Return wire type selection method and device for single-ended grounding cable

Abstract

The invention discloses a return wire type selection method and device for a single-ended grounding cable. The method comprises the following steps: acquiring a laying environment of a single-ended grounding cable in a single-ended grounding system, and determining at least one target material type matched with the laying environment; determining a target section range corresponding to the return line of each target material type in which the flowing short-circuit current can meet a thermal stability condition when the single-ended grounding system has a short-circuit fault; various types of return lines matched with the target material type and the target section range are determined as alternative return lines; obtaining performance parameters and cost parameters of each alternative return line, and performing comprehensive scoring on each alternative return line according to the performance parameters and the cost parameters; and determining the alternative return line with the highest comprehensive score as a target return line corresponding to the single-ended grounding cable. The technical problem that cost waste or safety accidents are easily caused due to unreasonable type selection of the return wire of the single-ended grounding cable in engineering is solved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a method and device for selecting a return line of a single-ended grounding cable. Background Art

[0002] When a ground fault occurs in a cable line with a single-end grounding sheath, an extremely high overvoltage will be induced on the metal sheath. To ensure the safety of the power system, the national standard "Design Specifications for Power Engineering Cables" (GB50217) stipulates that when the metal sheath of a single-core cable of 110kV and above in an AC system is directly grounded at one end, a conductor with both ends properly grounded must be laid along the cable line, which is called a return line.

[0003] However, the relevant standards have relatively loose requirements for the selection of return lines, emphasizing only the need to meet functional requirements without taking the economic efficiency of the return lines into consideration. This loose standard results in the selection of return lines in actual projects often relying on the experience of previous cable lines of the same voltage level. The various parameter margins of the return lines selected in actual projects are too large, which not only increases costs, but also lacks pertinence and consideration of adapting to local conditions.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present application provide a method and device for selecting a return line of a single-ended grounding cable, so as to at least solve the technical problem that the selection of the return line of a single-ended grounding cable in a project is unreasonable, which may easily lead to cost waste or safety accidents.

[0006] According to one aspect of an embodiment of the present application, a method for selecting a return line for a single-ended grounding cable is provided, including: obtaining the laying environment of the single-ended grounding cable in a single-ended grounding system, and determining at least one target material type that matches the laying environment; determining a target cross-sectional range corresponding to a return line of each target material type through which a short-circuit current can meet thermal stability conditions when a short-circuit fault occurs in the single-ended grounding system; determining a plurality of models of return lines that match the target material type and the target cross-sectional range as alternative return lines; obtaining performance parameters and cost parameters of each alternative return line, and comprehensively scoring each alternative return line based on the performance parameters and cost parameters; and determining the alternative return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

[0007] Optionally, the target material type reflow line includes at least one of the following: an aluminum alloy reflow line with strong corrosion resistance but poor vibration resistance, a copper reflow line with strong conductivity and oxidation resistance, a high temperature resistant special reflow line, a vibration resistant special reflow line, a polymer composite material reflow line with strong corrosion resistance, strong vibration resistance, strong conductivity, strong oxidation resistance and high temperature resistance.

[0008] Optionally, determining a target cross-sectional range corresponding to a return line of each target material type through which a short-circuit current can meet a thermal stability condition when a short-circuit fault occurs in a single-ended grounding system, including: for a return line of each target material type, determining a short-circuit current and a short-circuit duration flowing through the return line when a short-circuit fault occurs in the single-ended grounding system, and calculating a short-circuit current thermal effect of the return line using the following formula: In the formula, Q ki Represents the thermal effect of short-circuit current, I ki Indicates the short-circuit current, t k Indicates the short circuit duration; obtain the first current carrying capacity of the return line of the target material type at the maximum allowable operating temperature and the second current carrying capacity at the rated operating temperature, and calculate the first thermal stability coefficient corresponding to the target material type using the following formula: In the formula, C i Indicates the first thermal stability coefficient, A Ki Indicates the first current carrying capacity, A Li Indicates the second current carrying capacity; the minimum value of the target cross-sectional range corresponding to the return line of the target material type is calculated using the following formula: In the formula, S imin Indicates the minimum value of the target section range.

[0009] Optionally, determining the short-circuit current flowing through the return line when a short-circuit fault occurs in the single-ended grounding system includes: when the number of return lines to be laid is one, determining that when a short-circuit fault occurs in the single-ended grounding system, the short-circuit current flowing through the single-ended grounding cable is used as the short-circuit current flowing through the return line; when the number of return lines to be laid is multiple, determining that when a short-circuit fault occurs in the single-ended grounding system, the short-circuit current flowing through the single-ended grounding cable, the unit length resistance of each return line, the frequency of the single-ended grounding system, and the conductivity of the earth are obtained, and the short-circuit current flowing through each return line is calculated using the following formula: In the formula, I ki represents the short-circuit current flowing through the i-th return line, I k The short-circuit current flowing through a single-ended grounded cable, k i represents the proportion of the short-circuit current flowing through the i-th return line in the short-circuit current flowing through the single-ended grounding cable, n represents the number of return lines to be laid, Z1, Z2, …, Z n They represent the unit length impedance of the 1st, 2nd, …, nth return lines, Z1 / / Z2 / / … / / Z n It represents the total unit length impedance of n return lines connected in parallel, Z i represents the unit length impedance of the i-th return line, and Z i =R i +X i , R i represents the resistance per unit length of the i-th return line, X i represents the reactance per unit length of the ith return line, D e represents the equivalent resistance of the earth, f represents the frequency of the single-ended grounding system, and ρ represents the earth conductivity.

