A method for evaluating and warning the hazards of low-amplitude direct lightning strikes in distribution networks

Abstract

The present application relates to the field of power grid protection system protection technology, and in particular to a method for evaluating and warning the hazard of low-amplitude direct lightning strikes in distribution networks. The method comprises: measuring the maximum value of the grounding resistance, the tower height and the tower spacing of the target tower in the distribution network; calculating the corrected grounding shunt coefficient corresponding to each tower according to the maximum value of the grounding resistance of the target tower, the tower height and the tower spacing; obtaining the lightning current amplitude of the distribution network, and calculating the tower top overvoltage of the target tower according to the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude; when the tower top overvoltage is greater than or equal to the preset tolerance voltage threshold of the target tower, outputting a warning that the distribution network is subject to severe direct lightning strike hazards; otherwise, no warning is output. It aims to solve the problem of how to accurately calculate the tower top overvoltage of the tower.

Description

Technical Field

[0001] The present application relates to the field of power grid protection system protection technology, and in particular to a method for evaluating and warning the hazard of low-amplitude direct lightning strikes in distribution networks. 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, which makes it 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. Compared with induced lightning, direct lightning has a larger impulse voltage, which can easily cause damage to transmission lines and power equipment, causing large-scale power outages.

[0003] In order to accurately assess the damage to the power grid caused by low-amplitude lightning strikes, the traditional method is to use a regulatory formula to calculate the overvoltage on the top of the tower directly struck by the lightning rod 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 overvoltage on the top of the tower exceeds the maximum overvoltage amplitude. If the amplitude exceeds this, it means that the damage is serious. The regulatory formula is as follows:

[0004]

[0005] In the formula, U is the tower top overvoltage, β is the grounding shunt coefficient of the tower, is the maximum value of the tower grounding resistance, I L is the lightning current amplitude;

[0006] However, in the process of conceiving and implementing this application, the applicant found that the tower top overvoltage calculated based on the formula has a large error with the voltage amplitude that the tower can withstand in the actual power grid, and it is easy for the severity of the lightning strike on the tower to be inconsistent with the calculated result. After research, it was found that the main reason is that the value of the ground shunt coefficient given in the regulation formula is inaccurate.

[0007] In view of this, a low-amplitude direct lightning hazard assessment and early warning method for distribution network after correcting the grounding shunt coefficient is needed to achieve accurate calculation of the tower top overvoltage, thereby improving the safety and stability of the distribution network. Summary of the invention

[0008] The main purpose of this application is to provide a distribution network low-amplitude direct lightning hazard assessment and early warning method, aiming to solve the problem of how to accurately calculate the tower top overvoltage.

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

[0010] S10, measuring the maximum grounding resistance, tower height and tower spacing of the target tower in the distribution network;

[0011] S20, calculating the modified grounding shunt coefficient corresponding to each tower according to the maximum grounding resistance of the target tower, the tower height and the tower span, wherein the calculation expression of the modified grounding shunt coefficient is as follows:

[0012]

[0013]

[0014]

[0015]

[0016] In the formula, To correct the ground shunt coefficient, is the maximum value of grounding resistance, h is the height of the tower, and d is the distance between the towers;

[0017] S30, obtaining the lightning current amplitude of the distribution network, and calculating the tower top overvoltage of the target tower according to the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude;

[0018] S40, when the tower top overvoltage is greater than or equal to the preset withstand voltage threshold of the target tower, output a warning that the distribution network suffers from a serious direct lightning strike; otherwise, do not output a warning.

[0019] Optionally, before step S30, the method further includes:

[0020] When a lightning to ground flash is detected in the distribution network, determining the distance between the location where the lightning to ground flash occurs and the target tower;

[0021] When the distance is less than or equal to the preset distance threshold, step S30 is executed.

[0022] Optionally, in S40, the step of outputting a warning that the distribution network is subjected to severe direct lightning damage includes:

[0023] Determining a target lightning impulse withstand voltage range within which the tower top overvoltage is located;

[0024] Outputting a warning level corresponding to the target lightning impulse withstand voltage interval, wherein the warning level is positively correlated with the value of the tower top overvoltage, and the warning level is positively correlated with the severity of the lightning hazard suffered by the distribution network.

