A method, system, computer device, and storage medium for cable cross-section selection

Abstract

The present invention discloses a method, a system, a computer device and a storage medium for cable cross-section selection, including calculating a first cable cross-section according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop, and performing thermal stability verification; obtaining the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and the threshold value; respectively obtaining the circuit breaker operation time corresponding to different types of the DC circuit breaker according to the operation characteristic curve of the DC circuit breaker and a preset short-circuit current value; performing thermal stability verification on the preset short-circuit current value and the operation time to obtain a first cross-section current expression and a second cross-section current expression; obtaining a relationship expression between the cable cross-section and the rated current according to the first and second cross-section current expressions, and obtaining the cable cross-sectional area according to the relationship expression. The present invention can directly obtain the cable cross-section size according to the rated current of the circuit breaker, simplifies the workload, and improves the safety and stability of the operation of the DC power supply system.

Description

Technical Field

[0001] The present invention relates to the technical field of DC power supply systems, and particularly to a method, a system, a computer device, and a storage medium for selecting a cable cross-section in a DC power supply system. Background Art

[0002] Currently, the cable cross-section in a DC power supply system is usually selected according to two conditions: the long-term allowable current-carrying capacity of the cable and the allowable voltage drop of the circuit. However, in actual engineering, due to the breaker grading coordination, the rated current of the breaker may be selected relatively large, resulting in the situation that the breaker does not operate when the cable is short-circuited and the cable is burned out. Therefore, the thermal stability of the cable under short-circuit conditions also needs to be considered. The thermal stability verification of the cable usually calculates the magnitude of the short-circuit current and the corresponding breaker operating time under the current cable cross-section, and verifies whether the cable cross-section meets the thermal stability requirements. If not, the cable cross-section is appropriately increased, and the above verification process is repeated until a suitable cable cross-section is found. The problem with the existing technology is that multiple repeated verification processes are required for the cable thermal stability verification to find a suitable cable cross-section, which not only has a large workload but also is prone to errors, thus affecting the safety and stability of the operation of the DC power supply system. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a method, a system, a computer device, and a storage medium for selecting a cable cross-section in a DC power supply system, which can solve the problem of a large amount of repeated calculations in the existing technology, can directly obtain the cable cross-section size from the rated current of the DC breaker, without repeated verification work, and while simplifying the workload, also improves the accuracy of the calculation results.

[0004] In a first aspect, the present invention provides a method for selecting a cable cross-section, the method comprising:

[0005] Calculating a first cable cross-section according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the circuit in the DC power supply system, and performing thermal stability verification on the first cable cross-section;

[0006] Obtaining the type of the DC breaker according to the comparison relationship between the rated current of the DC breaker and a threshold, the type including a first DC breaker and a second DC breaker;

[0007] Obtaining the breaker operating times corresponding to different types of the DC breaker according to the DC breaker operating characteristic curve and a preset short-circuit current value, the preset short-circuit current value being a multiple value of the rated current, and the breaker operating times including a first operating time and a second operating time;

[0008] Perform thermal stability verification on the preset short-circuit current value and the first operating time to obtain the first cross-sectional current expression, and perform thermal stability verification on the preset short-circuit current value and the second operating time to obtain the second cross-sectional current expression;

[0009] Based on the first cross-sectional current expression and the second cross-sectional current expression, obtain the relational expression between the cable cross-sectional area and the rated current;

[0010] Based on the relational expression, obtain the cable cross-sectional area in the DC power supply system through the rated current of the DC circuit breaker.

[0011] Further, calculate the first cable cross-section using the following formula:

[0012] I pc ≥I ca1

[0013]

[0014] In the formula, I pc is the allowable current-carrying capacity of the cable, I ca1 is the calculated circuit for long-term operation of the loop, S cac is the calculated cross-section of the cable, ρ is the resistivity coefficient, L is the cable length, I ca is the calculated circuit for allowable voltage drop, △U p is the allowable voltage drop of the loop;

[0015] Calculate the thermal stability verification using the following formula:

[0016]

[0017] In the formula, S is the cable cross-sectional area, I d is the short-circuit current, t is the operating time of the circuit breaker, and K is the conductor temperature coefficient.