[0010] Optionally, a third current carrying capacity of the single-ended grounding cable at the maximum allowable operating temperature and a fourth current carrying capacity at the rated operating temperature are obtained, and a second thermal stability coefficient corresponding to the single-ended grounding cable is calculated using the following formula: In the formula, C s Indicates the second thermal stability coefficient, A Ks Indicates the third current carrying capacity, A Ls Indicates the fourth current carrying capacity; obtains the outer radius and inner radius of the sheath of the single-ended grounding cable, and calculates the maximum value of the target cross-sectional range using the following formula: In the formula, S imax Indicates the maximum value of the target cross-section range, r so Represents the outer radius of the sheath of a single-ended grounding cable, r si Indicates the inner radius of the sheath of a single-ended grounding cable.

[0011] Optionally, the type of performance parameters includes at least one of the following: rated working current and unit conductivity of the alternative return line; the type of cost parameters includes at least one of the following: price per unit length, rated service life, annual depreciation rate, and annual maintenance cost of the alternative return line.

[0012] Optionally, a comprehensive score is given to each candidate return line according to the performance parameter and the cost parameter, including: obtaining the load level of the single-ended grounding system, and determining the performance weight according to the load level; randomly determining an alternative return line from multiple candidate return lines as a reference return line, and determining that the comprehensive score of the reference return line is 1; for any alternative return line other than the reference return line among the multiple candidate return lines, the comprehensive score of the alternative return line is calculated using the following formula: Among them, F i represents the comprehensive score of the i-th candidate reflow line, λ represents the performance weight, and A ref Indicates the unit length price of the reference return line, A i represents the price per unit length of the i-th alternative return line, k ref Denotes the rated service life of the reference return line, k i represents the rated service life of the i-th alternative return line, M ref represents the annual maintenance cost of the reference return line, M i represents the annual maintenance cost of the i-th alternative return line, I i represents the rated operating current of the i-th alternative return line, Iref Indicates the rated operating current of the reference return line, ρ i represents the unit conductivity of the i-th candidate return line, ρ ref Represents the unit conductivity of the reference return line, ε i represents the annual depreciation rate of the i-th alternative recirculation line, ε ref Represents the annual depreciation rate of the reference return line.

[0013] According to another aspect of an embodiment of the present application, a return line selection device for a single-ended grounding cable is also provided, including: a material selection module, used to obtain the laying environment of the single-ended grounding cable in a single-ended grounding system, and determine at least one target material type that matches the laying environment; a cross-section selection module, used to determine the target cross-section range corresponding to the return line of each target material type through which the short-circuit current flowing can meet the thermal stability condition when a short-circuit fault occurs in the single-ended grounding system; an alternative line selection module, used to determine multiple models of return lines that match the target material type and the target cross-section range as alternative return lines; a comprehensive scoring module, used to obtain performance parameters and cost parameters of each alternative return line, and comprehensively score each alternative return line based on the performance parameters and cost parameters; a return line selection module, used to determine the alternative return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

[0014] According to another aspect of an embodiment of the present application, a computer program product is further provided, the computer program product comprising: a computer program, wherein when the computer program is executed by a processor, the return line selection method of the single-ended grounding cable is implemented.

[0015] According to another aspect of an embodiment of the present application, an electronic device is further provided, comprising: a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to execute the above-mentioned return line selection method for a single-ended grounding cable through the computer program.

[0016] In an embodiment of the present application, the laying environment of a single-ended grounding cable in a single-ended grounding system is obtained, and at least one target material type matching the laying environment is determined; when a short-circuit fault occurs in the single-ended grounding system, the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current flowing can meet the thermal stability condition is determined; multiple models of return lines matching the target material type and the target cross-sectional range are determined as alternative return lines; performance parameters and cost parameters of each alternative return line are obtained, and each alternative return line is comprehensively scored based on the performance parameters and cost parameters; and the alternative return line with the highest comprehensive score is determined as the target return line corresponding to the single-ended grounding cable. In this way, one or more return line material types are determined according to the laying environment, and the cross-sectional range of the return line is further determined according to the thermal stability conditions to select qualified alternative return lines. Finally, the final target return line is determined by comprehensively analyzing the performance and cost of the alternative return lines. Through scientific calculation and analysis, the problem of excessive parameter margin during selection is avoided, ensuring that the selection of the return line can meet the functional requirements and have good economy, thereby solving the technical problem of unreasonable selection of return lines for single-ended grounding cables in engineering, which is easy to lead to cost waste or safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 It is a flow chart of an optional method for selecting a return line of a single-ended grounding cable according to an embodiment of the present application;

[0019] Figure 2 It is a structural schematic diagram of an optional return line selection device for a single-ended grounding cable according to an embodiment of the present application;

[0020] Figure 3 It is a schematic diagram of the structure of an optional electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] Example 1

[0024] According to an embodiment of the present application, a method for selecting a return line for a single-ended grounding cable is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0025] Figure 1 is a flow chart of a method for selecting a return line of a single-ended grounding cable provided in an embodiment of the present application, such as Figure 1 As shown, the method comprises the following steps:

[0026] Step S102, obtaining a laying environment of a single-ended grounding cable in a single-ended grounding system, and determining at least one target material type matching the laying environment;

[0027] Step S104, determining a target cross-sectional range corresponding to a return line of each target material type through which a short-circuit current can meet a thermal stability condition when a short-circuit fault occurs in a single-ended grounding system;

[0028] Step S106, determining a plurality of types of reflow lines that match the target material type and the target cross-sectional range as candidate reflow lines;

[0029] Step S108, obtaining performance parameters and cost parameters of each candidate reflow line, and comprehensively scoring each candidate reflow line according to the performance parameters and cost parameters;

[0030] Step S110, determining the candidate return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

[0031] The following describes the steps of the return line selection method for a single-ended grounding cable in combination with a specific implementation process.

