou satellite and the i-th time reference source, is the ionospheric delay between the k-th visible Beidou satellite and the i-th time reference source, is the tropospheric delay between the k-th visible Beidou satellite and the i-th time reference source, Δt ui is the antenna and processing conversion delay of the i-th time reference source, and c is the speed of light;

[0019] The method for obtaining the elevation angle includes:

[0020] Calculate the elevation angle between the i-th time reference source and the visible Beidou satellite k according to the following formula

[0021]

[0022] Where: are respectively the eastward, northward, and zenithal observation vectors of the k-th visible Beidou satellite at the i-th time reference source.

[0023] A further optimization solution is that the calculation method for the time deviation between each time reference source includes:

[0024] For N time reference sources, where there are N Beidou satellites visible to both time reference sources i and j (i≠j, i = 1, 2, …, N, j = 1, 2, …, N); k = 1, 2, …, N k ; then the time deviation between time reference source i and time reference source j with the visible Beidou satellite k as a reference is calculated according to the following formula: k ;

[0025]

[0026] The average time deviation based on peak removal average calculation is:

[0027]

[0028] The median value of the clock difference within the common visibility period is calculated based on the least squares fitting

[0029] A further optimization scheme is that the method for estimating the time deviation includes:

[0030] Based on the median value of the clock difference The estimated value that satisfies the incidence matrix is fitted through the least squares state estimation

[0031]

[0032] where G is the incidence matrix of, M is the number of incidence equations, N is the number of time reference sources,

[0033] The sum of squares A of the calculated value and the estimated value of the time deviation between time reference sources is:

[0034]

[0035] Taking the partial derivative of A with respect to gives:

[0036]

[0037] A further optimization scheme is that the calculation method for the time of each time reference source includes:

[0038] Determine the reference time T u1 , and the time of time reference source j is: where j = 2, 3, …, N.

[0039] A further optimization scheme is that the calculation method for the weight of each time reference source participating in the unified time of the entire power grid includes:

[0040] Obtain the levels of each time reference source and the time deviation between the time reference source and the unified time of the entire power grid;

[0041] Dynamically adjust the weights of each time reference source participating in the calculation of the unified time of the entire power grid according to the following rules:

[0042] The smaller the time deviation between the time reference source and the unified time of the entire power grid, the greater the weight;

[0043] When the time deviations between the time reference sources and the unified time of the entire power grid are the same, the higher the level of the time reference source, the greater the weight.

[0044] A further optimized solution is that the calculation method of the unified time of the entire power grid includes:

[0045] Calculate the average time based on the dynamic weighted average algorithm where α i represents the weight of the time reference source i participating in the calculation of the unified time of the entire power grid; T ui represents the time of the time reference source i;

[0046] Calculate the estimated value of the unified time of the entire power grid based on the Kalman filter algorithm

[0047] where represents the real-time calculated value of the unified time of the entire power grid this time, represents the estimated value of the unified time of the entire power grid this time, represents the estimated value of the unified time of the entire power grid last time, and K represents the filtering coefficient.

[0048] A further optimized solution is that the clock difference between the time reference source i and the unified time of the entire power grid is calculated according to the following formula:

[0049]

[0050] This solution also provides a system for establishing the unified time of the entire power grid based on Beidou satellites. The system is used to implement the method for establishing the unified time of the entire power grid based on Beidou satellites as described above. The system includes:

[0051] A deployment module for deploying time reference sources of different levels in the dispatching centers of the entire power grid; the time reference sources have the common view function;

[0052] A first calculation unit for calculating the common view data of the corresponding visible Beidou satellites according to each time reference source;

[0053] A second calculation unit for calculating the time deviation between each time reference source based on the common view data of each Beidou satellite and estimating the time deviation;

[0054] A third computing unit, configured to calculate the time of each time reference source, the weights participating in the unified time calculation of the entire power grid, and the unified time of the power system based on the estimated time deviation.

[0055] A synchronization module, configured to calculate the clock difference between each time reference source and the unified time of the entire power grid, and adjust the frequency and phase of the time reference source according to the clock difference, so that the time reference source is synchronized with the unified time of the entire power grid.

[0056] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0057] The method and system for establishing a unified time for the entire power grid based on Beidou satellites provided by the present invention; calculate the time deviation between each time reference source through the co-visible satellites between the time reference sources, estimate it, establish the unified time for the entire power grid, calculate the time deviation between each time reference source and the unified time of the entire power grid, and adjust the time of each time reference source in turn to achieve time synchronization of each site in the entire power grid.

