Visual calculation method for shielding failure trip-out rate of power transmission line in complex terrain

Abstract

The invention relates to the technical field of power transmission line risk assessment, in particular to a shielding failure trip-out rate visual calculation method for a power transmission line in a complex terrain. According to the technical scheme, the method comprises the following steps: determining a power transmission line under a complex terrain as a research main object, subdividing a power transmission line corridor, and obtaining three-dimensional data of the complex terrain by using a spatial analysis function of a GIS and a three-dimensional GIM model; and based on the obtained terrain profile data, calculating the lightning resistance level of the insulator and taking the lightning resistance level as the minimum shielding failure lightning current of the EGM, then calculating the lightning conductor strike distance circle radius, the conductor strike distance circle radius and the earth strike distance radius through a strike distance formula of the electrical geometric model, and establishing the electrical geometric model under the profile. According to the method, the influence of complex terrains on shielding failure of the power transmission line is comprehensively considered, scientific and effective support is provided for lightning protection of the power transmission line through accurate calculation and visual analysis, and the method is of great significance in guaranteeing safe and stable operation of a power grid.

Description

Technical Field

[0001] This invention relates to the field of transmission line risk assessment technology, and in particular to a method for visually calculating the tripping rate of transmission lines in complex terrain. Background Technology

[0002] Lightning disasters, listed as one of the ten most serious hazards by relevant UN organizations, pose a significant threat to the safe and stable operation of power systems. With the continuous expansion of my country's power grid construction, the coverage of overhead transmission lines is constantly extending, and line corridors are becoming increasingly dense, significantly increasing the probability of transmission lines being struck by lightning. Extensive operational experience shows that for high-tower and high-voltage transmission lines, lightning tripping accidents mainly occur in the form of bypass strikes. This is especially true when transmission lines traverse complex terrain, where the complexity of the topography greatly increases the difficulty of assessing bypass strike performance.

[0003] Transmission line corridors often face diverse and complex terrain environments, including winding, undulating mountains, valleys, and slopes. The diversity of topographic and geological parameters significantly increases the complexity of lightning protection work for transmission lines. For example, long-span lines crossing valleys and rivers face a significantly increased risk of lightning striking the conductor from the side, causing outages due to side strikes.

[0004] In existing technologies, conventional electrical geometric models (EGMs) use only a simple ground tilt angle to approximate complex terrain when calculating the tripping rate of transmission line corridors. This simplified approach cannot accurately reflect the actual impact of complex terrain on the risk of transmission line backflashover, resulting in a large deviation between the calculation results and the actual situation. This makes it difficult to formulate effective lightning protection measures and increases the risk to the safe operation of transmission lines.

[0005] Although the patent documents "A method and system for lightning protection of power grids in complex terrain areas" (CN119674887A) and "A system and method for assessing the lightning strike risk of transmission lines and storage medium" (CN119990740A) have studied the risk of lightning strikes on transmission lines in complex terrain and proposed corresponding calculation models based on lightning activity data, topographic features and other characteristics, they still use the ground tilt angle to approximate the complex terrain. They cannot accurately consider the impact of irregular mountain undulations on transmission lines in actual complex terrain areas, and it is difficult to specifically calculate and analyze the lightning strike trip rate of transmission line corridors in complex terrain.

[0006] Therefore, in order to achieve a refined and accurate assessment of the risk of power transmission line tripping due to indirect impacts in complex terrain, there is an urgent need for a calculation method that can fully incorporate the actual characteristics of complex terrain. Summary of the Invention

[0007] The purpose of this invention is to address the problem in the background technology that there are no corresponding lightning protection measures for the irregular undulation of mountains under complex terrain and the different shielding effects of different mountain terrains on transmission lines. The invention proposes a visualization calculation method for the tripping rate of transmission lines under complex terrain.

