A method for evaluating the hazard of low-amplitude induced lightning in distribution networks

Abstract

The present application relates to the technical field of power system protection, and in particular to a method for assessing the hazard of low-amplitude induced lightning in distribution networks. The method comprises: measuring the height of the target tower in the distribution network, and the soil resistivity in the area where the distribution network line is located; determining a correction resistance coefficient according to the tower height and the soil resistivity; obtaining the lightning current amplitude of the distribution network, and the distance between the lightning strike point and the target tower, and calculating the induced overvoltage amplitude of the target tower according to the correction resistance coefficient, the lightning current amplitude and the distance; when the induced overvoltage amplitude is greater than or equal to a preset dangerous overvoltage threshold, outputting an early warning that the distribution network is subject to severe induced lightning hazards; otherwise, no early warning is output. The method aims to solve the problem of how to accurately calculate the induced overvoltage amplitude in areas with high soil resistivity.

Description

Technical Field

[0001] The present application relates to the technical field of power system protection, and in particular to a method for evaluating the hazard of low-amplitude induced lightning in a distribution network. Background Art

[0002] Lightning strikes with a lightning current amplitude of less than 15kA are called low-amplitude lightning. The electromagnetic signal strength is weak and difficult to be captured by traditional lightning location systems. It is easy for the power grid to be struck by low-amplitude lightning and cause failures. There are two main types of power grid failures caused by low-amplitude lightning strikes: one is that lightning directly strikes the distribution line to generate direct overvoltage, and the other is that lightning strikes the ground and structures near the line to generate induced overvoltage. The probability of induced overvoltage often accounts for 80% of lightning strike failures.

[0003] In order to accurately assess the damage to the power grid when it is struck by induced overvoltage, the traditional method is to use the formula to calculate the amplitude of the induced overvoltage that directly hits the lightning tower when the distribution network is struck by lightning. When the power grid is struck by lightning, the severity of the damage to the power grid is judged based on whether the calculated amplitude of the induced overvoltage exceeds the line insulation level threshold. If the threshold is exceeded, it means that the damage is serious. The formula is as follows:

[0004]

[0005] In the formula, U is the induced overvoltage amplitude, I is the lightning current amplitude, h is the tower height, and D is the distance between the lightning strike point and the tower;

[0006] However, in the process of conceiving and implementing this application, the applicant found that there is a large error between the induced overvoltage amplitude calculated based on the formula and the induced overvoltage amplitude in the actual power grid, and it is easy for the severity of the induced lightning strike on the tower to be inconsistent with the calculated result. After research, it was found that the main reason is that the formula in the regulations does not take into account the impact of soil resistivity on the tower, and it cannot be applied in areas such as mountains or deserts with high soil resistivity.

[0007] In view of this, a low-amplitude induced lightning hazard assessment method for distribution networks that considers the influence of soil resistivity on towers is needed to achieve accurate induced overvoltage calculation, thereby improving the safety and stability of distribution networks. Summary of the invention

[0008] The main purpose of the present application is to provide a method for evaluating the hazard of low-amplitude induced lightning in a distribution network, aiming to solve the problem of how to accurately calculate the amplitude of induced overvoltage in areas with high soil resistivity.

[0009] To achieve the above-mentioned purpose, the present application provides a method for evaluating the hazard of low-amplitude induced lightning in a distribution network, the method comprising:

[0010] S10, measuring the height of the target tower in the distribution network and the soil resistivity in the area where the distribution network line is located;

[0011] S20, determining a correction resistance coefficient according to the tower height and the soil resistivity, wherein the calculation expression of the correction resistance coefficient is as follows:

[0012]

[0013] Where k is the correction resistance coefficient, is the soil resistivity, h is the tower height;

[0014] S30, obtaining the lightning current amplitude of the distribution network and the distance between the lightning strike point and the target tower, and calculating the induced overvoltage amplitude of the target tower according to the corrected resistance coefficient, the lightning current amplitude and the distance;

[0015] S40, when the induced overvoltage amplitude is greater than or equal to a preset dangerous overvoltage threshold, outputting a warning that the distribution network is subject to severe induced lightning damage; otherwise, no warning is output.

[0016] Optionally, in S40, the step of outputting a warning that the distribution network is seriously damaged by induced lightning includes:

[0017] Determining an absolute value of a difference between the induced overvoltage amplitude and the dangerous overvoltage threshold;

[0018] The induced lightning hazard warning level corresponding to the distribution network is determined according to the absolute value of the difference, wherein the induced lightning hazard warning level is positively correlated with the absolute value of the difference, and the induced lightning hazard warning level is positively correlated with the severity of the induced lightning hazard suffered by the distribution network.