[0018] Further, the step of obtaining the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and the threshold includes:

[0019] Calculate the difference between the rated current of the DC circuit breaker and the threshold, and determine whether the difference is greater than or equal to zero;

[0020] If so, the type of the DC circuit breaker is the first DC circuit breaker, and if not, the type of the DC circuit breaker is the second DC circuit breaker.

[0021] Further, calculate the first cross-sectional current expression using the following formula:

[0022] S≥0.17I n

[0023] The second cross-section current expression is calculated using the following formula:

[0024] S≥0.24I n

[0025] where S is the cross-sectional area of the cable and I n is the rated current.

[0026] Furthermore, the relationship expression between the cross-sectional area of the cable and the rated current is represented by the following formula:

[0027]

[0028] where S is the cross-sectional area of the cable and I n is the rated current.

[0029] In a second aspect, the present invention provides a cable cross-section selection system, which includes:

[0030] A thermal stability verification module, configured to calculate a first cable cross-section according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and perform thermal stability verification on the first cable cross-section;

[0031] A breaker type determination module, configured to obtain the type of the DC breaker according to the comparison relationship between the rated current of the DC breaker and a threshold value, where the type includes a first DC breaker and a second DC breaker;

[0032] A cross-section current analysis module, configured to respectively obtain the breaker operation times corresponding to different types of the DC breakers according to the DC breaker operation characteristic curve and a preset short-circuit current value, where the preset short-circuit current value is a multiple value of the rated current, and the breaker operation times include a first operation time and a second operation time; perform thermal stability verification on the preset short-circuit current value and the first operation time to obtain a first cross-section current expression, and perform thermal stability verification on the preset short-circuit current value and the second operation time to obtain a second cross-section current expression;

[0033] A cable cross-section calculation module, configured to obtain a relationship expression between the cross-sectional area of the cable and the rated current according to the first cross-section current expression and the second cross-section current expression; and obtain the cross-sectional area of the cable in the DC power supply system through the rated current of the DC breaker according to the relationship expression.

[0034] Furthermore, the thermal stability verification module includes a first cable cross-section calculation module and a thermal stability calculation module;

[0035] The first cable cross-section calculation module is configured to calculate a first cable cross-section, and the first cable cross-section is calculated using the following formula:

[0036] I pc ≥I ca1

[0037]

[0038] Wherein, I pc is the allowable current-carrying capacity of the cable, I ca1 is the long-term working calculation circuit of the loop, S cac is the calculated cross-section of the cable, ρ is the resistivity coefficient, L is the cable length, I ca is the calculation circuit of the allowable voltage drop, △U p is the allowable voltage drop of the loop;

[0039] The thermal stability calculation module is used to perform thermal stability verification, and the following formula is used to calculate the thermal stability verification:

[0040]

[0041] Wherein, S is the cross-sectional area of the cable, I d is the short-circuit current, t is the operating time of the circuit breaker, and K is the conductor temperature coefficient.

[0042] Furthermore, the cable cross-section calculation module includes a relational expression calculation module;

[0043] The relational expression calculation module is used to represent the relational expression between the cable cross-section and the rated current, and the following formula is used to represent the relational expression between the cable cross-sectional area and the rated current:

[0044]

[0045] Wherein, S is the cross-sectional area of the cable, I n is the rated current.

[0046] In a third aspect, an embodiment of the present invention further provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the above method are implemented.

[0047] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0048] The present invention provides a method, system, computer device and storage medium for selecting a cable cross-section. By using the method, it is not necessary to perform repeated calculations for thermal stability verification, and the corresponding cable cross-section size can be directly obtained from the rated current of the circuit breaker. The calculation is not only simple and convenient, but also has high accuracy, further improving the stability of the DC power supply system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic flow chart of the cable cross-section selection method provided by an embodiment of the present invention;

[0050] Figure 2 is the DC circuit breaker operation characteristic curve provided by an embodiment of the present invention;

[0051] Figure 3 Schematic structural diagram of the cable cross-section selection system provided by an embodiment of the present invention;

[0052] Figure 4 is the internal structure diagram of the computer device in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] Please refer to Figure 1 , a cable cross-section selection method proposed in the first embodiment of the present invention includes steps S10 to S60:

[0055] Step S10, calculate a first cable cross-section according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and perform thermal stability verification on the first cable cross-section.

