A method, device, equipment and medium for locating aging of distribution cables

Abstract

The present invention belongs to the technical field of cable operation and maintenance, and specifically discloses a method, device, equipment and medium for locating the aging of distribution cables, including: dividing the cable to be tested, establishing a local aging position set; establishing a local aging positioning model according to the local aging position set; calculating the estimated error of each local aging position combination according to the local aging positioning model; outputting the local aging degree estimate, the local aging position starting interval and the local aging position ending interval according to the estimated error; performing error analysis to output the final local aging degree estimate, the final local aging position starting interval and the final local aging position ending interval. The present invention divides the cable to be tested into several sections, and then establishes a set and an aging positioning model, and adopts a grid search method to convert the optimization problem for a cable into a sub-optimization problem of multiple position combinations, thereby reducing unknown quantities and greatly improving the accuracy and efficiency of calculations.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable operation and maintenance, and specifically relates to a method, device, equipment and medium for locating aging of distribution cables. Background Art

[0002] Cables play a vital role in urban power transmission. With the continuous improvement of economic level, urban overhead lines are gradually replaced by underground cables and internal pipeline cables. The development is particularly obvious in first- and second-tier cities. Power cables run through cities. Their safe, stable and reliable operation is an important factor in the urban energy system. Once a cable failure occurs, it directly affects the work and life of urban residents. Therefore, the safe operation and maintenance of urban cables is crucial. Cables have good mechanical and electrical properties. Most of the failures are caused by the aging of the insulation layer. There are many factors that affect aging, such as the cable material itself, the external operating environment, and human or foreign body damage. Each factor or multiple factors acting together will cause different degrees of cable aging. According to the stress that causes the aging of cable insulation, it can be roughly divided into thermal aging, electrical aging, water aging, chemical corrosion, mechanical aging, etc., but the root cause is high temperature heating. Continuous high temperature causes thermal aging and insulation aging. The main inducing factor. Generally, the aging detection methods are divided into online and offline detection methods. Online monitoring combines historical operation data with current data to evaluate the insulation status, while offline monitoring evaluates the insulation status by combining laboratory preventive tests with test results. Commonly used measurement methods include withstand voltage test, elongation at break, absorption ratio, leakage current, dielectric loss angle, etc., which can simulate the relationship model between cable faults and insulation aging to a certain extent. However, the distribution cable is laid over long distances and underground space is limited. It is difficult for operation and maintenance personnel to enter the lower end to check the specific fault nodes. They can only rely on the transmission of node fault information back to the background and calculate the relative position through data transmission and attenuation model. However, many fault location methods are not accurate, which makes it difficult for operation and maintenance personnel to determine the precise fault location, which has a great impact on fault inspection and repair. If there is a large error, it will also increase the operation and maintenance cost. Therefore, the fault location method of distribution cable is worth studying.

[0003] Further locating the local aging section of the cable based on the evaluation of the overall insulation condition of the cable helps to achieve targeted maintenance, thereby reducing the system operation and maintenance costs. However, there are few studies on the local aging location methods of cable insulation. Most existing studies rely on traveling wave injection, which makes it difficult to locate the local aging section of the cable where the insulation electrical parameters change smoothly. Summary of the invention

[0004] The purpose of the present invention is to provide a distribution cable aging positioning method, device, equipment and medium to solve the technical problem that the existing distribution network cable fault positioning method performs positioning through data transmission and attenuation model, and the positioning result is inaccurate.