[0008] The technical solution of this invention: A method for visually calculating the tripping rate of transmission lines under complex terrain, comprising the following steps:

[0009] S1: Identify the transmission lines under complex terrain as the main research object, divide the transmission line corridor, and use the spatial analysis function of GIS and the three-dimensional GIM model to obtain the three-dimensional data of the complex terrain.

[0010] S2: Based on the obtained terrain profile data, calculate the lightning withstand level of the insulator and use it as the minimum lightning strike current around the EGM. Then, calculate the strike distance radius of the lightning conductor, the strike distance radius of the conductor, and the strike distance radius of the ground through the strike distance formula of the electrical geometry model, and establish the electrical geometry model under this profile.

[0011] S3: Calculate the exposed arc length of the lightning conductor and the conductor under the minimum lightning strike current using the program, consider the mutual shielding effect between the exposed arcs, obtain the projected length of the exposed arc of the conductor when the lightning strike angle is vertically downward and store it.

[0012] S4: Calculate the oblique projection length L1(θ,I) of the exposed arc of the conductor under different elevation angles θ, determine the probability distribution of the lightning first incident angle, and determine the maximum lightning strike current by judging whether the horizontal oblique projection length of the exposed arc of the conductor is 0.

[0013] S5: Convert the horizontal oblique projection length of the exposed arc of the conductor into the effective projection length of the exposed arc, calculate the number of times the line shield fails and causes flashover, and then obtain the backlash trip rate of the profile and the backlash trip rate of the micro-element.

[0014] S6: Perform segmented calculations for each span of the transmission line, and transfer half of the backlash trip rate on each side of the tower to the tower. Assess the backlash trip risk of the transmission line corridor through the backlash trip rate of the tower.

[0015] Optionally, in step S1, the entire complex terrain transmission line corridor is divided into segments at a fixed interval ΔL, and the extracted data includes the conductor-to-ground height, relative centerline distance, and complex terrain elevation of the entire complex terrain transmission line corridor.

[0016] Optionally, in step S2, the lightning withstand level I of the insulator is calculated using a formula. c And as the minimum lightning strike current I around the EGM min Lightning resistance level I c The calculation formula is:

[0017]

[0018] In the formula: U -50％ U is the 50% impulse flashover voltage of the insulator's negative polarity, expressed in kV. max Z is the system's highest operating voltage, in kV; Z0 is the lightning channel surge impedance, in Ω; Z c This represents the lightning channel impedance, measured in Ω.

[0019] Optionally, in step S2, the radius r of the lightning conductor's strike distance circle is calculated using the strike distance formula of the electrical geometric model. s , radius r of the conductor striking distance circle c and the radius of the ground strike distance r g The specific calculation formula is as follows:

[0020] r s =10I 0.65 ,

[0021] r c =1.63×(5.015I) 0.578 -0.001U ph ) 1.125 ,

[0022]

[0023] In the formula: r s r is the radius of the strike distance circle of the lightning protection wire, in meters (m). c r is the radius of the conductor striking distance circle, in meters (m). g U is the radius of the ground strike distance, in meters; I is the amplitude of the lightning current, in kA; U ph The instantaneous value of the working voltage on the conductor, in kV; h c The height of the conductor above the ground is expressed in meters (m).

[0024] Optionally, in step S3, the profile S is calculated using a Matlab program. i Minimum lightning strike current I min The lengths of the exposed arcs AB and AF of the lower lightning protection conductor, and the exposed arcs BC, CD, DE, FG, GD, and HI of the conductor, are calculated and stored in matrix form. These results are used to determine the maximum lightning current I when the lightning protection conductor is fully shielded from the conductor. max .

[0025] Optionally, in step S4, the value of θ ranges from -π / 2 to π / 2, with each calculation interval Δθ = 5°. The probability distribution of different lightning incident angles is calculated using the formula:

[0026]

[0027] In the formula: θ is the lightning incident angle, in rad; g(θ) is the probability distribution of the lightning incident angle, and the lightning current increment is ΔI = 0.1kA.

