Calculation method of shielding flashover rate of crossing line considering multi-factor influence

Abstract

A method for calculating the shielding failure flashover rate of crossing lines considering the influence of multiple factors is proposed. According to the parameters of transmission lines and towers, the three-dimensional electrical geometry model is determined, and the lightning activity parameters are obtained. Considering the terrain inclination and lightning incidence angle, the improved electrical geometry model considering the terrain inclination and the improved electrical geometry model considering the lightning incidence angle are constructed. The ground striking distance after considering the terrain inclination is calculated. The inclined projection area is calculated. When considering the lightning shielding effect between crossing lines, according to the intersection of the arc surfaces of the two electrical geometry models, the intersection cross-sectional area under different lightning currents is calculated S . Based on the calculated inclined projection area and intersection cross-sectional area, the shielding failure flashover rate of each line section of the transmission line is calculated. This method can calculate the shielding failure flashover rate according to the actual parameters of the crossing lines, which is close to the actual working condition, and meets the calculation requirements of the shielding failure flashover rate of the crossing lines.

Description

Technical Field

[0001] This invention relates to the field of lightning resistance performance evaluation of power lines, and specifically to a method for calculating the tripping rate of cross-crossing power lines that takes into account the influence of multiple factors. Background Technology

[0002] With the large-scale construction of transmission lines, crossings between lines are inevitable in order to improve land resource utilization and conserve line corridors. Long-term power grid operation experience shows that the longer the span and the more circuits within the line corridor, the greater the probability of being struck by lightning. In practical engineering, the lightning strike trip rate is an important evaluation indicator of a line's lightning resistance performance. Currently, the main methods for calculating the lightning strike trip rate are the code method and the electrical geometric model method. The code method is simple to calculate but considers fewer factors and cannot reflect the specific characteristics of the line. The electrical geometric model method can build a model based on the actual information of the line; however, for crossing lines, the protective arc of the lower line can provide some lightning shielding to the exposed arc of the upper line, making a two-dimensional electrical geometric model often insufficient for calculation requirements. Summary of the Invention

[0003] The purpose of this invention is to propose a method for calculating the tripping rate of crossing lines by considering multiple factors, through the construction of an improved electrical geometric model of the crossing lines. This method can calculate the tripping rate based on the actual parameters of the crossing lines, which is close to the actual operating conditions and meets the calculation requirements of the tripping rate of crossing lines.

[0004] The technical solution adopted in this invention is as follows:

[0005] The calculation method for the tripping rate of crossing lines considering multiple factors includes the following steps:

[0006] Step 1: Based on the obtained transmission line and tower parameters, determine the three-dimensional electrical geometry model and obtain lightning activity parameters;

[0007] Step 2: Based on the three-dimensional electrical geometry model in Step 1, considering both the terrain tilt angle and the lightning incident angle, an improved electrical geometry model considering the terrain tilt angle and an improved electrical geometry model considering the lightning incident angle were constructed.

[0008] Step 3: Based on the improved electrical geometry model considering the terrain inclination angle in Step 2, calculate the ground strike distance after considering the terrain inclination angle; based on the improved electrical geometry model considering the lightning incident angle in Step 2, calculate the tilted projected area.

[0009] Step 4: Based on the ground strike distance and tilted projected area calculated in Step 3, and considering the lightning shielding effect between crossing lines, calculate the intersection area under different lightning currents according to the intersection of the arc surfaces of the two electrical geometric models.；

[0010] Step 5: Based on the oblique projection area calculated in Step 3 and the intersecting cross-sectional area calculated in Step 4, calculate the tripping rate of each line segment of the transmission line.

[0011] In step 1, the transmission line parameters include the spatial location of the conductors and ground wires; the tower parameters include the tower type, tower height, and crossarm length; and the lightning activity parameters include the ground flash density and the lightning current amplitude distribution function.

