A method for correcting ground electric field measurement interference caused by HVDC ground current.

Abstract

This invention discloses a method for correcting interference in geoelectric field measurements caused by HVDC ground current, belonging to the field of DC transmission line interference prevention technology. Addressing the problem of electromagnetic interference and data quality impact caused by HVDC ground current on geoelectric field measurements at seismic observation stations, this method involves collecting converter station operation data and screening data requiring correction; organizing geoelectric field signal template sequences; using dynamic time programming to filter interference signal intervals; calculating the ratio of signal variation amplitude to normal-order variables; fitting a function relationship between the ratio and distance based on multi-station data and finding the minimum value; and finally correcting the interference signal based on the minimum value. This method effectively eliminates the interference of HVDC ground current on geoelectric field measurements, ensuring the accuracy of geoelectric field observation data, providing technical support for the electromagnetic interference resistance of seismic monitoring stations, and improving the stability and reliability of seismic monitoring systems.

Description

Technical Field

[0001] This invention relates to a method for correcting interference in ground electric field measurements caused by HVDC ground current, belonging to the field of ground electric field observation research. Background Technology

[0002] With the increasing demand for electricity, more and more embedded DC transmission lines are being built and put into operation to meet this demand, inevitably causing electromagnetic interference to seismic monitoring stations around the lines. However, the occurrence time of this electromagnetic interference is highly random, and the frequency and amplitude of its impact are difficult to predict, seriously affecting the normal operation of seismic monitoring stations. The interference of HVDC to the ground electric field is essentially due to the loading of unbalanced ground current from the converter station. To reduce the impact of the ground current on the observation of the ground electric field, a method for correcting interference signals is urgently needed to ensure that the data quality and monitoring effect of seismic monitoring stations are not disturbed, and to guarantee the stable operation of seismic observation stations.

[0003] The current research progress on the observation of the Earth's electric field is as follows: (1) Chinese Patent: "A Calculation Principle and Method for a Geoelectric Resistivity and Geoelectric Field Observation Network" (Announcement No.: CN109541676A). This patent uses harmonic analysis to analyze geoelectric field data, employing trigonometric functions to fit the observed data. This effectively filters out high-frequency interference signals in the observed data while acquiring relevant information such as the signal's period, phase, and amplitude. However, the interference removal method mentioned in this patent has two problems: ① The patent uses trigonometric functions to fit the geoelectric field data, filtering only high-frequency interference in the signal. This may result in the inability to identify interference from ground currents. ② The relationship between the interference source and the distance to the measurement station is not considered in the signal filtering process. Under the calculation mode of this patent, the filtering effect may be poor.

[0004] (2) Chinese Patent “A Design Method and System for an Earthquake Geoelectric Field Observation Device” (Announcement No.: CN119511385A) invented a new type of geoelectric field observation device that can adapt to the needs of different terrains and environments. At the same time, the addition of measurement line orientation selection and electrode stability judgment mechanism improves the reliability and accuracy of data. However, this patent has the following problems: ① It does not have the ability to identify interference. In the case of interference, it can only measure the interfered signal, and the measurement data has low reference value for earthquake judgment. ② It only ensures the accuracy of geoelectric field measurement from the hardware level, but does not consider processing the geoelectric field observation data from the algorithm level. That is, the hardware accuracy meets the standard, but problems such as data interference, error accumulation and effective signal masking may occur.