[0028] Optionally, in step S5, the horizontal oblique projection lengths L1(θ,I) of all exposed arcs of the conductor are converted into effective exposed arc projection lengths L'1(θ,I) using a formula:

[0029] L'1(θ,I)=L1(θ,I)·cosθ,

[0030] In the formula, L'1(θ,I) is the effective exposed arc projection length in meters; L1(θ,I) is the horizontal oblique projection length of the exposed arc in meters; θ is the lightning incident angle in rad; and I is the lightning current amplitude in kA.

[0031] Considering different lightning incidence angles, the number of times N of line shielding failure causes flashover is considered. sf Represented as:

[0032]

[0033] Where: N sf The number of flashovers, measured in times per 100km. 2 ·a; N g This refers to the lightning density, measured in lightning strikes per km. 2 ·a;I max I represents the maximum lightning strike current, measured in kA. min L'1(θ,I) represents the minimum lightning strike current, in kA; L'1(θ,I) represents the effective exposed arc projection length, in m; θ represents the lightning incident angle, in rad; I represents the lightning current amplitude, in kA; g(θ) represents the probability distribution of the lightning incident angle; and f(I) represents the lightning current probability density function.

[0034] Optionally, in step S5, to simplify the calculation, N is... sf The integral calculation is transformed into the sum of differentials, and the specific calculation formula is as follows:

[0035]

[0036] In the formula, N sf The number of flashovers, measured in times per 100km. 2 ·a; N g This refers to the lightning density, measured in lightning strikes per km. 2 ·a;I max I represents the maximum lightning strike current, measured in kA. minL'1(θ,I) represents the minimum lightning strike current (kA); L'1(θ,I) represents the effective exposed arc projection length (m); θ represents the lightning incident angle (rad); I represents the lightning current amplitude (kA); g(θ) represents the lightning incident angle probability distribution; P(I) represents the lightning current probability, expressed as f(I+ΔI)-f(I). Substituting the calculated L1(θ,I) matrix into the above formula yields the profile S. i Number of flashovers Through formula R st =N sf ·P trip The profile S can then be calculated. i The tripping rate of the backlash is calculated, and the tripping rate of the backlash of this profile is multiplied by the segmentation spacing ΔL to approximate the infinitesimal element ΔL. i The tripping rate of the circuit breaker

[0037] In the formula: R st The tripping rate is measured in trips per 100km. 2 ·a; N sf The number of flashovers, measured in times per 100km. 2 ·a;P trip P represents the probability of tripping after a flashover for a line without automatic reclosing. trip ≈1, Line P equipped with automatic reclosing trip ≈0.8~0.95.

[0038] Optionally, in step S6, after obtaining all infinitesimal elements ΔL... i The tripping rate of the circuit breaker Then, each span of the transmission line is calculated in segments, and the tripping rate of half of the spans on both sides of a certain tower is attributed to the tower.

[0039] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0040] Breaking away from the limitations of traditional methods that only simplify complex terrain based on ground inclination angle, this paper establishes an electrical geometric model (EGM) based on elevation data of actual terrain, which can more accurately calculate the out-of-line tripping rate of transmission lines under complex terrain. It fully considers the impact of irregular terrain such as mountain undulations on the risk of out-of-line tripping, making the assessment results more in line with the actual situation.

[0041] By analyzing and saving the EGM of complex terrain under different lightning currents and lightning leader incidence angles, the changes in the electrical geometry model are presented intuitively. This makes it easy to clearly observe the changes in the development path of the lightning leader (such as mountain tops, slopes, valleys, etc.) and its impact on the probability of backflashover, and to gain a deeper understanding of the shielding effect of complex terrain on transmission lines.

[0042] This provides a basis for scientific lightning risk assessment of transmission line corridors in complex terrain, which helps to develop targeted lightning protection measures. By accurately assessing the tripping rate of each tower, differentiated protection can be implemented according to the risk level of different sections, thereby improving the effectiveness of lightning protection work.

