A method for assessing the safety impact of power cables on railway communication signal cables

Abstract

The present invention provides a method for assessing the safety impact of power cables on railway communication signal cables, which belongs to the technical field of power cables, and includes obtaining the laying routes and design drawings of power cables and communication signal cables in the detection target range, dividing the laying routes into standard sections, weakly affected sections and strongly affected sections, and calculating the length of each section; selecting sampling points of corresponding proportion in each section according to the ratio of the length of each section to the total length of the laying route, and respectively collecting the short-circuit current of the sampling points when a short-circuit fault occurs in the power cable; calculating the induced electromotive force on the communication signal cable at the corresponding position; and judging the degree of safety impact of the power cable on the communication signal cable according to the induced electromotive force. This method aims at the problem that the existing technology cannot accurately analyze the degree of impact of the communication signal cable in the same trench laying, and can judge the degree of safety impact of each section according to the situation, so as to conduct accurate and efficient analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of power cables, and in particular to a method for evaluating the safety impact of power cables on railway communication signal cables. Background Art

[0002] Due to the limitation of space corridor and construction cost, it is sometimes necessary to lay 10kV power supply cables and communication signal cables in the same trench during railway construction. These cables are close to each other, and the electrical cables in the same electromagnetic environment are closely connected to each other through various electromagnetic coupling methods.

[0003] According to the technical conditions for the operation of power cables, for three-core power cables, ideally, the vector sum of the three-phase currents flowing through the three conductive cores during normal symmetrical operation is zero. At this time, no induced voltage is generated on the metal sheath of the cable, and no induced current is generated after both ends of the cable are grounded. However, when a core-to-sheath short circuit occurs in the power cable, the short-circuit current will generate electrostatic induction components and electromagnetic induction components on the communication signal cable through mutual capacitance and mutual inductance, and the induced voltage value may endanger the safe operation of the communication signal cable.

[0004] In order to avoid the influence between them, the cables are generally required to be separated by a certain distance. For the railway passenger dedicated line system, how to determine the spacing between the power cable and the communication signal cable and the maximum parallel distance allowed for the two cables so that the longitudinal induced electromotive force value generated by the short-circuit current on the core wire of the communication signal cable does not exceed the allowable value is an important issue of general concern in design and operation.

[0005] Therefore, for the cables that have already been laid, how to analyze the degree of impact and check for safety hazards is an issue that needs to be addressed urgently. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for evaluating the safety impact of power cables on railway communication signal cables, which can judge the degree of safety impact of each section according to the situation, so as to perform accurate and efficient analysis.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for evaluating the safety impact of power cables on railway communication signal cables, comprising the following steps:

[0008] S1: Obtain the laying lines and design drawings of power cables and communication signal cables within the detection target range, divide the laying lines into standard sections, weakly affected sections and strongly affected sections according to the spacing changes and gap debris of the two cable laying lines, and calculate the length of each section;

[0009] S2: According to the ratio of the length of each section to the total length of the laid line, sampling points of corresponding proportion are selected in each section, and when a short circuit fault occurs in the power cable, the short circuit current of the sampling points is collected respectively;

[0010] S3: According to the location of the sampling point and the collected short-circuit current, the induced electromotive force on the communication signal cable at the corresponding location is calculated;

[0011] S4: Determine the degree of impact of power cables on the safety of communication signal cables based on the induced electromotive force.

[0012] In a preferred solution, in step S1, the steps of dividing the laying of the lines are as follows:

[0013] S1.1: According to the distribution of gaps and debris between the laid lines in the design drawing, the magnetic permeability coefficient is obtained. The section with a magnetic permeability coefficient lower than the preset value is regarded as a weakly conductive section, otherwise it is a strongly conductive section;

[0014] S1.2: Draw a spacing curve according to the spacing changes of the laid lines, and calculate the average spacing. The sections larger than the average spacing are regarded as wide spacing sections, and the rest are narrow spacing sections;

[0015] S1.3: In weak-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as weak-influence paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as standard paragraphs; in strong-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as standard paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as strong-influence paragraphs.

[0016] In a preferred solution, in step S3, the calculation formula of the induced electromotive force is as follows:

[0017] ;

[0018] in, E represents electromotive force;

[0019] D Indicates the metal sheath diameter of the communication signal cable;

[0020] Indicates short-circuit fault current;

[0021] m Indicates the center distance between the power cable and the communication signal cable;

[0022] ω represents the power supply angular frequency;

[0023] k represents the magnetic permeability coefficient;

[0024] represents the magnetic permeability of air, which is 4π×10 -7 H / m.

[0025] In a preferred solution, the process of obtaining the magnetic permeability coefficient includes: determining whether there is magnetic conductive material with a magnetic permeability greater than a magnetic permeability threshold in the gap debris; if not, the magnetic permeability coefficient is set to 1; if so, the magnetic permeability coefficient is obtained based on the volume of the magnetic conductive material.