[0005] In summary, with the increasing number of embedded DC transmission lines being constructed and put into operation in recent years, seismic monitoring stations near these lines are inevitably affected by electromagnetic interference. Currently, the impact of high-voltage DC transmission lines on seismic observation stations, especially in geoelectric field observation, has become a hot topic in this field. However, current research largely suffers from the following common problems: 1. There is a lack of complete judgment procedures for the interference caused by the ground current from high-voltage DC transmission lines. This invention can improve the accuracy of identifying this type of interference. 2. Most existing studies do not involve data sharing among multiple seismic observation stations. 3. Current research on interference in geoelectric field observation ignores the distance relationship between the interference source and the observation point. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for correcting interference in geoelectric field measurement caused by HVDC ground current. When a seismic observation station is interfered with by ground current during geoelectric field observation, the measured interference signal is corrected to ensure the accuracy of geoelectric field observation and to provide technical support for the anti-interference of seismic observation stations when they are interfered with by ground current.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a method for correcting ground electric field measurement interference caused by HVDC ground current, comprising: The operation data of the converter stations of the high-voltage direct current transmission lines around the seismic observation stations are obtained, and the geoelectric field data that needs to be corrected is selected as the matching sequence based on the operation data. Acquire historical normal ground electric field data, and construct a ground electric field signal template sequence based on the historical normal ground electric field data; The sequence to be matched is compared with the template sequence, and the interference signal range is selected from the sequence to be matched by a dynamic time planning algorithm. Based on the interference signal interval, calculate the change amplitude value of the sequence to be matched within the interference signal interval, and calculate the normal order variable of the template sequence in the corresponding interval; The ratio of the change amplitude value to the normal order variable is calculated as the order change correction value, and a function relationship is fitted based on the order change correction value and distance data from multiple seismic observation stations to determine the minimum value; Based on the minimum value, the interference signal in the sequence to be matched is corrected, and the corrected ground electric field data is output.

[0008] Furthermore, the acquisition of the operational data includes: acquiring the magnitude of the ground current leakage from the grounding electrode of the converter station of the high-voltage direct current transmission line. The maximum unbalanced current under normal operating conditions is 1% to 5% of the line rated current. When the magnitude of the ground current exceeds the maximum unbalanced current under normal operating conditions, it is determined that the ground electric field data for that day needs to be corrected. The sampling frequency of the ground electric field data is once per minute, with a total of 1440 data points per day.

[0009] Furthermore, the construction of the ground electric field signal template sequence includes: Obtain geoelectric field data for multiple historical normal dates; Calculate the average value of the ground electric field data at each time point to form the template sequence; The formula for calculating the template sequence is: (1); (2); in: Represents a set of template sequences. This represents the data in the template sequence set. Indicates the first sky A constant, normal electric field signal. The range of values ​​is , The range of values ​​is , The maximum number of days to collect normal ground electric field signals.

[0010] Furthermore, the sequence to be matched is the original geoelectric field observation data sequence on the day the interference occurred, represented as: (3); in: The sequence to be matched, for The observed values ​​of the ground electric field signal of the sequence to be matched at any given time. Values .

[0011] Furthermore, the step of filtering out interference signal intervals from the sequence to be matched using a dynamic time planning algorithm includes: The template sequence and the sequence to be matched are divided into multiple subsequences; the division step size of each subsequence is 10, and the overlap step size is 5, resulting in 287 subsequences. The formula is as follows: (4); in: , for X ,Y The Subsequences, The value range is 1 to 287; Calculate the distance between all point pairs in each corresponding subsequence to form a distance matrix; the formula for calculating the distance matrix is: (5); in: For the subsequence , Distance matrix of midpoint pairs ， The range of values ​​is , , The first Signal values ​​in a template sequence and a sequence to be matched; A sacrifice matrix is ​​constructed based on the distance matrix, and then populated; the construction of the sacrifice matrix is ​​represented as follows: (6); in: Indicates the first The sacrifice matrix of each subsequence, express and The minimum cumulative distance; Set boundary conditions and calculate the normalized distance; the setting of boundary conditions includes: (7); in, and The index in the subsequence; If the regularization distance is greater than a preset threshold, the subsequence is determined to be an interference signal interval.

[0012] Furthermore, the calculation of the change amplitude value, the normal order variable, and the order change correction value includes: For each interference signal sub-interval, calculate the change amplitude value of the sequence to be matched. and the normal order variables of the template sequence The formula is as follows: (8); in: Indicates the first The order change amplitude values ​​in the subsequences to be matched; for The magnitude of the ground electric field in the sequence to be matched at time 1; For the corresponding subsequence interval; The value range is the time interval of the subsequence; (9); in, Indicates the first Normal-order variables in a template sequence; for The magnitude of the ground electric field in the template sequence at time points; This refers to the corresponding interval used when calculating the magnitude of change; The ratio of the change magnitude to the normal order variable is defined as the order change correction value, as shown in the following formula: (10); in: Indicates the first The order correction value of each subsequence.