[0043] By accurately calculating the lightning strike trip rate and conducting risk assessments, we can identify the weak points of transmission lines in complex terrain in advance, take reasonable lightning protection measures, reduce the occurrence of lightning trip accidents, and thus ensure the high reliability of transmission lines and maintain the stability of the entire power grid.

[0044] In summary, this invention comprehensively considers the impact of complex terrain on lightning strikes on transmission lines. Through precise calculations and visualization analysis, it provides scientific and effective support for lightning protection of transmission lines, which is of great significance for ensuring the safe and stable operation of the power grid. Attached Figure Description

[0045] Figure 1 A flowchart illustrating a method for visually calculating the tripping rate of transmission lines in complex terrain;

[0046] Figure 2 A 3D GIM model and a schematic diagram of the subdivision of a power transmission line in complex terrain;

[0047] Figure 3 A schematic diagram of the line and terrain parameters extracted from the profile of the power transmission line corridor;

[0048] Figure 4 The EGM model diagram is shown when the lightning current incident angle is 90°.

[0049] Figure 5 The EGM model diagram is shown when the lightning current incident angle is 50°.

[0050] Figure 6 The diagram shows the EGM model with a lightning current incident angle of 130°. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0052] Example

[0053] like Figure 1 As shown, the present invention provides a visualization calculation of the tripping rate of transmission line corridors in complex terrain, comprising the following steps:

[0054] Step S1: Identify the transmission line under complex terrain as the main research object, and divide the entire transmission line corridor under complex terrain into sections with a fixed interval ΔL, such as... Figure 2As shown, 3D data of complex terrain was obtained using the spatial analysis function of GIS and a 3D GIM model. The main focus was on extracting relevant data such as the conductor-to-ground height, distance from the centerline, and elevation of the complex terrain along the entire transmission line corridor. The extracted profile S... i Data such as Figure 3 As shown in the figure, the conductor and ground wire heights of the transmission line and the complex terrain can be seen.

[0055] Step S2: After obtaining the terrain profile data of the transmission line corridor in complex terrain, process the profile S... i The tripping rate of the insulator is calculated, and the lightning withstand level I of the insulator is calculated using equation (1). c And as the minimum lightning strike current I around the EGM min The minimum lightning strike current I calculated in this example min =2.2kA;

[0056]

[0057] In the formula: U -50％ The impulse flashover voltage of the insulator's negative polarity is 50% (kV); U max The system's highest operating voltage is kV; Z0 is the lightning channel surge impedance in Ω; Z c Lightning channel impedance, Ω;

[0058] The radius r of the lightning conductor's strike distance circle is calculated using the strike distance formulas (2) to (4) of the electrical geometric model. S , radius r of the conductor striking distance circle C and the radius of the ground strike distance r g And establish the electrical geometry model under this section.

[0059] r s =10I 0.65 (2)

[0060] r c =1.63×(5.015I) 0.578 -0.001U ph ) 1.125 (3)

[0061]

[0062] In the formula: r S r is the radius of the lightning strike distance circle, in meters. c r is the radius of the conductor strike distance circle, in meters. g I is the radius of the ground strike distance, in meters; I is the amplitude of the lightning current, in kilometers per hour (kA); U is the radius of the ground strike distance, in meters (m); U is the amplitude of the lightning current, in kilometers per hour (kA); U is the radius of the ground strike distance, in meters (m); I is the amplitude of the lightning current, in kilometers per hour (kA); U is the radius of the ground strike distance, in meters (m); U is the radius of the ground strike distance, in kilometers (kA); U is Ph The instantaneous value of the working voltage on the conductor, in kV; h C The height of the conductor above the ground, in meters (m).