[0058] The method and system for establishing a unified time for the entire power grid based on Beidou satellites provided by the present invention; the establishment of the unified time for the entire power grid does not depend on the operating conditions of individual time reference sources, and at the same time, widely distributed time reference sources of different levels can be used as co-visible time reference sources for other co-visible time synchronization devices to achieve true time synchronization of the entire power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0060] Figure 1 It is a schematic flowchart of the method for establishing a unified time for the entire power grid based on Beidou satellites;

[0061] Figure 2 It is a schematic structural diagram of the system for establishing a unified time for the entire power grid based on Beidou satellites. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0063] At present, the time synchronization of the power grid mainly focuses on the local time synchronization of secondary equipment under the jurisdiction of control centers, substations, and power plants at all levels, without achieving the time synchronization of the entire power grid across control centers, substations, and power plants. There are sporadic scientific research pilots and literature that use the satellite common view method to achieve time synchronization between different sites.

[0064] Most of the existing satellite common view methods use a master-slave hierarchical approach to achieve time synchronization. This method has two deficiencies: First, if the master-slave span is greater than 2000 km, there may be no common view satellites. Second, the failure of the common view receiver at the master station will prevent the slave stations from effectively tracing the synchronization.

[0065] To solve the above technical problems, the present invention provides the following embodiments:

[0066] Embodiment 1

[0067] This embodiment provides a method for establishing a unified time for the entire power grid based on Beidou satellites, as Figure 1 shown, including:

[0068] Step 1: Deploy time reference sources of different levels in the control centers of the entire power grid; the time reference sources have the common view function;

[0069] The deployment of time reference sources of different levels in the control centers of the entire power grid includes the method:

[0070] Classify the power grid control and support units at or above the provincial level of the entire power grid;

[0071] Deploy time reference sources of different levels for different levels of units; among them, the higher the level of the unit, the higher the level of the deployed time reference source; the higher the accuracy and stability of the time reference source, the higher the level corresponding to the time reference source.

[0072] In the specific implementation process, a hydrogen atomic frequency standard source is configured for the national control center and set as the first-level time reference source; a cesium atomic frequency standard source is configured for the network provincial control center and set as the second-level time reference source.

[0073] Step 2: Calculate the common view data of the corresponding Beidou satellites according to each time reference source;

[0074] The common view data includes the satellite-ground clock difference and the elevation angle;

[0075] The method for obtaining the satellite-ground clock difference includes:

[0076] Calculate the satellite-ground clock difference between the time reference source i and the kth visible Beidou satellite according to the following formula

[0077]

[0078] where: is the satellite-to-ground clock difference between the kth visible BeiDou satellite and the i-th time reference source, is the pseudorange between the kth visible BeiDou satellite and the i-th time reference source, is the true distance between the kth visible BeiDou satellite and the ith time reference source, is the ionospheric delay between the kth visible BeiDou satellite and the i-th time reference source, is the tropospheric delay between the kth visible BeiDou satellite and the ith time reference source, Δt ui is the antenna and processing conversion delay of the i-th time reference source, and c is the speed of light;

[0079] The method for obtaining the elevation angle comprises:

[0080] The elevation angle between the time reference source i and the visible Beidou satellite k is calculated according to the following formula:

[0081]

[0082] in: are the observation vectors of the east, north and sky of the kth visible Beidou satellite at the ith time reference source, respectively.

[0083] Step 3: Calculate the time deviation between each time reference source based on the common view data of each Beidou satellite, and estimate the time deviation;

[0084] The method for calculating the time deviation between the time reference sources includes:

[0085] For N time reference sources, where time reference sources i, j (i≠j, i=1, 2, ..., N, j=1, 2, ..., N) have N BeiDou satellites that can be viewed together k ; k = 1, 2, ..., N k ; Then the time deviation between time reference source i and time reference source j with Beidou satellite k as reference is calculated according to the following formula:

[0086]

[0087] The average time deviation is calculated based on the peak-free average:

[0088]

[0089] The median clock error within the common view period is calculated based on the least squares fitting method.

[0090] Methods for estimating time deviation include:

[0091] Based on the median clock error The estimated values that satisfy the incidence matrix are fitted by least squares state estimation

[0092]

[0093] where G is the incidence matrix, M is the number of incidence equations, N is the number of time reference sources,

[0094] The sum of squares A of the calculated values and the estimated values of the time deviations between the time reference sources is:

[0095]

[0096] Taking the partial derivative of A with respect to gives:

[0097]

[0098] Step 4: Calculate the time of each time reference source, the unified time of the entire power grid, and the weights of each time reference source participating in the calculation of the unified time of the entire power grid based on the estimated time deviation;

[0099] The calculation method of the time of each time reference source includes:

[0100] Determine the reference time T u1 , and the time of the time reference source j is: where j = 2, 3,..., N.

[0101] In the specific implementation process, the time of the time reference source where the Beidou common view server is located is used as the reference time T u1 .

