Multi-circuit cable sheath current overload processing method, storage medium and electronic device

Abstract

The application provides a multi-circuit cable sheath current overload processing method, and belongs to the technical field of electrical engineering, and comprises the following steps: S1, determining the relevant basic parameters of the cable; S2, determining the current phase sequence combination of the cable core when the sheath current of the target section cable is the minimum; S3, judging whether the sheath current of the target section cable meets the rated requirement according to the current phase sequence combination; deciding to enter step S4 or S5; S4, according to the current phase sequence combination of the cable core determined in step S2, calculating whether the sheath current of other cables except the target section cable is overloaded to decide to change the current phase sequence combination mode of the starting power station of the power transmission line or change the sheath cross interconnection mode of the target section cable; S5, changing the basic parameters of the target section cable, and repeating steps S2-S3 until the sheath current of the target section cable meets the rated requirement; the application can make the current of the cable sheath not exceed the rated value without changing the cross interconnection mode of the laid cable sheath.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical engineering, and in particular relates to a method for processing current overload of a multi-circuit cable sheath, a storage medium and electronic equipment. Background Art

[0002] As the cableization rate of urban power grids continues to increase, the number of multiple high-voltage cable lines laid in parallel within tunnels is increasing. Due to the mutual influence between multiple lines, excessive current may occur in the cable sheath, thereby endangering the safe operation of the cable.

[0003] High-voltage cables are grounded through their metal sheaths, providing a stable zero-potential reference point and reliable shielding. Cross-connected grounding not only reduces sheath current losses by offsetting the induced voltages across the three-phase sheaths during normal operation, but also provides a fault current path for high-voltage cable faults. Therefore, it is widely adopted. To protect the high-voltage cable's outer sheath insulation and metal sheath from lightning strikes or switching overvoltages, sheath protectors are installed at cross-connections.

[0004] In the existing technology, when the sheath current of a multi-circuit cable is overloaded or a new cable is to be laid, a simulation calculation is generally performed first. Then, the optimal current phase sequence combination is selected based on the calculation results. The cross-connection method of the cable sheath is replaced according to this combination to reduce the current of the cable sheath to meet the set requirements. However, this method is difficult to replace the cross-connection method of the sheath of the laid cable in some tunnels with more complex laying conditions, which increases the difficulty of maintenance or laying operations. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for processing current overload of a multi-circuit cable sheath, a storage medium and an electronic device, which can prevent the current of the cable sheath from exceeding the rated value without changing the cross-connection mode of the laid cable sheath.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The method for handling current overload of a multi-circuit cable sheath comprises the following steps:

[0008] S1. Determine the relevant basic parameters of all cables;

[0009] S2. Determine the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum based on the basic parameters;

[0010] S3, judging whether the sheath current of the target cable segment meets the rated requirement according to the current phase sequence combination of the cable core in step S2; if so, proceeding to step S41, otherwise proceeding to step S5;

[0011] S41. Based on the current phase sequence combination of the cable cores determined in step S2, calculate whether the sheath current of the cables other than the target segment cable is overloaded according to this current phase sequence combination. If not, directly change the current phase sequence combination of the starting power station of the transmission line to this current phase sequence combination; if there is an overload, proceed to step S42.

[0012] S42, changing the sheath cross-connection mode of the target cable segment so that the core current phase sequence combination corresponding to the sheath is the current phase sequence combination determined in step S2;

[0013] S5. Change the basic parameters of the target cable segment, and then repeat steps S2-S3 until the sheath current of the target cable segment meets the rated requirements.

[0014] Preferably, the cable in step S1 is divided into several large sections of interconnected cables, each of which contains three small sections of interconnected cables; the relevant parameters include: the core current value I of each loop n , the length of the three small cable segments l m , grounding resistance R1 and R2 of each cable section, soil resistivity ρ, earth leakage resistance R d , Cable center distance S ij , core current frequency f and sheath resistance of each small section of cable Among them I n Indicates the current value of the cable core numbered n, n = 1, 2, 3...; l m Indicates the length of the cable segment numbered m, where m = 1, 2, 3; S ij is the center distance between cables numbered i and j, and the value range of i and j is 1 to n; Indicates the sheath resistance R of the cable numbered k s , the value range of k is 1 to n.