[0032] In order to solve the technical problem that the unreasonable selection of the return line of the single-ended grounding cable in the project easily leads to cost waste or safety accidents, this application proposes a method for selecting the return line of the single-ended grounding cable. The implementation process of the method is as follows:

[0033] When selecting a single-ended grounding cable and its return line material, the laying environment can be considered first, because different environmental conditions (such as temperature, humidity, chemical corrosiveness, etc.) will affect the physical and chemical properties of the return line, and thus affect its safety and reliability. For example, in a highly corrosive environment, if a material with poor corrosion resistance is selected, it may cause the return line to be damaged prematurely, causing safety hazards. Suitable materials can better resist the influence of environmental factors, thereby extending the service life of the grounding cable and reducing replacement frequency and maintenance costs. Taking all factors into consideration, the embodiment of the present application first obtains the laying environment of the single-ended grounding cable in the single-ended grounding system when selecting the return line, and determines at least one target material type that matches the laying environment.

[0034] Among them, the return line of the target material type may include at least one of the following: an aluminum alloy return line with strong corrosion resistance but poor vibration resistance, a copper return line with strong conductivity and oxidation resistance, a high temperature resistant special return line, a vibration resistant special return line, a polymer composite material return line with strong corrosion resistance, vibration resistance, conductivity, oxidation resistance and high temperature resistance. These types of return lines can be selected according to the environment.

[0035] For example, in corrosive environments, such as at the seaside or in industrial areas, aluminum alloy return lines with strong corrosion resistance but poor vibration resistance should be selected; in environments requiring high conductivity and oxidation resistance, such as high-voltage power transmission systems, copper return lines with strong conductivity and oxidation resistance should be selected; in high-temperature environments, such as near heat sources, high-temperature resistant special return lines should be selected; in environments with frequent vibrations, such as near rail transit or industrial equipment, vibration-resistant special return lines should be selected; in complex and changeable environments, such as places where corrosion, vibration, high temperature and high conductivity are required at the same time, polymer composite return lines with strong corrosion resistance, vibration resistance, conductivity, oxidation resistance and high temperature resistance should be selected.

[0036] In a single-ended grounding system, once a short circuit occurs, a very large short-circuit current will flow through the return line. If the cross-section of the return line is too small and cannot withstand such a large current, the return line will overheat or even melt, causing a safety accident. Therefore, it is very important to select a return line cross-section range that meets thermal stability requirements.

[0037] As an optional implementation, determining the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current can meet the thermal stability condition can be performed in the following manner:

[0038] For each target material type return line, determine the short-circuit current and short-circuit duration that will flow through the return line when a short-circuit fault occurs in a single-ended ground system.

[0039] The duration of the short circuit flowing through the return line can be determined by simulating a short circuit fault under laboratory conditions and recording the total time from the occurrence of the short circuit to the clearing of the fault; or testing in an actual single-ended grounding system and recording the duration of the short circuit; the duration of the short circuit current flowing through the return line can also be obtained by using power system simulation software.

[0040] To determine the short-circuit current flowing through the return line, the following steps can be used:

[0041] When the number of return lines to be laid is one, the short-circuit current flowing through the single-ended grounding cable is used as the short-circuit current flowing through the return line.

[0042] When there are multiple return lines to be laid, firstly obtain the short-circuit current flowing through the single-ended grounding cable, the resistance per unit length of each return line, the frequency of the single-ended grounding system, and the earth conductivity.

[0043] Considering that the earth equivalent resistance is one of the key parameters for evaluating the performance of the grounding system, its size directly affects the safety and reliability of the system. When a short-circuit fault occurs, the short-circuit current will return to the power supply through the earth. The earth equivalent resistance affects the distribution of the short-circuit current in the earth, and then affects the current distribution of the return line. In order to accurately evaluate and design the grounding and return paths in a single-ended grounding system, the earth equivalent resistance can be calculated in the following way:

[0044]

[0045] Where D e represents the equivalent resistance of the earth, f represents the frequency of the single-ended grounding system, and ρ represents the earth conductivity.

[0046] Then calculate the reactance per unit length of each return line:

[0047]

[0048] Where, X i represents the reactance per unit length of the ith return line, R i represents the resistance per unit length of the i-th return line, and the impedance per unit length of each return line is obtained according to the following formula:

[0049] Z i =R i +X i

[0050] In the formula, Z irepresents the unit length impedance of the i-th return line, and the short-circuit current flowing through each return line is calculated using the following formula:

[0051]

[0052] In the formula, I ki represents the short-circuit current flowing through the i-th return line, I k The short-circuit current flowing through a single-ended grounded cable, k i represents the proportion of the short-circuit current flowing through the i-th return line in the short-circuit current flowing through the single-ended grounding cable, n represents the number of return lines to be laid, Z1, Z2, …, Z n They represent the unit length impedance of the 1st, 2nd, …, nth return lines, Z1 / / Z2 / / … / / Z n It represents the total impedance per unit length after n return lines are connected in parallel.

[0053] After obtaining the short-circuit current of each return line, the short-circuit current thermal effect of the return line is calculated using the following formula:

[0054]

[0055] In the formula, Q ki represents the short-circuit current thermal effect of the ith return line, I ki represents the short-circuit current of the ith return line, t k Indicates the short circuit duration.

[0056] After obtaining the short-circuit current thermal effect of each return line, the first current carrying capacity of the return line of the target material type at the maximum allowable operating temperature and the second current carrying capacity at the rated operating temperature are obtained, and the first thermal stability coefficient corresponding to the target material type is calculated using the following formula:

[0057]

[0058] In the formula, C i Indicates the first thermal stability coefficient, A Ki Indicates the first current carrying capacity, A Li represents the second current carrying capacity; finally, the minimum value of the target cross-sectional range corresponding to the return line of the target material type is calculated according to the following formula:

[0059]

[0060] In the formula, S imin It represents the minimum value of the target cross-sectional range of the i-th reflow line. The minimum value of the target cross-sectional range of reflow lines of the same material type is the same.