[0026] In a preferred solution, the calculation expression for the magnetic permeability coefficient is obtained according to the volume of the magnetic conductive material as follows:

[0027] ;

[0028] Where k is the magnetic permeability coefficient, It is i The volume of the magnetic material, It is i The magnetic permeability of a magnetic material, represents the magnetic permeability of air, n is the total number of magnetic conductive materials within the calculation range, and M is the total volume between the two cables within the calculation range, where the boundary of the calculation range is the common tangent of the two cables.

[0029] In the preferred scheme, in step S4, the degree of safety impact of the power cable on the communication signal cable is judged according to the induced electromotive force, including: judging whether there is a strong impact section where the induced electromotive force exceeds the warning value according to the induced electromotive force on the communication signal cable at the corresponding position of each sampling point in the strong impact section, and if so, an alarm is issued; if not, further judging whether there is a standard section where the induced electromotive force exceeds the warning value, and if so, an alarm is issued; if not, further judging whether there is a weak impact section where the induced electromotive force exceeds the warning value, and if so, an alarm is issued; if not, it is deemed that the safety meets the requirements.

[0030] The present invention provides a method for assessing the safety impact of power cables on railway communication signal cables, which has the following beneficial effects:

[0031] 1. By scientifically dividing the laid lines into standard sections, weak impact sections and strong impact sections, this method realizes the refined assessment of areas with different safety impact levels, thereby improving the accuracy and pertinence of the assessment. Secondly, the magnetic permeability coefficient is used to reflect the magnetic permeability of the environment where the cable is located, providing effective data support for comprehensive control of cable safety. Furthermore, by giving priority to judging sections with a high possibility of safety problems, this method can quickly locate potential risks, greatly reduce judgment time, and improve the accuracy of problem location and evaluation efficiency. The present invention not only improves the assessment level of the safety impact of power cables on communication signal cables, but also provides a strong guarantee for the safe operation of railway communication systems, realizes accurate and efficient safety analysis, and has significant practical application value.

[0032] 2. In step S1 of the present invention, the division of standard paragraphs, weak impact paragraphs and strong impact paragraphs enables the distinction of priority and importance in the judgment process, which can ensure that no omissions occur while reducing the workload and can accurately judge safety.

[0033] 3. In step S3, the obtained magnetic permeability coefficient can reflect the approximate magnetic permeability situation, which is very effective for controlling the overall environment where the cable is located.

[0034] 4. In step S4, since the division of sections cannot absolutely represent the strength of the induced electromotive force, but can indicate the possibility of a safety problem, it can provide a reasonable priority for the execution of the judgment, and is used to give priority to judging sections with a high possibility of safety problems. If the problem is judged directly, the judgment time can be greatly reduced, with higher problem location accuracy and higher efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0036] Figure 1 It is an implementation flow chart of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution will be clearly and completely described below in combination with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be understood that in various embodiments of the present invention, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0039] It should be understood that in the present invention, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0040] It should be understood that in the present invention, "plurality" refers to two or more than two. "And / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "Contains A, B and C", "Contains A, B, C" means that A, B, and C are all included, "Contains A, B or C" means that one of A, B, and C is included, and "Contains A, B and / or C" means that any one, any two, or any three of A, B, and C are included.

[0041] The technical solution of the present invention is described in detail with specific embodiments below. The embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0042] Combination Figure 1 The specific embodiments of the present invention are described in further detail.

[0043] When the power cable and the communication signal cable are laid in the same trench, there is coupling capacitance between the power cable and the communication signal cable, and the power cable and the communication signal cable themselves also have capacitance to the ground. When an asymmetric fault occurs in the power cable, these distributed capacitances will generate electrostatic transmission voltage on the communication signal cable. The transmission voltage value is related to factors such as the type of power cable fault and the geometric dimensions between cables. This influence is called capacitive coupling influence, that is, electrostatic influence. One end of the metal sheath (shielding layer) of the power cable should be grounded, and the electrostatic induction component on the core wire of the communication signal cable should be zero.

[0044] The influence of electromagnetic induction component is the influence of inductive coupling. When a ground short circuit occurs in the power cable, the short circuit current flowing through the power cable sheath generates an alternating magnetic field in space, and its magnetic lines of force intersect with the adjacent communication signal cable, generating an induced electromotive force on the communication signal cable; or because of the mutual inductance between the power cable and the communication signal cable, the two induce an electromotive force on the communication signal cable through this inductive coupling. Since this induced electromotive force is distributed along the axial direction of the communication signal cable core, it is also called longitudinal induced electromotive force.

