Method for positioning ground fault of underground cable

Abstract

The invention specifically relates to a method for positioning a ground fault of an underground cable, and belongs to the technical field of data processing methods for positioning the ground fault of the underground cable by using a matrix. According to the invention, the combination of the traveling wave speed and time is selected by considering the difference of the traveling wave propagation speed in different fault scenes; the method comprises the following steps of: forming a fault difference matrix by selecting a distance from a traveling wave generated at a fault point to endpoints of a main line and each branch line, and subtracting the fault difference matrix from a fixed difference matrix formed by network topology of an underground cable to form a position judgment difference matrix; whether the fault point specifically occurs on the main line or the specific branch line of the underground cable is judged through the position judgment difference matrix, and finally the specific position of the fault point is calculated through the traveling wave arrival speed and time collected by the traveling wave collector, so that the calculation difficulty is greatly reduced on the premise of not depending on the electrical parameters of the cable, and the working efficiency is improved. Therefore, the ground fault of the underground cable can be quickly and accurately positioned.

Description

Technical Field

[0001] The present invention specifically relates to a method for locating an underground cable grounding fault, and belongs to the technical field of data processing methods for locating underground cable grounding faults using a matrix (G06F17 / 16). Background Art

[0002] Underground cables have an insulating outer layer, which can effectively prevent cable aging, insulation shedding, and corrosion by acidic and alkaline gases and water vapor in the atmosphere, thereby improving the safety of power transmission. The laying method of underground cables avoids the failure of overhead lines due to external factors such as wind, rain, and animal bites, and improves the reliability of the power grid. However, the insulation layer of the cable will corrode under harsh environmental conditions such as high temperature and humidity, the insulation layer will be exposed due to improper operation during construction, or the cable will be damaged by various external factors such as lightning strikes and animal bites, which will cause grounding faults in underground cables. When a grounding fault occurs in an underground cable, it will not only affect the normal operation of the power system, but may also pose a threat to personal safety. Therefore, after the cable is laid, detection measures need to be taken to detect the fault in time and deal with it in the early stage of the fault or before serious consequences occur, so as to ensure the safety and stability of the power system. The Chinese patent application number is CN202310455087.0, and the patent name is: Traveling wave positioning method and device for multi-branch faults in distribution network based on time difference matrix data fitting. This method constructs a reference time difference matrix under simulated fault conditions and compares it with the fault time difference matrix after the actual fault occurs to identify the main fault line. However, this strategy does not fully consider the differences in downlink propagation speeds in different fault scenarios. At the same time, the matrix fitting of each value leads to a sharp increase in calculations, huge storage requirements, and a prolonged fault judgment cycle. In addition, the fault location process also requires the use of a complex distance point calculation method, which makes the entire location method too cumbersome and has poor location accuracy. Summary of the invention

[0003] The technical problem to be solved by the present invention is: how to quickly and accurately locate the occurrence position of the grounding fault of the underground cable.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for locating an underground cable grounding fault, comprising the following steps:

[0005] Step 1: Draw the network topology of the underground cable structure using A s and A m to indicate the starting and ending points of the main line of the underground cable; the endpoints of the n branch lines from the starting end to the end of the main line of the underground cable are represented by A1, A2, ..., to A nThe n branch lines from the starting end to the end of the main line of the underground cable and the branch nodes of the main line of the underground cable are represented by B1, B2, ..., to B n To represent; establish an underground cable coordinate system on the depth plane where the underground cable is located, wherein the underground cable coordinate system takes the starting end of the main line of the underground cable as the origin, the direction from the starting end to the end of the main line of the underground cable as the X-axis, and the straight line perpendicular to the X-axis and located in the depth plane where the underground cable is located as the Y-axis;

[0006] Step 2: Calculate A1, A2, ..., and A in the underground cable coordinate system in sequence by the following formula (1): n to the B1, B2, ..., and B n The distance between