[0005] To achieve the above object, the present invention adopts the following scheme to achieve it:

[0006] In a first aspect, a method for locating aging of a distribution cable comprises the following steps:

[0007] Divide the cable to be tested into P segments, and obtain P+1 endpoints;

[0008] Select any two of the P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0009] Establishing a local aging location model according to the local aging location set;

[0010] Calculate the estimation error of each local aging position combination according to the local aging positioning model;

[0011] All estimation errors are sorted, t local aging position combinations with the smallest estimation errors are selected, and local aging degree estimation values, local aging position start intervals, and local aging position end intervals are obtained according to the t local aging position combinations;

[0012] Determine whether the local aging position start interval and the local aging position end interval meet the threshold condition. If the threshold condition is met, output the local aging degree estimate, the local aging position start interval and the local aging position end interval; otherwise, divide the local aging position start interval and the local aging position end interval into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and output the local aging degree estimate, the local aging position start interval and the local aging position end interval at the last iteration;

[0013] According to the output local aging degree estimation value, local aging position starting interval and local aging position ending interval, error analysis is performed to output the final local aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval.

[0014] A further improvement of the present invention is that the step of establishing a local aging positioning model according to the local aging position set specifically includes:

[0015] A monitoring signal of different frequencies is input to each local aging position combination to obtain a local aging parameter corresponding to each local aging position combination, a first-end leakage current, a terminal leakage current, a first-end voltage, and a terminal voltage corresponding to the monitoring signals of different frequencies;

[0016] Obtain the transfer function of each local aging position combination and the head-end equivalent admittance of the entire cable under test;

[0017] Calculate the estimated terminal voltage and the estimated head end leakage current according to the transfer function of each local aging position combination and the head end equivalent admittance of the entire cable to be tested;

[0018] A local aging positioning model is established based on the estimated terminal voltage signal, estimated first-end leakage current, first-end voltage, terminal current and local aging parameters corresponding to monitoring signals of different frequencies.

[0019] A further improvement of the present invention is that: the local aging parameters include the local aging starting position L b , local aging termination position L e and the estimated aging degree γ.

[0020] A further improvement of the present invention is that the step of sorting all estimation errors, selecting t local aging position combinations with the smallest estimation errors, and obtaining the local aging degree estimation value, the local aging position starting interval, and the local aging position ending interval according to the t local aging position combinations specifically includes:

[0021] Sort all the estimated errors by numerical value and select t local aging position combinations with the smallest estimated errors;

[0022] The largest local aging starting position among the t local aging position combinations is used as the maximum value of the local aging position starting interval, and the smallest local aging starting position among the t local aging position combinations is used as the minimum value of the local aging position starting interval;

[0023] The largest local aging termination position among the t local aging position combinations is used as the maximum value of the local aging position termination interval, and the smallest local aging termination position among the t local aging position combinations is used as the minimum value of the local aging position termination interval;

[0024] The local aging degree estimation value is obtained by averaging all aging degree estimation values ​​corresponding to t local aging position combinations.

[0025] A further improvement of the present invention is that: specifically, the threshold condition is that the range of the local aging position starting interval is greater than the local aging position threshold, and the range of the local aging position ending interval is also greater than the local aging position threshold.

[0026] A further improvement of the present invention is that the step of performing error analysis based on the output local aging degree estimation value, local aging position starting interval and local aging position ending interval to output the final local aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval specifically includes:

[0027] Get aging history data;

[0028] Generate a test set based on aging history data;

[0029] According to the test set, error analysis is performed to obtain the local aging starting position positioning error, local aging ending position positioning error and local aging degree error;

[0030] Correct the local aging position starting interval according to the local aging starting position positioning error to obtain the final local aging position starting interval;

[0031] According to the local aging termination position positioning error, the local aging position termination interval is corrected to obtain the final local aging position termination interval;

[0032] The local aging degree estimate is corrected according to the local aging degree error to obtain the final local aging degree estimate.

[0033] A further improvement of the present invention is that the size of t is positively correlated with P, the value of P is 8, and the value of t is 4.