[0045] The longitudinal induced electromotive force generated by the power cable on the metal sheath of the communication signal cable is related to the short-circuit fault current of the power cable, the shielding factor, the diameter of the metal sheath of the communication signal cable and the distance between them.

[0046] A method for assessing the safety impact of power cables on railway communication signal cables, such as Figure 1 As shown, the following steps are included:

[0047] S1: Obtain the laying routes and design drawings of power cables and communication signal cables within the detection target range, divide the laying routes into standard sections, weak impact sections and strong impact sections according to the spacing changes and gap debris of the two cable laying lines, and calculate the length of each section.

[0048] The steps for laying the line are as follows:

[0049] S1.1: According to the distribution of gaps and debris between the laid lines in the design drawing, the magnetic permeability coefficient is obtained. The sections with a magnetic permeability coefficient lower than the preset value are regarded as weakly conductive sections, otherwise they are strongly conductive sections.

[0050] S1.2: Draw a spacing curve based on the spacing changes of the laid lines and calculate the average spacing. The sections larger than the average spacing are considered wide-spacing sections, and the rest are narrow-spacing sections.

[0051] S1.3: In weak-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as weak-influence paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as standard paragraphs; in strong-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as standard paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as strong-influence paragraphs.

[0052] Among them, standard paragraphs, weak-impact paragraphs and strong-impact paragraphs are a rough division based on actual conditions, but they are statistically able to reflect the differences in the degree of influence of paragraphs. Therefore, the emphasis can be tilted between different paragraphs to facilitate subsequent data analysis.

[0053] S2: According to the ratio of the length of each section to the total length of the laid line, sampling points of corresponding proportion are selected in each section, and when a short circuit fault occurs in the power cable, the short-circuit current of the sampling points is collected respectively.

[0054] S3: According to the location of the sampling point and the collected short-circuit current, the induced electromotive force on the communication signal cable at the corresponding location is calculated.

[0055] In the calculation, the longitudinal induced electromotive force generated by the power cable on the metal sheath of the communication signal cable is affected by many factors, including cable geometry, layout, fault current, etc. These will be reflected in the formula. The calculation formula of the induced electromotive force is as follows:

[0056] ;

[0057] in, E represents electromotive force;

[0058] D Indicates the metal sheath diameter of the communication signal cable, in mm;

[0059] Indicates short-circuit fault current, unit: A;

[0060] m Indicates the center distance between the power cable and the communication signal cable, unit: m;

[0061] ω represents the power angular frequency, unit: Hz;

[0062] k represents the magnetic permeability coefficient;

[0063] represents the magnetic permeability of air, which is 4π×10 -7 H / m.

[0064] The process of obtaining the magnetic permeability coefficient includes: judging whether there is magnetic conductive material with a magnetic permeability greater than a magnetic permeability threshold in the gap debris; if not, the magnetic permeability coefficient is set to 1; if so, the magnetic permeability coefficient is obtained according to the volume of the magnetic conductive material.

[0065] If the gap debris is mainly non-magnetic material (such as soil, gravel, etc.), whose magnetic permeability is close to the magnetic permeability of air, then the magnetic permeability threshold can be set relatively low, such as 5 If there may be strong magnetic materials in the gap, such as iron filings, iron ore, etc., the magnetic permeability threshold should be set higher, such as 10 or higher to ensure that these materials are correctly identified and included in the calculation of the magnetic permeability coefficient.

[0066] The calculation expression of the magnetic permeability coefficient is obtained according to the volume of the magnetic conductive material as follows:

[0067] ;

[0068] Where k is the magnetic permeability coefficient, It is i The volume of the magnetic material, It is i The magnetic permeability of a magnetic material, represents the magnetic permeability of air, n is the total number of magnetic conductive materials within the calculation range, and M is the total volume between the two cables within the calculation range, where the boundary of the calculation range is the common tangent of the two cables.

[0069] Due to the complex environment where the cable is located, the actual magnetic permeability cannot be accurately calculated. Therefore, although this calculation method cannot accurately calculate the magnetic permeability, the obtained magnetic permeability coefficient can reflect the approximate magnetic permeability situation, which is very effective for controlling the overall environment where the cable is located.

[0070] S4: Determine the degree of impact of power cables on the safety of communication signal cables based on the induced electromotive force.

[0071] The degree of safety impact of the power cable on the communication signal cable is judged according to the induced electromotive force, including: judging whether there is a strong impact section where the induced electromotive force exceeds the warning value according to the induced electromotive force on the communication signal cable at the corresponding position of each sampling point in the strong impact section, if so, an alarm is triggered; if not, further judging whether there is a standard section where the induced electromotive force exceeds the warning value, if so, an alarm is triggered; if not, further judging whether there is a weak impact section where the induced electromotive force exceeds the warning value, if so, an alarm is triggered; if not, it is deemed that the safety meets the requirements.

