Simplified calculation method of cable electromagnetic induction voltage, medium and equipment

Abstract

This invention discloses a simplified calculation method, medium, and equipment for electromagnetic induction voltage in cables. The method determines the cable laying location and core diameter based on line design parameters, and obtains the proportionality coefficient K of the electromagnetic induction voltage of the out-of-operation line relative to the cable length. Based on the cable design length and the proportionality coefficient K, the electromagnetic induction voltage of the out-of-operation line under the maximum transmission capacity of 720MW is calculated. The electromagnetic induction voltage is converted to the rated transmission power, and the relationship between electromagnetic induction voltage and power is determined. By considering the cable line cross-section, length, average laying distance from ground, design current carrying capacity, and the relationship between the slope of the electromagnetic induction voltage with respect to cable length and the cable cross-section and average distance from ground, simulation, physical, and statistical analyses are performed. A simplified relationship is obtained from the physical analysis, and experiments and fitting are conducted to obtain an accurate simplified calculation formula, ensuring the accuracy of the results.

Description

Technical Field

[0001] This invention relates to the technology of calculating electromagnetic induction voltage in cables, specifically to a simplified calculation method, medium, and equipment for electromagnetic induction voltage in cables. Background Technology

[0002] With the deepening of urbanization, the number of sensitive users and critical loads in urban centers is increasing, and the demands on urban aesthetics are constantly rising. As a result, power transmission corridor resources are becoming increasingly scarce. Cables, with their advantages of high power transmission reliability, low land occupation, aesthetic appeal, and low electromagnetic pollution, are gradually being used extensively in high-voltage urban power grids, with some cities already achieving cable coverage rates exceeding 90%. As urban integrated utility tunnel construction plans continue to be implemented, cable laying within tunnels will gradually become the mainstream method for future cable line installations. Therefore, the urgent problem to be solved is how to quickly calculate the electromagnetic induction voltage of cables in tunnel conditions, rapidly convert the electromagnetic induction voltage under different cable laying locations and transmission capacities, to assist in accurate and convenient analysis and decision-making for cable line designs, and to effectively verify the electromagnetic induction voltage at both ends of the cable.

[0003] The calculation of induced voltage and current in power lines is a crucial basis for selecting grounding switch parameters during the design phase. While publications such as "Development of Non-Crosslinked 220kV Polypropylene Insulated Power Cables," "Research on Key Technologies for Pre-laying and Post-burying of 220kV Submarine Cables for Deep-Sea and Ultra-Long Distances," "Practical Experience with Induced Voltages and Currents in Double-Circuit Transmission Lines," "Vector Positioning Method for Transmission Line Field Strength," "The Influence of Humidity on Power Frequency Electric Field Measurement of High-Voltage Transmission Lines," and "Power Engineering Design Handbook" conduct calculations on electromagnetic and electrostatic induction in power lines, most focus on overhead lines. In recent years, with breakthroughs in the manufacturing and application technologies of high-voltage cables, high-voltage cables have achieved widespread application. Research on cables, such as "Simulation Calculation and Influence Factor Analysis of Induced Voltage of Metal Sheath" and "Analysis of Influence Factors of Induced Voltage in Three-Phase Cable Sheaths," primarily focuses on the induced voltage and current in cable sheaths. With the increasing prevalence of high-voltage cables, the impact of cable lines on equipment selection and insulation coordination calculations during the design and construction phases cannot be ignored. Therefore, some scholars have conducted research on overvoltage calculations within cables. The papers "Research on the Characteristics and Influence of Switching Overvoltage of Ultra-High Voltage Cables Based on EMTP Simulation Platform", "Simulation and Suppression Research on Switching Overvoltage Characteristics of 220kV Long-Distance Power Cables", "Calculation and Analysis of Overvoltage Along the Sheath of High-Voltage Cables Based on PSCAD / EMTDC", "The Overvoltage of Hybrid Transmission Line of LongDistance Ultra-high Voltage Cable and Overhead Line", and "Research on Temporary Overvoltage of High-Voltage Submarine Cables" study the switching overvoltage of cable lines and propose suppression measures. They recommend methods such as parallel high-voltage reactance, installation of surge arresters, and closing resistors for suppression at different line lengths, providing a reference for subsequent line design and insulation coordination.The papers "Simulation Analysis of Asymmetrical Short-Circuit Transient Overvoltage of Transmission Lines Combined with 500 kV XLPE Submarine Cable and Overhead Line" study and analyze the transient overvoltage, reactive power configuration, and surge arrester configuration of submarine cable lines and submarine cable lines within the wind farm system. They derive recommended reactive power configuration schemes with uniform distribution on both sides of the submarine cable and overvoltage suppression measures within the wind farm. These measures ensure that the transient overvoltage remains within the required specifications, providing a reference for reactive power configuration in subsequent main body design and submarine cable design. The papers "Calculation of Induced Voltage and Current in Double-Circuit Cable-Overhead Line Hybrid Line" and "Study on Electromagnetic Induction of AC Cable Lines to Parallel DC Cable Lines" respectively study the induced voltage and current of double-circuit cable-overhead hybrid lines and AC cables to DC cables. However, both only consider the operating conditions of two cables and do not study the laying method and location. For current urban cable-based power lines, with cable tunnels as the primary method and various laying methods such as cable trenches and cable trays coexisting, complex coupling relationships exist between multiple cables. This differs from the induced voltage and current under the previous scenario of only considering two cables and overhead cable coupling. Whether the electromagnetic induction voltage of the cable is affected by the cable laying location and method remains to be studied. Summary of the Invention