[0061] As an optional implementation, in order to ensure that the cross-section of the return line does not exceed the thermal stability of the single-ended grounding cable and avoid damage due to overheating during a short circuit fault, the maximum value of the target cross-section range of the return line can be further determined. This process can be performed according to the following steps:

[0062] First, obtain the third current carrying capacity of the single-ended grounding cable at the maximum allowable operating temperature and the fourth current carrying capacity at the rated operating temperature, and use the following formula to calculate the second thermal stability coefficient corresponding to the single-ended grounding cable:

[0063]

[0064] In the formula, C s Indicates the second thermal stability coefficient, A Ks Indicates the third current carrying capacity, which refers to the maximum continuous current carrying capacity of a single-ended grounding cable at the highest allowable operating temperature, A Ls It represents the fourth current carrying capacity, which refers to the maximum continuous current carrying capacity of a single-ended grounding cable at the rated operating temperature.

[0065] Then, based on the outer radius and inner radius of the sheath of the single-ended grounding cable obtained, the maximum value of the target cross-sectional range is calculated using the following formula:

[0066]

[0067] In the formula, S imax represents the maximum value of the target cross section range of the i-th target, r so Represents the outer radius of the sheath of a single-ended grounding cable, r si Represents the inner radius of the sheath of a single-ended grounding cable. The maximum value of the target cross-section range of return lines of the same material type is the same.

[0068] It is important to note that before performing these calculations, ensure that all units used are consistent, for example, if the current carrying capacity is in amperes and the radius is in meters, the units should be kept consistent during the calculation.

[0069] After the target cross-sectional range corresponding to the reflow line of the target material type is obtained, multiple models of reflow lines matching the target material type and the target cross-sectional range are determined as candidate reflow lines.

[0070] For each alternative return line, it is also necessary to screen it comprehensively based on factors such as performance and cost. Specifically, the performance parameters and cost parameters of each alternative return line are obtained, and each alternative return line is comprehensively scored based on the performance parameters and cost parameters, and the alternative return line with the highest comprehensive score is determined as the target return line corresponding to the single-ended grounding cable.

[0071] Among them, the types of performance parameters include at least one of the following: rated working current and unit conductivity of the alternative return line; the types of cost parameters include at least one of the following: unit length price, rated service life, annual depreciation rate, and annual maintenance cost of the alternative return line.

[0072] The process of comprehensively evaluating each candidate reflow line based on performance and cost parameters can be carried out using the following steps:

[0073] S1, obtaining the rated working current and unit conductivity of the candidate return line; the type of cost parameter includes at least one of the following: unit length price, rated service life, annual depreciation rate, and annual maintenance cost of the candidate return line;

[0074] S2, obtaining the load level of the single-ended grounding system and determining the performance weight according to the load level;

[0075] Among them, the load level of the single-ended grounding system usually reflects the load characteristics and importance of the system. For example, the load level can be divided into primary load (most important), secondary load (relatively important) and tertiary load (general), and the load level can be obtained through system design documents, operation records or communication with system managers.

[0076] Performance weights reflect the importance of different performance indicators in the evaluation. Different performance indicators can be given different weights according to different load levels. A weight table can be prepared in advance to determine the weights of various performance indicators according to the load level. For example: for level 1 load, safety weight is high and economy weight is low; for level 2 load, safety weight is high and economy weight is medium; for level 3 load, safety weight is medium and economy weight is high.

[0077] S3, randomly determining an alternative return line from multiple alternative return lines as a reference return line, and determining that the comprehensive score of the reference return line is 1;

[0078] S4. For any candidate return line other than the reference return line among the multiple candidate return lines, the comprehensive score of the candidate return line is calculated using the following formula:

[0079]

[0080] Among them, F i represents the comprehensive score of the i-th candidate reflow line, λ represents the performance weight, and A ref Indicates the unit length price of the reference return line, A i represents the price per unit length of the i-th alternative return line, k ref Denotes the rated service life of the reference return line, k i represents the rated service life of the i-th alternative return line, M refrepresents the annual maintenance cost of the reference return line, M i represents the annual maintenance cost of the i-th alternative return line, I i represents the rated operating current of the i-th alternative return line, I ref Indicates the rated operating current of the reference return line, ρ i represents the unit conductivity of the i-th candidate return line, ρ ref Represents the unit conductivity of the reference return line, ε i represents the annual depreciation rate of the i-th alternative recirculation line, ε ref Represents the annual depreciation rate of the reference return line.

[0081] After calculating and obtaining the comprehensive score of each candidate reflow line, the reflow line with the highest score is selected as the final target reflow line.

[0082] In an embodiment of the present application, the laying environment of a single-ended grounding cable in a single-ended grounding system is obtained, and at least one target material type matching the laying environment is determined; when a short-circuit fault occurs in the single-ended grounding system, the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current flowing can meet the thermal stability condition is determined; multiple models of return lines matching the target material type and the target cross-sectional range are determined as alternative return lines; performance parameters and cost parameters of each alternative return line are obtained, and each alternative return line is comprehensively scored based on the performance parameters and cost parameters; and the alternative return line with the highest comprehensive score is determined as the target return line corresponding to the single-ended grounding cable. In this way, one or more return line material types are determined according to the laying environment, and the cross-sectional range of the return line is further determined according to the thermal stability conditions to select qualified alternative return lines. Finally, the final target return line is determined by comprehensively analyzing the performance and cost of the alternative return lines. In this process, scientific calculation and analysis are used to avoid the problem of excessive parameter margin during selection, ensuring that the selection of the return line can meet the functional requirements and have good economy, thereby solving the technical problem of unreasonable selection of return lines for single-ended grounding cables in engineering, which can easily lead to cost waste or safety accidents.

