Pole tower safety monitoring method and system based on centralized beidou double-frequency RTK positioning solution algorithm

Abstract

The application discloses a kind of based on centralized Beidou double-frequency RTK positioning algorithm tower safety monitoring method and system, the method includes the following steps: Beidou signal is demodulated and is expanded;The demodulated and expanded Beidou signal is formed with the identification information of current receiving terminal communication frame;Communication frame is identified decoding;The single-point positioning result of the data after decoding is obtained by single-point positioning solution;According to single-point positioning result, establish virtual reference station;Comprehensive mobile station observation data and reference station correction data are carried out RTK real-time positioning solution, after completing RTK real-time solution, compare the difference period of mobile station and reference station data, according to difference period, different solution quality grade is divided, and the final RTK positioning result or safety alarm is output based on solution quality grade.The application is sent to solution center by communication means unified solution, reduce the precision error caused by transmission delay, improve the efficiency and accuracy of tower safety monitoring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tower safety monitoring, in particular to a tower safety monitoring method and system based on centralized Beidou dual-frequency RTK positioning solution algorithm. BACKGROUND

[0002] In recent years, smart grid has become the main direction of power grid technology development, and the spatial information security of smart grid should be paid more and more attention. At present, many power grid companies still use GPS terminal equipment, so the use of Beidou in positioning scenarios should be promoted. With the improvement of Beidou system, the GPS and Beidou are completely changed to positioning by Beidou, which maximizes the security of power grid information.

[0003] The power transmission tower undertakes the important task of transmitting electric energy in the whole power engineering. However, most of the power transmission towers are distributed in areas with unstable ground conditions or high frequency of geological disasters, so they are prone to tilt or collapse due to natural disasters such as typhoon, rainstorm, snow disaster, flood, landslide, etc., which has a great adverse effect on power transmission. At present, the inspection of power transmission towers is mostly manual inspection or unmanned aerial vehicle auxiliary inspection, which is high in cost and cannot be monitored in time.

[0004] In order to realize real-time and effective monitoring of power transmission towers, some power grid enterprises also use multiple GNSS systems for joint solution. After setting up a terminal on the power transmission tower to complete the RTK positioning, the information is transmitted back to the system interface and displayed. However, the positioning terminal which integrates receiving, processing, solution and sending into one is expensive and has high power consumption. Such a terminal needs to be placed on each power transmission tower in the monitoring system, which does not save much in terms of material cost compared with unmanned aerial vehicle auxiliary inspection. SUMMARY

[0005] In order to overcome the defects and deficiencies of the prior art, the present application provides a tower safety monitoring method and system based on centralized Beidou dual-frequency RTK positioning solution algorithm. The present application solves the problems of high cost and high price of the terminal with Beidou receiving positioning solution module, and makes it suitable for the use scenario of the tower through the Beidou positioning algorithm, and realizes the real-time and accuracy of positioning.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] The present application provides a tower safety monitoring method based on centralized Beidou dual-frequency RTK positioning solution algorithm, which comprises the following steps:

[0008] The Beidou signal is demodulated and expanded;

[0009] The demodulated and despreaded Beidou signal and the identification information of the current receiving terminal form a communication frame;

[0010] The communication frame is identified and decoded;

[0011] The decoded data is subjected to single-point positioning calculation, ionospheric error is calculated by using Beidou double frequency, pseudo-range estimation is obtained, the pseudo-range positioning result obtained by calculation is subjected to receiver autonomous integrity detection by using pseudo-range residual error decision method, and single-point positioning result is obtained;

[0012] A virtual reference station is established according to the single-point positioning result, a short baseline is formed, and RTCM3 data and original observation data of the receiver are subjected to differential operation;

[0013] RTK real-time positioning calculation is performed by integrating mobile station observation data and reference station correction data, single-difference between different satellites and the mobile station and the reference station is performed, residual double-difference observation equation is obtained by double-difference between satellites, residual double-difference observation equation matrix is obtained by differential processing of multiple satellites, floating-point solution is obtained by measurement update through Kalman filtering, fixed solution is obtained by fixing integer ambiguity through LAMBDA algorithm, validity verification is performed by calculating residual double-difference again, and final positioning data of each node is obtained;

[0014] After the RTK real-time calculation is completed, the differential age of the mobile station and the reference station data is compared, different calculation quality levels are divided according to the differential age, and final RTK positioning result or safety alarm is output based on the calculation quality level.

[0015] As a preferred technical solution, the identification information of the current receiving terminal is an ID code unique to each receiving terminal, which is inserted in the observation data of a single Beidou RTCM3.2 protocol in the form of hexadecimal data and located in front of the frame header of the RTCM data frame.