[0004] The present invention provides a simplified calculation method, medium, and device for electromagnetic induction voltage in cables, which can at least solve one of the technical problems in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A simplified calculation method for the voltage of electromagnetic induction in a cable includes the following steps: S100. Determine the cable laying location and cable core diameter based on the line design parameters, and obtain the proportionality coefficient K of the electromagnetic induction voltage of the cable out of service relative to the cable length. S200. Based on the cable design length and the proportionality coefficient K between the electromagnetic induction voltage of the out-of-operation line and the cable length, calculate the electromagnetic induction voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line. S300: Combine the transmission power to convert the electromagnetic induction voltage to the rated transmission power, and determine the relationship between the electromagnetic induction voltage and the power.

[0006] Furthermore, the method for calculating the proportionality coefficient K of the electromagnetic induction voltage of the cable outage line relative to the cable length in step S100 of the present invention includes:

[0007] In the formula, U is the voltage at the current location of the out-of-service line; ω is the length of the out-of-service line; I is the current at the current position of the out-of-service line; ω is the system angular frequency; IAai, IBai, and ICai are the currents of phases A, B, and C of the i-th operating line, respectively; MAai, MBai, and MCai are the mutual inductances between phases A, B, and C of the i-th operating line and the out-of-service line A, respectively. Mdai and Idai These represent the mutual inductance between the out-of-service line and the ground, and the leakage current from the out-of-service line to the ground, respectively; L is the self-inductance per unit length of the out-of-service line. K 2 is a constant, H is the average height of the cable core above the ground, d is the conductor diameter, and C is the capacitance to ground. K c This is a constant related to the capacitor current. K d The power of the distance from the ground. U 1 represents the grounding voltage. According to large-scale simulation fitting, the following can be determined:

[0008] Furthermore, the method for calculating the electromagnetic induced voltage of the out-of-service line under the maximum transmission capacity of 720MW in step S200 of the present invention includes: Cable design length data Combining the ratio of electromagnetic induction voltage of the cable outage line to cable length K The electromagnetic induced voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line is calculated using the following formula:

[0009] In the formula, l is the length of the cable line to the tunnel, k is a proportionality coefficient, and the value is the slope of the electromagnetic induction voltage of the cable with respect to the cable length.

[0010] Furthermore, the method for determining the relationship between electromagnetic induction voltage and power in step S300 of the present invention includes: Considering that the grounding voltage is not zero, it is approximated that the residual voltage on the grounding side is a certain value C3 under a certain fixed operating condition. At this time, the electromagnetic induced voltage is converted to the rated transmission power according to the design transmission power:

[0011] In the formula, C3 and C4 are constants, and P is the transmission power. For double-circuit cable trench laying, the values ​​are as follows: .