[0007] (1)

[0008] In formula (1), is the distance from the endpoint of the i-th branch line among the n branch lines to the B1, B2, ..., and B n The distance between is the X-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the X-axis coordinate of the i-th branch node among the n branch nodes; is the Y-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the Y-axis coordinate of the i-th branch node among the n branch nodes;

[0009] The A is calculated by the following formula (2): s to the B1, B2, ..., and B n The distance between

[0010] (2)

[0011] In formula (2), It is the A s The X-axis coordinate of It is the A s The Y-axis coordinate of

[0012] The distances between the endpoints of the n branch lines and the n branch nodes and the distances between the A and B are calculated by the following formula (3): s The difference in distances to the n branch nodes,

[0013] (3);

[0014] In formula (3), is the distance between the endpoint of the i-th branch line in the n branch lines and the i-th branch node in the n branch nodes and the A s The difference in distance to the i-th branch node among the n branch nodes;

[0015] The distances between the endpoints of the n branch lines and the n branch nodes and the distances between A1, A2, ..., and A n-1 The difference in distances to the n branch nodes,

[0016] (4);

[0017] In formula (3), is the difference between the distance between the endpoint of the i-th branch line among the n branch lines and the i-th branch node among the n branch nodes and the distance between the endpoint of the j-th branch line among the n-1 branch lines and the i-th branch node among the n branch nodes;

[0018] The distances between the endpoints of the n branch lines and the n branch nodes are compared with A s , A1, A2, …, and A n-1 The differences in the distances to the n branch nodes are collected to form a fixed difference matrix Q, as shown in the following equation (4):

[0019] (4);

[0020] Step 3: Install traveling wave collectors at the starting and ending points of the main line of the underground cable; also install traveling wave collectors at the ending points of the n branch lines of the underground cable; when a ground fault occurs in the underground cable, define the time and speed of the traveling wave generated by the fault point F to reach the starting end of the main line of the underground cable as and ; Define the time and speed of the traveling wave generated by the fault point F to reach the end of the main line of the underground cable are and ; Define the time and speed of the traveling wave generated by the fault point F to reach the terminal of the i-th branch line among the n branch lines of the underground cable as and ;

[0021] Step 4: Calculate the distance between the endpoints of the n branch lines and the fault point F and the distance between the A and the fault point F by using the following formula (5): s The difference in distance to the fault point F,

[0022] (5)

[0023] In formula (5), is the distance between the endpoint of the i-th branch line in the n branch lines and the fault point F and the distance between the i-th branch line and the fault point F and the A s The difference in distance to the fault point F; is the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F; It is the A s The distance to the fault point F;

[0024] The distances between the endpoints of the n branch lines and the fault point F and the distances between A1, A2, ..., and A n-1 The difference in distance to the fault point F,

[0025] (6)

[0026] In formula (6), is the difference between the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F and the distance between the endpoint of the j-th branch line among the n-1 branch lines and the fault point F; is the distance between the endpoint of the jth branch line among the n-1 branch lines and the fault point F;

[0027] The distances between the endpoints of the n branch lines and the fault point F are compared with A s , A1, A2, …, and A n-1 The distance differences between the fault point F and the fault point F are collected to form a fault difference matrix N, as shown in the following formula (7):

[0028] (7);

[0029] Step 5: Subtract the fixed difference matrix Q from the fault difference matrix N to obtain a position determination difference matrix , as shown in the following formula (8),

[0030] (8);

[0031] If the position judgment difference matrix If all the elements in a column except the first column are 0, it is considered that the fault point F is located on the main line of the underground cable;

[0032] The distance from the fault point F to the starting end of the main line of the underground cable is calculated according to the following formula (9): ,

[0033] (9);

[0034] If the position judgment difference matrix Except for the first column, if there is a column with all elements less than 0, and all the elements of the remaining columns are greater than or equal to 0, then the fault point F is considered to be on the branch line corresponding to the column with all elements less than 0;

[0035] The distance from the fault point F to the end point of the branch where the fault point F is located is calculated according to the following formula (10): ,

[0036] (10)

[0037] In formula (10), It is the speed at which the traveling wave collector at the end point of the branch where the fault point F is located receives the traveling wave generated when the fault point F fails; The time it takes for the traveling wave generated when a fault occurs at the fault point F to reach the end point of the branch where the fault point F is located.