[0072] The specific range of the warning value should be determined according to the specific specifications of the communication signal cable, the safety margin required by the system, and industry standards. For example, if the maximum induced electromotive force allowed in the design specification is 10V, considering the 10% safety margin, the warning value can be set to 9V. In actual operation, this value may need to be adjusted and optimized according to the specific situation.

[0073] Since the division of paragraphs cannot absolutely represent the strength of the induced electromotive force, but can indicate the possibility of safety problems, it can provide a reasonable priority for the execution of judgment, and is used to give priority to judging paragraphs with a high possibility of safety problems. If the problem is judged directly, the judgment time can be greatly reduced, with higher problem location accuracy and higher efficiency.

[0074] The division of standard paragraphs, weak impact paragraphs and strong impact paragraphs enables the distinction of priority and importance in the judgment process, which can ensure that no mistakes occur while reducing the workload and can accurately judge safety.

[0075] This embodiment can pre-divide the sections according to different situations to reflect the probability of occurrence of safety problems, and then determine the priority of subsequent judgments. Therefore, it can achieve accurate and efficient analysis, accurately grasp the safety impact between cables, and prevent uncontrollable problems.

[0076] In the embodiments provided in the present application, it should be understood that the disclosed structures and methods can be implemented in other ways. When implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium, including several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0077] The above contents are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for assessing the safety impact of power cables on railway communication signal cables, characterized in that: The following steps are involved: S1: Obtain the laying lines and design drawings of power cables and communication signal cables within the detection target range, divide the laying lines into standard sections, weakly affected sections and strongly affected sections according to the spacing changes and gap debris of the two cable laying lines, and calculate the length of each section; The steps for laying the line include: S1.1: According to the distribution of gaps and debris between the laid lines in the design drawing, the magnetic permeability coefficient is obtained. The section with a magnetic permeability coefficient lower than the preset value is regarded as a weakly conductive section, otherwise it is a strongly conductive section; S1.2: Draw a spacing curve according to the spacing changes of the laid lines, and calculate the average spacing. The sections larger than the average spacing are regarded as wide spacing sections, and the rest are narrow spacing sections; S1.3: In weak-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as weak-influence paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as standard paragraphs; in strong-leading paragraphs, the parts that are also wide-spaced paragraphs are regarded as standard paragraphs, and the parts that are also narrow-spaced paragraphs are regarded as strong-influence paragraphs; S2: According to the ratio of the length of each section to the total length of the laid line, sampling points of corresponding proportion are selected in each section, and when a short circuit fault occurs in the power cable, the short circuit current of the sampling points is collected respectively; S3: According to the location of the sampling point and the collected short-circuit current, the induced electromotive force on the communication signal cable at the corresponding location is calculated; The calculation formula of the induced electromotive force is: ； in, E represents electromotive force; D Indicates the metal sheath diameter of the communication signal cable; Indicates short-circuit fault current; m Indicates the center distance between the power cable and the communication signal cable; ω represents the power supply angular frequency; k represents the magnetic permeability coefficient; represents the magnetic permeability of air, which is 4π×10 -7 H / m; The calculation expression of the magnetic permeability coefficient is obtained according to the volume of the magnetic conductive material: ； Where k is the magnetic permeability coefficient, It is i The volume of the magnetic material, It is i The magnetic permeability of a magnetic material, represents the magnetic permeability of air, n is the total number of magnetically conductive materials within the calculation range, M is the total volume between the two cables within the calculation range, where the boundary of the calculation range is the common tangent of the two cables; S4: Determine the degree of impact of power cables on the safety of communication signal cables based on the induced electromotive force.

2. A method for assessing the safety impact of power cables on railway communication signal cables according to claim 1, characterized in that: The process of obtaining the magnetic permeability coefficient includes: judging whether there is magnetic conductive material with a magnetic permeability greater than a magnetic permeability threshold in the gap debris, if not, setting the magnetic permeability coefficient to 1, and if so, obtaining the magnetic permeability coefficient according to the volume of the magnetic conductive material.

3. A method for assessing the safety impact of power cables on railway communication signal cables according to claim 1, characterized in that: In the step S4, the degree of safety impact of the power cable on the communication signal cable is judged according to the induced electromotive force, including: judging whether there is a strong impact section where the induced electromotive force exceeds the warning value according to the induced electromotive force on the communication signal cable at the corresponding position of each sampling point in the strong impact section, if so, an alarm is triggered; if not, further judging whether there is a standard section where the induced electromotive force exceeds the warning value, if so, an alarm is triggered; if not, further judging whether there is a weak impact section where the induced electromotive force exceeds the warning value, if so, an alarm is triggered; if not, it is considered that the safety meets the requirements.

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