[0034] In a second aspect, a distribution cable aging positioning device includes:

[0035] Division module: used to divide the cable to be tested into P segments and obtain P+1 endpoints;

[0036] Set establishment module: used to select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0037] Local aging positioning model building module: used to build a local aging positioning model according to a local aging position set;

[0038] Estimation error calculation module: used to calculate the estimation error of each local aging position combination according to the local aging positioning model;

[0039] Local aging data generation module: used to sort all estimation errors, select t local aging position combinations with the smallest estimation errors, and obtain the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval according to the t local aging position combinations;

[0040] Judgment module: used to judge whether the local aging position starting interval and the local aging position ending interval meet the threshold condition. If the threshold condition is met, the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval are output; otherwise, the local aging position starting interval and the local aging position ending interval are divided into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval at the last iteration are output;

[0041] Output module: used to perform error analysis based on the output old localization degree estimation value, local aging position starting interval and local aging position ending interval to output the final local aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval.

[0042] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for locating aging of distribution cables when executing the computer program.

[0043] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for locating aging of a distribution cable is implemented.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] 1. The present invention divides the cable to be tested into several sections, then establishes a collection and aging positioning model, and adopts a grid search method to transform the optimization problem for a cable into a sub-optimization problem of multiple position combinations, thereby reducing unknown quantities and greatly improving the accuracy and efficiency of calculation;

[0046] 2. The present invention improves the accuracy of positioning by performing error analysis;

[0047] 3. The present invention improves the overall robustness by limiting P and t. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0049] In the attached picture:

[0050] Figure 1 This is a flow chart of a method for locating aging of a distribution cable according to the present invention;

[0051] Figure 2 The present invention is a structural block diagram of a distribution cable aging positioning device. DETAILED DESCRIPTION

[0052] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0053] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0054] Example 1

[0055] A method for locating aging of distribution cables, such as Figure 1 As shown, the following steps are included:

[0056] S1. Divide the cable to be tested into P segments to obtain P+1 endpoints;

[0057] Specifically, P is a positive integer, and P+1 endpoints include the cable head end and the cable end end;

[0058] S2, select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0059] Specifically, the set of local aging position combinations is denoted as L, and the i-th element in the set L is denoted as (L b,i ,L e,i );

[0060] Specifically, L b，i Medium b Indicates the starting position of local aging, L e，i Medium e Indicates the location where local aging ends.

[0061] Specifically, the steps in S1 and S2 are based on the grid search method.

[0062] S3, establishing a local aging positioning model according to the local aging position set;

[0063] Specifically, S3 includes the following steps:

[0064] S31, passing monitoring signals of different frequencies into each local aging position combination to obtain local aging parameters corresponding to each local aging position combination, as well as the first-end leakage current, the terminal leakage current, the first-end voltage, and the terminal voltage corresponding to the monitoring signals of different frequencies;

[0065] Specifically, when different frequency monitoring signals are input to each local aging position combination in S31, a cable transfer function measurement method based on power line communication (PLC) is adopted. The power supply side and the load side of the PLC system are respectively provided with a power line communication modem (PLM), which can act as a monitoring signal injection module and a signal measurement unit. The voltage at both ends of the cable can be measured by the PLM at both ends of the cable, thereby calculating the transfer function of the cable;

[0066] Specifically, the local aging parameters include the local aging starting position L b , local aging termination position L e and the estimated value of aging degree γ;

[0067] Specifically, the estimated value γ of the aging degree is the ratio of the capacitance of the local aging position combination to the capacitance of the intact segment;

[0068] Specifically, the intact section capacitance is the capacitance of the portion other than the combination of local aging positions in the entire cable to be tested;

[0069] Specifically, n monitoring signals with different frequencies are injected, where the frequency of the i-th monitoring signal is recorded as f i , the voltage of the i-th monitoring signal is recorded as U inj , the frequency is f i The head-end voltage corresponding to the monitoring signal is recorded as U i1 (f i ), the terminal voltage is denoted as U i2 (f i ), the first-end leakage current is recorded as I i1 (f i ), the terminal leakage current is recorded as I i2 (f i ).