[0019] Optionally, the value of the dangerous overvoltage threshold is associated with the insulation strength of the target tower.

[0020] Optionally, the value of the dangerous overvoltage threshold is positively correlated with the insulation strength of the target tower.

[0021] Optionally, the calculation expression of the induced overvoltage amplitude is as follows:

[0022]

[0023] Where U is the induced overvoltage amplitude, I is the lightning current amplitude, k is the correction resistance coefficient, and D is the distance between the lightning strike point and the tower.

[0024] In addition, to achieve the above-mentioned purpose, the present application also provides an application of the above-mentioned distribution network low-amplitude induced lightning hazard assessment method in areas where the soil resistivity is greater than 300 ohms.

[0025] This application has at least the following beneficial effects:

[0026] The induced overvoltage amplitude is calculated by combining the tower height with the introduced soil resistivity, so that the induced overvoltage amplitude can be accurately calculated in areas with high soil resistivity, thereby improving the safety and stability of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a first embodiment of a method for evaluating the hazard of low-amplitude induced lightning in a power distribution network of the present application;

[0028] Figure 2 A schematic diagram of the architecture of the hardware operating environment of the power grid protection system involved in the embodiment of the present application.

[0029] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] In order to better understand the above technical solution, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0031] First embodiment

[0032] Reference Figure 1 In this embodiment, the method for evaluating the hazard of low-amplitude induced lightning in a distribution network includes the following steps:

[0033] S10, measuring the height of the target tower in the distribution network and the soil resistivity in the area where the distribution network line is located;

[0034] In this embodiment, any pole tower in the distribution network is selected as a target pole tower, and the pole tower height of the target pole tower in the distribution network is measured by manual and / or electronic equipment. In this embodiment, the pole tower height refers to the height from the bottom cross arm of the pole tower to the ground, and the soil resistivity of the area where the distribution network line is located can be obtained by measuring or searching relevant data.

[0035] S20, determining a correction resistance coefficient according to the tower height and the soil resistivity, wherein the calculation expression of the correction resistance coefficient is as follows:

[0036]

[0037] Where k is the correction resistance coefficient, is the soil resistivity, and h is the tower height.

[0038] For example, assuming that the tower heights are 7m, 9m, and 12m, and the soil resistivity is 800Ω*m, 850Ω*m, 900Ω*m, 950Ω*m, and 1000Ω*m, the two values ​​are calculated as shown in the following table:

[0039] Table 1. Resistance coefficient k in the examples

[0040]

[0041] It should be noted that the construction principle of the above calculation expression is as follows:

[0042] Assuming that the soil resistivity in low resistivity areas is 300Ω*m, the grounding body resistance is usually required to be no more than 10Ω, while the soil resistivity in high resistivity areas such as mountains and deserts is up to 1000Ω*m, and the grounding body resistance is usually required to be no more than 30Ω. From the above two sets of data, it can be obtained that the ratio of ground body resistance to soil resistivity is about 0.03. After the lightning current hits the ground, only a part of it flows to the tower and line through the grounding body, and the calculation expression of the voltage amplitude correction can be obtained as follows:

[0043]

[0044] Since the traditional calculation formula for the induced voltage amplitude is:

[0045]

[0046] We can get:

[0047]

[0048] Sort it out, .

[0049] It can be understood that the value of the soil resistivity in this embodiment is greater than 300Ω.

[0050] S30, obtaining the lightning current amplitude of the distribution network and the distance between the lightning strike point and the target tower, and calculating the induced overvoltage amplitude of the target tower according to the corrected resistance coefficient, the lightning current amplitude and the distance;

[0051] In this embodiment, after obtaining the corrected resistance coefficient, the lightning current amplitude of the distribution network and the measured distance between the lightning strike point and the target tower can be obtained through the distribution network lightning detection system, and the induced overvoltage amplitude of the target tower is calculated based on the corrected resistance coefficient, the lightning current amplitude and the distance.

[0052] Optionally, the calculation expression of the induced overvoltage amplitude is as follows:

[0053]

[0054] Where U is the induced overvoltage amplitude, I is the lightning current amplitude, k is the correction resistance coefficient, and D is the distance between the lightning strike point and the tower.

[0055] S40, when the induced overvoltage amplitude is greater than or equal to a preset dangerous overvoltage threshold, outputting a warning that the distribution network is subject to severe induced lightning damage; otherwise, no warning is output.

