Ultra-high voltage transmission line lightning protection simulation calculation method and system

Abstract

The invention provides an ultra-high voltage transmission line lightning protection simulation calculation method and system. The method comprises the following steps: creating a double-index model of lightning current; the method comprises the following steps: acquiring related data of a wire and a lightning conductor of an ultra-high voltage transmission line and corresponding tower data, and constructing a flashover judgment model of an insulator; calculating a power frequency grounding resistance value based on soil resistivity data measured at the bottom of a related tower in each region; calculating an impact grounding resistance value based on the power frequency grounding resistance value, and creating an impact grounding resistance module according to the relationship between the power frequency grounding resistance value and the impact grounding resistance value; and continuously changing the size of the lightning current of the double-index model, carrying out simulation calculation by using the impulse grounding resistance module, judging whether the insulator flashover occurs according to the flashover judgment model, and determining the amplitude of the lightning current when the line just breaks down. According to the method, errors are reduced, optimization of lightning protection simulation calculation of the power transmission line is facilitated, loss caused by lightning disasters is reduced, and economical efficiency and safety of a power system are improved.

Description

Technical Field

[0001] The present invention belongs to the field of lightning protection simulation calculation, and in particular relates to a lightning protection simulation calculation method and system for ultra-high voltage transmission lines. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Some UHV transmission line corridors need to pass through areas with undulating mountains, complex terrain, frequent lightning activities and high soil resistivity in mountainous areas. The lightning protection design of UHV AC and DC transmission lines faces severe tests.

[0004] In order to improve the accuracy of lightning protection estimation, ATP-EMTP simulation software is generally used to model and simulate various parts of the line according to line data. However, the relationship between the current amplitude flowing through the grounding body and the change in soil resistance caused by soil ionization is not considered in the grounding part of the tower, so the impulse grounding resistance used for calculation needs to be corrected.

[0005] In the existing impulse grounding resistance module of UHV transmission line lightning protection simulation calculation, the regulation method directly uses the power frequency grounding resistance fitting or multiplies it by an impulse coefficient to simulate the impulse grounding resistance of the tower during analysis and calculation. This method uses general experience to simulate the impulse grounding resistance of the tower, without considering the actual environmental factors, and ignores the fact that the impulse grounding resistance of the tower will change with the change of soil ionization degree caused by the change of lightning current value entering the ground.

[0006] Some researchers also use the TACS module in the ATP-EMTP simulation software to simulate the impulse grounding resistance. Although it takes into account the change of the tower impulse resistance with the change of the impulse current value, the simulation uses a combination of multiple components, and there will be certain errors in the calculation accuracy. Summary of the invention

[0007] In order to solve the above problems, the present invention proposes a lightning protection simulation calculation method and system for ultra-high voltage transmission line. The present invention not only takes into account that the impact grounding resistance of the tower will change with the change of the soil ionization degree caused by the change of the lightning current value entering the ground, but also puts the simulation steps into only one component for simulation calculation, thereby reducing errors, helping to optimize the lightning protection simulation calculation of the transmission line, reduce the losses caused by lightning disasters, and improve the economy and safety of the power system.

[0008] According to some embodiments, the present invention adopts the following technical solutions:

[0009] A lightning protection simulation calculation method for ultra-high voltage transmission lines comprises the following steps:

[0010] Create a double exponential model of lightning current;

[0011] Obtain relevant data of UHV transmission lines including conductors, lightning arresters and corresponding tower data, and build a flashover determination model for insulators;

[0012] Calculate the power frequency grounding resistance value based on the soil resistivity data measured at the bottom of the relevant towers in each region;

[0013] Based on the power frequency grounding resistance value, the impulse grounding resistance value is calculated, and according to the relationship between the power frequency grounding resistance value and the impulse grounding resistance value, an impulse grounding resistance module is created;

[0014] The magnitude of the lightning current of the double exponential model is continuously changed, and the impulse grounding resistance module is used for simulation calculation. It is determined whether the insulator flashes over according to the flashover determination model, and the amplitude of the lightning current when the line fails is determined.

[0015] As an optional implementation, the double exponential model of the lightning current is:

[0016] i L (t) = AI m (e -αt -e -βt )

[0017] Where: I m is the amplitude of the lightning current (kA); the constants A, α and β are determined by the waveform of the lightning current.