[0070] S32, obtaining the transfer function of each local aging position combination and the head-end equivalent admittance of the entire cable to be tested;

[0071] S33, calculating an estimated terminal voltage and an estimated head-end leakage current according to the transfer function of each local aging position combination and the head-end equivalent admittance of the entire cable to be tested;

[0072] The transfer function is expressed as H tThe equivalent admittance of the entire cable under test is represented by Y0;

[0073] Specifically, the estimated terminal voltage U m2 :

[0074] U m2 =H t U inj ;

[0075] Estimated first-end leakage current I m1 :

[0076] I m1 =Y0U inj ;

[0077] S34, establishing a local aging positioning model according to the estimated terminal voltage signal, the estimated first-end leakage current, the first-end voltage, the terminal current and the local aging parameters corresponding to the monitoring signals of different frequencies;

[0078]

[0079] sL b =L b，i , L e =L e，i , γ i ≥1;

[0080] In the formula, γ i represents the estimated aging degree corresponding to the i-th local aging position combination, U m2 (f k ) indicates the frequency is f k The estimated terminal voltage corresponding to the monitoring signal; I m1 (f k ) indicates the frequency is f k The estimated first-end leakage current corresponding to the monitoring signal; U i1 (f k ) indicates the frequency is f k The head-end voltage corresponding to the monitoring signal; I i2 (f k ) indicates the frequency is f k λ is a weight coefficient, λ is used to adjust the weight between the voltage estimation error and the current estimation error, and in this embodiment, λ is 1.

[0081] S4, calculating the estimation error of each local aging position combination according to the local aging positioning model;

[0082] Specifically, S4 includes:

[0083]

[0084] In the formula, E i represents the estimation error corresponding to the i-th local aging position combination;

[0085] S5, sorting all the estimation errors, selecting t local aging position combinations with the smallest estimation errors, and obtaining the local aging degree estimation value, the local aging position starting interval, and the local aging position ending interval according to the t local aging position combinations;

[0086] Specifically, S5 includes:

[0087] S51, sorting all the estimated errors by numerical value, and selecting t local aging position combinations with the smallest estimated errors;

[0088] Specifically, t is a positive integer, and the size of t is positively correlated with P;

[0089] The value of t should be as small as possible to ensure the robustness of the algorithm;

[0090] S52, taking the largest local aging starting position among the t local aging position combinations as the maximum value of the local aging position starting interval, and taking the smallest local aging starting position among the t local aging position combinations as the minimum value of the local aging position starting interval;

[0091] Specifically, the largest local aging starting position means that among the t local aging position combinations, the distance from the starting end point of the cable to be tested to the local aging starting position is the largest.

[0092] Specifically, the starting interval of the local aging position is recorded as [L b1 ,L b2 ];

[0093] The largest local aging termination position among the t local aging position combinations is used as the maximum value of the local aging position termination interval, and the smallest local aging termination position among the t local aging position combinations is used as the minimum value of the local aging position termination interval;

[0094] Specifically, the local aging position termination interval is recorded as [L e1 ,L e2 ];

[0095] Specifically, the smallest local aging starting position means that among the t local aging position combinations, the distance from the termination end point of the cable to be tested to the local aging termination position is the largest.

[0096] Averaging all aging degree estimation values ​​corresponding to t local aging position combinations to obtain a local aging degree estimation value;

[0097] S6, judging whether the local aging position starting interval and the local aging position ending interval meet the threshold condition, if the threshold condition is met, outputting the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval; otherwise, dividing the local aging position starting interval and the local aging position ending interval into P segments respectively, obtaining a new local aging position set and iterating until the threshold condition is met or the maximum number of iterations is reached, and outputting the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval at the last iteration;

[0098] Specifically, the threshold condition is that the range of the local aging position starting interval is greater than the local aging position threshold, and the range of the local aging position ending interval is also greater than the local aging position threshold;

[0099] In order to improve the computational efficiency of each step of the optimization solution, the value of the grid division number P is set to 8. Because the local aging positioning model is highly nonlinear, the position combination with the smallest estimated error obtained in each screening and iteration does not necessarily coincide with the actual local aging position. Therefore, the number of local aging position combinations t with the smallest error is set to 4 to ensure the robustness of the algorithm. At the same time, the value of t will increase with the increase of the grid division number P. In addition, the maximum number of iterations N and the local aging position threshold α need to be set. For industrial needs, α is set to 0.05km. On the test data set, the average number of iterations is 3, so N is set to 10 in this chapter to ensure the convergence of the positioning algorithm.