[0083] Example 2

[0084] According to an embodiment of the present application, a return line selection device for a single-ended grounding cable is provided for implementing the return line selection method for a single-ended grounding cable in Embodiment 1. Figure 2 As shown, the return line selection device for the single-ended grounding cable at least includes: a material selection module 21, a cross-section selection module 22, an alternative line selection module 23, a comprehensive scoring module 24, and a return line selection module 25, wherein:

[0085] A material selection module 21 is used to obtain the laying environment of the single-ended grounding cable in the single-ended grounding system and determine at least one target material type matching the laying environment;

[0086] A cross-section selection module 22 is used to determine a target cross-section range corresponding to a return line of each target material type through which a short-circuit current can meet a thermal stability condition when a short-circuit fault occurs in a single-ended grounding system;

[0087] The candidate line selection module 23 is used to determine multiple types of reflow lines that match the target material type and the target cross-sectional range as candidate reflow lines;

[0088] A comprehensive scoring module 24 is used to obtain the performance parameters and cost parameters of each candidate reflow line, and to comprehensively score each candidate reflow line according to the performance parameters and cost parameters;

[0089] The return line selection module 25 is used to determine the candidate return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

[0090] The functions of each module of the return line selection device for a single-ended grounding cable are described below in conjunction with a specific implementation process.

[0091] In order to solve the technical problem that the unreasonable selection of the return line of the single-ended grounding cable in the project easily leads to cost waste or safety accidents, this application proposes a method for selecting the return line of the single-ended grounding cable. The implementation process of the method is as follows:

[0092] When selecting a single-ended grounding cable and its return line material, the laying environment can be considered first, because different environmental conditions (such as temperature, humidity, chemical corrosiveness, etc.) will affect the physical and chemical properties of the return line, and thus affect its safety and reliability. For example, in a highly corrosive environment, if a material with poor corrosion resistance is selected, it may cause the return line to be damaged prematurely, causing safety hazards. Suitable materials can better resist the influence of environmental factors, thereby extending the service life of the grounding cable and reducing replacement frequency and maintenance costs. Taking all factors into consideration, the embodiment of the present application first obtains the laying environment of the single-ended grounding cable in the single-ended grounding system when selecting the return line, and determines at least one target material type that matches the laying environment.

[0093] Among them, the return line of the target material type may include at least one of the following: an aluminum alloy return line with strong corrosion resistance but poor vibration resistance, a copper return line with strong conductivity and oxidation resistance, a high temperature resistant special return line, a vibration resistant special return line, a polymer composite material return line with strong corrosion resistance, vibration resistance, conductivity, oxidation resistance and high temperature resistance. These types of return lines can be selected according to the environment.

[0094] For example, in corrosive environments, such as at the seaside or in industrial areas, aluminum alloy return lines with strong corrosion resistance but poor vibration resistance should be selected; in environments requiring high conductivity and oxidation resistance, such as high-voltage power transmission systems, copper return lines with strong conductivity and oxidation resistance should be selected; in high-temperature environments, such as near heat sources, high-temperature resistant special return lines should be selected; in vibrating and frequent environments, such as near rail transit or industrial equipment, vibration-resistant special return lines should be selected; in complex and changeable environments, such as places where corrosion, vibration, high temperature and high conductivity are required at the same time, polymer composite return lines with strong corrosion resistance, vibration resistance, conductivity, oxidation resistance and high temperature resistance should be selected.

[0095] In a single-ended grounding system, once a short circuit occurs, a very large short-circuit current will flow through the return line. If the cross-section of the return line is too small and cannot withstand such a large current, it will cause the return line to overheat or even melt, thus causing a safety accident. Therefore, it is very important to select a return line cross-section range that meets the thermal stability requirements.

[0096] As an optional implementation, determining the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current can meet the thermal stability condition can be performed in the following manner:

[0097] For each target material type return line, determine the short-circuit current and short-circuit duration flowing through the return line when a short-circuit fault occurs in a single-ended grounding system;

[0098] The duration of the short circuit flowing through the return line can be determined by: simulating a short circuit fault under laboratory conditions and recording the total time from the occurrence of the short circuit to the clearing of the fault; or testing in an actual single-ended grounding system and recording the duration of the short circuit; the duration of the short circuit current flowing through the return line can also be obtained by using simulation software for a single-ended grounding system.

[0099] To determine the short-circuit current flowing through the return line, the following method can be used:

[0100] When the number of return lines to be laid is one, the short-circuit current flowing through the single-ended grounding cable is used as the short-circuit current flowing through the return line.

[0101] When there are multiple return lines to be laid, firstly obtain the short-circuit current flowing through the single-ended grounding cable, the resistance per unit length of each return line, the frequency of the single-ended grounding system, and the earth conductivity.

[0102] Considering that the earth equivalent resistance is one of the key parameters for evaluating the performance of the grounding system, its size directly affects the safety and reliability of the system. When a short-circuit fault occurs, the short-circuit current will return to the power supply through the earth. The earth equivalent resistance affects the distribution of the short-circuit current in the earth, and then affects the current distribution of the return line. In order to accurately evaluate and design the grounding and return paths in the single-ended grounding system, the earth equivalent resistance can be calculated in the following way:

[0103]

[0104] Where D e represents the equivalent resistance of the earth, f represents the frequency of the single-ended grounding system, and ρ represents the earth conductivity.