[0016] As a preferred technical solution, while the communication frame is identified and decoded, data anti-collision algorithm correction is performed by random access ALOHA algorithm;

[0017] and / or;

[0018] Satellite prn numbers of the mobile station and the reference station correction data are compared before calculation, and the decoding data of the common-observation satellites of the two are reserved.

[0019] As a preferred technical solution, the decoded data is subjected to single-point positioning calculation, ionospheric error is calculated by using Beidou double frequency, and the specific steps include:

[0020]

[0021] Wherein, ρ is the pseudo-range calculated by double frequency, is the carrier wavelength of frequency L1. is the carrier wavelength of the frequency L2, P1 is the pseudo-range read in the observation data received by the satellite frequency L1, P2 is the pseudo-range read in the observation data received by the satellite frequency L2, C1 is the satellite differential code bias of the satellite frequency L1, and C2 is the satellite differential code bias of the satellite frequency L2.

[0022] As a preferred technical solution, the pseudo-range positioning result calculated is subjected to receiver autonomous integrity detection using a pseudo-range residual decision method, and a single-point positioning result is obtained, specifically including:

[0023] The pseudo-range error equation is constructed for single-point positioning, and is expressed as:

[0024]

[0025]

[0026] wherein, is the pseudo-range residual, δx k , δy k , and δz k are offset amounts of x, y, and z relative to the previous epoch single-point positioning result in the Earth-Centered Earth-Fixed coordinate system, respectively, are the first three coefficients obtained by Taylor series expansion of the satellite-geodetic geometric distance at the approximate coordinates of the station, c is the speed of light, and δt k is the clock error of the monitoring node receiving module, δt p is the satellite clock error, represents the single-point positioning estimate of the previous epoch, is the current epoch pseudo-range error estimate obtained by the ionosphere-free linear combination algorithm, is the ionospheric error, is the tropospheric error.

[0027] The pseudo-range error equation matrix is obtained under multiple observation satellites, and the single-point positioning result is obtained by the least square method.

[0028] As a preferred technical solution, the steps of receiver autonomous integrity detection include:

[0029] All observed Beidou satellites are screened one by one, and after screening out each Beidou satellite, the pseudo-range residual after the current Beidou satellite is calculated again by the single-point positioning algorithm. The residual obtained by using all satellites for single-point positioning before screening out is subtracted from the residual obtained by single-point positioning after screening out a satellite, and if the difference is greater than a preset threshold, the observation data of the satellite is not used. All Beidou satellites are screened one by one, and finally the satellites with a difference greater than the preset threshold are screened out, and the result is obtained by re-performing single-point positioning.

[0030] As a preferred technical solution, the residual double-difference observation equation is expressed as:

[0031]

[0032] wherein i is a flow station, j is a reference station, p is a reference satellite with the largest selected elevation angle, q is other satellites, is a measured carrier phase double-difference value, is a measured pseudorange double-difference value, is a station-star geometric distance double-difference value, and λ is the wavelength of the frequency band of the Beidou satellite, and is a station-to-station single-difference ambiguity, which is negligible in the case of a short baseline, and ε P is a natural error term.

[0033] As a preferred technical solution, the Kalman filter is expressed as:

[0034]

[0035]

[0036]

[0037] wherein the superscripts + and - represent the current epoch solution parameter and the previous epoch solution parameter, respectively, k x k represents a parameter vector to be solved, v k is a constructed residual double-difference equation H(x k ) is a measurement matrix from x k to the residual observation value, R k is a process noise matrix, P k is a covariance matrix of x k is a Kalman matrix, and I is an identity matrix.

[0038] As a preferred technical solution, different solution quality levels are divided according to the difference in age, and specifically include:

[0039] The solution quality levels include a first quality level, a second quality level, and a third quality level;

[0040] The solution result of the first quality level is taken as the final RTK positioning result;

[0041] The solution result of the second quality level is horizontally fitted and corrected;

[0042] The solution result of the third quality level is discarded, and the number of times of the solution result of the third quality level is detected, and when the number of times exceeds a set threshold, a safety alarm is output.

[0043] The application also provides a tower safety monitoring system based on a centralized Beidou double-frequency RTK positioning solution algorithm, comprising: a Beidou RTK receiving module, a signal processing module, a communication module, a signal receiving and decoding module, a solution and monitoring platform, and a CORS center.

[0044] The Beidou RTK receiving module demodulates and despreads the received Beidou signal and transmits it to the signal processing module.