[0056] In this embodiment, the induced overvoltage amplitude calculated based on the corrected resistance coefficient is compared with the preset dangerous overvoltage threshold. When the induced overvoltage amplitude is greater than or equal to the preset dangerous overvoltage threshold, it indicates that the lightning-to-ground flash poses a serious threat to the safety of the lines and equipment, and an early warning that the distribution network is suffering from serious induced lightning hazards is output to prompt operation and maintenance personnel to focus on the lightning-to-ground flash and its nearby lines and equipment; if it is less than, it indicates that the lightning-to-ground flash is less harmful and no alarm is required.

[0057] Optionally, in this embodiment, the setting of the dangerous overvoltage threshold is not unified across the entire network, and towers with weak insulation should consider appropriately lowering the value of the threshold. Therefore, the value of the dangerous overvoltage threshold is associated with the insulation strength of the target tower and is positively correlated.

[0058] Optionally, in this embodiment, in order to determine whether the lightning strike suffered by the distribution network is an induced lightning strike, the judgment is made according to the distance between the location where the lightning ground flash occurs and the target tower. When the distance is greater than a preset distance threshold, it is determined to be an induced lightning strike. If the distance is less than or equal to the preset distance threshold, it is determined to be a direct lightning strike, and the lightning strike hazard assessment method of direct lightning strike is used for assessment.

[0059] In the technical solution provided in this embodiment, the induced overvoltage amplitude is calculated by combining the tower height with the introduced soil resistivity, so that the induced overvoltage amplitude can be accurately calculated in areas with high soil resistivity, thereby improving the safety and stability of the distribution network.

[0060] Second embodiment

[0061] In this embodiment, in S40, the step of outputting a warning that the distribution network is seriously damaged by induced lightning includes:

[0062] Step S41, determining the absolute value of the difference between the induced overvoltage amplitude and the dangerous overvoltage threshold;

[0063] Step S42, determining an induced lightning hazard warning level corresponding to the distribution network according to the absolute value of the difference, wherein the induced lightning hazard warning level is positively correlated with the difference, and the induced lightning hazard warning level is positively correlated with the severity of the induced lightning hazard suffered by the distribution network.

[0064] In this embodiment, the warning degree is proportional to the degree to which the induced overvoltage amplitude exceeds the dangerous overvoltage threshold. The larger the induced overvoltage amplitude, the stronger the induced lightning hazard warning level, and the more serious the induced lightning hazard suffered by the distribution network.

[0065] In addition, as an implementation scheme, the method for assessing the hazard of low-amplitude induced lightning in a distribution network described in the above-mentioned embodiment can also be applied in areas where the soil resistivity is greater than 300 ohms.

[0066] In addition, as an implementation solution, Figure 2 This is a schematic diagram of the architecture of the hardware operating environment of the power grid protection system involved in the embodiment of the present application.

[0067] like Figure 2 As shown, the power grid protection system may include: a processor 1001, such as a CPU, a memory 1005, a user interface 1003, a network interface 1004, and a communication bus 1002. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory, or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0068] Those skilled in the art will understand that Figure 1 The grid protection system architecture shown in the figure does not constitute a limitation on the grid protection system, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0069] like Figure 2As shown, the memory 1005 as a storage medium may include an operating system, a network communication module, a user interface module, and a distribution network low-amplitude induction lightning hazard assessment program. The operating system is a program for managing and controlling the hardware and software resources of the power grid protection system, the distribution network low-amplitude induction lightning hazard assessment program and other software or programs.

[0070] exist Figure 2 In the power grid protection system shown, the user interface 1003 is mainly used to connect to the terminal and communicate data with the terminal; the network interface 1004 is mainly used for the background server and communicates data with the background server; the processor 1001 can be used to call the distribution network low-amplitude induced lightning hazard assessment program stored in the memory 1005.

[0071] In this embodiment, the power grid protection system includes: a memory 1005, a processor 1001, and a distribution network low-amplitude induction lightning hazard assessment program stored in the memory and executable on the processor, wherein:

[0072] When the processor 1001 calls the power distribution network low-amplitude induction lightning hazard assessment program stored in the memory 1005, the following operations are performed:

[0073] S10, measuring the height of the target tower in the distribution network and the soil resistivity in the area where the distribution network line is located;

[0074] S20, determining a correction resistance coefficient according to the tower height and the soil resistivity, wherein the calculation expression of the correction resistance coefficient is as follows:

[0075]

[0076] Where k is the correction resistance coefficient, is the soil resistivity, h is the tower height;

[0077] S30, obtaining the lightning current amplitude of the distribution network and the distance between the lightning strike point and the target tower, and calculating the induced overvoltage amplitude of the target tower according to the corrected resistance coefficient, the lightning current amplitude and the distance;

[0078] S40, when the induced overvoltage amplitude is greater than or equal to a preset dangerous overvoltage threshold, outputting a warning that the distribution network is subject to severe induced lightning damage; otherwise, no warning is output.

