Calculation method, system and medium for lightning intrusion wave overvoltage considering working voltage

Abstract

The present invention discloses a method, system and medium for calculating lightning intrusion wave overvoltage considering the operating voltage, belonging to the field of substation intrusion wave overvoltage and its protection, including: (S1) obtaining the operating voltage U0 of the line at the lightning strike moment; (S2) calculating the time t required for the voltage across the arrester to reach the residual voltage value Uref under the influence of the operating voltage U0; (S3) calculating the maximum equipment overvoltage Umax according to Umax = 2at + U0; (S2) includes: calculating the critical distance lc between the equipment and the arrester; the critical distance lc satisfies: when the reflected wave of the equipment reaches the arrester, the potential of the arrester just reaches the residual voltage value Uref; obtaining the distance l between the equipment and the arrester, if l ≤ lc, then calculate the time t according to; if l > l

Description

Technical Field

[0001] The present invention belongs to the field of substation intrusion wave overvoltage and protection thereof, and more specifically, relates to a lightning intrusion wave overvoltage calculation method, system and medium taking working voltage into consideration. Background Art

[0002] With the rapid development of the economy, my country's requirements for substation reliability and stability are gradually increasing, and the insulation coordination of substation equipment needs to take into account the most stringent conditions.

[0003] Currently, the main methods for calculating substation equipment overvoltage include engineering algorithms and EMTP transient calculation methods. The EMTP algorithm requires researchers to build a simulation model using ATP visualization software and set parameters for each tower, lightning arrester, and insulator to calculate equipment overvoltage. The engineering algorithm, on the other hand, eliminates the need for complex modeling and uses empirical formulas to calculate equipment overvoltage, making it suitable for rapid assessment of substation equipment overvoltage.

[0004] The operating voltage of high-voltage lines is comparable to the insulation level of equipment. Therefore, the influence of the operating voltage must be considered in the calculation of lightning intrusion wave overvoltage. However, the existing engineering algorithms do not consider the influence of the operating voltage when calculating equipment overvoltage. Therefore, the equipment overvoltage obtained using the engineering algorithms is significantly different from the actual overvoltage. The insulation coordination scheme formed based on this increases the risk of the power system. Summary of the Invention

[0005] In response to the defects of the existing technology and the need for improvement, the present invention provides a method, system and medium for calculating lightning intrusion wave overvoltage taking into account the working voltage, the purpose of which is to achieve rapid and accurate calculation of lightning intrusion wave overvoltage of substation equipment.

[0006] To achieve the above object, according to one aspect of the present invention, a method for calculating lightning intrusion wave overvoltage taking into account operating voltage is provided, comprising the following steps:

[0007] (S1) obtaining the operating voltage U0 of the line at the moment of lightning strike;

[0008] (S2) Calculate the voltage at both ends of the arrester to reach the residual voltage value U under the influence of the working voltage U0 ref The time required t;

[0009] (S3) According to U max =2at+U0 Calculate the maximum overvoltage of the equipment U max ;

[0010] Where a is the steepness of the lightning intrusion wave.

[0011] Furthermore, step (S2) includes:

[0012] The critical distance l between the computing device and the lightning arrester c ; The critical distance l c satisfies: when the reflected wave of the device reaches the lightning arrester, the potential of the lightning arrester just reaches the residual voltage value U ref ;

[0013] Obtain the distance l between the device and the lightning arrester. If l ≤ l c , then calculate according to the time t required for the voltage at both ends of the lightning arrester to reach the residual voltage value U ref ; If l > l c , then calculate according to the time t required for the voltage at both ends of the lightning arrester to reach the residual voltage value U ref ;

[0014] where v is the propagation speed of the lightning intrusion wave on the line.

[0015] Furthermore,

[0016] According to another aspect of the present invention, there is provided a lightning intrusion overvoltage calculation device considering the working voltage, including:

[0017] A working voltage acquisition module for obtaining the working voltage U0 of the line at the moment of lightning strike;

[0018] A time calculation module for calculating the time t required for the voltage at both ends of the lightning arrester to reach the residual voltage value U ref under the influence of the working voltage U0;

[0019] And an overvoltage calculation module for calculating the maximum value U of the equipment overvoltage according to U max = 2at + U0 max ;

[0020] where a is the steepness of the lightning intrusion wave.