[0013] Furthermore, the fitting function relationship to determine the minimum value includes: Collect step correction values ​​from multiple seismic observation stations at different distances from the interfering grounding electrode; Fit the functional relationship between the step correction value and the distance; Extract the minimum value from the functional relationship. .

[0014] Furthermore, the correction of interference signals in the sequence to be matched includes: Based on the minimum value The step correction value is dynamically smoothed; the calculation formula is: (11); in, For smoothing values, To fit each subsequence, and These are the adjacent subsequences of each fitted subsequence. 、 、 Weighting factors for adjacent subsequences; Calculate the correction coefficient based on the smoothing value. The calculation formula is: (12); in, Indicates the first Correction coefficients for each subsequence; For the first subsequence At each time point, its correction coefficient for: (13); in, The range of values ​​is ; The interference signal in the sequence to be matched is corrected point by point using a correction coefficient, calculated as follows: (14); Corrected data Represented as: (15); in, The difference between the corrected signal and the signal to be corrected. for The corresponding change magnitude value of the sequence to be matched, for Corresponding correction coefficient, for The value of the ground electric field signal that needs to be corrected at all times.

[0015] In a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0016] Thirdly, the present invention provides a device for correcting ground electric field measurement interference caused by HVDC ground current, comprising: Memory, used to store computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of any of the methods described above.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a method for correcting interference in geoelectric field measurements caused by HVDC ground current. The method involves collecting converter station operational data and filtering the data requiring correction; organizing a geoelectric field signal template sequence; using dynamic time programming to filter interference signal intervals; calculating the ratio of the signal variation amplitude to the normal order variable; fitting a function relationship between the ratio and distance based on data from multiple stations and finding the minimum value; and finally correcting the interference signal based on the minimum value. This method effectively eliminates the interference of HVDC ground current on geoelectric field measurements, ensures the accuracy of geoelectric field observation data, provides technical support for the electromagnetic interference resistance of seismic monitoring stations, and improves the stability and reliability of seismic monitoring systems. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for correcting ground electric field measurement interference caused by HVDC ground current, provided by an embodiment of the present invention. Figure 2This is a schematic diagram of the normal order variables of the geoelectric field at a seismic observation station near the Earth's pole, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the amplitude of the step change of the geoelectric field at a seismic observation station near the Earth's pole, provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the geoelectric field step correction value of a seismic observation station near the Earth's pole provided in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0020] Example 1: This example introduces a method for correcting ground electric field measurement interference caused by HVDC ground current, including: The operation data of the converter stations of the high-voltage direct current transmission lines around the seismic observation stations are obtained, and the geoelectric field data that needs to be corrected is selected as the matching sequence based on the operation data. Acquire historical normal ground electric field data, and construct a ground electric field signal template sequence based on the historical normal ground electric field data; The sequence to be matched is compared with the template sequence, and the interference signal range is selected from the sequence to be matched by a dynamic time planning algorithm. Based on the interference signal interval, calculate the change amplitude value of the sequence to be matched within the interference signal interval, and calculate the normal order variable of the template sequence in the corresponding interval; The ratio of the change amplitude value to the normal order variable is calculated as the order change correction value, and a function relationship is fitted based on the order change correction value and distance data from multiple seismic observation stations to determine the minimum value; Based on the minimum value, the interference signal in the sequence to be matched is corrected, and the corrected ground electric field data is output.

[0021] The method for correcting ground electric field measurement interference caused by HVDC ground current provided in this embodiment involves the following steps in its application: Step 1: Collect operational data of high-voltage direct current transmission line converter stations around the seismic observation stations, and preliminarily screen out the data that needs to be corrected based on the facility records.