[0056] The cable cross-section in the DC power supply system is usually selected according to two conditions: the long-term allowable current-carrying capacity of the cable and the allowable voltage drop of the loop. However, in actual engineering, due to the breaker grading coordination, the rated current of the circuit breaker may be selected relatively large, resulting in the situation that the circuit breaker does not operate and burns out the cable when the cable is short-circuited. Therefore, the thermal stability of the cable under short-circuit conditions should also be considered to meet the requirements.

[0057] According to the regulations in the existing Electric Power DL / T 5044 "Design Technical Regulations for DC Power Supply Systems in Electric Power Engineering", the cable cross-section should be selected according to two conditions: the long-term allowable current-carrying capacity of the cable and the allowable voltage drop of the loop, and should be calculated according to the following formula:

[0058] I pc ≥I ca1

[0059]

[0060] Wherein, I pc is the allowable current-carrying capacity of the cable, I ca1 is the long-term working calculation circuit of the loop, S cac is the calculated cross-section of the cable, ρ is the resistivity coefficient, L is the cable length, I ca is the calculation circuit of the allowable voltage drop, △U p is the allowable voltage drop of the loop, where for copper conductors ρ = 0.0184Ω·mm 2 / m, and for aluminum conductors ρ = 0.031Ω·mm 2 / m.

[0061] Then, it is necessary to check the thermal stability of the cable, that is, calculate the magnitude of the short-circuit current and the corresponding breaker operating time under the initially selected cable cross-section, and check whether the cable cross-section meets the thermal stability requirements. Similarly, in accordance with the electric power industry standard DL / T5155 "Technical Regulations for the Design of Station Service Power of 220kV~1000kV Substations", when the short-circuit duration ≤ 5s, the cross-sectional area of the cable should meet the following conditions:

[0062]

[0063] Wherein, S is the cross-sectional area of the cable, I d is the short-circuit current, t is the operating time of the breaker to cut off the current, K is the conductor temperature coefficient, where for conductor insulation PVC ≤ 300mm 2 take 115, and for XLPE take 143.

[0064] According to the existing cable cross-section calculation method, the thermal stability check of the cable requires multiple repeated check processes to find a suitable cable cross-section. First, calculate the magnitude of the short-circuit current and the corresponding breaker operating time under the initially selected cable cross-section, and check whether the cable cross-section meets the thermal stability requirements. If it does not meet the requirements, appropriately increase the cable cross-section and repeat the above check process until a suitable cable cross-section is found. That is to say, the original method requires multiple repeated calculations to find a suitable cable cross-section, with a large workload and easy to make mistakes. To solve the situation of large calculation amount and difficult to ensure accuracy in the existing technology, the present invention proposes a more simple calculation method on the basis of the existing technology.

[0065] Step S20, obtain the type of the DC breaker according to the comparison relationship between the rated current of the DC breaker and the threshold, and the type includes the first DC breaker and the second DC breaker.

[0066] Taking a standard two-stage C-type trip unit miniature DC circuit breaker as an example, the circuit breakers are classified according to the rated current of the DC circuit breaker. The specific steps are as follows:

[0067] Step S201, calculate the difference between the rated current of the DC circuit breaker and the threshold value, and determine whether the difference is greater than or equal to zero;

[0068] Step S202, if it is, the type of the DC circuit breaker is the first DC circuit breaker; if not, the type of the DC circuit breaker is the second DC circuit breaker.

[0069] In this embodiment, 32A is selected as the threshold value. Therefore, when the rated current I of the DC circuit breaker n is less than or equal to 32A, it can be used as the first DC circuit breaker; when its rated current is greater than 32A, the DC circuit breaker is the second DC circuit breaker. The following analyzes according to the characteristics of different types of circuit breakers.

[0070] Step S30, according to the action characteristic curve of the DC circuit breaker and the preset short-circuit current value, respectively obtain the circuit breaker action time corresponding to different types of the DC circuit breakers. The preset short-circuit current value is a multiple value of the rated current, and the circuit breaker action time includes a first action time and a second action time.

[0071] Step S40, perform thermal stability verification on the preset short-circuit current value and the first action time to obtain a first cross-sectional current expression, and perform thermal stability verification on the preset short-circuit current value and the second action time to obtain a second cross-sectional current expression.

[0072] Step S50, according to the first cross-sectional current expression and the second cross-sectional current expression, obtain a relationship expression between the cable cross-sectional area and the rated current.