[0063] Step S3: Using a Matlab program, calculate the profile S. i Minimum lightning strike current I min The lengths of the exposed arcs AB and AF of the lower lightning protection conductor, and the exposed arcs BC, CD, DE, FG, GD, and HI of the conductor are determined. By judging the relative positions of the conductor and ground wire and considering the mutual shielding effect between the exposed arcs, the final profile S is obtained. i Minimum lightning strike current I min Furthermore, the projected length L1(I) of the exposed arc of the conductor when the lightning strike angle is vertically downward is calculated. The calculated results are stored in matrix form for calculating the backlash trip rate and determining the maximum backlash current I when the lightning protection wire is fully shielded. max ;

[0064] Step S4: Based on step S3, the case of different lightning strike incident angles is realized by calculating the exposed arc oblique projection length L1(θ,I) of the conductor under different elevation angles θ. The EGM model under different lightning current incident angles is as follows: Figures 4-6 As shown in the figure, the location information of the lightning protection wire and the conductor, their exposure arcs, the ground strike distance curve, and the calculated L1(θ,I) are marked. Figure 4 The visualization results at an incident angle of 90° under IkA show that the exposed arc projection length of the lightning protection wire is 45.6m, and the exposed arc projection length of the conductor is 4.4m. Figures 5-6 The visualization results for incident angles of 50° and 130° at IkA show that, due to the influence of the mountain on the left, the exposed arc projection lengths of the conductor are 16.2m and 12.6m at incident angles of 50° and 130°, respectively. This visualization allows for a better analysis of the impact of complex terrain on EGM, and thus a more accurate calculation of the transmission line's tripping rate. The value of θ ranges from -π / 2 to π / 2, with a calculation interval of Δθ = 5. 0 In reality, the incident angle of lightning follows a certain probability distribution. Equation (5) is used to calculate the probability distribution of different lightning incident angles.

[0065]

[0066] In the formula: θ is the lightning incident angle, in rad; g(θ) is the probability distribution of the lightning incident angle, and the lightning current increment is ΔI = 0.1kA.

[0067] Store the horizontal oblique projection length L1(θ,I) of the exposed arc of the conductor at each angle in a matrix. Check if L1(θ,I) is 0. If it is 0, it means that the conductor is completely shielded by the lightning conductor and the ground. Otherwise, change the lightning current to I = I + ΔI and continue to repeat steps S2, S3, and S4 to calculate the exposed arc of the conductor and check again until L1(θ,I) is 0 for all values. At this point, the current lightning current is the maximum lightning strike current I. max The lightning current increment is ΔI = 0.1kA. The calculated matrix L1(θ,I) for different lightning current incident angles and different lightning current amplitudes is shown in Table 1.

[0068] Table 1. Calculation results of L1(θ,I) for different lightning current incident angles under different lightning current amplitudes.

[0069]

[0070]

[0071] Step S5: Through step 4, the conductor's position under lightning current [I] can be obtained. min ,I max The L1(θ,I) matrix under the lightning first-injection angle [-π / 2,π / 2] is used to convert all the horizontal oblique projection lengths L1(θ,I) of the exposed arc of the conductor into the effective exposed arc projection lengths L'1(θ,I) through equation (6).

[0072] L'1(θ,I)=L1(θ,I)·cosθ (6)

[0073] Considering different lightning incidence angles, the number of times N of line shielding failure causes flashover is considered. sf It can be represented as:

[0074]

[0075] Where: N g The density of ground flashes is given in times per km. 2 ·a;f(I) is the probability density function of lightning current.

[0076] To simplify the calculation, the integral calculation is converted into the differential summation calculation, and equation (7) is transformed into equation (8).

[0077]

[0078] In the formula: P(I) is the lightning current probability, expressed as f(I+ΔI)-f(I);

[0079] Substituting the calculated L1(θ,I) matrix into equation (8) yields the profile S. i Number of flashovers The profile S can be calculated using equation (9). i The tripping rate of the backlash is calculated, and the tripping rate of the backlash of this profile is multiplied by the segmentation spacing ΔLI to approximate the value of the infinitesimal element ΔL. i The tripping rate of the circuit breaker The calculation in this example is The tripping rate due to the impact is 0.0062 times / (100 km·year).