[0012] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0013] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0014] As can be seen from the above technical solution, this invention, by considering the cable line cross-section, length, average laying distance from the ground, and design current-carrying capacity, and the relationship between the slope of the electromagnetic induction voltage with respect to the cable length and the cable cross-section and average distance from the ground, has conducted specific simulation analysis and implementation. Physical and statistical analyses are performed on the relationships, simplified formulas are obtained based on the physical analysis, and accurate simplified calculation formulas are obtained based on experiments and fitting, ensuring the accuracy of the calculation results. Due to its simplicity and the elimination of the need for repeated professional analysis, it is suitable for engineers of various specialties to conduct preliminary equipment selection and evaluation for projects, and is applicable to the verification of spacing on both sides during cable line design, as well as the operational analysis and estimation after construction, etc., with a wide range of applications. Attached Figure Description

[0015] Figure 1 A flowchart illustrating a simplified calculation method for the electromagnetic induction voltage of a cable; Figure 2 Design the cross-sectional diagram for cable laying; Figure 3 The graph shows the relationship between the measured electromagnetic induction voltage of the cable and its length slope, as well as the cable cross-section and cable laying height under different average laying heights. Figure 4 This is a graph showing the electromagnetic induction voltage curves of cables at different lengths and laying heights. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0017] To address the issue of rapidly calculating electromagnetic induction voltage in cable tunnels, this paper aims to quickly convert electromagnetic induction voltage under different cable laying locations and transmission capacities. This will assist in accurate and convenient analysis and decision-making for cable line designs. Furthermore, it addresses the problem of effectively verifying the electromagnetic induction voltage at both ends of the cable line, providing a suitable method for calculating cable electromagnetic induction voltage. The method establishes a deterministic relationship between cable length, laying location, cable cross-section, power flow, and electromagnetic induction voltage, enabling rapid and relatively accurate calculation of electromagnetic induction voltage in practical applications of cable lines.

[0018] like Figure 1 As shown, the specific method for calculating the electromagnetic induction voltage of a cable includes the following steps: S100. Determine the cable laying location and cable core diameter based on the line design parameters, and obtain the proportionality coefficient K of the electromagnetic induction voltage of the cable out of service relative to the cable length. S200. Based on the cable design length and the proportionality coefficient K between the electromagnetic induction voltage of the out-of-operation line and the cable length, calculate the electromagnetic induction voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line. S300: Combine the transmission power to convert the electromagnetic induction voltage to the rated transmission power, and determine the relationship between the electromagnetic induction voltage and the power.

[0019] The specific steps are as follows: S100. Determine the cable laying location and cable core diameter based on the line design parameters, and obtain the proportionality coefficient K of the electromagnetic induction voltage of the cable out of service relative to the cable length. The cable laying location is determined based on the line design parameters. For example... Figure 2 As shown, according to the cross-sectional diagram of the cable laying given in the design, the cable consists of conductor 1, semi-conductive wrapping tape 2, conductor shield 3, insulation 4, insulation shield 5, semi-conductive resistive water expansion buffer layer 6, corrugated aluminum sheath 7, and non-metallic sheath 8, which are sequentially wrapped. Calculate the average distance from the ground of the first layer of cables directly. The average distance from the ground is the distance from the center of the cable to the ground, taking into account the distance from the cable support to the ground. From the manufacturer's cable structure diagram data sheet, the cable outer radius is approximately 0.1537 meters / 2 = 0.08 meters. The average distance of the cable from the ground is the distance from the support to the ground plus the cable outer radius, which is 0.7 + 0.08 = 0.78 meters.

[0020] Based on the designed cable cross-section and the cable structure data provided by the manufacturer, the core diameter is read as 61.9mm ≈ 0.062 meters, and the proportionality coefficient K of the electromagnetic induction voltage of the cable outage line relative to the cable length is obtained. The cable structure data is shown in Table 1: Table 1. Cable Structure Data Sheet Provided by Manufacturer

[0021] Based on a transmission capacity of 720MW, and considering the laying location's height above the ground and the cable core diameter, the ratio of the electromagnetic induced voltage of the out-of-service cable line to the cable length is calculated. K ;