[0025] Optionally, the maximum value of the tower grounding resistance is greater than the actual grounding resistance of the target tower.

[0026] Optionally, the calculation expression of the tower top overvoltage is:

[0027]

[0028] Where U is the overvoltage at the top of the tower. To correct the ground shunt coefficient, is the maximum value of the tower grounding resistance, I L is the lightning current amplitude.

[0029] In addition, to achieve the above-mentioned purpose, the present application also provides an application of the distribution network low-amplitude direct lightning hazard assessment and early warning method as described above in the main network line direct lightning hazard assessment.

[0030] This application has at least the following beneficial effects:

[0031] By combining the tower grounding resistance, tower height, and tower spacing to modify the grounding shunt coefficient in the program, the overvoltage at the top of the target tower can be calculated more accurately, making the hazard assessment more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of the first embodiment of the method for evaluating and warning the hazard of low-amplitude direct lightning strikes in a distribution network of the present application;

[0033] Figure 2 It is a schematic diagram of the β1 experimental data curve and the fitting curve involved in the embodiment of the present application;

[0034] Figure 3 It is a schematic diagram of the β2 experimental data curve and the fitting curve involved in the embodiment of the present application;

[0035] Figure 4 It is a schematic diagram of the β3 experimental data curve and the fitting curve involved in the embodiment of the present application;

[0036] Figure 5 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.

[0037] 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

[0038] 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.

[0039] First embodiment

[0040] Reference Figure 1 In this embodiment, the distribution network low-amplitude direct lightning hazard assessment and early warning method includes the following steps:

[0041] S10, measuring the maximum grounding resistance, tower height and tower spacing of the target tower in the distribution network;

[0042] In this embodiment, any tower in the distribution network is selected as a target tower, and the maximum grounding resistance, tower height and tower spacing of the target tower in the distribution network are measured manually and / or by electronic equipment.

[0043] The maximum value of the grounding resistance is determined according to the maximum grounding resistance allowed in the grounding grid construction regulations of the region. Optionally, in order to leave a certain margin for hazard assessment, the maximum value of the grounding resistance should be greater than the actual grounding resistance.

[0044] The tower height refers to the height from the bottom cross arm of the tower to the ground.

[0045] The tower span refers to the distance between the target tower and the next tower.

[0046] S20, calculating the modified grounding shunt coefficient corresponding to each tower according to the maximum grounding resistance of the target tower, the tower height and the tower span, wherein the calculation expression of the modified grounding shunt coefficient is as follows:

[0047]

[0048]

[0049]

[0050]

[0051] In the formula, To correct the ground shunt coefficient, is the maximum value of grounding resistance, h is the tower height, and d is the tower spacing;

[0052] It should be noted that, refer to Figure 2-4The β1 experimental data curve and fitting curve, the β2 experimental data curve and fitting curve, and the β3 experimental data curve and fitting curve shown in FIG. 1 are shown in FIG. 1 . In this embodiment, the first corrected ground shunt coefficient , the second corrected ground shunt coefficient and the third modified ground shunt factor , are obtained by fitting the experimental data on the relationship between tower grounding resistance, tower height, tower span and shunt coefficient.

[0053] For example, in a specific implementation, the maximum grounding resistance of a tower in a region is set to is 10Ω, the tower height h is 9m, and the tower spacing d is 150m. Substitute it into the above formula to calculate the corrected grounding shunt coefficient:

[0054]

[0055]

[0056]

[0057] For example, in another specific implementation, the maximum grounding resistance of a tower in a region is set to The resistance is 30Ω, the tower height h is 8m, and the tower spacing d is 100m. Substitute them into the above formula to calculate the corrected grounding shunt coefficient:

[0058]

[0059]

[0060]

[0061]

[0062] S30, obtaining the lightning current amplitude of the distribution network, and calculating the tower top overvoltage of the target tower according to the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude;

[0063] In this embodiment, after obtaining the corrected grounding shunt coefficient, the lightning current amplitude of the distribution network can be obtained through the distribution network lightning detection system, and the tower top overvoltage of the target tower can be calculated based on the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude.

[0064] Optionally, the calculation expression of the tower top overvoltage is:

[0065]

[0066] Where U is the overvoltage at the top of the tower. To correct the ground shunt coefficient, is the maximum value of the tower grounding resistance, I L is the lightning current amplitude.