[0080] R st =N sf ·P trip (9)

[0081] In the formula: P trip P represents the probability of tripping after a flashover for a line without automatic reclosing. trip ≈1, Line P equipped with automatic reclosing trip ≈0.8~0.95;

[0082] Step S6: After obtaining all infinitesimal elements ΔL i The tripping rate of the circuit breaker Subsequently, segmented calculations were performed for each span of the transmission line. The tripping rate from the backlashes on both sides of a certain tower was allocated to the tower itself, and the backlash tripping rate of the tower was used to assess the risk of backlash tripping in transmission line corridors under complex terrain. The calculated backlash tripping rate for the 200km transmission line in this example was 0.0124 times / year. Furthermore, the impact of terrain on the EGM model can be studied through visualization.

[0083] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A method for visually calculating the tripping rate of transmission lines in complex terrain, characterized in that, Includes the following steps: S1: Identify the transmission lines under complex terrain as the main research object, divide the transmission line corridor, and use the spatial analysis function of GIS and the three-dimensional GIM model to obtain the three-dimensional data of the complex terrain. S2: Based on the obtained terrain profile data, calculate the lightning withstand level of the insulator and use it as the minimum lightning strike current around the EGM. Then, calculate the strike distance radius of the lightning conductor, the strike distance radius of the conductor, and the strike distance radius of the ground through the strike distance formula of the electrical geometry model, and establish the electrical geometry model under this profile. S3: Calculate the exposed arc length of the lightning conductor and the conductor under the minimum lightning strike current using the program, consider the mutual shielding effect between the exposed arcs, obtain the projected length of the exposed arc of the conductor when the lightning strike angle is vertically downward and store it. S4: Calculate the oblique projection length L1(θ,I) of the exposed arc of the conductor under different elevation angles θ, determine the probability distribution of the lightning first incident angle, and determine the maximum lightning strike current by judging whether the horizontal oblique projection length of the exposed arc of the conductor is 0. S5: Convert the horizontal oblique projection length of the exposed arc of the conductor into the effective projection length of the exposed arc, calculate the number of times the line shield fails and causes flashover, and then obtain the backlash trip rate of the profile and the backlash trip rate of the micro-element. S6: Perform segmented calculations for each span of the transmission line, and transfer half of the backlash trip rate on each side of the tower to the tower. Assess the backlash trip risk of the transmission line corridor through the backlash trip rate of the tower.

2. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 1, characterized in that, In step S1, the entire complex terrain transmission line corridor is divided into segments at a fixed interval ΔL. The extracted data includes the conductor-to-ground height, relative centerline distance, and complex terrain elevation of the entire complex terrain transmission line corridor.

3. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 1, characterized in that, In step S2, the lightning withstand level I of the insulator is calculated using the formula. c And as the minimum lightning strike current I around the EGM min Lightning resistance level I c The calculation formula is: In the formula: U -50％ U is the 50% impulse flashover voltage of the insulator's negative polarity, expressed in kV. max Z is the system's highest operating voltage, in kV; Z0 is the lightning channel surge impedance, in Ω; Z c This represents the lightning channel impedance, measured in Ω.

4. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 3, characterized in that, In step S2, the radius r of the lightning conductor's strike distance circle is calculated using the strike distance formula of the electrical geometric model. s , radius r of the conductor striking distance circle c and the radius of the ground strike distance r g The specific calculation formula is as follows: r s ＝10I 0.65 ， r c =1.63×(5.015I 0.578 -0.001U ph ) 1.125 , In the formula: r s r is the radius of the strike distance circle of the lightning protection wire, in meters (m). c r is the radius of the conductor striking distance circle, in meters (m). g The radius of the ground impact distance is in meters. I represents the amplitude of the lightning current, in kA; U ph The instantaneous value of the working voltage on the conductor, in kV; h c The height of the conductor above the ground is expressed in meters (m).

5. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 1, characterized in that, In step S3, the profile S is calculated using the Matlab program. i Minimum lightning strike current I min The lengths of the exposed arcs AB and AF of the lower lightning protection conductor, and the exposed arcs BC, CD, DE, FG, GD, and HI of the conductor, are calculated and stored in matrix form. These results are used to determine the maximum lightning current I when the lightning protection conductor is fully shielded from the conductor. max .

6. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 1, characterized in that, In step S4, the value of θ ranges from -π / 2 to π / 2, and the calculation interval is Δθ = 5°. The probability distribution of different lightning incident angles is calculated using the formula: In the formula: θ is the lightning incident angle, in rad; g(θ) is the probability distribution of the lightning incident angle, and the lightning current increment is ΔI = 0.1kA.

7. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 1, characterized in that, In step S5, the horizontal oblique projection lengths L1(θ,I) of all exposed arcs of the conductor are converted into effective exposed arc projection lengths L'1(θ,I) using the following formula: L'1(θ,I)=L1(θ,I)·cosθ, In the formula, L'1(θ,I) is the effective exposed arc projection length in meters; L1(θ,I) is the horizontal oblique projection length of the exposed arc in meters. θ is the lightning incident angle, in rad; I is the lightning current amplitude, in kA. Considering different lightning incidence angles, the number of times N of line shielding failure causes flashover is considered. sf Represented as: Where: N sf The number of flashovers, measured in times per 100km. 2 ·a; N g This refers to the lightning density, measured in lightning strikes per km. 2 ·a;I max I represents the maximum lightning strike current, measured in kA. min L'1(θ,I) represents the minimum lightning strike current, in kA; L'1(θ,I) represents the effective exposed arc projection length, in meters. θ is the lightning incident angle, in rad; I is the lightning current amplitude, in kA; g(θ) is the probability distribution of the lightning incident angle; f(I) is the lightning current probability density function.

8. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 7, characterized in that, In step S5, to simplify the calculation, N is... sf The integral calculation is transformed into the sum of differentials, and the specific calculation formula is as follows: In the formula, N sf The number of flashovers, measured in times per 100km. 2 ·a; N g This refers to the lightning density, measured in lightning strikes per km. 2 ·a;I max I represents the maximum lightning strike current, measured in kA. min L'1(θ,I) represents the minimum lightning strike current, in kA; L'1(θ,I) represents the effective exposed arc projection length, in meters. θ is the lightning incident angle in rad; I is the lightning current amplitude in kA; g(θ) is the probability distribution of the lightning incident angle; P(I) is the lightning current probability, expressed as f(I+ΔI)-f(I). Substituting the calculated L1(θ,I) matrix into the above formula, the profile S is obtained. i Number of flashovers Through formula R st =N sf ·P trip The profile S can then be calculated. i The tripping rate of the backlash is calculated, and the tripping rate of the backlash of this profile is multiplied by the segmentation spacing ΔL to approximate the infinitesimal element ΔL. i The tripping rate of the circuit breaker In the formula: R st The tripping rate is measured in trips per 100km. 2 ·a; N sf The number of flashovers, measured in times per 100km. 2 ·a;P trip P represents the probability of tripping after a flashover for a line without automatic reclosing. trip ≈1, Line P equipped with automatic reclosing trip ≈0.8~0.

95.

9. The method for visually calculating the tripping rate of transmission lines in complex terrain according to claim 8, characterized in that, In step S6, after obtaining all infinitesimal elements ΔL i The tripping rate of the circuit breaker Then, each span of the transmission line is calculated in segments, and the tripping rate of half of the spans on both sides of a certain tower is attributed to the tower.

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