[0105] Then calculate the reactance per unit length of each return line:

[0106]

[0107] Where, X i represents the reactance per unit length of the ith return line, R i represents the resistance per unit length of the i-th return line, and the impedance per unit length of each return line is obtained according to the following formula:

[0108] Z i =R i +X i

[0109] In the formula, Z i represents the unit length impedance of the i-th return line, and the short-circuit current flowing through each return line is calculated using the following formula:

[0110]

[0111] In the formula, I ki represents the short-circuit current flowing through the i-th return line, I k The short-circuit current flowing through a single-ended grounded cable, k i represents the proportion of the short-circuit current flowing through the i-th return line in the short-circuit current flowing through the single-ended grounding cable, n represents the number of return lines to be laid, Z1, Z2, …, Z n They represent the unit length impedance of the 1st, 2nd, …, nth return lines, Z1 / / Z2 / / … / / Z n It represents the total impedance per unit length after n return lines are connected in parallel.

[0112] After obtaining the short-circuit current of each return line, the short-circuit current thermal effect of the return line is calculated using the following formula:

[0113]

[0114] In the formula, Q ki represents the short-circuit current thermal effect of the ith return line, I ki represents the short-circuit current of the ith return line, t k Indicates the short circuit duration.

[0115] After obtaining the short-circuit current thermal effect of each return line, the first current carrying capacity of the return line of the target material type at the maximum allowable operating temperature and the second current carrying capacity at the rated operating temperature are obtained, and the first thermal stability coefficient corresponding to the target material type is calculated using the following formula:

[0116]

[0117] In the formula, C i Indicates the first thermal stability coefficient, A Ki Indicates the first current carrying capacity, A Li Indicates the second current carrying capacity; the minimum value of the target cross-sectional range corresponding to the return line of the target material type is calculated using the following formula. Finally, the minimum value of the target cross-sectional range is obtained according to the following formula:

[0118]

[0119] In the formula, S imin Indicates the minimum value of the target section range.

[0120] As an optional implementation, the maximum value of the target cross-sectional range can also be determined, thereby more accurately selecting the most suitable reflow line, which can be done by following the steps below:

[0121] Obtain the third current carrying capacity of the single-ended grounding cable at the maximum allowable operating temperature and the fourth current carrying capacity at the rated operating temperature, and use the following formula to calculate the second thermal stability coefficient corresponding to the single-ended grounding cable:

[0122]

[0123] In the formula, C s Indicates the second thermal stability coefficient, A Ks Indicates the third current carrying capacity, which refers to the maximum continuous current carrying capacity of a single-ended grounding cable at the highest allowable operating temperature, A Ls It represents the fourth current carrying capacity, which refers to the maximum continuous current carrying capacity of a single-ended grounding cable at the rated operating temperature.

[0124] Then, based on the outer radius and inner radius of the sheath of the single-ended grounding cable obtained, the maximum value of the target cross-sectional range is calculated using the following formula:

[0125]

[0126] In the formula, Simax Indicates the maximum value of the target cross-section range, r so Represents the outer radius of the sheath of a single-ended grounding cable, r si Indicates the inner radius of the sheath of a single-ended grounding cable.

[0127] It is important to note that before performing these calculations, ensure that all units used are consistent, for example, if the current carrying capacity is in amperes and the radius is in meters, the units should be kept consistent during the calculation.

[0128] After obtaining the above cross-sectional range, multiple models of reflow lines matching the target material type and the target cross-sectional range are determined as candidate reflow lines.

[0129] For each alternative return line, it is also necessary to screen it comprehensively based on factors such as performance and cost. Specifically, the performance parameters and cost parameters of each alternative return line are obtained, and each alternative return line is comprehensively scored based on the performance parameters and cost parameters, and the alternative return line with the highest comprehensive score is determined as the target return line corresponding to the single-ended grounding cable.

[0130] Among them, the types of performance parameters include at least one of the following: rated working current and unit conductivity of the alternative return line; the types of cost parameters include at least one of the following: unit length price, rated service life, annual depreciation rate, and annual maintenance cost of the alternative return line.

[0131] The process of comprehensively evaluating each candidate reflow line based on performance and cost parameters can be carried out using the following steps:

[0132] S1, obtaining the rated working current and unit conductivity of the candidate return line; the type of cost parameter includes at least one of the following: unit length price, rated service life, annual depreciation rate, and annual maintenance cost of the candidate return line;

[0133] S2, obtaining the load level of the single-ended grounding system and determining the performance weight according to the load level;

[0134] Among them, the load level of the single-ended grounding system usually reflects the load characteristics and importance of the system. For example, the load level can be divided into primary load (most important), secondary load (relatively important) and tertiary load (general), and the load level can be obtained through system design documents, operation records or communication with system managers.

[0135] Performance weights reflect the importance of different performance indicators in the evaluation. Different performance indicators can be given different weights according to different load levels. A weight table can be prepared in advance to determine the weights of various performance indicators according to the load level. For example: for level 1 load, safety weight is high and economy weight is low; for level 2 load, safety weight is high and economy weight is medium; for level 3 load, safety weight is medium and economy weight is high.

[0136] S3, randomly determining an alternative return line from multiple alternative return lines as a reference return line, and determining that the comprehensive score of the reference return line is 1;

[0137] S4. For any candidate return line other than the reference return line among the multiple candidate return lines, the comprehensive score of the candidate return line is calculated using the following formula:

[0138]

[0139] Among them, F i represents the comprehensive score of the i-th candidate reflow line, λ represents the performance weight, and A ref Indicates the unit length price of the reference return line, A i represents the price per unit length of the i-th alternative return line, k ref Denotes the rated service life of the reference return line, k i represents the rated service life of the i-th alternative return line, M ref represents the annual maintenance cost of the reference return line, M i represents the annual maintenance cost of the i-th alternative return line, I i represents the rated operating current of the i-th alternative return line, I ref Indicates the rated operating current of the reference return line, ρ i represents the unit conductivity of the i-th candidate return line, ρ ref Represents the unit conductivity of the reference return line, ε i represents the annual depreciation rate of the i-th alternative recirculation line, ε ref Represents the annual depreciation rate of the reference return line.