[0102] The calculation method of the weights of each time reference source participating in the unified time of the entire power grid includes:

[0103] Obtain the level of each time reference source and the time deviation between the time reference source and the unified time of the entire power grid;

[0104] Dynamically adjust the weights of each time reference source participating in the unified time of the entire power grid according to the following rules:

[0105] The smaller the time deviation between the time reference source and the unified time of the entire power grid, the greater the weight;

[0106] The higher the level of the time reference source, the greater the weight.

[0107] Specifically, for example, the weights α of each time reference source participating in the calculation of the unified time of the entire power grid iis dynamic, with a value range of 0 to 10, and determines the weight for calculating the unified time of the entire power grid based on the level of the frequency standard source and the operating conditions of the time reference source. The time deviation between the primary time reference source and the unified time of the entire power grid is within 0 to 2 ns, and the weight α i has a value range of 8 to 10; the time deviation between the secondary time reference source and the unified time of the entire power grid is within 0 to 2 ns, and the weight α i has a value range of 6 to 8; the time deviation between the primary time reference source and the unified time of the entire power grid is within 2 to 5 ns, and the weight α i has a value range of 5 to 8; the time deviation between the secondary time reference source and the unified time of the entire power grid is within 2 to 5 ns, and the weight α i has a value range of 3 to 6; the time deviation between the time reference source and the unified time of the entire power grid is within 5 to 10 ns, and the weight α i has a value range of 1 to 2; if the device fails or the time deviation from the unified time of the entire power grid is greater than 10 ns, its α i takes a value of 0.

[0108] The calculation method of the unified time of the power system includes:

[0109] Calculate the average time based on the dynamic weighted average algorithm where α i represents the weight of the time reference source i participating in the calculation of the unified time of the entire power grid; T ui represents the time of the time reference source i;

[0110] Calculate the estimated value of the unified time of the entire power grid based on the Kalman filter algorithm

[0111] where represents the real-time calculated value of the unified time of the entire power grid this time, represents the filtered value of the unified time of the entire power grid this time, represents the filtered value of the unified time of the entire power grid last time, and K is the filtering coefficient.

[0112] Step Five: Based on Step Four, calculate the clock difference between each time reference source and the unified time of the entire power grid, and adjust the frequency and phase of the time reference source according to the clock difference to synchronize the time reference source with the unified time of the entire power grid.

[0113] The clock difference between the time reference source i and the unified time of the entire power grid is calculated according to the following formula:

[0114]

[0115] Example 2

[0116] This embodiment provides a system for establishing a unified time for the entire power grid based on Beidou satellites. The system is used to implement the method for establishing a unified time for the entire power grid based on Beidou satellites described in Embodiment 1. The system includes:

[0117] A deployment module for respectively deploying time reference sources of different levels at the dispatching centers of the entire power grid; the time reference sources have the common view function; the specific structure of the system is as Figure 2 shown. In this embodiment, a hydrogen atomic frequency standard source is configured for the national-level dispatching center and set as the primary time reference source; a cesium atomic frequency standard source is configured for the provincial-level dispatching center and set as the secondary time reference source. Each time reference source is configured with a Beidou satellite signal receiver, and communication is carried out between each time reference source, between each time reference source and the Beidou common view server through the power dispatching communication network.

[0118] A first calculation unit for calculating the common view data of the corresponding visible Beidou satellites according to each time reference source;

[0119] A second calculation unit for calculating the time deviation between each time reference source based on the common view data of each Beidou satellite and estimating the time deviation;

[0120] A third calculation unit for calculating the time of each time reference source, the weight participating in the unified time calculation of the entire power grid, and the unified time of the power system based on the estimated time deviation;

[0121] A synchronization module for calculating the clock difference between each time reference source and the unified time of the entire power grid, and adjusting the frequency and phase of the time reference source according to the clock difference to synchronize the time reference source with the unified time of the entire power grid.

[0122] In this embodiment, the establishment of the unified time for the entire power grid does not depend on the operating conditions of individual time reference sources. At the same time, the widely distributed primary and secondary time reference sources can be used as the common view time reference sources for other common view time synchronization devices to achieve true full-network time synchronization.

[0123] The specific embodiments described above have further elaborated on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for establishing a unified time for the entire power grid based on Beidou satellites, characterized in that, Including: Step 1: Deploy time reference sources of different levels at the control centers of the entire power grid respectively; The time reference source has a common view function; Step 2: Calculate the common view data of the corresponding Beidou satellites according to each time reference source; Step 3: Calculate the time deviation between each time reference source based on the common view data of each Beidou satellite, and estimate the time deviation; Step 4: Calculate the time of each time reference source, the unified time of the entire power grid, and the weight of each time reference source participating in the calculation of the unified time of the entire power grid based on the estimated time deviation; Step 5: Calculate the clock difference between each time reference source and the unified time of the entire power grid based on Step 4, and adjust the frequency and phase of the time reference source according to the clock difference to synchronize the time reference source with the unified time of the entire power grid.

2. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 1, wherein The method of respectively deploying time reference sources of different levels at the control centers of the entire power grid includes: Classify the control centers of the entire power grid; Deploy time reference sources of different levels at control centers of different levels; Among them, the higher the level of the site, the higher the level of the deployed time reference source; the higher the accuracy and stability of the time reference source, the higher the corresponding level of the time reference source.

3. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 2, wherein The common view data includes satellite-ground clock difference and elevation angle; The method for obtaining the satellite-ground clock difference includes: Calculate the clock offset between the time reference source i and the k-th visible Beidou satellite according to the following formula Wherein: is the satellite-ground clock difference between the k-th visible Beidou satellite and the i-th time reference source; is the pseudo-range between the k-th visible Beidou satellite and the i-th time reference source; is the true range between the k-th visible Beidou satellite and the i-th time reference source; is the ionospheric delay between the k-th visible Beidou satellite and the i-th time reference source; is the tropospheric delay between the k-th visible Beidou satellite and the i-th time reference source, and Δt ui is the antenna and processing conversion delay of the i-th time reference source, and c is the speed of light; The method for obtaining the elevation angle includes: Calculate the elevation angle of the time reference source i and the visible Beidou satellite k according to the following formula Wherein: They are respectively the eastward, northward, and zenithward observation vectors of the k-th visible Beidou satellite at the i-th time reference source.

4. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 3, wherein The method for calculating the time deviation between each time reference source includes: For N time reference sources, where for time reference sources i and j (i≠j, i = 1, 2, …, N, j = 1, 2, …, N), there are N Beidou satellites that are visible to both; k = 1, 2, …, N k ; then the time deviation between time reference source i and time reference source j with the visible Beidou satellite k as the reference is calculated according to the following formula: k ; Based on peak removal average, the average time deviation is: Calculate the median value of the clock offset during the common-visibility period based on the least-squares fitting 5. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 3, characterized in that, The method for estimating the time deviation includes: Based on the median value of clock error The estimated value satisfying the incidence matrix is fitted by least squares state estimation where G is the incidence matrix, M is the number of incidence equations, N is the number of time reference sources, The sum of the squares of the calculated value and the estimated value of the time deviation between time reference sources is A: Derive the partial derivative of with respect to A to obtain:

6. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 5, characterized in that, The method for calculating the time of each time reference source includes: Determine the reference time T u1 , the time of the time reference source j is: where j = 2, 3, …, N.

7. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 6, characterized in that, The method for calculating the weight of each time reference source participating in the unified time of the entire power grid includes: Obtain the level of each time reference source and the time deviation between the time reference source and the unified time of the entire power grid; Dynamically adjust the weight of each time reference source participating in the calculation of the unified time of the entire power grid according to the following rules: The smaller the time deviation between the time reference source and the unified time of the entire power grid, the greater the weight; When the time deviations between the time reference source and the unified time of the entire power grid are the same, the higher the level of the time reference source, the greater the weight.

8. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 7, characterized in that, The method for calculating the unified time of the entire power grid includes: Calculate the average time based on the dynamic weighted average algorithm where α i represents the weight of the time reference source i participating in the unified time calculation of the entire power grid; T ui represents the time of the time reference source i; Calculate the estimated value of the unified time of the entire power grid based on the Kalman filtering algorithm wherein represents the real-time calculated value of the unified time of the entire power grid this time, represents the estimated value of the unified time of the entire power grid this time, represents the estimated value of the unified time of the entire power grid last time, and K represents the wave coefficient.

9. The method for establishing a unified time for the entire power grid based on Beidou satellites according to claim 8, characterized in that, The clock difference between time reference source i and the unified time of the entire power grid is calculated according to the following formula:

10. A system for establishing a unified time for the entire power grid based on Beidou satellites, characterized in that, The system is used to implement the method for establishing the unified time of the entire power grid based on Beidou satellites described in any one of claims 1-9. The system includes: A deployment module for respectively deploying time reference sources of different levels at the control centers of the entire power grid; the time reference source has a common view function; A first calculation unit for calculating the common view data of the corresponding visible Beidou satellites according to each time reference source; A second calculation unit for calculating the time deviation between each time reference source based on the common view data of each Beidou satellite and estimating the time deviation; A third calculation unit for calculating the time of each time reference source, the weight participating in the calculation of the unified time of the entire power grid, and the unified time of the entire power grid based on the estimated time deviation; A synchronization module for calculating the clock difference between each time reference source and the unified time of the entire power grid, and adjusting the frequency and phase of the time reference source according to the clock difference to synchronize the time reference source with the unified time of the entire power grid.

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