[0100] S7, performing error analysis based on the output local aging degree estimation value, local aging position starting interval, and local aging position ending interval to obtain a final local aging degree estimation value, a final local aging position starting interval, and a final local aging position ending interval;

[0101] Specifically, S7 includes the following steps:

[0102] S71, obtaining aging history data;

[0103] Specifically, the aging history data are different local aging conditions of the cable, including: cable length, historical local aging starting position, historical local aging ending position and historical local aging degree estimation;

[0104] S72, generating a test set according to the aging history data;

[0105] For example, the test set consists of 275 measurement data including different local aging conditions of several cables;

[0106] The measurement data include cable length, historical local aging starting position, historical local aging ending position and historical local aging degree estimation;

[0107] Specifically, the cable length is 10 km; the starting position of historical local aging varies within [0 km, 9 km], and the variation interval is 1 km; the ending position of historical local aging varies within [1 km, 10 km], and the variation interval is 1 km; the estimated value of historical local aging degree varies within [1.1, 1.5], and the variation interval is 0.1. The above values ​​are for example only and are not limited to the above values.

[0108] S73, performing error analysis according to the test set to obtain a local aging start position positioning error, a local aging end position positioning error, and a local aging degree error;

[0109]

[0110]

[0111]

[0112] In the formula, is the local aging starting position positioning error; E is the local aging termination position positioning error; γ is the local aging degree estimation error; Ns is the total number of data in the test set; is the historical local aging starting position of the i-th data in the data set; is the starting interval of the test local aging position obtained by S1-S6 for the i-th data; is the local aging position termination interval, is the test local aging position termination interval obtained by S1-S6 for the i-th data; γ (i) Represents the estimated value of the historical local aging degree of the i-th data in the test set, is the local aging degree estimation value obtained by S1-S6 for the i-th data;

[0113] S74, correcting the local aging position starting interval according to the local aging starting position positioning error to obtain a final local aging position starting interval;

[0114] Specifically, the final local aging position starting interval is [the minimum value of the local aging position starting interval minus the local aging starting position positioning error, the maximum value of the local aging position starting interval plus the local aging starting position positioning error];

[0115] According to the local aging termination position positioning error, the local aging position termination interval is corrected to obtain the final local aging position termination interval;

[0116] Specifically, the final local aging position starting interval is [the minimum value of the local aging position starting interval minus the local aging starting position positioning error, the maximum value of the local aging position starting interval plus the local aging starting position positioning error];

[0117] Correct the local aging degree estimate value according to the local aging degree error to obtain the final local aging degree estimate value;

[0118] Specifically, the final local aging degree estimation value ∈ [local aging degree estimation value minus local aging degree error, local aging degree estimation value plus local aging degree error].

[0119] Example 2

[0120] A distribution cable aging positioning device, such as Figure 2 As shown, including:

[0121] Division module: used to divide the cable to be tested into P segments and obtain P+1 endpoints;

[0122] Set establishment module: used to select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0123] Local aging positioning model building module: used to build a local aging positioning model according to a local aging position set;

[0124] Estimation error calculation module: used to calculate the estimation error of each local aging position combination according to the local aging positioning model;

[0125] Local aging data generation module: used to sort all estimation errors, select t local aging position combinations with the smallest estimation errors, and obtain the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval according to the t local aging position combinations;

[0126] Judgment module: used to judge whether the local aging position starting interval and the local aging position ending interval meet the threshold condition. If the threshold condition is met, the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval are output; otherwise, the local aging position starting interval and the local aging position ending interval are divided into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval at the last iteration are output;

[0127] Output module: used to perform error analysis based on the output old localization degree estimation value, local aging position starting interval and local aging position ending interval to output the final local aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval.