[0045] The signal processing module sends the demodulated and despread Beidou signal and the identification information of the current receiving terminal to the signal receiving and decoding module through the communication module.

[0046] The signal receiving and decoding module identifies and decodes the received data.

[0047] The solution and monitoring platform performs single-point positioning solution on the decoded data, obtains pseudorange estimates by calculating ionospheric errors using Beidou double-frequency, performs receiver autonomous integrity detection on the calculated pseudorange positioning results using the pseudorange residual error decision method, and sends the single-point positioning results to the CORS center.

[0048] The CORS center establishes a virtual reference station according to the single-point positioning results, forms a short baseline, and returns the RTCM3 data of the virtual reference station to the solution and monitoring platform for differential operation with the original observation data of the receiver.

[0049] The solution and monitoring platform performs RTK real-time positioning solution by comprehensively processing the observation data of the flow station and the correction data of the reference station, performs single-difference between stations and double-difference between satellites to obtain residual double-difference observation equations, performs differential processing on multiple satellites to obtain a residual double-difference observation equation matrix, completes measurement update through Kalman filtering to obtain a floating-point solution, fixes the integer ambiguity through the LAMBDA algorithm to obtain a fixed solution, re-calculates the residual double difference for effectiveness verification, and obtains the final positioning data of each node.

[0050] After completing the RTK real-time solution, the difference period between the flow station and the reference station data is compared, different solution quality levels are divided according to the difference period, and the final RTK positioning results or safety alarms are output based on the solution quality level.

[0051] Compared with the prior art, the application has the following advantages and beneficial effects:

[0052] This invention identifies the raw observation data received by each tower monitoring node by attaching an ID code, and sends it to the calculation center for unified calculation via communication. It also reduces the accuracy error caused by transmission delay through algorithm model establishment and data optimization. It does not use local settlement at the monitoring node, thereby reducing the cost of the Beidou module, power consumption and installation size. The calculation center then reliably monitors the safety of the tower in real time, which can effectively improve the safety and stability of power lines. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the tower safety monitoring method based on the centralized BeiDou dual-frequency RTK positioning algorithm of the present invention.

[0054] Figure 2 This is a schematic diagram of the structural framework of the tower safety monitoring system based on the centralized BeiDou dual-frequency RTK positioning algorithm of the present invention;

[0055] Figure 3 This is a flowchart illustrating the RTK differential localization algorithm of the present invention.

[0056] Figure 4 This is a flowchart illustrating the data optimization algorithm of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0058] Example 1

[0059] like Figure 1 As shown, this embodiment provides a tower safety monitoring method based on a centralized BeiDou dual-frequency RTK positioning algorithm, including the following steps:

[0060] S1: De-amplify and amplify the BeiDou signal;

[0061] S2: Combine the de-amplified BeiDou signal with the identification information of the current receiving terminal to form a communication frame;

[0062] In this embodiment, the identification information of the current receiving terminal is a unique ID code for each receiving terminal, which is inserted in hexadecimal data format into the observation data of a single BeiDou RTCM3.2 protocol and located before the frame header of the RTCM data frame.

[0063] S3: Identify and decode communication frames;

[0064] In the embodiment, the random access ALOHA algorithm is used to modify the data anti-collision algorithm while identifying and decoding the communication frame.

[0065] In the embodiment, the satellite PRN number of the flow station and the reference station correction data is compared before solving, and the decoding data of the common view satellite of both is reserved.

[0066] S4: Single point positioning solution is performed on the decoded data, ionospheric error is calculated by using Beidou double frequency, pseudo-range estimation is obtained, pseudo-range positioning result is detected by using pseudo-range residual decision method, and single point positioning result is obtained.

[0067] In the embodiment, single point positioning solution is performed on the decoded data, ionospheric error is calculated by using Beidou double frequency, and the specific steps include:

[0068]

[0069] Wherein, ρ is the pseudo-range calculated by double frequency, is the carrier wavelength of frequency L1, is the carrier wavelength of frequency L2, P1 is the pseudo-range read in the observation data of receiving the satellite frequency L1, P2 is the pseudo-range read in the observation data of receiving the satellite frequency L2, C1 is the satellite differential code bias of satellite frequency L1, and C2 is the satellite differential code bias of satellite frequency L2.