[0038] Beneficial effects of the present invention: The present invention takes into account the differences in the propagation speed of downlink waves in different fault scenarios and selects a combination of the speed of the traveling wave and the time. The distance from the traveling wave at the fault point to the end points of the main line and each branch line is selected to form a fault difference matrix, which is subtracted from the fixed difference matrix formed by the network topology of the underground cable to form a position judgment difference matrix. The position judgment difference matrix is ​​used to determine whether the fault point occurs on the main line or a specific branch line of the underground cable. Finally, the specific position of the fault point is calculated through the speed and time of the traveling wave arrival collected by the traveling wave collector. Without relying on the electrical parameters of the cable, the calculation difficulty is greatly reduced, and the underground cable grounding fault is quickly and accurately located. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a method for locating an underground cable grounding fault. DETAILED DESCRIPTION

[0040] The following is a further description of a method for locating an underground cable grounding fault according to the present invention in conjunction with specific embodiments and drawings.

[0041] Example

[0042] The method for locating an underground cable grounding fault in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0043] Step 1: Draw the network topology of the underground cable structure using A s and A mTo indicate the starting and ending points of the main line of the underground cable; the endpoints of the n branch lines from the starting point to the end of the main line of the underground cable are represented by A1, A2, ..., to A n To represent; the n branch lines from the starting end to the end of the main line of the underground cable and the branch nodes of the main line of the underground cable are represented by B1, B2, ..., to B n To express; establish an underground cable coordinate system on the depth plane where the underground cable is located. The underground cable coordinate system takes the starting end of the main line of the underground cable as the origin, the direction from the starting end to the end of the main line of the underground cable as the X-axis, and the straight line perpendicular to the X-axis and located in the depth plane where the underground cable is located as the Y-axis;

[0044] Step 2: Calculate A1, A2, ..., and A in the underground cable coordinate system using the following formula (1): n to B1, B2, ..., and B n The distance between

[0045] (1)

[0046] In formula (1), is the endpoint of the i-th branch line among the n branch lines to B1, B2, ..., and B n The distance between is the X-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the X-axis coordinate of the i-th branch node among the n branch nodes; is the Y-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the Y-axis coordinate of the i-th branch node among the n branch nodes;

[0047] A is calculated by the following formula (2): s to B1, B2, ..., and B n The distance between

[0048] (2)

[0049] In formula (2), Yes A s The X-axis coordinate of Yes A s The Y-axis coordinate of

[0050] The distance between the endpoints of n branch lines and n branch nodes and A are calculated by the following formula (3): s The difference in distances to n branch nodes,

[0051] (3);

[0052] In formula (3), is the distance between the endpoint of the i-th branch line in the n branch lines and the i-th branch node in the n branch nodes and A s The difference in distance to the i-th branch node among n branch nodes;

[0053] The distances between the endpoints of n branch lines and n branch nodes and A1, A2, ..., and A are calculated by the following formula (4): n-1 The difference in distances to n branch nodes,

[0054] (4);

[0055] In formula (3), is the difference between the distance between the endpoint of the i-th branch line in the n branch lines and the i-th branch node in the n branch nodes and the distance between the endpoint of the j-th branch line in the n-1 branch lines and the i-th branch node in the n branch nodes;

[0056] Compare the distances between the endpoints of n branch lines and n branch nodes with A s , A1, A2, …, and A n-1 The differences in the distances to the n branch nodes are collected to form a fixed difference matrix Q, as shown in the following equation (4):