[0067] S40, when the tower top overvoltage is greater than or equal to the preset withstand voltage threshold of the target tower, output a warning that the distribution network suffers from a serious direct lightning strike; otherwise, do not output a warning.

[0068] In this embodiment, the tower top overvoltage calculated based on the modified ground shunt coefficient is compared with the preset withstand voltage threshold of the target tower. When the tower top overvoltage is greater than or equal to the preset withstand voltage threshold of the target tower, an early warning is output that the distribution network is seriously damaged by direct lightning strikes, so as to prompt the operation and maintenance personnel to focus on the lightning ground flash and its nearby lines and equipment; otherwise, it means that the lightning ground flash overvoltage is within the tolerable range of the insulator, the degree of damage is low, and no early warning is required. No early warning is output.

[0069] Optionally, the preset withstand voltage threshold is related to the insulator model of the tower. For example, the model is FPQ3-10 / 4T20 pin-type composite insulator, and its withstand voltage threshold U set It is 90kV.

[0070] In the technical solution provided in this embodiment, the grounding shunt coefficient in the program is corrected by combining the tower grounding resistance, tower height, and tower spacing, so as to more accurately calculate the tower top overvoltage of the target tower, making the hazard assessment more practical.

[0071] Second embodiment

[0072] In this embodiment, before step S30, the method further includes:

[0073] Step S50, when a lightning to ground flash is detected in the distribution network, determining the distance between the location where the lightning to ground flash occurs and the target tower;

[0074] Step S60: When the distance is less than or equal to a preset distance threshold, execute step S30.

[0075] In this embodiment, in order to determine whether the lightning strike suffered by the distribution network is a direct lightning strike, the judgment is made based on the distance between the location where the lightning ground flash occurs and the target tower. When the distance is less than or equal to the preset distance threshold, it is determined to be a direct lightning strike, and the tower top overvoltage calculation step in step S30 is executed.

[0076] If the distance is greater than the preset distance threshold, it is judged as an induced lightning strike, and the lightning strike hazard assessment method of the induced lightning strike is used for assessment.

[0077] Third embodiment

[0078] In this embodiment, in S40, the step of outputting a warning that the distribution network is seriously damaged by direct lightning strikes includes:

[0079] Step S41, determining the target lightning impulse withstand voltage interval where the tower top overvoltage is located;

[0080] Step S42, outputting the warning level corresponding to the target lightning impulse withstand voltage interval, wherein the warning level is positively correlated with the value of the tower top overvoltage, and the warning level is positively correlated with the severity of the lightning hazard suffered by the distribution network.

[0081] In this embodiment, when the tower top overvoltage exceeds the threshold, the output warning level is related to the lightning impulse withstand voltage interval in which the tower top overvoltage is located. The larger the interval, the more serious the lightning strike is and the higher the warning level.

[0082] In addition, as another implementation scheme, the distribution network low-amplitude direct lightning hazard assessment and early warning method described in the above-mentioned embodiment can also be applied to the main network line direct lightning hazard assessment.

[0083] In addition, as an implementation solution, Figure 5 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.

[0084] like Figure 5 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.

[0085] Those skilled in the art will understand that Figure 5 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.

[0086] like Figure 5 As 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 direct lightning hazard assessment and early warning program. Among them, 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 direct lightning hazard assessment and early warning program and other software or programs.

[0087] exist Figure 1 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 direct lightning hazard assessment and early warning program stored in the memory 1005.

[0088] In this embodiment, the power grid protection system includes: a memory 1005, a processor 1001, and a distribution network low-amplitude direct lightning hazard assessment and early warning program stored in the memory and executable on the processor, wherein:

[0089] When the processor 1001 calls the distribution network low-amplitude direct lightning hazard assessment and early warning program stored in the memory 1005, the following operations are performed:

[0090] S10, measuring the maximum grounding resistance, tower height and tower spacing of the target tower in the distribution network;

[0091] S20, calculating the modified grounding shunt coefficient corresponding to each tower according to the maximum grounding resistance of the target tower, the tower height and the tower span, wherein the calculation expression of the modified grounding shunt coefficient is as follows:

[0092]

[0093]

[0094]

[0095]

[0096] In the formula, To correct the ground shunt coefficient, is the maximum value of grounding resistance, h is the height of the tower, and d is the distance between the towers;

[0097] S30, obtaining the lightning current amplitude of the distribution network, and calculating the tower top overvoltage of the target tower according to the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude;

[0098] S40, when the tower top overvoltage is greater than or equal to the preset withstand voltage threshold of the target tower, output a warning that the distribution network suffers from a serious direct lightning strike; otherwise, do not output a warning.