[0022] In the formula, U is the voltage at the current location of the out-of-service line; I is the length of the out-of-service line; I is the current at the current position of the out-of-service line; ω is the system angular frequency; I Aai I Bai I CaiThese represent the phase currents A, B, and C of the i-th circuit in operation; M Aai M Bai M cai The i-th phases of the operating line A, B, and C are mutually inductive with the suspended line A, respectively. Mdai and Idai These represent the mutual inductance between the out-of-service line and the ground, and the leakage current from the out-of-service line to the ground, respectively; L is the self-inductance per unit length of the out-of-service line. K 2 is a constant, H is the average height of the cable core above the ground, d is the conductor diameter, and C is the capacitance to ground. K c This is a constant related to the capacitor current. K d Let the distance from the ground be a power of the distance. According to large-scale simulation fitting, we know that:

[0023] S200. Based on the cable design length and the proportionality coefficient K between the electromagnetic induction voltage of the out-of-operation line and the cable length, calculate the electromagnetic induction voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line. The design documents provide cable design length data. Combining the ratio of electromagnetic induction voltage of the cable outage line to cable length K The electromagnetic induced voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line is calculated using the following formula:

[0024] In the formula, l is the length of the cable line to the tunnel, and k is a proportionality coefficient, which is the slope of the electromagnetic induction voltage of the cable with respect to the cable length.

[0025] S300, Combine the transmission power to convert the electromagnetic induced voltage to the rated transmission power, and determine the relationship between the electromagnetic induced voltage and the power; The electromagnetic induced voltage is converted to the rated transmission power according to the designed transmission power:

[0026] In the formula, C3 and C4 are constants, and P is the transmission power. For the double-circuit laying case, the values ​​are as follows:

[0027] The present invention will now be described in further detail with reference to the accompanying drawings: First, determine that the average distance between the cable laying location and the ground is 0.78 meters, and the cable cross-section is 2500 mm². 2 The cable has a diameter of 0.062m, a length of 60km, and a transmission capacity of 400MW.

[0028] Then calculate the proportionality coefficient K of the electromagnetic induced voltage of the cable with respect to the cable length:

[0029] Determine the electromagnetic induction voltage U of the cable under a fixed length and a 720MW operating line condition. 720 :

[0030] Calculate the constant C3:

[0031] The result means that the average distance between the cable and the ground at the laying location is 0.8 meters, and the cross-section is 2500 mm². 2 When the diameter is 0.062m, the C3 constant for power calculation is -3.789.

[0032] Calculate the electromagnetic induced voltage at the corresponding power:

[0033] The result is returned to the user, completing the rapid calculation of the cable's electromagnetic induction voltage. If the grounding switches on both sides are Class A, the electromagnetic induction voltage of 1.478kV exceeds the Class A switch limit of 1.4kV. Therefore, consider reducing the electromagnetic induction voltage by modifying the cable laying layer to the fourth layer, which is equivalent to modifying the cable's distance from the ground. The fourth layer cable support is approximately 2.6 meters above the ground, and the calculation is as follows:

[0034]

[0035]

[0036]

[0037] At this point, by modifying the installation location, the electromagnetic induction voltage can be kept within the limits of Class A switches, thus avoiding the need for switch replacement.

[0038] This method considers the relationship between electromagnetic induced voltage and the average cable laying height when calculating electromagnetic induced voltage, such as the formula for calculating the proportionality coefficient K. Figure 3 The measured efficiency curve shown is obtained by fitting it with physical analysis; thus, the relationship between cable length and electromagnetic induced voltage is obtained:

[0039] in This is the coefficient relating capacitance and capacitor current.

[0040] like Figure 4As shown, the formula for electromagnetic induction voltage U is obtained by simplifying the formula for electromagnetic induction voltage with respect to P. Since the power factor of the power grid is required to be relatively small within ±0.95, and under a certain power factor, the current I is proportional to the transmitted power P, a simplified formula for electromagnetic induction voltage U is obtained by simplifying the formula for electromagnetic induction voltage with respect to P:

[0041] The value of its constant C4 was obtained by fitting the results after statistical simulation calculations.