[0012] Three-dimensional electrical geometry model such as Figure 3 As shown, where: h 3 and h 4 represents the ground elevation of points C and D, respectively. b 3 and b 4 represents the crossarm lengths at points C and D, respectively.

[0013] The lightning current amplitude distribution function refers to the probability distribution of lightning current amplitude on transmission line towers in general areas of my country, excluding parts of southern and northwestern Shaanxi and Inner Mongolia. This distribution can be calculated using the following formula:

[0014] .

[0015] In step 2, the height of each point in the conductor is calculated as follows:

[0016] ;

[0017] In the formula, h x The height of each point on the conductor; H This refers to the height of the tower connection point relative to the ground. f The vertical arc of the line to the ground; L This refers to the distance between the gears.

[0018] Improved electrical geometry model considering terrain inclination angle, such as Figure 4 As shown. and Both are angle variables in the calculation process. The formula for calculating the ground strike distance without considering other factors is as follows:

[0019] ;

[0020] h Tower height, unit: m; I This represents the amplitude of the lightning current, in kA.

[0021] An improved electrical geometry model considering the lightning incident angle, such as Figure 2 As shown. The height of the lightning protection wire above the ground at point A.

[0022] In step 3, when considering the terrain slope angle, the main effect is on the ground impact distance. The changes in the ground impact distance after considering the terrain slope angle are shown below:

[0023] ;

[0024] ;

[0025] ;

[0026] In the formula, h 3. h 4. b 3. b 4 represents the height of the two conductors above the ground and the length of the crossarm, respectively; r g1 To account for the ground strike distance after considering the terrain slope, β The slope angle is the topographic inclination.

[0027] In step 3, the probability distribution formula for the lightning incident angle and the formula for calculating the line projected area after considering the lightning incident angle are as follows:

[0028] ;

[0029]

[0030] ;

[0031] In the formula, The probability distribution of the lightning incident angle; λ The angle of incidence of lightning; r gmax The ground fault distance under the maximum winding current; K The height of the highest point of the protective arc surface of the lightning protection wire and the exposed arc surface of the conductor above the ground; r s This refers to the line distance.

[0032] In step 4, the two electrical geometric models include: an electrical geometric model of a double-circuit line on the same tower and an electrical geometric model of a single-circuit line. The intersection situation in this invention occurs when a double-circuit line on the same tower and a single-circuit line cross each other. The electrical geometric model of the double-circuit line on the same tower is as follows: Figure 3 As shown, the electrical geometric model of a single-circuit line is as follows: Figure 5 As shown.

[0033] The intersection of arc surfaces differs depending on the lightning current, as shown in the following examples: Figure 7As shown, the upper sloping line section is the area where the protective arc surface of the lower layer line intersects with the exposed arc surface of the upper layer line in the crossing line; the grid section is the area where the protective arc surface of the lower layer line intersects with the protective arc surface of the upper layer line in the crossing line.

[0034] This invention considers that the protective arc surface of the lower line is completely within the span. When the lightning current is small, the crossing situation is as shown in Figure 6(a). This situation can be calculated according to the following formula: The following calculation formula is for the left side of Figure 6(a) to Figure 6(d). The right side of Figure 6(a) to Figure 6(d) is similar to the following calculation, only the lightning current amplitude needs to be divided.

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] ;

[0042] ;

[0043] As the lightning current increases, the crossover situation is shown in Figure 6(b). This situation can be calculated using the following formula:

[0044] ;

[0045] ;

[0046] ;

[0047] ;

[0048] In the formula, h 1. h 2. h 3 and h 4 are respectively Figure 3 The height of the conductor above the ground at points A, B, C, and D. d 1. d 2. d 3 and d 4 represents the length of the crossarm at the connection points A, B, C, and D.