[0070] In the embodiment, the pseudo-range residual decision method is used to detect the receiver autonomous integrity of the calculated pseudo-range positioning result, and the single point positioning result is obtained, and the specific steps include:

[0071] The pseudo-range error equation is constructed for single point positioning, which is represented as:

[0072]

[0073]

[0074] Wherein, is the pseudo-range residual, δx k , δy k , and δz k are the offset amounts of x, y, and z relative to the previous epoch single point positioning result in the Earth-Centered Earth-Fixed coordinate system, are the first three coefficients obtained by Taylor series expansion of the star-geometric distance at the approximate coordinates of the station, c is the speed of light, δt k is the clock difference of the monitoring node receiving module, δt p is the satellite clock difference, represents the single point positioning estimation value of the previous epoch, is the current epoch pseudorange error estimate obtained by the ionosphere-free linear combination algorithm, is the ionosphere error, is the troposphere error;

[0075] The pseudorange error equation matrix is obtained under multiple observation satellites, and the single point positioning result is obtained by the least square method.

[0076] In this embodiment, the steps of receiver autonomous integrity detection include:

[0077] All observed Beidou satellites are filtered one by one, and after filtering out each Beidou satellite, the pseudorange residual error after the current Beidou satellite is calculated by the single point positioning algorithm again. The residual error obtained by using all satellites before filtering out is subtracted from the residual error obtained by using all satellites after filtering out a satellite. If the difference is greater than a preset threshold, the observation data of the satellite is not used. All Beidou satellites are filtered one by one, and finally the single point positioning result is obtained after the satellites with a difference greater than the preset threshold are filtered out.

[0078] S5: According to the single point positioning result, a virtual reference station is established, a short baseline is formed, and RTCM3 data and receiver original observation data are differentially operated;

[0079] S6: The RTK real-time positioning solution is calculated by integrating the rover station observation data and the reference station correction data. The inter-station single difference is performed on the data of different satellites, rover stations and reference stations, the inter-satellite double difference is performed to obtain the residual double difference observation equation, the residual double difference observation equation matrix is obtained by differentially processing multiple satellites, the measurement update is completed by Kalman filtering to obtain the float solution, the fixed solution is obtained by fixing the integer ambiguity by LAMBDA algorithm, the effectiveness is verified by calculating the residual double difference again, and the final positioning data of each node is obtained;

[0080] In this embodiment, the residual double difference observation equation is expressed as:

[0081]

[0082] Wherein, i is the rover station, j is the reference station, p is the reference satellite with the largest selected elevation angle, and q is the other satellite, is the measured carrier phase double difference value, is the measured pseudorange double difference value, is the station-satellite geometric distance double difference value, and λ is the wavelength of the Beidou satellite frequency band, and is the ambiguity after inter-station single difference, which is ignored in the case of short baseline, and ε P is the natural error term.

[0083] In the embodiment, the Kalman filter is represented as:

[0084]

[0085]

[0086]

[0087] wherein the superscripts + and - represent the current epoch solution parameter and the last epoch solution parameter respectively, x k represents the parameter vector to be solved, v k is the constructed residual double difference equation H(x k ) is a measurement matrix from x k to the residual observation value, R k is a process noise matrix, P k is the covariance matrix of x k , K k is the Kalman matrix, and I is the unit matrix.

[0088] S7: After completing the RTK real-time solution, the difference age of the flow station and the reference station data is compared, different solution quality levels are divided according to the difference age, and the final RTK positioning result or a safety alarm is output based on the solution quality level.

[0089] In the embodiment, different solution quality levels are divided according to the difference age, which specifically includes:

[0090] The solution quality level includes a first quality level, a second quality level and a third quality level;

[0091] The solution result of the first quality level is taken as the final RTK positioning result;

[0092] The solution result of the second quality level is subjected to horizontal fitting correction;

[0093] The solution result of the third quality level is discarded, and the number of times of detecting the solution result of the third quality level is detected, and when the set threshold is exceeded, a safety alarm is output.

[0094] Embodiment 2

[0095] As shown in Figure 2 , the embodiment provides a tower safety monitoring system based on a centralized Beidou double-frequency RTK positioning solution algorithm, which includes a Beidou RTK receiving module, a signal processing module, a communication module, a signal receiving and decoding module, a solution and monitoring platform, and a CORS center.

[0096] In the embodiment, the Beidou positioning receiving module is installed at a higher position or the top of the tower to achieve an unobstructed receiving environment; the signal processing module processes the frequency to timely process each received Beidou data packet; the communication module is installed at a higher position or the top of the tower to achieve an unobstructed sending environment; the service range of the CORS center contains the distribution area of the entire monitoring node; the signal receiving and decoding module has a good anti-collision processing protocol; the solving and monitoring platform and the CORS center are located in a good network environment to reduce the time delay caused by network congestion.