[0015] Preferably, step S2 includes the following sub-steps:

[0016] S21. Determine the current phase sequence combination of the cable cores in each loop;

[0017] S22, calculating the sheath current of the target cable segment according to the current phase sequence combination of the cable core determined in step S21;

[0018] S23, repeating steps S21-22, wherein the current phase sequence combinations of the cable cores determined in step S21 are not repeated each time, until all current phase sequence combinations are selected;

[0019] S24. Based on the calculation results of the above steps, determine the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum.

[0020] Preferably, step S22 includes the following sub-steps:

[0021] S221. Solve the mutual inductive reactance between cable sheaths;

[0022] The mutual inductance between the cable sheaths per unit length is determined by the following formula:

[0023]

[0024] Among them, X ij D represents the mutual inductance between the sheaths of cables numbered i and j per unit length. e is the equivalent depth of the earth loop, which is determined by the following formula

[0025]

[0026] S222. Solve the induced electromotive force matrix E generated by the cable core current in the cable sheath

[0027] First, solve the inductive reactance matrix B caused by the cable core current in the cable sheath, which is determined by the formula:

[0028]

[0029] in It represents the inductive reactance matrix generated by the cable sheath of loop T2 to the core current of loop T1. The values ​​of T1 and T2 are both in the range of 1 to n.

[0030] It is determined by the following formula

[0031]

[0032] Wherein, t1=1+3(T1-1), t2=1+3(T2-1);

[0033] The induced electromotive force E generated by the cable core current in the cable sheath is determined by the following formula

[0034]

[0035] Where I is the cable core current matrix, is the current value of the cable core numbered 1 to n;

[0036] S223. Solve the inductive reactance matrix D of the cable sheath caused by the cable sheath current

[0037] The inductive reactance matrix D of the cable sheath caused by the cable sheath current is determined by the following formula:

[0038]

[0039] in It indicates the inductive reactance generated by the sheath of the T2 loop cable to the current of the T1 loop cable sheath;

[0040] It is determined by the following formula

[0041]

[0042] Among them, when T1=T2, The main diagonal elements are all zero;

[0043] S224. Calculate the total impedance ZZ of the cable sheath current loop

[0044] ZZ is determined by the following formula:

[0045] ZZ=Z+R d[n×n] +jD

[0046] Where Z is the cable sheath impedance matrix, R d[n×n] is the earth leakage resistance matrix, R d[n×n] The element values ​​are all R d The n-order square matrix;

[0047] Z is determined by the following formula:

[0048]

[0049] Among them, Z1~Z n is the sheath impedance of cables numbered 1 to n, Z n Determined by the following formula:

[0050]

[0051] S225, solve the cable sheath current

[0052] Determined by the following formula

[0053] I s =ZZ -1 E

[0054] Among them, I s is the cable sheath current matrix

[0055]

[0056] in, It is the current value of the cable sheath numbered 1 to n.

[0057] A computer-readable storage medium stores a computer program, wherein the computer program enables a computer to execute any one of the above-mentioned methods for handling multi-circuit cable sheath current overload.

[0058] An electronic device comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for processing a multi-circuit cable sheath current overload as described above is implemented.