[0049] As the lightning current increases, the crossover situation is shown in Figure 6(c). This situation can be calculated using the following formula:

[0050] ;

[0051] ;

[0052] ;

[0053] ;

[0054] ;

[0055] ;

[0056] As the lightning current increases, the crossover situation is shown in Figure 6(d). This situation can be calculated using the following formula:

[0057] ;

[0058] ;

[0059] ;

[0060] .

[0061] Due to the different tower structures, the intersection situations vary considerably. Figures 6(a) to 6(d) only show some possible scenarios. In actual programming calculations, it is necessary to compare the height relationship between the electrical geometric models of the two transmission lines. The comparison process is as follows:

[0062] ① Compare the relationship between the highest point of the protection arc surface of the lower transmission line and the grounding distance of the upper line. If the arc is higher than the grounding distance, the two electrical geometric models intersect; if the arc is lower than the grounding distance, the two electrical geometric models do not intersect.

[0063] ② When the highest point of the protective arc surface of the lower transmission line is higher than the grounding distance of the upper line, compare the positional relationship between the highest point of the protective arc surface of the lower transmission line and the three exposed arcs and protective arcs of the upper line.

[0064] ③ After determining the position of the highest point of the protective arc surface of the lower transmission line, compare the height of the intersection of the protective arc and the exposed arc in the lower line with the positional relationship between the three layers of exposed arcs and the protective arc in the upper line.

[0065] ④ Finally, compare the height of the lightning protection wire in the lower transmission line with the position of the three-layer exposed arc and the protective arc of the upper line.

[0066] ⑤ After determining the positional relationship, the intersection area can be cut according to the intersection situation, and then the tripping rate can be calculated.

[0067] In step 4, the calculation formulas for double-circuit sections on the same tower and cross-span sections are as follows:

[0068] P 同塔双回 = S 暴露面积 / ( S 暴露面积 + S 保护面积 ) ;

[0069] P 交叉跨越 =( S 暴露面积 - S ) / ( S 暴露面积 + S 保护面积 ) ;

[0070] P 同塔双回 For double-circuit lines on the same tower, the swerving rate is... P 交叉跨越 This refers to the bypass rate of a double-circuit line on the same tower when an intersection occurs. S 暴露面积 and S 保护面积 They are respectively Figure 3 The exposed projection area of ​​the conductor and the protected projection area of ​​the lightning conductor are shown in the figure. S is the intersection area of ​​the two electrical geometric models when a crossing occurs, specifically... Figure 7 The cross-sectional area of ​​the upper sloping line in the diagram.

[0071] In step 5, the line segment is a span, including lightning protection wire and conductor.

[0072] The formula for calculating the trip rate due to over-the-horizon operation is as follows:

[0073] ;

[0074] In the formula, The line's tripping rate due to backlash. The line's skewing rate, For the maximum winding current, The critical flashover current, d Exposure distance is calculated using the following formula:

[0075] ;

[0076] according to Figure 3 It can be seen that in the formula, h 1 andh 4 represents the ground elevation at points A and D, respectively.

[0077] f ( I () is the probability density function of lightning current. η The arc-building rate is calculated using the following formula:

[0078] ;

[0079] ;

[0080] In the formula, E The average operating voltage (RMS) gradient of the insulator string, in kV / m; Given the magnitude of the lightning current, This is a variable representing the amplitude of the lightning current. Furthermore, the above formula involves... , Specific data can be found in GB / T 50064-2014, the specification for overvoltage protection and insulation coordination design of AC electrical installations.

[0081] This invention provides a method for calculating the tripping rate of crossing lines that takes into account multiple factors. The technical advantages are as follows:

[0082] 1) The method of the present invention can be calculated by programming based on the actual parameters of the crossing line, and the obtained bypass trip rate is close to the actual working condition, which to a certain extent meets the calculation requirements of the bypass trip rate of the crossing line.

[0083] 2) In step 4 of this invention, the cross-sectional area is approximated by combining graphics in the case of intersection, which facilitates calculation while ensuring the accuracy of the calculation. Attached Figure Description

[0084] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0085] Figure 1 This is a flowchart of the calculation method of the present invention.