[0057] (4);

[0058] Step 3: Install traveling wave collectors at the starting and ending points of the main line of the underground cable; also install traveling wave collectors at the end points of the n branch lines of the underground cable; when a ground fault occurs in the underground cable, the time and speed of the traveling wave generated by the fault point F to reach the starting end of the main line of the underground cable are defined as and ; Define the time and speed of the traveling wave generated by the fault point F to reach the end of the main line of the underground cable as and ; Define the time and speed of the traveling wave generated by the fault point F to reach the terminal of the i-th branch line among the n branch lines of the underground cable as and ;

[0059] Step 4: Calculate the distance between the endpoints of the n branch lines and the fault point F and A by the following formula (5): s The difference in distance to the fault point F,

[0060] (5)

[0061] In formula (5), is the distance between the endpoint of the i-th branch line and the fault point F and A s The difference in distance to the fault point F; is the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F; Yes A s The distance to the fault point F;

[0062] The distances between the endpoints of the n branch lines and the fault point F and A1, A2, ..., and A are calculated by the following formula (6): n-1 The difference in distance to the fault point F,

[0063] (6)

[0064] In formula (6), It is the difference between the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F and the distance between the endpoint of the j-th branch line among the n-1 branch lines and the fault point F; is the distance between the endpoint of the jth branch line in the n-1 branch lines and the fault point F;

[0065] The distances between the endpoints of the n branch lines and the fault point F are compared with A s , A1, A2, …, and A n-1 The distance differences between the fault point F and the fault point F are collected to form the fault difference matrix N, as shown in the following formula (7):

[0066] (7);

[0067] Step 5: Subtract the fixed difference matrix Q from the fault difference matrix N to obtain the position judgment difference matrix , as shown in the following formula (8),

[0068] (8);

[0069] If the position judgment difference matrix If all the elements in a column except the first column are 0, it is considered that the fault point F is located on the main line of the underground cable;

[0070] The distance from the fault point F to the starting end of the main line of the underground cable is calculated according to the following formula (9): ,

[0071] (9);

[0072] If the position judgment difference matrix Except for the first column, if there is a column with all elements less than 0, and all the elements of the remaining columns are greater than or equal to 0, then the fault point F is considered to be on the branch line corresponding to the column with all elements less than 0;

[0073] The distance from the fault point F to the end point of the branch where the fault point F is located is calculated according to the following formula (10): ,

[0074] (10)

[0075] In formula (10), It is the speed at which the traveling wave collector at the end point of the branch where the fault point F is located receives the traveling wave generated when the fault point F fails; The time it takes for the traveling wave generated when a fault occurs at the fault point F to reach the end point of the branch where the fault point F is located.