[0021] Furthermore, the time calculation module includes: a critical distance calculation unit, a distance measurement unit, a first time calculation unit, and a second time calculation unit;

[0022] The critical distance calculation unit is used to calculate the critical distance l c ; When the distance between the device and the lightning arrester is l c , the reflected wave generated by the device just reaches the location of the lightning arrester when the voltage at both ends of the lightning arrester reaches the residual voltage value U ref ;

[0023] The distance measurement unit is used to obtain the distance l between the device and the lightning arrester, and if l ≤ l c , then trigger the first time calculation unit, if l > lc When it does, trigger the second time calculation unit;

[0024] The first time calculation unit is used to calculate according to the time t required for the voltage across the arrester to reach the residual voltage value U ref ;

[0025] The second time calculation unit is used to calculate according to the time t required for the voltage across the arrester to reach the residual voltage value U ref ;

[0026] where v is the propagation speed of the lightning intrusion wave on the line.

[0027] Furthermore,

[0028] According to another aspect of the present invention, a computer-readable storage medium includes a stored computer program. When the computer program is executed by a processor, it controls the device where the computer-readable storage medium is located to execute the above-mentioned lightning intrusion wave overvoltage calculation method considering the working voltage provided by the present invention.

[0029] Generally speaking, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0030] (1) The present invention uses an engineering algorithm to calculate the lightning intrusion wave overvoltage of equipment, and fully considers the influence of the working voltage of high-voltage level lines on the lightning intrusion wave overvoltage during the calculation process, which is more in line with the actual working conditions during lightning strikes. Therefore, it can improve the accuracy of the lightning intrusion wave overvoltage calculation of substation equipment while ensuring the rapidity and convenience of the calculation.

[0031] (2) When the voltage across the arrester reaches the residual voltage value before or after the equipment reflection wave reaches the arrester, the waveform distributions of the voltages across the arrester and the equipment are different. The present invention introduces a critical distance, which satisfies: when the equipment reflection wave reaches the arrester, the potential of the arrester just reaches the residual voltage value; and based on the relationship between the actual distance between the equipment and the arrester and this critical distance, the actual waveform distributions of the voltages across the arrester and the equipment are determined, and the corresponding equipment overvoltage is calculated. Thereby, the calculated equipment overvoltage can be adapted to the actual distance between the equipment and the arrester, further improving the accuracy of the equipment overvoltage and avoiding excessive costs for the lightning protection of the power system over long distances. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the line structure for calculating the lightning intrusion wave overvoltage provided by the embodiment of the present invention;

[0033] Figure 2Schematic diagram of the waveform distribution of the voltages at both ends of the arrester and the device when the actual distance between the device provided in the embodiment of the present invention and the arrester is less than or equal to the critical distance;

[0034] Figure 3 Schematic diagram of the waveform distribution of the voltages at both ends of the arrester and the device when the actual distance between the device provided in the embodiment of the present invention and the arrester is greater than the critical distance;

[0035] Figure 4 Schematic diagram of the method for calculating the lightning-induced overvoltage considering the working voltage provided in the embodiment of the present invention. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0038] Before explaining the technical solution of the present invention in detail, the relevant technical principles are briefly introduced as follows:

[0039] Figure 1 The shown is a schematic diagram of the line structure for calculating the lightning-induced overvoltage. Among them, the lightning intrusion wave enters the substation from point A, the arrester is at point B, and the device is at point C.

[0040] After the lightning intrusion wave enters the substation from point A and propagates along the line, when it passes through point B where the arrester is located, the voltage at both ends of the arrester begins to rise and reaches the residual voltage value U ref and then remains unchanged; after the lightning intrusion wave passes through point B, it continues to propagate forward. After reaching point C, the reflected wave formed by the reflection of the device propagates towards the arrester.

[0041] Since the working voltage of the high-voltage level line can be comparable to the insulation level of the device, it will affect the lightning-induced overvoltage; when the lightning intrusion occurs, the working voltage of the line is denoted as U0. Then, at the moment of lightning intrusion, the initial voltages at both ends of the arrester and the device are both U0.

[0042] When the distance between the device and the arrester is relatively close, the voltage at both ends of the arrester will reach the residual voltage value U ref after the reflected wave at point C reaches point B. In this case, the waveform distributions of the voltages at both ends of the arrester and the device are asFigure 2 As shown; among them, at the moment of 2l / v, the reflected wave at point C reaches point B, and at the moment of t2, the voltage across the arrester reaches the residual voltage value U ref ; before the reflected wave at point C reaches point B, the potential at point B rises with a gradient of a, and after the reflected wave at point C reaches point B, the potential at point B rises with a gradient of 2a and reaches U at the moment of t2 ref ;

[0043] When the distance between the equipment and the arrester is relatively far, the voltage across the arrester will reach the residual voltage value U before the reflected wave at point C reaches point B ref , in this case, the waveform distributions of the voltages at both ends of the arrester and the equipment are as Figure 3 shown; among them, at the moment of 2l / v, the reflected wave at point C reaches point B, and at the moment of t1, the voltage across the arrester reaches the residual voltage value U ref ; after the lightning intrusion wave reaches point B, the potential at point B rises with a gradient of a and reaches U at the moment of t1 ref .