[0022] Step one involves collecting operational data of the converter station of the high-voltage direct current transmission line, mainly focusing on the magnitude of the ground current leaking from the grounding electrode of the converter station during the operation of the high-voltage direct current transmission line.

[0023] The magnitude of the ground current is mainly affected by the operation mode of the high-voltage direct current transmission line. Under normal operating conditions, its unbalanced current is 1% to 5% of the line's rated current.

[0024] In step one, the data that needs to be corrected is initially screened based on the records of the facility. If the magnitude of the ground current exceeds the maximum unbalanced current under normal operating conditions, it is considered that the ground electric field signal observed by the seismic station on that day needs to be corrected.

[0025] Step 2: Organize the template sequence of the output ground electric field signal.

[0026] In step two, the sampling frequency of the geoelectric field signal is 1 minute, which means that 1440 data points are generated per day.

[0027] Step two involves organizing the output template sequence, which includes the following steps: Collect normal geoelectric field signals measured by seismic observation stations. t The maximum number of days to collect normal ground electric field signals; 2) Calculate the output template sequence; Calculate the average value of the normal electric field signal at the corresponding time, template sequence. X It can be represented as: (1); (2); in: Represents a set of template sequences. This represents the data in the template sequence set. Indicates the first sky A constant, normal electric field signal. The range of values ​​is , The range of values ​​is , The maximum number of days to collect normal ground electric field signals.

[0028] Step 3: The initial screening data is used as the sequence to be matched and compared with the template sequence. Through dynamic time planning, the sequence containing the precise interference signal is accurately selected.

[0029] In step three, the initial screening data is used as the sequence to be matched. The geoelectric field data observed by the seismic observation stations on the day the interference occurred are output as the sequence to be matched without any processing. This can be represented as: (3); in: The sequence to be matched, for The observed values ​​of the ground electric field signal of the sequence to be matched at any given time. Values .

[0030] Step three involves using dynamic time programming to precisely filter out the exact sequence of interference signals, which includes the following steps: 1) Divide the template sequence and the sequence to be matched into subsequences; the step size is 10, and the overlap step size is 5, that is, the original sequence and the sequence to be matched are divided into 287 subsequences, which can be represented as: (4); in: , for X , Y The Subsequences, The value range is 1 to 287.

[0031] 2) Calculate the distance between all point pairs in each corresponding subsequence and form a distance matrix. d ,in d It can be represented as: (5); in: For the subsequence , Distance matrix of midpoint pairs ， The range of values ​​is , , The first The template sequence and the signal values ​​in the sequence to be matched.

[0032] Construct the sacrifice matrix D The formula is as follows: (6); in: Indicates the first The sacrifice matrix of each subsequence, express and The minimum cumulative distance; 3) Fill the sacrifice matrix and set boundary conditions; it can be expressed as: (7); in, and The index in the subsequence; 4) Output the regularization distance and set a threshold to accurately filter out interference intervals; if the regularization distance is greater than the threshold, it is determined that the data in the subsequence needs to be corrected.

[0033] Step 4: Calculate the magnitude of change and normal-order variables in each subsequence of the sequence to be matched and the template sequence. The magnitude of change is calculated based on the data of the sequence to be matched, and the normal-order variables are calculated based on the original sequence data. The following rules apply: S Indicates the magnitude of change. Z This represents a normal-order variable.

[0034] The magnitude of change is calculated based on the subsequence interval, and can be expressed as: (8); in: Indicates the first The order change amplitude values ​​in the subsequences to be matched; for The magnitude of the ground electric field in the sequence to be matched at time 1; For the corresponding subsequence interval; The value range is the time interval of the subsequence; (9); in, Indicates the first Normal-order variables in a template sequence; for The magnitude of the ground electric field in the template sequence at time points; This refers to the corresponding interval used when calculating the magnitude of change; Step 5: Calculate the ratio between the two. Based on the measurement data from multiple seismic observation stations, fit the functional relationship between the ratio and the distance, and calculate its minimum value.