[0128] Example 3

[0129] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for locating aging of a distribution cable is implemented, including the following steps:

[0130] Used to divide the cable to be tested into P segments to obtain P+1 endpoints;

[0131] Used to select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0132] Used to establish a local aging positioning model based on a local aging position set;

[0133] Used to calculate the estimation error of each local aging position combination according to the local aging positioning model;

[0134] It is used to sort all the estimation errors, select t local aging position combinations with the smallest estimation errors, and obtain the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval according to the t local aging position combinations;

[0135] Used to determine whether the local aging position start interval and the local aging position end interval meet the threshold condition. If the threshold condition is met, the estimated aging degree, the local aging position start interval and the local aging position end interval are output; otherwise, the local aging position start interval and the local aging position end interval are divided into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and the estimated aging degree, the local aging position start interval and the local aging position end interval at the last iteration are output;

[0136] It is used to perform error analysis based on the output aging degree estimation value, local aging position starting interval and local aging position ending interval to output the final aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval.

[0137] Example 4

[0138] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, a method for locating aging of a distribution cable is implemented, comprising the following steps:

[0139] Used to divide the cable to be tested into P segments to obtain P+1 endpoints;

[0140] Used to select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set;

[0141] Used to establish a local aging positioning model based on a local aging position set;

[0142] Used to calculate the estimation error of each local aging position combination according to the local aging positioning model;

[0143] It is used to sort all the estimation errors, select t local aging position combinations with the smallest estimation errors, and obtain the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval according to the t local aging position combinations;

[0144] Used to determine whether the local aging position start interval and the local aging position end interval meet the threshold condition. If the threshold condition is met, the estimated aging degree, the local aging position start interval and the local aging position end interval are output; otherwise, the local aging position start interval and the local aging position end interval are divided into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and the estimated aging degree, the local aging position start interval and the local aging position end interval at the last iteration are output;

[0145] It is used to perform error analysis based on the output aging degree estimation value, local aging position starting interval and local aging position ending interval to output the final aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval.

[0146] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0147] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0148] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0149] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for locating aging of distribution cables, characterized in that: The following steps are involved: Divide the cable to be tested into P segments, and obtain P+1 endpoints; Select any two of the P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set; Establishing a local aging location model according to the local aging location set; Calculate the estimation error of each local aging position combination according to the local aging positioning model; All estimation errors are sorted, t local aging position combinations with the smallest estimation errors are selected, and local aging degree estimation values, local aging position start intervals, and local aging position end intervals are obtained according to the t local aging position combinations; Determine whether the local aging position start interval and the local aging position end interval meet the threshold condition. If the threshold condition is met, output the local aging degree estimate, the local aging position start interval and the local aging position end interval; otherwise, divide the local aging position start interval and the local aging position end interval into P segments, obtain a new local aging position set, and iterate until the threshold condition is met or the maximum number of iterations is reached, and output the local aging degree estimate, the local aging position start interval and the local aging position end interval at the last iteration; Error analysis is performed based on the output local aging degree estimation value, local aging position starting interval and local aging position ending interval to obtain the final local aging degree estimation value, final local aging position starting interval and final local aging position ending interval.

2. A method for locating aging of distribution cables according to claim 1, characterized in that: The step of establishing a local aging positioning model according to the local aging position set specifically includes: A monitoring signal of different frequencies is input to each local aging position combination to obtain a local aging parameter corresponding to each local aging position combination, a first-end leakage current, a terminal leakage current, a first-end voltage, and a terminal voltage corresponding to the monitoring signals of different frequencies; Obtain the transfer function of each local aging position combination and the head-end equivalent admittance of the entire cable under test; Calculate the estimated terminal voltage and the estimated head end leakage current according to the transfer function of each local aging position combination and the head end equivalent admittance of the entire cable to be tested; A local aging positioning model is established according to the estimated terminal voltage, estimated first-end leakage current, first-end voltage, terminal leakage current and local aging parameters corresponding to monitoring signals of different frequencies.