[0099] When the processor 1001 calls the distribution network low-amplitude direct lightning hazard assessment and early warning program stored in the memory 1005, the following operations are performed:

[0100] When a lightning to ground flash is detected in the distribution network, determining the distance between the location where the lightning to ground flash occurs and the target tower;

[0101] When the distance is less than or equal to the preset distance threshold, step S30 is executed.

[0102] When the processor 1001 calls the distribution network low-amplitude direct lightning hazard assessment and early warning program stored in the memory 1005, the following operations are performed:

[0103] Determining a target lightning impulse withstand voltage range within which the tower top overvoltage is located;

[0104] Outputting a warning level corresponding to the target lightning impulse withstand voltage interval, wherein the warning level is positively correlated with the value of the tower top overvoltage, and the warning level is positively correlated with the severity of the lightning hazard suffered by the distribution network.

[0105] 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.

[0106] Therefore, the present application also provides a computer-readable storage medium, which stores a distribution network low-amplitude direct lightning hazard assessment and early warning program. When the distribution network low-amplitude direct lightning hazard assessment and early warning program is executed by a processor, it implements the various steps of the distribution network low-amplitude direct lightning hazard assessment and early warning method described in the above embodiment.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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 comprising 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.

[0112] 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 The steps for the functions specified in one or more boxes.

[0113] 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 claims. 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.

[0114] 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.

[0115] 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 evaluating and warning the hazard of low-amplitude direct lightning strikes in a distribution network, characterized in that: The method comprises the following steps: S10, measuring the maximum grounding resistance, tower height and tower spacing of the target tower in the distribution network; S20, calculating the modified grounding shunt coefficient corresponding to each tower according to the maximum grounding resistance of the target tower, the tower height and the tower span, wherein the calculation expression of the modified grounding shunt coefficient is as follows: ； ； ； ； In the formula, To correct the ground shunt coefficient, is the maximum value of the tower grounding resistance, h is the tower height, and d is the tower spacing; S30, obtaining the lightning current amplitude of the distribution network, and calculating the tower top overvoltage of the target tower according to the corrected grounding shunt coefficient, the maximum value of the tower grounding resistance and the lightning current amplitude; S40, when the tower top overvoltage is greater than or equal to the preset withstand voltage threshold of the target tower, output a warning that the distribution network suffers from a serious direct lightning strike; otherwise, do not output a warning.

2. The method for evaluating and warning the hazard of low-amplitude direct lightning strikes in a distribution network according to claim 1, characterized in that: Before step S30, the method further includes: When a lightning to ground flash is detected in the distribution network, determining the distance between the location where the lightning to ground flash occurs and the target tower; When the distance is less than or equal to the preset distance threshold, step S30 is executed.

3. The method for evaluating and warning the hazard of low-amplitude direct lightning strikes 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 direct lightning strikes includes: Determining a target lightning impulse withstand voltage range within which the tower top overvoltage is located; Outputting a warning level corresponding to the target lightning impulse withstand voltage interval, wherein the warning level is positively correlated with the value of the tower top overvoltage, and the warning level is positively correlated with the severity of the lightning hazard suffered by the distribution network.

4. The method for evaluating and warning the hazard of low-amplitude direct lightning strikes in a distribution network according to claim 1, characterized in that: The maximum value of the tower grounding resistance is greater than the actual grounding resistance of the target tower.

5. The method for evaluating and warning the hazard of low-amplitude direct lightning strikes in a distribution network according to claim 1, characterized in that: The calculation expression of the tower top overvoltage is: ； Where U is the overvoltage at the top of the tower. To correct the ground shunt coefficient, is the maximum value of the tower grounding resistance, I L is the lightning current amplitude.

6. An application of the distribution network low-amplitude direct lightning hazard assessment and early warning method as claimed in claim 1 in the main network line direct lightning hazard assessment.

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