[0018] As an optional implementation method, before constructing the flashover judgment model of the insulator, a multi-wave impedance model of the tower is first constructed. The tower is divided into multiple sections according to the geometric structure. Each section is divided into a main body and a support part. It is assumed that each part is evenly distributed, and the wave impedance is calculated according to the geometric dimensions of each part.

[0019] As an optional implementation, the process of calculating the impulse grounding resistance value based on the power frequency grounding resistance value includes: the impulse grounding resistance R T The relationship with the power frequency grounding resistance R0 is:

[0020]

[0021] Where I is the current amplitude flowing through the grounding body; I g The minimum current required to ionize the soil.

[0022] As a further embodiment, the current amplitude I flowing through the grounding body and the minimum current I that causes soil ionization g The relationship is:

[0023]

[0024] Where ρ is soil resistivity; E0 is critical field strength.

[0025] As an optional implementation, the process of determining whether an insulator flashes over according to the flashover determination model includes inputting the lightning current amplitude into a double exponential model of the lightning current, generating a voltage difference across the insulator, creating a volt-second characteristic curve of the insulator, and determining whether the insulator flashes over by determining whether the voltage difference across the insulator and the volt-second characteristic curve have an intersection.

[0026] A lightning protection simulation calculation system for ultra-high voltage transmission lines, comprising:

[0027] A lightning current model creation module is configured to create a double exponential model of lightning current;

[0028] A flashover determination model creation module is configured to obtain data related to the UHV transmission line including conductors, lightning arresters and corresponding tower data, and construct a flashover determination model for insulators;

[0029] The power frequency grounding resistance value calculation module is configured to calculate the power frequency grounding resistance value based on the soil resistivity data measured at the bottom of the relevant tower in each region;

[0030] A simulation creation module is configured to calculate the impulse grounding resistance value based on the power frequency grounding resistance value, and create an impulse grounding resistance module according to the relationship between the power frequency grounding resistance value and the impulse grounding resistance value;

[0031] The flashover judgment module is configured to continuously change the magnitude of the lightning current of the double exponential model, use the impulse grounding resistance module to perform simulation calculations, judge whether the insulator flashes according to the flashover judgment model, and determine the amplitude of the lightning current when the line fails.

[0032] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps in the above method are completed.

[0033] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps in the above method are completed.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention takes into account that the impulse grounding resistance of the pole tower will change with the change of the soil ionization degree caused by the change of the lightning current value entering the ground, and can continuously update the impulse grounding resistance value with the change of the current amplitude flowing into the grounding body, thereby greatly improving the accuracy of the simulation; at the same time, the simulation steps are only put into one component for simulation calculation, which reduces the error, helps to optimize the lightning protection simulation calculation of the transmission line, reduce the losses caused by lightning disasters, and improve the economy and safety of the power system.

[0036] The present invention utilizes ATP-EMTP simulation software to simulate the process of lightning current strike back or shielding on the transmission line, focusing on optimizing the model of impulse grounding resistance, thereby solving the problems of low accuracy of impulse grounding resistance and concise simulation modeling process in the prior art.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0039] Figure 1 is a waveform diagram of a double exponential model of an embodiment;

[0040] Figure 2 is a schematic diagram of an actual model of a tower in an embodiment;

[0041] Figure 3 is a schematic diagram of a multi-wave impedance model of an embodiment;

[0042] Figure 4 is a schematic diagram of a flashover determination model of an embodiment;

[0043] Figure 5 is a schematic diagram of a simulation model of an embodiment;

[0044] Figure 6 is a flow chart of an embodiment. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0046] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0048] In the absence of conflict, the embodiments in this application and the features in the embodiments may be combined with each other.

[0049] Embodiment 1

[0050] A lightning protection simulation calculation method for ultra-high voltage transmission lines comprises the following steps:

[0051] Step S1: Create a double exponential model of lightning current, the waveform is as follows Figure 1 As shown;

[0052] Double exponential waveform is widely used in power systems to simulate lightning current, and its expression is:

[0053] i L (t) = AI m (e -αt -e -βt )

[0054] Where: I m is the amplitude of the lightning current (kA); the constants A, α and β are determined by the waveform of the lightning current.

[0055] According to actual measurement statistics, my country's regulations recommend that the lightning current wave head and wave tail time be taken as 2.6μs and 50μs respectively during lightning protection calculations. Therefore, a 2.6 / 50μs double exponential waveform is selected as the lightning current waveform, and the expression can be determined as:

[0056] i L (t)=1.058I m (e -15000t -e -1860000t )

[0057] The dual exponential lightning current source module provided by ATP-EMTP software can generate a 2.6 / 50μs lightning current waveform, such as Figure 1 shown.