[0097] In the embodiment, after the Beidou RTK receiving module receives the Beidou signal, the signal is demodulated and despread and transmitted to the signal processing module for data processing.

[0098] In the embodiment, the Beidou RTK receiving module converts the received Beidou dual-frequency signal into a format to be solved after demodulation and despreading. The Beidou RTK positioning receiving and demodulating module is only used for receiving the Beidou dual-frequency signal, demodulation and despreading. The received signal is converted into data conforming to the RTCM3.2 protocol by the built-in Beidou processing chip, which meets the protocol standard supported by most manufacturers. The decoding and solving are not continued, so as to reduce the cost and power consumption of the Beidou positioning module.

[0099] The signal processing module sends the combined Beidou data and the identification information of the current receiving terminal according to the agreed protocol through the communication module.

[0100] In the embodiment, the agreed protocol means that the Beidou data and the identification information of the current receiving terminal are combined into the data part of the communication frame. According to the provisions of different communication modes, the communication frame header and the frame tail are added to become a complete communication frame which is sent through the communication module.

[0101] In the embodiment, the identification information of the current receiving terminal combined by the signal processing module is an ID code unique to each receiving terminal, which is inserted in the observation data of a single Beidou RTCM3.2 protocol in hexadecimal data format and located in front of the RTCM data frame header.

[0102] In the embodiment, when the communication module sends, each node uses the round broadcasting mode to send, that is, instead of receiving and sending immediately, each node sends the data to be solved in the set fixed time slot, so as to reduce the pressure of data collision of the receiving end and increase the reliability of the original observation data.

[0103] In the embodiment, the communication module can improve the sending capacity as much as possible without increasing the obvious packet loss rate, so as to reduce the error of the Beidou RTK positioning caused by the fragmentation transmission time delay.

[0104] The signal receiving and decoding module identifies and decodes the received data.

[0105] In the embodiment, the data anti-collision algorithm is modified by the random access ALOHA algorithm while the received data to be solved is identified and decoded, so as to prevent the quality of the original observation data from being reduced due to the multi-channel data converging into the solving end.

[0106] In the embodiment, the decoded data is subjected to single point positioning solution by the solving and monitoring platform, ionospheric error is calculated by using the Beidou double frequency, pseudo-range estimation is obtained, the pseudo-range positioning result calculated is subjected to receiver autonomous integrity detection by using the pseudo-range residual decision method, and the single point positioning result is sent to the CORS center.

[0107] In the embodiment, when the single point positioning solution is performed, the ionospheric error part in the single point positioning is corrected by establishing the Beidou double frequency correction model.

[0108] In the embodiment, the ionospheric error correction formula of the Beidou double frequency is expressed as:

[0109]

[0110] In the formula, ρ is the pseudo-range calculated by the double frequency, is the carrier wavelength of the frequency L1, is the carrier wavelength of the frequency L2, P1 is the pseudo-range read in the observation data of the satellite frequency L1, P2 is the pseudo-range read in the observation data of the satellite frequency L2, C1 is the satellite differential code bias of the satellite frequency L1, and C2 is the satellite differential code bias of the satellite frequency L2.

[0111] In the embodiment, the single point positioning is performed by constructing the pseudo-range error equation, and the basic formula is as follows:

[0112]

[0113]

[0114] wherein, is the pseudo-range residual, δx k , δy k , and δz k are the offset amounts of x, y, and z relative to the single point positioning result of the last epoch in the Earth-Centered Earth-Fixed coordinate system respectively, are the first three coefficients obtained by Taylor series expansion of the star-geometric distance at the approximate coordinates of the station, c is the speed of light, δt k is the clock difference of the monitoring node receiving module, δt p is the satellite clock difference, indicates the single point positioning estimation of the last epoch, is the current epoch pseudo-range error estimation obtained by the ionosphere-free linear combination algorithm Iono Free LC. is ionospheric error, is tropospheric error.

[0115] When the monitoring node receiving module simultaneously observes n satellites, n equations as above can be listed to obtain a pseudo-range error equation matrix, and a single point positioning result is obtained by least square method.

[0116] V = B X - L

[0117] X T = (B T B) -1 B T L

[0118] Wherein, according to the pseudo-range residual equation listed above, a pseudo-range residual equation matrix can be constructed under multiple observed satellites, V is a residual vector, B is a pseudo-range residual equation conversion matrix, X is a to-be-estimated vector, L is an error vector, and the to-be-estimated vector X can be obtained through the pseudo-range residual equation matrix.