[0059] The beneficial effects of the present invention are:

[0060] By first determining the current phase sequence combination with the minimum sheath current of the target section cable, and under the condition that this current phase sequence combination meets the sheath current requirement of the target section cable, it is calculated whether the sheath current of other sections of the cable will exceed the rated value according to this current phase sequence combination. If it does not exceed, the current phase sequence combination of the starting power station of the transmission line can be directly changed to this current phase sequence combination; even if it exceeds, it is necessary to change the existing cross-interconnection method of the sheath of the target section cable, and it can be calculated according to the actual situation, and the relevant parameters of the existing cable can be changed as little as possible, so that the current phase sequence of the power station can be directly replaced, which greatly improves the efficiency of maintenance or cable laying. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flow chart of the present invention;

[0062] Figure 2 This is a schematic diagram of the cross-section of cable laying in Example 1. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0064] Example 1

[0065] like Figure 1 As shown, the present invention provides a method for processing current overload of a multi-circuit cable sheath, comprising the following steps:

[0066] S1. Determine the relevant basic parameters of all cables;

[0067] The cable is divided into several large interconnected cable sections, and each large section contains three small interconnected cable sections;

[0068] The relevant parameters include: the core current value I of each loop n , the length of the three small cable segments l m, the grounding resistance R1 and R2 of each large cable section (the grounding resistance R1 and R2 of each large cable section are not necessarily equal, and the specific resistance is determined according to the actual situation), soil resistivity ρ, earth leakage resistance R d , Cable center distance S ij , core current frequency f and sheath resistance of each small section of cable Among them I n Indicates the current value of the cable core numbered n, n = 1, 2, 3...; l m Indicates the length of the cable segment numbered m, where m = 1, 2, 3; S ij is the center distance between cables numbered i and j, and the value range of i and j is 1 to n; Indicates the sheath resistance R of the cable numbered k s , the value range of k is 1 to n.

[0069] S2. Determine the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum based on the basic parameters;

[0070] The specific steps include:

[0071] S21. Determine the current phase sequence combination of the cable cores in each loop;

[0072] S22, calculating the sheath current of the target cable segment according to the current phase sequence combination of the cable core determined in step S21;

[0073] like Figure 2 As shown (this embodiment is based on Figure 2 The three-circuit cable shown is used for specific illustration; other numbers of circuits are also possible, depending on actual conditions. In a three-circuit cable, two circuits are arranged in a small "pink" shape (i.e., three cables are arranged closely together in a "pink" shape), and one circuit is arranged in a large "pink" shape (i.e., one cable is on top, and the other two cables are arranged parallel and side by side below, forming a large "pink" shape). The serial number in the cable is the cable number (i.e., the specific value of n). Note that any other arrangement is possible.

[0074] The solution process specifically includes the following steps:

[0075] S221. Solve the mutual inductive reactance between cable sheaths;

[0076] The mutual inductance between the cable sheaths per unit length is determined by the following formula:

[0077]

[0078] Among them, X ij D represents the mutual inductance between the sheaths of cables numbered i and j per unit length. eis the equivalent depth of the earth loop, which is determined by the following formula

[0079]

[0080] S222. Solve the induced electromotive force matrix E generated by the cable core current in the cable sheath

[0081] First, solve the inductive reactance matrix B caused by the cable core current in the cable sheath, which is determined by the formula:

[0082]

[0083] Among them B 21 It represents the inductive reactance matrix generated by the cable sheath of the first circuit to the core current of the second circuit. The meanings of other matrices in the inductive reactance matrix B are similar.

[0084] in

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] The induced electromotive force E generated by the cable core current in the cable sheath is determined by the following formula

[0095]

[0096] Where I is the cable core current matrix, It is the current value of the cable core numbered 1 to 9;

[0097] S223. Solve the inductive reactance matrix D of the cable sheath caused by the cable sheath current

[0098] The inductive reactance matrix D of the cable sheath caused by the cable sheath current is determined by the following formula:

[0099]

[0100] Among them D21 It represents the inductive reactance matrix generated by the cable sheath of the first circuit to the current of the cable sheath of the second circuit. The meanings of other matrices contained in the inductive reactance matrix D are similar.