[0035] In step five, the ratio of the two is calculated and defined as the step correction value. R It can be represented as: (10); in: Indicates the first The order correction value of each subsequence.

[0036] In step five, the fitting ratio is based on multiple seismic observation stations. R The functional relationship between distance and the interference is calculated, and its minimum value is determined. The key feature is that, under the same interference conditions, observation data from multiple seismic stations at different distances from the interfering grounding electrode are collected, and the data is fitted... R The functional relationship with distance is derived as follows. R The minimum value is R min .

[0037] Step 6: Correct the interference signal in the sequence to be matched based on the minimum value.

[0038] Step six is ​​based on the minimum value R min This involves correcting interference signals in the sequence to be matched. The steps include: 1) Dynamic smoothing R ; based on the fitted subsequence R h.min and its adjacent subsequences R h-1.min and R h+1.min For the current sequence R Smoothing is performed, and the smoothing value is... It can be represented as: (11); in, For smoothing values, To fit each subsequence, and These are the adjacent subsequences of each fitted subsequence. 、 、 Weighting factors are applied to adjacent subsequences; the weights are used to mitigate abrupt changes in subsequence boundaries. ϕ The value is 0. 2 ; φ The value is 0.6; γ The value is 0.2.

[0039] Step 2: Calculate the correction coefficient k It can be represented as: (12); in, Indicates the first Correction coefficients for each subsequence; For the first subsequence At each time point, its correction coefficient for: (13); in, The range of values ​​is .

[0040] Step 3: By subtracting the signal offset caused by interference, the data in the sequence to be matched that needs correction are corrected point by point; this can be expressed as: (14); Corrected data Represented as: (15); in, The difference between the corrected signal and the signal to be corrected. for The corresponding change magnitude value of the sequence to be matched, for Corresponding correction coefficient, for The value of the ground electric field signal that needs to be corrected at all times.

[0041] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0042] As attached Figure 1 The algorithm flowchart proposed in this invention, a method for correcting interference signals in HVDC ground current measurement of ground electric field, specifically includes the following steps: Collect operational data of high-voltage direct current transmission line converter stations around seismic observation stations, and preliminarily screen out data that need correction based on facility records.

[0043] Assume the rated current of the grounding electrode of a converter station of a high-voltage direct current transmission line is 1000A. During normal operation, the unbalanced current is 5% of the rated current (i.e., 50A), causing interference to the geoelectric field measurement data of nine surrounding seismic observation stations. The known distances from the stations to the grounding electrode, from farthest to closest, are: 12km, 170km, 220km, 300km, 360km, 390km, 465km, 490km, and 555km.

[0044] Based on the normalization distance threshold, if the normalization distance of the 137th sacrifice matrix is ​​greater than the set threshold, it is determined that the signal data of this subsequence needs to be corrected.

[0045] The values ​​of the 137th subsequence of the template sequence and the 137th subsequence of the sequence to be matched, output by a seismic observation station located 170 km from the grounding electrode of a high-voltage direct current transmission line, are shown in Table 1 below: Table 1 Subsequence signal values

[0046] Calculate the magnitude of the order change of this subsequence: ; The step amplitude value of a seismic observation station located 170 km from the grounding electrode of the high-voltage direct current transmission line is 63 mV / km. Repeat the above steps to calculate the step amplitude values ​​of the corresponding sequences for the remaining 8 seismic observation stations. The step amplitude values ​​of the same subsequence to be matched for the surrounding 9 seismic observation stations are as follows: Figure 1 As shown; Calculate the normal order variable for this subsequence: ; The normal order variable for a seismic observation station 170 km from the grounding electrode of a high-voltage direct current transmission line is 15 mV / km. Repeat the above steps to calculate the normal order variables for the corresponding sequences of the remaining 8 seismic observation stations. The normal order variables for the same template subsequence of the surrounding 9 seismic observation stations are as follows: Figure 2 As shown; Calculate the ratio of the two and the step correction value. R It can be represented as: ; The step correction value of a seismic observation station located 170 km from the grounding electrode of a high-voltage direct current transmission line can be obtained. R The value is 4.2. Repeat the above steps to calculate the step correction values ​​for the remaining 8 seismic observation stations. The step correction values ​​for the surrounding 9 seismic observation stations are shown in Table 2 below: Table 2 Step Correction Values R