[0079] When the processor 1001 calls the power distribution network low-amplitude induction lightning hazard assessment program stored in the memory 1005, the following operations are performed:

[0080] Determining an absolute value of a difference between the induced overvoltage amplitude and the dangerous overvoltage threshold;

[0081] The induced lightning hazard warning level corresponding to the distribution network is determined according to the absolute value of the difference, wherein the induced lightning hazard warning level is positively correlated with the absolute value of the difference, and the induced lightning hazard warning level is positively correlated with the severity of the induced lightning hazard suffered by the distribution network.

[0082] In addition, it can be understood by a person skilled in the art that all or part of the processes in the method for implementing the above embodiment can be completed by instructing the relevant hardware through a computer program. The computer program includes program instructions, and the computer program can be stored in a storage medium, which is a computer-readable storage medium. The program instructions are executed by at least one processor in the power grid protection system to implement the process steps of the embodiment of the above method.

[0083] Therefore, the present application also provides a computer-readable storage medium, which stores a distribution network low-amplitude induced lightning hazard assessment program. When the distribution network low-amplitude induced lightning hazard assessment program is executed by a processor, it implements the various steps of the distribution network low-amplitude induced lightning hazard assessment method described in the above embodiment.

[0084] The computer-readable storage medium may be a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk, or an optical disk, etc., which are computer-readable storage media that can store program codes.

[0085] It should be noted that since the storage medium provided in the embodiment of the present application is the storage medium used to implement the method of the embodiment of the present application, based on the method introduced in the embodiment of the present application, the person skilled in the art can understand the specific structure and deformation of the storage medium, so it is not repeated here. All storage media used in the method of the embodiment of the present application belong to the scope of protection of this application.

[0086] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0087] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0088] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0089] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0090] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The present application may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0091] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0092] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for assessing the hazard of low-amplitude induced lightning in a distribution network, characterized in that: The method comprises the following steps: S10, measuring the height of the target tower in the distribution network and the soil resistivity in the area where the distribution network line is located; S20, determining a correction resistance coefficient according to the tower height and the soil resistivity, wherein the calculation expression of the correction resistance coefficient is as follows: ； Where k is the correction resistance coefficient, is the soil resistivity, h is the tower height; S30, obtaining the lightning current amplitude of the distribution network and the distance between the lightning strike point and the target tower, and calculating the induced overvoltage amplitude of the target tower according to the corrected resistance coefficient, the lightning current amplitude and the distance; S40, when the induced overvoltage amplitude is greater than or equal to a preset dangerous overvoltage threshold, outputting a warning that the distribution network is subject to a serious induced lightning hazard; otherwise, no warning is output; The calculation expression of the induced overvoltage amplitude is as follows: ； Where U is the induced overvoltage amplitude, I is the lightning current amplitude, k is the correction resistance coefficient, and D is the distance between the lightning strike point and the tower.

2. The method for evaluating the hazard of low-amplitude induction lightning in a distribution network according to claim 1, characterized in that: In S40, the step of outputting a warning that the distribution network is seriously damaged by induced lightning includes: Determining an absolute value of a difference between the induced overvoltage amplitude and the dangerous overvoltage threshold; The induced lightning hazard warning level corresponding to the distribution network is determined according to the absolute value of the difference, wherein the induced lightning hazard warning level is positively correlated with the absolute value of the difference, and the induced lightning hazard warning level is positively correlated with the severity of the induced lightning hazard suffered by the distribution network.

3. The method for evaluating the hazard of low-amplitude induction lightning in a distribution network according to claim 1, characterized in that: The value of the dangerous overvoltage threshold is associated with the insulation strength of the target tower.

4. The method for evaluating the hazard of low-amplitude induction lightning in a distribution network according to claim 1, characterized in that: The value of the dangerous overvoltage threshold is positively correlated with the insulation strength of the target tower.

5. An application of the method for evaluating the hazard of low-amplitude induced lightning in a distribution network as claimed in claim 1 in areas where the soil resistivity is greater than 300 ohms.

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