Claims

1. A method for locating an underground cable grounding fault, characterized in that: The following steps are involved: Step 1: Draw the network topology of the underground cable structure using A s and A m to indicate the starting and ending points of the main line of the underground cable; the endpoints of the n branch lines from the starting end to the end of the main line of the underground cable are represented by A1, A2, ..., to A n The n branch lines from the starting end to the end of the main line of the underground cable and the branch nodes of the main line of the underground cable are represented by B1, B2, ..., to B n To represent; establish an underground cable coordinate system on the depth plane where the underground cable is located, wherein the underground cable coordinate system takes the starting end of the main line of the underground cable as the origin, the direction from the starting end to the end of the main line of the underground cable as the X-axis, and the straight line perpendicular to the X-axis and located in the depth plane where the underground cable is located as the Y-axis; Step 2: Calculate A1, A2, ..., and A in the underground cable coordinate system in sequence by the following formula (1): n to B1, B2, ..., and B n The distance between （1） In formula (1), is the distance from the endpoint of the i-th branch line among the n branch lines to the B1, B2, ..., and B n The distance between is the X-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the X-axis coordinate of the i-th branch node among the n branch nodes; is the Y-axis coordinate of the endpoint of the i-th branch line among the n branch lines; is the Y-axis coordinate of the i-th branch node among the n branch nodes; The A is calculated by the following formula (2): s to the B1, B2, ..., and B n The distance between （2） In formula (2), It is the A s The X-axis coordinate of It is the A s The Y-axis coordinate of The distances between the endpoints of the n branch lines and the n branch nodes and the distances between the A and B are calculated by the following formula (3): s The difference in distances to the n branch nodes, （3）； In formula (3), is the distance between the endpoint of the i-th branch line in the n branch lines and the i-th branch node in the n branch nodes and the A s The difference in distance to the i-th branch node among the n branch nodes; The distances between the endpoints of the n branch lines and the n branch nodes and the distances between A1, A2, ..., and A n-1 The difference in distances to the n branch nodes, （4）； In formula (3), is the difference between the distance between the endpoint of the i-th branch line among the n branch lines and the i-th branch node among the n branch nodes and the distance between the endpoint of the j-th branch line among the n-1 branch lines and the i-th branch node among the n branch nodes; The distances between the endpoints of the n branch lines and the n branch nodes are compared with A s , A1, A2, …, and A n-1 The differences in the distances to the n branch nodes are collected to form a fixed difference matrix Q, as shown in the following equation (4): （4）； Step 3: Install traveling wave collectors at the starting and ending points of the main line of the underground cable; also install traveling wave collectors at the ending points of the n branch lines of the underground cable; when a ground fault occurs in the underground cable, define the time and speed of the traveling wave generated by the fault point F to reach the starting end of the main line of the underground cable as and ; Define the time and speed of the traveling wave generated by the fault point F to reach the end of the main line of the underground cable are and ; Define the time and speed of the traveling wave generated by the fault point F to reach the terminal of the i-th branch line among the n branch lines of the underground cable as and ; Step 4: Calculate the distance between the endpoints of the n branch lines and the fault point F and the distance between the A and the fault point F by using the following formula (5): s The difference in distance to the fault point F, （5） In formula (5), is the distance between the endpoint of the i-th branch line in the n branch lines and the fault point F and the distance between the i-th branch line and the fault point F and the A s The difference in distance to the fault point F; is the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F; It is the A s The distance to the fault point F; The distances between the endpoints of the n branch lines and the fault point F and the distances between A1, A2, ..., and A n-1 The difference in distance to the fault point F, （6） In formula (6), is the difference between the distance between the endpoint of the i-th branch line among the n branch lines and the fault point F and the distance between the endpoint of the j-th branch line among the n-1 branch lines and the fault point F; is the distance between the endpoint of the jth branch line among the n-1 branch lines and the fault point F; The distances between the endpoints of the n branch lines and the fault point F are compared with A s , A1, A2, …, and A n-1 The distance differences between the fault point F and the fault point F are collected to form a fault difference matrix N, as shown in the following formula (7): （7）； Step 5: Subtract the fixed difference matrix Q from the fault difference matrix N to obtain a position determination difference matrix , as shown in the following formula (8), （8）； If the position judgment difference matrix If all the elements in a column except the first column are 0, it is considered that the fault point F is located on the main line of the underground cable; The distance from the fault point F to the starting end of the main line of the underground cable is calculated according to the following formula (9): , （9）； If the position judgment difference matrix Except for the first column, if there is a column with all elements less than 0, and all the elements of the remaining columns are greater than or equal to 0, then the fault point F is considered to be on the branch line corresponding to the column with all elements less than 0; The distance from the fault point F to the end point of the branch where the fault point F is located is calculated according to the following formula (10): , （10） In formula (10), It is the speed at which the traveling wave collector at the end point of the branch where the fault point F is located receives the traveling wave generated when the fault point F fails; The time it takes for the traveling wave generated when a fault occurs at the fault point F to reach the end point of the branch where the fault point F is located.

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