[0119] In the embodiment, the receiver autonomous integrity detection mode for the single point positioning result is as follows: all observed Beidou satellites are filtered one by one, and after filtering out one Beidou satellite, the pseudo-range residual after the current Beidou satellite is calculated again by the single point positioning algorithm. The residual obtained by using all satellites before filtering out for single point positioning is subtracted from the residual obtained by single point positioning after filtering out a satellite, and if the difference is greater than a specified threshold, the satellite error is large, and the observation data of the satellite is not used in the following calculation. All Beidou satellites are filtered one by one, and finally the satellites with large errors are filtered out to obtain the result by re-performing single point positioning.

[0120] In the embodiment, the CORS center establishes a virtual reference station with a baseline length of about 1km according to the single point positioning result to form a short baseline, and returns the RTCM3 data of the virtual reference station to the solution and monitoring platform for differential operation with the original observation data of the receiver.

[0121] In the embodiment, the network RTK technology based on the CORS center is adopted, of course, the embodiment is not limited to the form of implementing the network RTK technology, and the virtual reference station technology, the regional correction parameter technology, the main and auxiliary station technology, and the comprehensive error interpolation technology can be adopted, but it must be emphasized that the network RTK technology is essential. If the traditional RTK technology is used, the reference station near the tower monitoring node is used to send differential correction data, which will increase the pressure of data transmission and data collision, and the positioning accuracy is unstable due to different differential ages caused by different distances of different reference stations.

[0122] As Figure 3The RTK real-time positioning solution is performed by combining the flow station observation data and the reference station correction data. The inter-station single difference is performed on the data of different satellites and the flow station and the reference station, and then the inter-satellite double difference is performed to obtain a residual double difference observation equation. The residual double difference observation equation matrix is obtained by performing the difference processing on multiple satellites. The floating point solution is obtained by completing the measurement update through the Kalman filtering. The fixed solution is obtained by fixing the integer ambiguity through the LAMBDA algorithm. The effectiveness is verified by calculating the residual double difference again. Finally, the positioning data of each node is obtained by using the big data processing and optimization algorithm, and is displayed on the monitoring platform. In the embodiment, the residual double difference observation equation is:

[0123]

[0124] wherein i is the flow station, j is the reference station, p is the reference satellite with the largest selected elevation angle, q is the other satellite, is the measured carrier phase double difference value, is the measured pseudorange double difference value, is the station-satellite geometric distance double difference value, and λ is the wavelength of the frequency band of the Beidou satellite, and is the ambiguity after the inter-station single difference, which can be ignored in the case of a short baseline, and ε P is a natural error term.

[0125] In the embodiment, the Kalman filtering formula used is:

[0126]

[0127]

[0128]

[0129] wherein the superscripts + and - represent the current epoch solution parameter and the last epoch solution parameter, respectively, k x k represents a parameter vector to be solved, including the receiver position, velocity, acceleration, etc., k is the measurement matrix from x k to the residual observation value, R k is a process noise matrix, P k is the covariance matrix of x k , K k is a Kalman matrix, and I is an identity matrix.

[0130] In the embodiment, the solution platform compares satellite PRN numbers of the flow station and the reference station before solving, and retains decoding data of common-view satellites of both, so as to reduce the amount of data needed in solving.

[0131] In the embodiment, after the RTK real-time solution is completed, the difference age of the flow station and the reference station data is compared, different solution quality levels are divided according to the difference age, the solution result with high solution quality is determined as the final RTK positioning result, the solution result with medium solution quality is subjected to horizontal fitting correction to prevent the mutation of occasional data from causing system misjudgment, and the solution result with poor short-time solution quality is directly discarded, and the system issues an alarm when long-term poor solution quality is monitored.

[0132] As shown in Figure 4 For most cases with a difference age less than 10, the solution result is not subjected to optimization processing, for a small part of the difference age being 10 to 30, the solution result is subjected to horizontal correction fitting, and for an extreme case with the difference age being greater than 30, the solution result is directly discarded.

[0133] In the embodiment, the horizontal correction fitting judgment process is as follows:

[0134] Data obtained in the epoch and the previous 9 historical epochs are taken as samples to estimate double-difference residual error values in the epoch:

[0135] The estimated value y i N = kx i +b

[0136] wherein

[0137]

[0138] x i represents the time of the current epoch relative to the historical sample epoch, and i is 10 when the sampling number is 10. y i represents residual error values of the solution result after double-difference in each sample epoch.