3. A method for locating aging of distribution cables according to claim 2, characterized in that: The local aging parameters include the local aging starting position L b , local aging termination position L e and the estimated aging degree γ.

4. A method for locating aging of distribution cables according to claim 1, characterized in that: The step of sorting all estimation errors, selecting t local aging position combinations with the smallest estimation errors, and obtaining the local aging degree estimation value, the local aging position starting interval, and the local aging position ending interval according to the t local aging position combinations specifically includes: Sort all the estimated errors by numerical value and select t local aging position combinations with the smallest estimated errors; The largest local aging starting position among the t local aging position combinations is used as the maximum value of the local aging position starting interval, and the smallest local aging starting position among the t local aging position combinations is used as the minimum value of the local aging position starting interval; The largest local aging termination position among the t local aging position combinations is used as the maximum value of the local aging position termination interval, and the smallest local aging termination position among the t local aging position combinations is used as the minimum value of the local aging position termination interval; The local aging degree estimation value is obtained by averaging all aging degree estimation values ​​corresponding to t local aging position combinations.

5. A method for locating aging of distribution cables according to claim 1, characterized in that: Specifically, the threshold condition is that the range of the local aging position start interval is greater than the local aging position threshold, and the range of the local aging position end interval is also greater than the local aging position threshold.

6. A method for locating aging of distribution cables according to claim 1, characterized in that: The step of performing error analysis according to the output local aging degree estimation value, local aging position starting interval and local aging position ending interval to obtain the final local aging degree estimation value, the final local aging position starting interval and the final local aging position ending interval specifically includes: Get aging history data; Generate a test set based on aging history data; According to the test set, error analysis is performed to obtain the local aging starting position positioning error, local aging ending position positioning error and local aging degree error; Correct the local aging position starting interval according to the local aging starting position positioning error to obtain the final local aging position starting interval; According to the local aging termination position positioning error, the local aging position termination interval is corrected to obtain the final local aging position termination interval; The local aging degree estimate is corrected according to the local aging degree error to obtain the final local aging degree estimate.

7. A method for locating aging of distribution cables according to claim 1, characterized in that: The size of t is positively correlated with P. The value of P is 8, and the value of t is 4.

8. A distribution cable aging positioning device, characterized in that: include: Division module: used to divide the cable to be tested into P segments and obtain P+1 endpoints; Set establishment module: used to select any two from P+1 endpoints to form a local aging position combination, obtain all local aging position combinations to establish a local aging position set; Local aging positioning model building module: used to build a local aging positioning model according to a local aging position set; Estimation error calculation module: used to calculate the estimation error of each local aging position combination according to the local aging positioning model; Local aging data generation module: used to sort all estimation errors, select t local aging position combinations with the smallest estimation errors, and obtain the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval according to the t local aging position combinations; Judgment module: used to judge whether the local aging position starting interval and the local aging position ending interval meet the threshold condition. If the threshold condition is met, the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval are output; otherwise, the local aging position starting interval and the local aging position ending interval are divided into P segments to obtain a new local aging position set for iteration until the threshold condition is met or the maximum number of iterations is reached, and the local aging degree estimation value, the local aging position starting interval and the local aging position ending interval at the last iteration are output; Output module: used to perform error analysis based on the output local aging degree estimate value, local aging position starting interval and local aging position ending interval to output the final local aging degree estimate value, the final local aging position starting interval and the final local aging position ending interval.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for locating aging of a distribution cable as described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, a method for locating aging of a distribution cable as described in any one of claims 1 to 7 is implemented.

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