[0101] in

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] S224. Calculate the total impedance ZZ of the cable sheath current loop

[0112] ZZ is determined by the following formula:

[0113] ZZ=Z+R d[9×9] +jD

[0114] Where Z is the cable sheath impedance matrix, R d[9×9] is the earth leakage resistance matrix, R d[n×n] The element values ​​are all R d The n-order square matrix;

[0115] Z (a diagonal matrix) is determined by the following formula:

[0116]

[0117] Among them, Z1~Z9 are the sheath impedances of cables numbered 1~9, Z n Determined by the following formula:

[0118]

[0119] Where n is the cable number, is the sheath resistance of the cable numbered n, X nn is the self-inductance of the cable sheath numbered n; l m is the length of three short lengths of cable;

[0120] That is to say

[0121]

[0122] S225, solve the cable sheath current

[0123] Determined by the following formula

[0124] I s =ZZ -1 E

[0125] Among them, I s is the cable sheath current matrix

[0126]

[0127] in, is the cable sheath current value numbered 1 to n. According to the above formula, the cable sheath current value under the selected cable core current phase sequence combination can be calculated;

[0128] S23, repeating steps S21-22, wherein the current phase sequence combinations of the cable cores determined in step S21 are not repeated each time, until all current phase sequence combinations are selected;

[0129] S24. Based on the calculation results of the above steps, determine the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum.

[0130] S3, judging whether the sheath current of the target cable segment meets the rated requirement according to the current phase sequence combination of the cable core in step S2; if so, proceeding to step S41, otherwise proceeding to step S5;

[0131] S41. Based on the current phase sequence combination of the cable cores determined in step S2, calculate whether the sheath current of the cables other than the target segment cable is overloaded according to this current phase sequence combination. If not, directly change the current phase sequence combination of the starting power station of the transmission line to this current phase sequence combination; if there is an overload, proceed to step S42.

[0132] S42, changing the sheath cross-connection mode of the target cable segment so that the core current phase sequence combination corresponding to the sheath is the current phase sequence combination determined in step S2;

[0133] S5. Change the basic parameters of the target cable segment, and then repeat steps S2-S3 until the sheath current of the target cable segment meets the rated requirements.

[0134] According to the method of the present invention, the sheath current value of the cable in the target section (whether it is maintenance or laying of new cables) can be made to reach a preset target (i.e., not exceeding the rated value) by directly replacing the current phase sequence of the power station of the transmission line. In this way, there is no need to replace the cross-interconnection method of the sheath of the laid cables, which greatly improves the efficiency of maintenance or cable laying. Of course, if too many changes are required to the relevant parameters of the laid cables in order to achieve only the replacement of the current phase sequence of the power station, the construction difficulty is greater than directly making small changes to the laid cables (this change is achieved by changing the current phase sequence of the power station so that the cable sheath current value of the entire transmission line meets the set requirements, and only the cable sheath current of the target section can meet the set requirements), then the latter solution is selected. The specific solution can be selected according to the actual construction difficulty.

[0135] Example 2

[0136] A computer-readable storage medium stores a computer program, wherein the computer program enables a computer to execute the method for handling multi-circuit cable sheath current overload as described in embodiment 1.

[0137] Example 3

[0138] An electronic 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, the method for processing multi-circuit cable sheath current overload described in the first embodiment is implemented.