[0140] After calculating and obtaining the comprehensive score of each reflow line, the reflow line with the highest score is selected as the final target reflow line.

[0141] It should be noted that the modules in the return line selection device for a single-ended grounding cable in the embodiment of the present application correspond one-to-one to the implementation steps of the return line selection method for a single-ended grounding cable in Example 1. Since a detailed description has been given in Example 1, some details not reflected in this embodiment can be referred to Example 1, and will not be repeated here.

[0142] Example 3

[0143] According to an embodiment of the present application, a computer program product is further provided. The computer program product includes a computer program, wherein when the computer program is executed by a processor, the return line selection method of the single-ended grounding cable in Example 1 is implemented.

[0144] According to an embodiment of the present application, a non-volatile storage medium is also provided, which includes a stored computer program, wherein the device where the non-volatile storage medium is located executes the return line selection method for the single-ended grounding cable in Example 1 by running the computer program.

[0145] According to an embodiment of the present application, a processor is further provided, which is used to run a computer program, wherein the return line selection method for a single-ended grounding cable in Example 1 is executed when the computer program is running.

[0146] According to an embodiment of the present application, an electronic device is also provided, which includes: a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to execute the return line selection method of the single-ended grounding cable in Example 1 through the computer program.

[0147] Specifically, the following steps are executed when the computer program is running: obtaining the laying environment of the single-ended grounding cable in the single-ended grounding system, and determining at least one target material type that matches the laying environment; determining the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current flowing can meet the thermal stability conditions when a short-circuit fault occurs in the single-ended grounding system; determining multiple models of return lines that match the target material type and the target cross-sectional range as alternative return lines; obtaining the performance parameters and cost parameters of each alternative return line, and comprehensively scoring each alternative return line based on the performance parameters and cost parameters; determining the alternative return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

[0148] As an optional implementation, the electronic device may be in the form of a mobile terminal, a computer terminal or a similar computing device. Figure 3 The hardware structure block diagram of an electronic device for implementing a method for selecting a return line of a single-ended grounding cable is shown. Figure 3As shown, the electronic device 30 may include one or more (302a, 302b, ..., 302n are used to illustrate) processors 302 (the processor 302 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 304 for storing data, and a transmission device 306 for communication functions. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the BUS bus), a network interface, a power supply and / or a camera. It can be understood by those skilled in the art that Figure 3 The structure shown is only for illustration and does not limit the structure of the above electronic device. Figure 3 More or fewer components as shown, or with Figure 3 Different configurations are shown.

[0149] It should be noted that the one or more processors 302 and / or other data processing circuits described above may generally be referred to herein as "data processing circuits". The data processing circuits may be embodied in whole or in part as software, hardware, firmware, or any other combination thereof. In addition, the data processing circuit may be a single independent processing module, or may be incorporated in whole or in part into any of the other components in the electronic device 30. As described in the embodiments of the present application, the data processing circuit acts as a processor control (e.g., selection of a variable resistor terminal path connected to an interface).

[0150] The memory 304 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the return line selection method of the single-ended grounding cable in the embodiment of the present application. The processor 302 executes various functional applications and data processing by running the software programs and modules stored in the memory 304, that is, to implement the vulnerability detection method of the above-mentioned application. The memory 304 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 304 may further include a memory remotely arranged relative to the processor 302, and these remote memories may be connected to the electronic device 30 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0151] The transmission device 306 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the electronic device 30. In one example, the transmission device 306 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 306 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0152] The display may be, for example, a touch screen liquid crystal display (LCD) that enables a user to interact with a user interface of the electronic device 30 .

[0153] The serial numbers of the above embodiments are only for description and do not represent the advantages or disadvantages of the embodiments.

[0154] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0155] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0156] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0157] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0158] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, 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 and includes several instructions for a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of each embodiment method of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc. Various media that can store program codes.

[0159] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for selecting a return line of a single-ended grounding cable, characterized in that: include: Acquire a laying environment of a single-ended grounding cable in a single-ended grounding system, and determine at least one target material type matching the laying environment; Determine a target cross-sectional range corresponding to a return line of each target material type through which a short-circuit current flowing can meet a thermal stability condition when a short-circuit fault occurs in the single-ended grounding system; Determine multiple models of reflow lines that match the target material type and the target cross-sectional range as candidate reflow lines; Obtaining performance parameters and cost parameters of each candidate reflow line, and comprehensively scoring each candidate reflow line according to the performance parameters and the cost parameters; The candidate return line with the highest comprehensive score is determined as the target return line corresponding to the single-ended grounding cable.

2. The method according to claim 1, characterized in that: The target material type of the reflow line includes at least one of the following: an aluminum alloy reflow line with strong corrosion resistance but poor vibration resistance, a copper reflow line with strong conductivity and oxidation resistance, a high temperature resistant special reflow line, a vibration resistant special reflow line, and a polymer composite material reflow line with strong corrosion resistance, vibration resistance, conductivity, oxidation resistance and high temperature resistance.