[0139] If the actual double difference residual after the epoch solution exceeds the set threshold value from the residual estimate value fitted by the horizontal correction, it is considered that the solution is unstable, and the double difference residual estimate value is used as the parameter in the Kalman filter equation for the monitoring node solution to be solved again, and the obtained solution result is considered to be a more reasonable result. The theoretical basis of using this method is that the position of the monitoring node is stable and unchanged in the ideal case, which is reflected in the chart curve that should be a small jitter horizontal line, but it is inevitable that the sudden change of weather conditions or the obstruction encountered in the information transmission process and other factors will cause the solution result to mutate. In order to reduce the system false alarm caused by the unreliable positioning result, the horizontal correction fitting is used to make the data change more reasonable, and the fitting method is only used when the difference age is 10 to 30, and the fitting condition is limited to the "more" unreasonable solution result, so as to avoid the system false negative.

[0140] The application adds ID code to the original observation data of each tower monitoring node for identification, sends to the solution center for unified solution through communication means, and establishes algorithm model and optimizes data to reduce the precision error caused by transmission delay, so as to reduce the module cost of the Beidou module, reduce the power consumption and installation volume by not using the local settlement of the monitoring node, and then the solution center can reliably and real-timely monitor the safety of the tower, which can effectively improve the safety and stability of the power line.

[0141] The above embodiment is the preferred embodiment of the application, but the embodiment of the application is not limited to the above embodiment, and any change, modification, substitution, combination, simplification made without departing from the spirit and principle of the application should be an equivalent replacement method, which is included in the protection scope of the application.

Claims

1. A tower safety monitoring method based on a centralized Beidou dual-frequency RTK positioning solution algorithm, characterized in that, The method comprises the following steps: demodulating and despreading the Beidou signal; forming a communication frame by combining the demodulated and despread Beidou signal with the identification information of the current receiving terminal; recognizing and decoding the communication frame; performing single-point positioning calculation on the decoded data, calculating ionospheric error by using the Beidou dual-frequency, performing receiver autonomous integrity detection on the calculated pseudo-range positioning result by using the pseudo-range residual decision method, and obtaining the single-point positioning result; establishing a virtual reference station according to the single-point positioning result, forming a short baseline, and performing differential operation on the RTCM3 data and the original observation data of the receiver; performing RTK real-time positioning calculation by comprehensively using the observation data of the rover station and the correction data of the reference station, performing single-difference between the data of different satellites and the rover station and the reference station, performing double-difference between the stars to obtain the residual double-difference observation equation, performing differential processing on multiple satellites to obtain the residual double-difference observation equation matrix, completing measurement updating by Kalman filtering to obtain the floating-point solution, fixing the integer ambiguity by the LAMBDA algorithm to obtain the fixed solution, performing validity verification by calculating the residual double-difference again, and obtaining the final positioning data of each node; the residual double-difference observation equation is expressed as: where i is the flow station, j is the reference station, p is the reference satellite with the largest selected elevation angle, and q is the other satellites, is the measured carrier phase double difference value, is the measured pseudorange double difference value, is the station-star geometric distance double difference value, and λ is the wavelength of the frequency band of the Beidou satellite, and is the ambiguity after the inter-station single difference, is negligible in the case of short baseline, and ε P is the natural error term; after completing the RTK real-time calculation, comparing the differential age of the data of the rover station and the reference station, dividing different calculation quality levels according to the differential age, and outputting the final RTK positioning result or safety alarm based on the calculation quality level.

2. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning solution algorithm according to claim 1, characterized in that, The identification information of the current receiving terminal is an ID code unique to each receiving terminal, which is inserted into the observation data of a single Beidou RTCM3.2 protocol in the form of hexadecimal data and located in front of the frame header of the RTCM data frame.

3. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning resolution algorithm according to claim 1, characterized in that, At the same time of recognizing and decoding the communication frame, the random access ALOHA algorithm is used to perform data anti-collision algorithm correction. and / or Before the calculation, the satellite prn numbers of the rover station and the reference station correction data are compared, and the decoded data of the common-observation satellites of the two are reserved.

4. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning resolution algorithm according to claim 1, characterized in that, The single-point positioning calculation on the decoded data, the calculation of ionospheric error by using the Beidou dual-frequency, specifically includes: wherein p is the pseudo-range calculated by the dual-frequency, is the carrier wavelength of frequency L1, is the carrier wavelength of frequency L2, P1 is the pseudo-range read in the observation data received from the satellite at frequency L1, P2 is the pseudo-range read in the observation data received from the satellite at frequency L2, C1 is the satellite differential code bias of the satellite at frequency L1, and C2 is the satellite differential code bias of the satellite at frequency L2.

5. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning resolution algorithm according to claim 1, characterized in that, The receiver autonomous integrity detection on the calculated pseudo-range positioning result by using the pseudo-range residual decision method, and the single-point positioning result, specifically includes: The pseudo-range error equation for single-point positioning is constructed and expressed as: wherein, is the pseudo-range residual, δx k , δy k , δz k are the offset of x, y, z respectively relative to the previous epoch single point positioning result in the geocentric geodetic coordinate system, are the first three coefficients of the Taylor series expansion of the satellite-geodetic geometry distance at the approximate coordinates of the station, c is the speed of light, δt k is the clock error of the monitoring node receiving module, δt p is the satellite clock error, represents the single point positioning estimate of the previous epoch, is the pseudo-range error estimate of the current epoch obtained by the ionosphere-free linear combination algorithm, is the ionosphere error, is the troposphere error; The pseudo-range error equation matrix is obtained under multiple observation satellites, and the single-point positioning result is obtained by the least square method.

6. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning resolution algorithm according to claim 1, characterized in that, The steps of the receiver autonomous integrity detection include: All observed Beidou satellites are filtered one by one, and after filtering out one Beidou satellite, the pseudo-range residual after the single-point positioning algorithm calculation of the current Beidou satellite is performed again, the residual obtained by using all satellites for single-point positioning before the filtering is subtracted from the residual obtained by using the single-point positioning after filtering out a satellite, if the difference is greater than a preset threshold, the observation data of the satellite is not used, all Beidou satellites are filtered one by one, and finally the satellites with a difference greater than the preset threshold are filtered out, and the result is obtained by re-performing single-point positioning.

7. The tower safety monitoring method based on the centralized Beidou dual-frequency RTK positioning resolution algorithm according to claim 1, characterized in that, The Kalman filtering is expressed as: wherein the superscripts + and - represent the current epoch solution parameter and the previous epoch solution parameter respectively, x k represents the parameter vector to be solved, v k is the constructed residual double difference equation, H(x k ) is the measurement matrix from x k to the residual observation value, R k is the process noise matrix, P k is the covariance matrix of x k , K k is the Kalman matrix, and I is the identity matrix.

8. The method according to claim 1, wherein the method is characterized in that, The different calculation quality levels are divided according to the differential age, specifically including: The calculation quality levels include the first quality level, the second quality level and the third quality level; The calculation result of the first quality level is taken as the final RTK positioning result; The results of the second quality level are horizontally fitted and corrected; The results of the third quality level are discarded, the number of times of detecting the results of the third quality level is counted, and when the number of times exceeds a set threshold, a safety alarm is output.

9. A tower safety monitoring system based on a centralized Beidou dual-frequency RTK positioning solution algorithm, characterized in that, The tower safety monitoring method based on the centralized Beidou double-frequency RTK positioning algorithm of any one of claims 1-8, comprising a Beidou RTK receiving module, a signal processing module, a communication module, a signal receiving and decoding module, a calculation and monitoring platform, and a CORS center. The Beidou RTK receiving module demodulates and despread the received Beidou signal and transmits it to the signal processing module. The signal processing module sends the demodulated and despread Beidou signal and the identification information of the current receiving terminal to the signal receiving and decoding module through the communication module. The signal receiving and decoding module identifies and decodes the received data. The calculation and monitoring platform performs single-point positioning calculation on the decoded data, calculates ionospheric error using Beidou double-frequency, performs receiver autonomous orthogonality detection on the calculated pseudorange positioning result using pseudorange residual error decision method, and sends the single-point positioning result to the CORS center. The CORS center establishes a virtual reference station according to the single-point positioning result, forms a short baseline, and returns the RTCM3 data of the virtual reference station to the calculation and monitoring platform for differential operation with the original observation data of the receiver. The calculation and monitoring platform performs RTK real-time positioning calculation on the flow station observation data and the reference station correction data, performs single-difference between stations on different satellites and flow stations and reference stations, performs double-difference between stars to obtain residual double-difference observation equation, performs differential processing on multiple satellites to obtain residual double-difference observation equation matrix, completes measurement update through Kalman filtering to obtain floating-point solution, fixes the integer ambiguity through LAMBDA algorithm to obtain fixed solution, re-calculates the residual double-difference for effectiveness verification, and obtains the final positioning data of each node. After completing the RTK real-time calculation, the difference period of the flow station and the reference station data is compared, different calculation quality levels are divided according to the difference period, and the final RTK positioning result or safety alarm is output based on the calculation quality level.

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