[0139] In the embodiments disclosed herein, computer storage media can be tangible media that can contain or store programs for use by or in conjunction with an instruction execution system, device, or apparatus. Computer storage media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. More specific examples of computer storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0140] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0141] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for handling current overload of a multi-circuit cable sheath, characterized in that: The following steps are involved: S1. Determine the relevant basic parameters of all cables; the cables described in step S1 are divided into several large sections of interconnected cables, each large section contains three small sections of interconnected cables; the basic parameters include: the core current value I of each loop n , the length of the three small cable segments l m , grounding resistance R1 and R2 of each cable section, soil resistivity ρ, earth leakage resistance R d , Cable center distance S ij , core current frequency f and sheath resistance R of each small section of cable sk ; Among them I n Indicates the current value of the cable core numbered n, n = 1, 2, 3...; l m Indicates the length of the cable segment numbered m, where m = 1, 2, 3; S ij is the center distance between cables numbered i and j, and the value range of i and j is 1 to n; Indicates the sheath resistance R of the cable numbered k s , the value range of k is 1 to n; S2. Determine, based on the basic parameters, the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum. Step S2 includes the following sub-steps: S21. Determine the current phase sequence combination of the cable cores in each loop; S22, calculating the sheath current of the target cable segment according to the current phase sequence combination of the cable core determined in step S21; S23, repeating steps S21-22, wherein the current phase sequence combinations of the cable cores determined in step S21 are not repeated each time, until all current phase sequence combinations are selected; S24. Determine, based on the calculation results of the above steps, the current phase sequence combination of the cable core when the sheath current of the target cable segment is minimum; S3, judging whether the sheath current of the target cable segment meets the rated requirement according to the current phase sequence combination of the cable core in step S2; if so, proceeding to step S41, otherwise proceeding to step S5; S41. Based on the current phase sequence combination of the cable cores determined in step S2, calculate whether the sheath current of the cables other than the target segment cable is overloaded according to this current phase sequence combination. If not, directly change the current phase sequence combination of the starting power station of the transmission line to this current phase sequence combination; if there is an overload, proceed to step S42. S42, changing the sheath cross-connection mode of the target cable segment so that the core current phase sequence combination corresponding to the sheath is the current phase sequence combination determined in step S2; S5. Change the basic parameters of the target cable segment, and then repeat steps S2-S3 until the sheath current of the target cable segment meets the rated requirements.

2. The method for handling current overload of a multi-circuit cable sheath according to claim 1, characterized in that: Step S22 The following steps are included: S221. Solve the mutual inductive reactance between cable sheaths; The mutual inductance between the cable sheaths per unit length is determined by the following formula: Among them, X ij D represents the mutual inductance between the sheaths of cables numbered i and j per unit length. e is the equivalent depth of the earth loop, which is determined by the following formula S222. Solve the induced electromotive force matrix E generated by the cable core current in the cable sheath First, solve the inductive reactance matrix B caused by the cable core current in the cable sheath, which is determined by the formula: in It represents the inductive reactance matrix generated by the cable sheath of loop T2 to the core current of loop T1. The values ​​of T1 and T2 are both in the range of 1 to n. It is determined by the following formula Wherein, t1=1+3(T1-1), t2=1+3(T2-1); The induced electromotive force E generated by the cable core current in the cable sheath is determined by the following formula Where I is the cable core current matrix, is the current value of the cable core numbered 1 to n; S223. Solve the inductive reactance matrix D of the cable sheath caused by the cable sheath current The inductive reactance matrix D of the cable sheath caused by the cable sheath current is determined by the following formula: in It represents the inductive reactance matrix generated by the sheath of the cable of the T2 loop to the current of the cable sheath of the T1 loop; It is determined by the following formula Among them, when T1=T2, The main diagonal elements are all zero; S224. Calculate the total impedance ZZ of the cable sheath current loop ZZ is determined by the following formula: ZZ=Z+R d[n×n] +jD Where Z is the cable sheath impedance matrix, R d[n×n] is the earth leakage resistance matrix, R d[n×n] The element values ​​are all R d The n-order square matrix; Z is determined by the following formula: Among them, Z1~Z n is the sheath impedance of cables numbered 1 to n, Z n Determined by the following formula: S225, solve the cable sheath current Determined by the following formula I s =ZZ -1 E Among them, I s is the cable sheath current matrix in, It is the current value of the cable sheath numbered 1 to n.

3. A computer-readable storage medium storing a computer program, characterized in that: The computer program enables a computer to execute the method for processing multi-circuit cable sheath current overload according to any one of claims 1-2.

4. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for processing current overload of a multi-circuit cable sheath as described in any one of claims 1 to 2 is implemented.

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