[0058] Step S2: Obtain the relevant data of the UHV transmission line including the conductor, lightning arrester and the corresponding tower data. The actual tower model is as follows: Figure 2 As shown in the figure, the multi-wave impedance model of the tower is constructed as follows Figure 3 As shown;

[0059] Taking into account that different tower heights and structures will lead to different tower wave impedances, in order to achieve accurate calculation results, the most widely used method is to establish a multi-wave impedance model. This model is built based on the principle that the wave impedance at different heights of the vertical conductor is different. The multi-wave impedance model better considers the propagation of waves in the tower, making its simulation calculation results more convincing.

[0060] The multi-wave impedance model of the tower is to divide the tower into multiple sections according to the geometric structure. Each section is divided into the main body and the support part. It is assumed that each part is evenly distributed. The wave impedance can be calculated according to the geometric dimensions of each part. Figure 2 The schematic diagram of the constructed tower multi-wave impedance model is shown in Figure 3 shown.

[0061] Among them, the wave impedance of the main part is:

[0062]

[0063] Where: h k (k=1,2,3), r Tk (k=1,2,3),R Tk (k=1,2,3), r B , R B for Figure 2 The length of the corresponding part.

[0064] It is found that the wave impedance with a bracket is usually about 10% smaller than that without a bracket. The wave impedance Z of each part of the bracket is Lk It is 9 times the corresponding main part, that is:

[0065] Z Lk =9Z Tk

[0066] Actual measurements show that it takes longer for electromagnetic waves to pass through a multi-conductor system containing a bracket. In the simulation, the length of the bracket part of the model can be taken as 1.5 times that of the corresponding main part.

[0067] For the wave impedance Z of the cross arm Ak , can be calculated using the following formula:

[0068]

[0069] Where: h k is the height above the ground corresponding to the kth cross arm, r Ak It is the equivalent radius of the cross arm of the kth part, which can be taken as 1 / 4 of the width of the cross arm at the main node of the tower.

[0070] The establishment of the tower model is mainly to connect the lightning current module and the grounding module, that is, the lightning current needs to pass through the line and the tower to flow into the grounding module.

[0071] Step S3: Create an insulator flashover determination model, such as Figure 4 As shown;

[0072] The intersection method, i.e. the volt-second characteristic curve of the insulator, is used to determine the flashover. The volt-second characteristic curve of the insulator is a curve showing the relationship between the highest overvoltage level that the insulator can withstand and the continuous discharge time. During the calculation and simulation, the overvoltage waveform is compared with the volt-second characteristic curve. When the two curves have an intersection, it is considered that the current insulator flashes over, and the flashover voltage is the voltage corresponding to the first intersection. When the two curves have no intersection, it is considered that the insulator has not flashed over.

[0073] The specific process is as follows: when the lightning current amplitude is input into the double exponential lightning current model, a voltage difference will appear at both ends of the insulator. The volt-second characteristic curve of the insulator can be created in the compilation module of the ATP-EMTP simulation software (different insulators have different volt-second characteristic curves). At this time, the voltage difference at both ends of the insulator and the intersection of the volt-second characteristic curve can be used to determine whether the insulator flashes.

[0074] Step S4: based on the soil resistivity data measured at the bottom of the relevant tower in each region, obtain the corresponding power frequency grounding resistance value;

[0075] Step S5: Create an impulse grounding resistance module. In the lightning protection simulation of UHV transmission lines, due to the large amplitude of lightning current, the current flowing into the grounding body will cause a drastic change in soil ionization, thereby causing a change in impulse grounding resistance. At this time, it is necessary to measure the soil resistivity to obtain the power frequency resistance value, and the impulse grounding resistance R T The relationship with the power frequency grounding resistance R0 is:

[0076]

[0077] Where I is the current amplitude flowing through the grounding body; I g The minimum current required to ionize the soil.

[0078] And I and I g There is the following relationship:

[0079]

[0080] ρ is soil resistivity; E0 is critical field strength, which is generally taken as 400kV / m here.