[0073] Step S60, according to the relationship expression, through the rated current of the DC circuit breaker, obtain the cable cross-sectional area in the DC power supply system.

[0074] Please refer to Figure 2 , first select several multiple values of the rated current as the short-circuit current threshold values, and then find the maximum action time for the circuit breaker to trip corresponding to these short-circuit current threshold values from the Figure 2 action characteristic curve of the standard two-stage C-type trip unit miniature DC circuit breaker shown. Here, we select 2I n , 3I n , 5I n and 10I n four short-circuit current values as the short-circuit current threshold values. From the Figure 2 action characteristic curve, it can be seen that as the rated current I nA circuit breaker with ≤ 32 A, and the maximum operating times corresponding to these four short - circuit current thresholds are 140 s, 45 s, 15 s, and 4 s respectively.

[0075] Then substitute each short - circuit current threshold and the corresponding maximum operating time into the above thermal stability verification formula, and we can get:

[0076] ① When 2I n the operating time is 140 s, and at this time

[0077] ② When 3I n the operating time is 45 s, and at this time

[0078] ③ When 5I n the operating time is 15 s, and at this time

[0079] ④ When 10I n the operating time is 4 s, and at this time

[0080] According to the operating time corresponding to the short - circuit current value, it can be clearly seen that the longer the time, the more obvious the heat dissipation effect of the cable, and the actual required cross - sectional area should be less than the calculated value. According to the above formula, we can obtain the relationship between the cable cross - section and the rated current in the first DC circuit breaker:

[0081] S≥0.17I n

[0082] Next, according to Figure 2 the operating characteristic curve, we select the rated current I n > 32 A for the corresponding operating time of the circuit breaker, and substitute it into the thermal stability verification formula. It can be seen from Figure 2 that for the circuit breaker with rated current I n > 32 A, the operating time under the above - selected four short - circuit current thresholds is about twice that of the circuit breaker with rated current I n ≤32 A. Therefore, referring to the above calculation process, it can be obtained that for the circuit breaker with rated current I n > 32 A, the relationship between the cable cross - section and the rated current is:

[0083]

[0084] From the above two relational expressions between the cable cross-section and the rated current, it can be seen that the cable cross-section is directly proportional to the rated current of the circuit breaker, and has little relation with the magnitude of the short-circuit current. This is because the long-time delay protection of the circuit breaker is an inverse-time protection. When the short-circuit current is large, the action time is short; when the short-circuit current is small, the action time is long. For the determination of the cable cross-section size, there is a partial cancellation effect between the short-circuit current and the action time. It should be understood that the selection of the above-mentioned rated current multiple value is random. When any other multiple value is selected as the threshold, the above-mentioned relational expression can still be obtained. The specific process can refer to the above steps and will not be recalculated here.

[0085] Through the above analysis, the relational expression between the cable cross-section S and the rated current I of the circuit breaker can be obtained. n is:

[0086]

[0087] That is to say, through the above expression, the cable cross-section size can be directly obtained from the rated current of the circuit breaker, thus eliminating the need for repeated verification work and greatly simplifying the workload. It should be understood that for other types of circuit breakers, the expression relationship between the cable cross-section and the rated current can be calculated and analyzed according to the steps of the present invention, which will not be elaborated one by one here.

[0088] For the method for selecting a cable cross-section provided in this embodiment, compared with the traditional method that requires multiple repeated verification processes to find a suitable cable cross-section for the cable thermal stability verification, which is not only time-consuming and laborious but also prone to errors, the present invention analyzes the action characteristics of the circuit breaker to obtain the relationship between the cable cross-section and the rated current, so that the cable cross-section size can be directly obtained according to the rated current of the circuit breaker, avoiding repeated verification work, not only simplifying the workload, but also having high accuracy, and further improving the safety and stability of the operation of the DC power supply system.