3. The method according to claim 1, characterized in that Determining the target cross-sectional range corresponding to the return line of each target material type through which the short-circuit current flowing can meet the thermal stability condition when a short-circuit fault occurs in the single-ended grounding system, including: For each return line of the target material type, determine the short-circuit current and short-circuit duration flowing through the return line when a short-circuit fault occurs in the single-ended grounding system, and calculate the short-circuit current thermal effect of the return line using the following formula: In the formula, Q ki represents the short-circuit current thermal effect, I ki represents the short-circuit current, t k Indicates the duration of the short circuit; Obtain the first current carrying capacity of the return line of the target material type at the maximum allowable operating temperature and the second current carrying capacity at the rated operating temperature, and calculate the first thermal stability coefficient corresponding to the target material type using the following formula: In the formula, C i Denotes the first thermal stability coefficient, A Ki represents the first current carrying capacity, A Li represents the second current carrying capacity; The minimum value of the target cross-sectional range corresponding to the reflow line of the target material type is calculated using the following formula: In the formula, S imin Indicates the minimum value of the target cross-section range.

4. The method according to claim 3, characterized in that: Determining the short-circuit current flowing through the return line when a short-circuit fault occurs in the single-ended grounding system includes: In the case where the number of return lines to be laid is one, determining that when a short-circuit fault occurs in the single-ended grounding system, the short-circuit current flowing through the single-ended grounding cable is used as the short-circuit current flowing through the return line; When there are multiple return lines to be laid, determine when a short-circuit fault occurs in the single-ended grounding system, obtain the short-circuit current flowing through the single-ended grounding cable, the unit length resistance of each return line, the single-ended grounding system frequency, and the earth conductivity, and use the following formula to calculate the short-circuit current flowing through each return line: In the formula, I ki represents the short-circuit current flowing through the i-th return line, I k represents the short-circuit current flowing through the single-ended grounding cable, k i represents the proportion of the short-circuit current flowing through the i-th return line in the short-circuit current flowing through the single-ended grounding cable, n represents the number of return lines to be laid, Z1, Z2, …, Z n They represent the unit length impedance of the 1st, 2nd, …, nth return lines, Z1 / / Z2 / / … / / Z n It represents the total unit length impedance of n return lines connected in parallel, Z i represents the unit length impedance of the i-th return line, and Z i =R i +X i , R i represents the resistance per unit length of the ith return line, X i represents the reactance per unit length of the ith return line, D e represents the earth equivalent resistance, f represents the single-ended grounding system frequency, and ρ represents the earth conductivity.

5. The method according to claim 3, characterized in that: The method further comprises: The third current carrying capacity of the single-ended grounding cable at the maximum allowable operating temperature and the fourth current carrying capacity at the rated operating temperature are obtained, and the second thermal stability coefficient corresponding to the single-ended grounding cable is calculated using the following formula: In the formula, C s The second thermal stability coefficient, A Ks represents the third current carrying capacity, A Ls represents the fourth current carrying capacity; The outer radius and inner radius of the sheath of the single-ended grounding cable are obtained, and the maximum value of the target cross-sectional range is calculated using the following formula: In the formula, S imax represents the maximum value of the target cross-sectional range, r so represents the outer radius of the sheath of the single-ended grounding cable, r si It represents the inner radius of the sheath of the single-ended grounding cable.

6. The method according to claim 1, characterized in that The type of the performance parameter includes at least one of the following: the rated working current and unit conductivity of the alternative return line; The type of the cost parameter includes at least one of the following: the price per unit length of the candidate return line, the rated service life, the annual depreciation rate, and the annual maintenance cost.

7. The method according to claim 6, characterized in that A comprehensive score is given to each candidate reflow line according to the performance parameter and the cost parameter, including: Obtaining a load level of the single-ended grounding system, and determining a performance weight according to the load level; Randomly determine an alternative return line from the plurality of alternative return lines as a reference return line, and determine the comprehensive score of the reference return line to be 1; For any candidate return line other than the reference return line among the plurality of candidate return lines, the comprehensive score of the candidate return line is calculated using the following formula: Among them, F i represents the comprehensive score of the i-th candidate reflow line, λ represents the performance weight, A ref Indicates the price per unit length of the reference return line, A i represents the price per unit length of the i-th alternative return line, k ref represents the rated service life of the reference return line, k i represents the rated service life of the i-th alternative return line, M ref represents the annual maintenance cost of the reference return line, M i represents the annual maintenance cost of the i-th alternative return line, I i represents the rated operating current of the i-th alternative return line, I ref represents the rated operating current of the reference return line, ρ i represents the unit conductivity of the i-th candidate return line, ρ ref represents the unit conductivity of the reference return line, ε i represents the annual depreciation rate of the i-th alternative recirculation line, ε ref Represents the annual depreciation rate of the reference return line.

8. A return line selection device for a single-ended grounding cable, characterized in that: include: A material selection module, used for obtaining the laying environment of the single-ended grounding cable in the single-ended grounding system, and determining at least one target material type matching the laying environment; A cross-section selection module, used to determine a target cross-section range corresponding to a return line of each target material type through which a short-circuit current can meet a thermal stability condition when a short-circuit fault occurs in the single-ended grounding system; An alternative line selection module, used to determine multiple models of reflow lines matching the target material type and the target cross-sectional range as alternative reflow lines; A comprehensive scoring module, used for obtaining the performance parameters and cost parameters of each candidate reflow line, and performing a comprehensive scoring on each candidate reflow line according to the performance parameters and the cost parameters; The return line selection module is used to determine the candidate return line with the highest comprehensive score as the target return line corresponding to the single-ended grounding cable.

9. A computer program product, characterized in that include: A computer program, wherein when the computer program is executed by a processor, the method for selecting a return line for a single-ended grounding cable according to any one of claims 1 to 7 is implemented.

10. An electronic device, characterized in that: include: A memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the return line selection method for a single-ended grounding cable according to any one of claims 1 to 7 through the computer program.

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