[0042] In summary, this invention, by considering cable line cross-section, length, average laying distance from ground, and design current-carrying capacity, and taking into account the relationship between the slope of electromagnetic induced voltage with respect to cable length and the cable cross-section and average distance from ground, conducted specific simulation analysis and implementation. Physical and statistical analyses were performed on the relationships, a simplified formula was obtained based on the physical analysis, and an accurate simplified calculation formula was obtained based on experiments and fitting, ensuring the accuracy of the calculation results. Due to its simplicity and lack of the need for specialized analysis, it is suitable for engineers of various specialties to conduct preliminary equipment selection and evaluation for projects, and is applicable to the verification of spacing on both sides during cable line design, as well as post-construction operational analysis and estimation, demonstrating a wide range of applications.

[0043] This calculation method considers the impact of the design current-carrying capacity on the electromagnetic induction voltage. It performs simulation analysis on commonly used cables in the domestic market and performs fitting to obtain a clear fixed relationship between the cable's electromagnetic induction voltage and transmission capacity. This method is more comprehensive and the calculation results are more meaningful.

[0044] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0045] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0046] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the mobile source emission prediction methods based on time-series feature migration described in the above embodiments.

[0047] It is understood that the systems, devices, and storage media provided in the embodiments of the present invention correspond to the methods provided in the embodiments of the present invention, and the explanations, examples, and beneficial effects of the relevant content can be referred to the corresponding parts of the above methods.

[0048] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state disk (SSD)).

[0049] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0050] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A simplified calculation method for the voltage of electromagnetic induction in a cable, characterized in that, Includes the following steps, S100. Determine the cable laying location and cable core diameter based on the line design parameters, and obtain the proportionality coefficient K of the electromagnetic induction voltage of the cable out of service relative to the cable length. S200. Based on the cable design length and the proportionality coefficient K between the electromagnetic induction voltage of the out-of-operation line and the cable length, calculate the electromagnetic induction voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line. S300: Combine the transmission power to convert the electromagnetic induction voltage to the rated transmission power, and determine the relationship between the electromagnetic induction voltage and the power.

2. The simplified calculation method for cable electromagnetic induction voltage according to claim 1, characterized in that, The calculation method for the proportionality coefficient K of the electromagnetic induced voltage of the cable outage line relative to the cable length in step S100 includes: In the formula, U is the voltage at the current location of the out-of-service line; ω is the length of the out-of-service line; I is the current at the current position of the out-of-service line; ω is the system angular frequency. IAai, IBai, ICai These are the phase currents of the i-th circuit in operation, namely phases A, B, and C. MAai, MBai, MCai The i-th phases of the operating line A, B, and C are mutually inductive with the suspended line A, respectively. Mdai and Idai These represent the mutual inductance between the out-of-service line and the ground, and the leakage current from the out-of-service line to the ground, respectively; L is the self-inductance per unit length of the out-of-service line. K 2 is a constant, H is the average height of the cable core above the ground, d is the conductor diameter, and C is the capacitance to ground. K c This is a constant related to the capacitor current. K d The power of the distance from the ground. U 1 represents the grounding voltage. According to large-scale simulation fitting, the following can be determined: 。 3. The simplified calculation method for cable electromagnetic induction voltage according to claim 1, characterized in that, Step S200, the calculation method for the electromagnetic induced voltage of the out-of-service line under the maximum transmission capacity of 720MW of the medium-speed rail line, includes: Cable design length data Combining the ratio of electromagnetic induction voltage of the cable outage line to cable length K The electromagnetic induced voltage of the out-of-operation line under the maximum transmission capacity of 720MW of the operating line is calculated using the following formula: In the formula, l is the length of the cable line to the tunnel, k is a proportionality coefficient, and the value is the slope of the electromagnetic induction voltage of the cable with respect to the cable length.

4. The simplified calculation method for cable electromagnetic induction voltage according to claim 1, characterized in that, Step S300 determines the relationship between electromagnetic induced voltage and power using the following methods: The electromagnetic induced voltage is converted to the rated transmission power according to the designed transmission power: In the formula, C3 and C4 are constants, and P is the transmission power. For the double-circuit laying case, the values ​​are as follows: 。 5. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, the processor performs the method as described in any one of claims 1 to 4.

6. A computer device, comprising a memory and a processor, characterized in that, The memory stores a computer program that, when executed by the processor, causes the processor to perform the method as described in any one of claims 1 to 4.

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