[0089] Please refer to Figure 3 , based on the same inventive concept, a system for selecting a cable cross-section proposed in the second embodiment of the present invention includes:

[0090] A thermal stability verification module 10, configured to calculate a first cable cross-section according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and perform thermal stability verification on the first cable cross-section;

[0091] A circuit breaker type determination module 20, configured to obtain the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and the threshold, where the type includes a first DC circuit breaker and a second DC circuit breaker;

[0092] The cross-section current analysis module 30 is configured to obtain the breaker operation times corresponding to different types of the DC breakers respectively according to the operation characteristic curve of the DC breaker and a preset short-circuit current value, where the preset short-circuit current value is a multiple value of the rated current, and the breaker operation time includes a first operation time and a second operation time; perform thermal stability verification on the preset short-circuit current value and the first operation time to obtain a first cross-section current expression, and perform thermal stability verification on the preset short-circuit current value and the second operation time to obtain a second cross-section current expression;

[0093] The cable cross-section calculation module 40 is configured to obtain a relationship expression between the cable cross-sectional area and the rated current according to the first cross-section current expression and the second cross-section current expression; and obtain the cable cross-sectional area in the DC power supply system through the rated current of the DC breaker according to the relationship expression.

[0094] The technical features and technical effects of the cable cross-section selection system proposed in the embodiments of the present invention are the same as those of the method proposed in the embodiments of the present invention, and will not be elaborated here. Each module in the above cable cross-section selection system can be implemented in whole or in part by software, hardware, and their combination. The above-mentioned modules can be embedded in the processor in the computer device in the form of hardware or be independent of the processor, or can be stored in the memory in the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to the above-mentioned modules.

[0095] Please refer to Figure 4 , the internal structure diagram of a computer device in an embodiment. The computer device may specifically be a terminal or a server. The computer device includes a processor, a memory, a network interface, a display, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. The computer program, when executed by the processor, implements the cable cross-section selection method. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device may be a touch layer covered on the display screen, or may be a button, a trackball, or a touchpad provided on the housing of the computer device, or may also be an external keyboard, a touchpad, or a mouse, etc.

[0096] Those of ordinary skill in the art can understand that Figure 4The structure shown is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computing device may include more or fewer components than those shown in the figure, or combine certain components, or have the same component arrangement.

[0097] In addition, an embodiment of the present invention further provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the above method are implemented.

[0098] In addition, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0099] In summary, an embodiment of the present invention provides a method, a system, a computer device, and a storage medium for selecting a cable cross-section. The method calculates a first cable cross-section by according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and performs a thermal stability check on the first cable cross-section; obtains the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and a threshold, where the type includes a first DC circuit breaker and a second DC circuit breaker; respectively obtains the circuit breaker action time corresponding to different types of the DC circuit breakers according to the DC circuit breaker action characteristic curve and a preset short-circuit current value, the preset short-circuit current value is a multiple value of the rated current, and the circuit breaker action time includes a first action time and a second action time; performs the thermal stability check on the preset short-circuit current value and the first action time to obtain a first cross-section current expression, and performs the thermal stability check on the preset short-circuit current value and the second action time to obtain a second cross-section current expression; obtains a relationship expression between the cable cross-section and the rated current according to the first cross-section current expression and the second cross-section current expression; obtains the cable cross-sectional area in the DC power supply system through the rated current of the DC circuit breaker according to the relationship expression. By analyzing the action characteristics of the circuit breaker, the present invention obtains the relationship between the cable cross-section and the rated current, so that the cable cross-section size can be directly obtained according to the rated current of the circuit breaker. The present invention solves the problems of large workload and easy error caused by repeated calculation of thermal stability check in the traditional method, not only simplifies the workload, but also has high accuracy, and further improves the safety and stability of the operation of the DC power supply system.

[0100] Each embodiment in this specification is described in a progressive manner. For parts that are the same or similar in each embodiment, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, reference can be made to the corresponding description in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0101] The above-described embodiments only represent several preferred embodiments of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the protection scope of the claimed rights.