[0047] Under the same interference conditions, observation data from multiple seismic stations at different distances from the interfering grounding electrode were collected and fitted. R The functional relationship with distance is derived as follows. R The minimum value is R min Their general relationship is as follows: Figure 3 As shown; According to the fitting function, we can obtain... R min =0.015.

[0048] Based on its adjacent subsequences R h-1.min =0.012 and R h+1.min =0.014 for the current sequence R Smoothing can be represented as: ; in: ϕ, φ, γ Weighting factors are applied to adjacent subsequences to weaken abrupt changes in subsequence boundaries through weighting; ϕ The value is 0. 2 ; φ The value is 0.6; γ The value is 0.2.

[0049] The smoothing value is 0.0142.

[0050] Calculate the correction factor k : ; Correction coefficientk 137 =0.213.

[0051] set up k 138 =0.21th subsequence χ The correction factor for each time point is: ; in, χ The value range is 681~690.

[0052] Subtracting the signal offset caused by interference, the data in the sequence to be matched is corrected point by point, which can be expressed as: ; Corrected data It can be represented as: ; The corrected data are shown in Table 3 below: Table 3 Template Sequence and Correction Signal

[0053] This embodiment provides a method for correcting interference in geoelectric field measurements caused by HVDC ground current. The method involves collecting converter station operational data and filtering the data requiring correction; organizing a geoelectric field signal template sequence; using dynamic time programming to filter interference signal intervals; calculating the ratio of the signal variation amplitude to the normal order variable; fitting a function relationship between the ratio and distance based on data from multiple stations and finding the minimum value; and finally correcting the interference signal based on the minimum value. This method can effectively eliminate the interference of HVDC ground current on geoelectric field measurements, ensure the accuracy of geoelectric field observation data, provide technical support for the electromagnetic interference resistance of seismic monitoring stations, and improve the stability and reliability of seismic monitoring systems.

[0054] Example 2: This example provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described in Example 1.

[0055] Example 3: This example provides a device for correcting ground electric field measurement interference caused by HVDC ground current, comprising: Memory, used to store computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of any of the methods described in Embodiment 1.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0057] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0058] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0059] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0060] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit its protection scope. Although this disclosure has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this disclosure, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims.

Claims

1. A method for correcting ground electric field measurement interference caused by HVDC ground current, characterized in that, include: The operation data of the converter stations of the high-voltage direct current transmission lines around the seismic observation stations are obtained, and the geoelectric field data that needs to be corrected is selected as the matching sequence based on the operation data. Acquire historical normal ground electric field data, and construct a ground electric field signal template sequence based on the historical normal ground electric field data; The sequence to be matched is compared with the template sequence, and the interference signal range is selected from the sequence to be matched by a dynamic time planning algorithm. Based on the interference signal interval, calculate the change amplitude value of the sequence to be matched within the interference signal interval, and calculate the normal order variable of the template sequence in the corresponding interval; The ratio of the change amplitude value to the normal order variable is calculated as the order change correction value, and a function relationship is fitted based on the order change correction value and distance data from multiple seismic observation stations to determine the minimum value; Based on the minimum value, the interference signal in the sequence to be matched is corrected, and the corrected ground electric field data is output.

2. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The acquisition of the operational data includes: acquiring the magnitude of the ground current leakage from the grounding electrode of the converter station of the high-voltage direct current transmission line. The maximum unbalanced current under normal operating conditions is 1% to 5% of the line rated current. When the magnitude of the ground current exceeds the maximum unbalanced current under normal operating conditions, it is determined that the ground electric field data needs to be corrected. The sampling frequency of the ground electric field data is once per minute, with a total of 1440 data points per day.

3. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The constructed Earth electric field signal template sequence includes: Obtain geoelectric field data for multiple historical normal dates; Calculate the average value of the ground electric field data at each time point to form the template sequence; The formula for calculating the template sequence is: （1）； （2）； in: Represents a set of template sequences. This represents the data in the template sequence set. Indicates the first sky A constant, normal electric field signal. The range of values ​​is , The range of values ​​is , The maximum number of days to collect normal ground electric field signals.

4. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The sequence to be matched is the original geoelectric field observation data sequence on the day the interference occurred, represented as: （3）； in: The sequence to be matched, for The observed values ​​of the ground electric field signal of the sequence to be matched at any given time. Values .

5. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The step of filtering out interference signal intervals from the sequence to be matched using a dynamic time planning algorithm includes: The template sequence and the sequence to be matched are divided into multiple subsequences; the division step size of each subsequence is 10, and the overlap step size is 5, resulting in 287 subsequences. The formula is as follows: （4）； in: , for X , Y The Subsequences, The value range is 1 to 287; Calculate the distance between all point pairs in each corresponding subsequence to form a distance matrix; the formula for calculating the distance matrix is: （5）； in: For the subsequence , Distance matrix of midpoint pairs ， The range of values ​​is , , The first Signal values ​​in a template sequence and a sequence to be matched; A sacrifice matrix is ​​constructed based on the distance matrix, and then populated; the construction of the sacrifice matrix is ​​represented as follows: （6）； in: Indicates the first The sacrifice matrix of each subsequence, express and The minimum cumulative distance; Set boundary conditions and calculate the normalized distance; the setting of boundary conditions includes: （7）； in, and For the index in the subsequence; If the regularization distance is greater than a preset threshold, the subsequence is determined to be an interference signal interval.

6. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The calculation of the change magnitude value, the normal order variable, and the order correction value includes: For each interference signal sub-interval, calculate the change amplitude value of the sequence to be matched. and the normal order variables of the template sequence The formula is as follows: （8）； in: Indicates the first The order change amplitude values ​​in the subsequences to be matched; for The magnitude of the ground electric field in the sequence to be matched at time t; For the corresponding subsequence interval; The value range is the time interval of the subsequence; （9）； in, Indicates the first Normal-order variables in a template sequence; for The magnitude of the ground electric field in the template sequence at time points; This refers to the corresponding interval used when calculating the magnitude of change; The ratio of the change magnitude to the normal order variable is defined as the order change correction value, as shown in the following formula: （10）； in: Indicates the first The order correction value of each subsequence.

7. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 1, characterized in that, The fitting function relationship to determine the minimum value includes: Collect step correction values ​​from multiple seismic observation stations at different distances from the interfering grounding electrode; Fit the functional relationship between the step correction value and the distance; Extract the minimum value from the functional relationship. .

8. The method for correcting ground electric field measurement interference caused by HVDC ground current according to claim 7, characterized in that, The correction of interference signals in the sequence to be matched includes: Based on the minimum value The step correction value is dynamically smoothed; the calculation formula is: （11）； in, For smoothing values, To fit each subsequence, and These are the adjacent subsequences of each fitted subsequence. 、 、 Weighting factors for adjacent subsequences; Calculate the correction coefficient based on the smoothing value. The calculation formula is: （12）； in, Indicates the first Correction coefficients for each subsequence; For the first subsequence At each time point, its correction coefficient for: （13）； in, The range of values ​​is ; The interference signal in the sequence to be matched is corrected point by point using a correction coefficient, calculated as follows: （14）； Corrected data Represented as: （15）； in, The difference between the corrected signal and the signal to be corrected. for The corresponding change magnitude value of the sequence to be matched, for Corresponding correction coefficient, for The value of the ground electric field signal that needs to be corrected at all times.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-8.

10. A device for correcting interference in ground electric field measurement caused by HVDC ground current, characterized in that, include: Memory, used to store computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of the method according to any one of claims 1-8.

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