[0081] Use the above relationship to create an impulse grounding resistance module. When running the simulation, you can enter the soil resistivity and power frequency grounding resistance value measured in step 4 on its setting page. The simulation model is as follows: Figure 5 As shown;

[0082] Step S6: Figure 6As shown, by changing the magnitude of the lightning current in step 1, the impulse grounding resistance module can automatically start simulation calculation. At this time, the insulator flashover determination model in step S3 is observed to determine whether the insulator flashes, and the amplitude of the lightning current when the line fails can be obtained.

[0083] In some embodiments, the magnitude of the lightning current in step 1 may be changed gradually, such as from small to large.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention without creative labor shall be included in the protection scope of the present invention.

Claims

1. A lightning protection simulation calculation method for ultra-high voltage transmission lines, characterized in that: The following steps are involved: Create a double exponential model of lightning current; Obtain relevant data of UHV transmission lines including conductors, lightning arresters and corresponding tower data, and build a flashover determination model for insulators; Calculate the power frequency grounding resistance value based on the soil resistivity data measured at the bottom of the relevant towers in each region; Based on the power frequency grounding resistance value, the impulse grounding resistance value is calculated, and according to the relationship between the power frequency grounding resistance value and the impulse grounding resistance value, an impulse grounding resistance module is created; The magnitude of the lightning current of the double exponential model is continuously changed, and the impulse grounding resistance module is used for simulation calculation. It is determined whether the insulator flashes over according to the flashover determination model, and the amplitude of the lightning current when the line fails is determined.

2. A lightning protection simulation calculation method for ultra-high voltage transmission line according to claim 1, characterized in that: The double exponential model of lightning current is: and L (t)=AI m (it -αt -e -βt ) Where: I m is the amplitude of the lightning current (kA); the constants A, α and β are determined by the waveform of the lightning current.

3. A lightning protection simulation calculation method for ultra-high voltage transmission lines as claimed in claim 1, characterized in that: Before constructing the flashover judgment model of the insulator, a multi-wave impedance model of the tower is first constructed. The tower is divided into multiple sections according to the geometric structure. Each section is divided into a main body and a bracket part. It is assumed that each part is evenly distributed, and the wave impedance is calculated according to the geometric dimensions of each part.

4. A lightning protection simulation calculation method for ultra-high voltage transmission lines as claimed in claim 1, characterized in that: Based on the power frequency grounding resistance value, the process of calculating the impulse grounding resistance value includes: the impulse grounding resistance R T The relationship with the power frequency grounding resistance R0 is: Where I is the current amplitude flowing through the grounding body; I g The minimum current required to ionize the soil.

5. A lightning protection simulation calculation method for ultra-high voltage transmission lines as claimed in claim 4, characterized in that: The current amplitude I flowing through the grounding body and the minimum current I required to ionize the soil g The relationship is: Where ρ is soil resistivity; E0 is critical field strength.

6. A lightning protection simulation calculation method for ultra-high voltage transmission lines as claimed in claim 1, characterized in that: The magnitude of lightning current in the double exponential model is gradually changed from small to large.

7. A lightning protection simulation calculation method for ultra-high voltage transmission lines as claimed in claim 1, characterized in that: The process of judging whether an insulator flashes over according to the flashover judgment model includes inputting the lightning current amplitude into the double exponential model of the lightning current, a voltage difference appears at both ends of the insulator, creating a volt-second characteristic curve of the insulator, and judging whether the insulator flashes over by judging whether the voltage difference at both ends of the insulator and the volt-second characteristic curve have an intersection.

8. A lightning protection simulation calculation system for ultra-high voltage transmission lines, characterized in that: include: A lightning current model creation module is configured to create a double exponential model of lightning current; A flashover determination model creation module is configured to obtain data related to the UHV transmission line including conductors, lightning arresters and corresponding tower data, and construct a flashover determination model for insulators; The power frequency grounding resistance value calculation module is configured to calculate the power frequency grounding resistance value based on the soil resistivity data measured at the bottom of the relevant tower in each region; A simulation creation module is configured to calculate the impulse grounding resistance value based on the power frequency grounding resistance value, and create an impulse grounding resistance module according to the relationship between the power frequency grounding resistance value and the impulse grounding resistance value; The flashover judgment module is configured to continuously change the magnitude of the lightning current of the double exponential model, use the impulse grounding resistance module to perform simulation calculations, judge whether the insulator flashes according to the flashover judgment model, and determine the amplitude of the lightning current when the line fails.

9. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the steps of the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the steps in the method according to any one of claims 1 to 7 are completed.

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