Claims

1. A method for selecting the cross-section of a cable, characterized in that, Including: Calculating a first cable cross-section area according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and performing a thermal stability check on the first cable cross-section area; Obtaining the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and a threshold value, where the type includes a first DC circuit breaker and a second DC circuit breaker; Obtaining the circuit breaker operation time corresponding to different types of the DC circuit breaker respectively according to the DC circuit breaker operation characteristic curve and a preset short-circuit current value, where the preset short-circuit current value is a multiple value of the rated current, and the circuit breaker operation time includes a first operation time and a second operation time; Performing a thermal stability check on the preset short-circuit current value and the first operation time to obtain a first cross-section current expression, and performing a thermal stability check on the preset short-circuit current value and the second operation time to obtain a second cross-section current expression; Obtaining a relationship expression between the cable cross-section area and the rated current according to the first cross-section current expression and the second cross-section current expression; Obtaining the cable cross-section area in the DC power supply system through the rated current of the DC circuit breaker according to the relationship expression; Wherein, the following formula is used to calculate the first cable cross-section area: I pc ≥I ca1 Where, I pc is the allowable current-carrying capacity of the cable, I ca1 is the long-term working calculation current of the circuit, S cac is the calculated cross-sectional area of the cable, ρ is the resistivity coefficient, L is the cable length, I ca is the calculation current of the allowable voltage drop, △U p is the allowable voltage drop of the circuit; The following formula is used to calculate the thermal stability check: Wherein, S is the cross-sectional area of the cable, and I d is the short-circuit current, t is the operating time of the circuit breaker, and K is the conductor temperature coefficient; The step of obtaining the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and the threshold value includes: Calculating the difference between the rated current of the DC circuit breaker and the threshold value, and determining whether the difference is greater than or equal to zero; If so, the type of the DC circuit breaker is the first DC circuit breaker, and if not, the type of the DC circuit breaker is the second DC circuit breaker; The following formula is used to calculate the first cross-section current expression: S≥0.17I n The following formula is used to calculate the second cross-section current expression: S≥0.24I n Wherein, S is the cross-sectional area of the cable, and I n is the rated current; The relationship expression between the cable cross-section area and the rated current is expressed by the following formula: Where S is the cross-sectional area of the cable and I n is the rated current.

2. A cable cross-section selection system, characterized in that, Including: A thermal stability check module, configured to calculate a first cable cross-section area according to the allowable current-carrying capacity of the cable and the allowable voltage drop of the loop in the DC power supply system, and perform a thermal stability check on the first cable cross-section area; A circuit breaker type determination module, configured to obtain the type of the DC circuit breaker according to the comparison relationship between the rated current of the DC circuit breaker and the threshold value, where the type includes a first DC circuit breaker and a second DC circuit breaker; including: Calculating the difference between the rated current of the DC circuit breaker and the threshold value, and determining whether the difference is greater than or equal to zero; If so, the type of the DC circuit breaker is the first DC circuit breaker, and if not, the type of the DC circuit breaker is the second DC circuit breaker; A cross-section current analysis module, configured to obtain the circuit breaker operation time corresponding to different types of the DC circuit breaker respectively according to the DC circuit breaker operation characteristic curve and a preset short-circuit current value, where the preset short-circuit current value is a multiple value of the rated current, and the circuit breaker operation time includes a first operation time and a second operation time; performing a thermal stability check on the preset short-circuit current value and the first operation time to obtain a first cross-section current expression, and performing a thermal stability check on the preset short-circuit current value and the second operation time to obtain a second cross-section current expression; The first cross-section current expression is calculated using the following formula: S≥0.17I n The second cross-section current expression is calculated using the following formula: S≥0.24I n Where S is the cross-sectional area of the cable and I n is the rated current; A cable cross-section calculation module, configured to obtain a relationship expression between the cable cross-sectional area and the rated current according to the first cross-section current expression and the second cross-section current expression; and obtain the cable cross-sectional area in the DC power supply system through the rated current of the DC circuit breaker according to the relationship expression; Wherein, the thermal stability verification module includes a first cable cross-section calculation module and a thermal stability calculation module; The first cable cross-section calculation module is configured to calculate a first cable cross-section, and the first cable cross-section is calculated using the following formula: I pc ≥ I ca1 Where, I pc is the allowable current-carrying capacity of the cable, I ca1 is the long-term working calculation current of the circuit, S cac is the calculated cross-sectional area of the cable, ρ is the resistivity, L is the length of the cable, I ca is the calculation current of the allowable voltage drop, △U p is the allowable voltage drop of the circuit; The thermal stability calculation module is configured to perform thermal stability verification, and the thermal stability verification is calculated using the following formula: Wherein, S is the cross-sectional area of the cable, and I d is the short-circuit current, t is the operating time of the circuit breaker, and K is the conductor temperature coefficient; The cable cross-section calculation module includes a relationship expression calculation module; The relationship expression calculation module is configured to represent the relationship between the cable cross-section and the rated current, and the relationship expression between the cable cross-sectional area and the rated current is represented using the following formula: Wherein, S is the cross-sectional area of the cable, and I n is the rated current.

3. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the method described in claim 1 are implemented.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method described in claim 1 are implemented.

Images