[0044] Comparing Figure 2 and Figure 3 it can be seen that at the moment of lightning strike, the operating voltage of the line will affect the voltages at both ends of the arrester and the equipment, and different distances between the equipment and the arrester will result in different waveform distributions of the voltages at both ends of the arrester and the equipment.

[0045] When the existing engineering algorithm calculates the overvoltage caused by lightning intrusion waves, the calculation formula used is U max =U ref +2al / v, where U max is the maximum value of the voltage across the equipment, U ref is the residual voltage value of the arrester, a is the steepness of the lightning intrusion wave, l is the electrical distance between the arrester and the equipment, and v is the propagation speed of the lightning intrusion wave on the line. The overvoltage of the equipment calculated based on this formula does not consider the influence of the operating voltage of the line at the moment of lightning strike. Therefore, the accuracy of the calculated overvoltage of the equipment is relatively low; in addition, this formula is only applicable to the case where the electrical distance l is relatively small. When l is relatively large, the maximum value of the overvoltage of the equipment calculated according to this formula is often too large. Correspondingly, more stringent requirements are imposed on the lightning protection of the power system, increasing the cost of the lightning protection of the power system.

[0046] To solve the above technical problems and achieve fast and accurate calculation of lightning intrusion overvoltage of substation equipment, the present invention provides a calculation method, system and medium for lightning intrusion overvoltage considering the operating voltage. The overall idea is as follows: while calculating the lightning intrusion overvoltage of equipment using engineering algorithms, the influence of the operating voltage of high-voltage level lines on the lightning intrusion overvoltage is considered to conform to the actual working conditions during lightning strikes. While ensuring the rapidity and convenience of calculation, the accuracy of calculating the lightning intrusion overvoltage of substation equipment is improved; on this basis, at different distances, the equipment overvoltage is calculated according to different waveform distributions, further improving the accuracy of the equipment overvoltage and reducing the cost of lightning protection for the power system.

[0047] The following are embodiments.

[0048] Embodiment 1:

[0049] A calculation method for lightning intrusion overvoltage considering the operating voltage, as Figure 4 shown, includes the following steps:

[0050] (S1) Obtain the operating voltage U0 of the line at the lightning strike moment;

[0051] In practical applications, the operating voltage U0 of the line at the lightning strike moment can be obtained using a mutual inductor, etc.;

[0052] (S2) Calculate the time t required for the voltage at both ends of the arrester to reach the residual voltage value U ref under the influence of the operating voltage U0;

[0053] In this embodiment, when the distance between the equipment and the arrester is different, the equipment overvoltage is calculated according to different voltage waveform distributions. Correspondingly, the calculation method of the time t required for the voltage at both ends of the arrester to reach the residual voltage value U ref is different; specifically, in this embodiment, step (S2) specifically includes:

[0054] Calculate the critical distance l c between the equipment and the arrester; the critical distance l c satisfies: when the reflected wave of the equipment reaches the arrester, the potential of the arrester just reaches the residual voltage value U ref ;

[0055] Obtain the distance l between the equipment and the arrester. If l ≤ l c , it indicates that the distance between the equipment and the arrester is relatively close. The voltage at both ends of the arrester will reach the residual voltage value U ref after the reflected wave at point C reaches point B. Then, calculate the time t according to the voltage waveform shown in Figure 2 , that is, calculate the time t required for the voltage at both ends of the arrester to reach the residual voltage value U according to ref ;

[0056] If l > l c , it indicates that the distance between the device and the lightning arrester is relatively far, and the voltage at both ends of the lightning arrester will reach the residual voltage value U before the reflected wave at point C reaches point B ref , then calculate the time t according to the voltage waveform shown in Figure 3 , that is, calculate the time t required for the voltage at both ends of the lightning arrester to reach the residual voltage value U according to ; ref

[0057] (S3) Calculate the maximum value U of the overvoltage of the device according to U max = 2at + U0 max ;

[0058] When l ≤ l c , substitute the calculation expression of t, and we can get

[0059] When l > l c , substitute the calculation expression of t, and we can get U max = 2U ref - U0;

[0060] Among them, a is the steepness of the lightning intrusion wave, and v is the propagation speed of the lightning intrusion wave on the line

[0061] Embodiment 2:

[0062] A lightning intrusion wave overvoltage calculation device considering the working voltage includes:

[0063] A working voltage acquisition module for obtaining the working voltage U0 of the line at the moment of lightning strike;

[0064] A time calculation module for calculating the time t required for the voltage at both ends of the lightning arrester to reach the residual voltage value U under the influence of the working voltage U0 ref ;

[0065] And an overvoltage calculation module for calculating the maximum value U of the overvoltage of the device according to U max = 2at + U0 max ;

[0066] Among them, a is the steepness of the lightning intrusion wave;

[0067] In this embodiment, the time calculation module includes: a critical distance calculation unit, a distance measurement unit, a first time calculation unit, and a second time calculation unit;

[0068] A critical distance calculation unit for calculating the critical distance l c ; when the distance between the device and the lightning arrester is l c , the voltage at both ends of the lightning arrester reaches the residual voltage value U​ref At this time, the reflected wave generated by the device just reaches the location of the lightning arrester; in this embodiment,

[0069] a distance measurement unit, configured to obtain the distance l between the device and the lightning arrester, and when l ≤ l c , then trigger the first time calculation unit, and when l > l c , trigger the second time calculation unit;

[0070] The first time calculation unit is configured to calculate the time t required for the voltage across the lightning arrester to reach the residual voltage value U in accordance with ref ;

[0071] The second time calculation unit is configured to calculate the time t required for the voltage across the lightning arrester to reach the residual voltage value U in accordance with ref ;

[0072] wherein, v is the propagation speed of the lightning intrusion wave on the line.

[0073] In this embodiment, for the specific implementation manners of each module, reference may be made to the description in the above Embodiment 1, and will not be repeated here.

[0074] Embodiment 3:

[0075] A computer-readable storage medium includes a stored computer program, and when the computer program is executed by a processor, it controls the device where the computer-readable storage medium is located to execute the lightning intrusion wave overvoltage calculation method considering the operating voltage provided in the above Embodiment 1.

[0076] Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A calculation method for lightning intrusion overvoltage considering the working voltage, characterized in that, It includes the following steps: (S1) Obtain the working voltage U0 of the line at the lightning strike moment; (S2) Calculate the time t required for the voltage across the arrester to reach the residual voltage value U under the influence of the working voltage U0. ref ​ (S3) Calculate the maximum overvoltage U of the device according to U max = 2at + U0 max ; where a is the steepness of the lightning intrusion wave; The step (S2) includes: Critical distance l between the computing device and the lightning arrester c ; Critical distance l c satisfies: when the reflected wave of the device reaches the lightning arrester, the potential of the lightning arrester exactly reaches the residual voltage value U ref ; Obtain the distance l between the device and the lightning arrester. If l ≤ l c , then calculate the time t required for the voltage across the lightning arrester to reach the residual voltage value U according to ref ; if l > l c , then calculate the time t required for the voltage across the lightning arrester to reach the residual voltage value U according to ref ; where v is the propagation speed of the lightning intrusion wave on the line.

2. The method for calculating lightning intrusion overvoltage considering the working voltage according to claim 1, characterized in that 3. A lightning intrusion wave overvoltage calculation device considering the working voltage, characterized in that, It includes: A working voltage acquisition module for obtaining the working voltage U0 of the line at the lightning strike moment; A time calculation module, which is used to calculate the time t required for the voltage across the arrester to reach the residual voltage value U under the influence of the working voltage U0 ref ; and an overvoltage calculation module for calculating the maximum overvoltage U of the device according to U max = 2at + U0 max ; where a is the steepness of the lightning intrusion wave; the time calculation module includes: a critical distance calculation unit, a distance measurement unit, a first time calculation unit, and a second time calculation unit; The critical distance calculation unit is configured to calculate the critical distance l c ; when the distance between the device and the lightning arrester is l c the voltage across the lightning arrester reaches the residual voltage value U ref the reflected wave generated by the device just reaches the location of the lightning arrester; The distance measurement unit is configured to obtain the distance l between the device and the lightning arrester, and trigger the first time calculation unit when l ≤ l c , and trigger the second time calculation unit when l > l c ; The first time calculation unit is configured to calculate according to the time t required for the voltage across the arrester to reach the residual voltage value U ref ; The second time calculation unit is configured to calculate according to the time t required for the voltage across the arrester to reach the residual voltage value U ref ; where v is the propagation speed of the lightning intrusion wave on the line.

4. The lightning intrusion wave overvoltage calculation device according to claim 3, characterized in that 5. A computer-readable storage medium, characterized in that, It includes a stored computer program, which when executed by a processor, controls the device where the computer-readable storage medium is located to execute the method for calculating the overvoltage of the lightning intrusion wave considering the working voltage according to claim 1 or 2.

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