[0086] Figure 2 It is an improved electrical geometry model that takes into account the lightning incident angle.

[0087] Figure 3 It is a three-dimensional electrical geometry model of a double-circuit line on the same tower.

[0088] Figure 4 It is an improved electrical geometry model that takes into account the terrain inclination angle.

[0089] Figure 5 It is a three-dimensional electrical geometry model of a single-circuit line.

[0090] Figure 6(a) is a schematic diagram of the crossover situation corresponding to the lightning current amplitude. Figure 1 ( I < I 2);

[0091] Figure 6(b) is a schematic diagram of the crossover situation corresponding to the lightning current amplitude. Figure 2 ( I 2< I < I 3);

[0092] Figure 6(c) is a schematic diagram of the crossover situation corresponding to the lightning current amplitude. Figure 3 ( I 3< I < I 4);

[0093] Figure 6(d) illustrates the crossover situation corresponding to the lightning current amplitude. Figure 4 ( I 4< I < I 1).

[0094] Figure 7 This is a diagram showing the crossing. Detailed Implementation

[0095] The calculation method for the tripping rate of cross-crossing lines considering multiple factors is proposed. Based on actual line parameters, mainly including the height of the tower connection point to the ground and the length of the crossarm, a three-dimensional electrical geometric model is constructed. The tripping rate of double-circuit lines on the same tower is calculated, followed by the calculation of the tripping rate of the cross-crossing line section after considering the lightning shielding effect. Finally, the tripping rate of the cross-crossing line is calculated considering factors such as the lightning incident angle and the terrain tilt angle. The method includes the following steps:

[0096] Step 1: Obtain actual data on the line corridor and lightning activity:

[0097] The obtained data includes the tower's height to ground, crossarm length, ground flash density, and lightning current probability density at the tower connection point. The lightning current probability density is calculated uniformly through integration, and specific information for the calculation examples below is shown in Table 1.

[0098]

[0099] Step 2: Factors such as the sag of the track section, the angle of lightning incidence, and the terrain slope were considered.

[0100] Taking into account the sag of the track section, the catenary equation is used to represent the height of each point within the track section.

[0101] The equation of the catenary is the one mentioned above. h x The calculation formula is as follows:

[0102] ;

[0103] The formula for calculating the arc projection length after considering the catenary equation is as follows:

[0104] ;

[0105] ;

[0106] ;

[0107] ;

[0108] ;

[0109]

[0110] ;

[0111] ;

[0112] In the formula, L Let the arc projection length be . H c The height of each conductor connection point relative to the ground. w This represents the straight-line distance between the points where two adjacent conductors connect. To protect the corner, f This is the longest sag distance in the range.

[0113] The formulas for calculating the protection width and the exposed width are as follows:

[0114] ;

[0115] ;

[0116] ;

[0117] ;

[0118] In the formula, x 1 represents the protected width, x3 represents the exposed width, and the calculation is adjusted according to the above formula. L The protected area and exposed area can be obtained by taking the corresponding conductor parameters.

[0119] The effects of lightning incidence angle and terrain tilt angle were considered, and the line tripping rate after taking these two factors into account was analyzed and calculated. The formula for calculating the tripping rate is as follows:

[0120] ;

[0121] Among them, the terrain dip angle mainly affects the terrain dip angle, and it is only necessary to... r g Change to r g1 Therefore, when considering the lightning incident angle, the area of ​​the oblique projection can be calculated using the formula based on the calculated vertical projection.

[0122] Step 3: Construct an improved electrical geometric model. Based on the geometric positional relationships, calculate the intersecting cross-sectional area between the crossing lines, and then calculate the tripping rate of the crossing line segment. Specifically, as follows... Figure 7 As shown.

[0123] The cross-sectional area of ​​the intersection needs to be calculated based on the positional relationship of the electrical geometry model formed by the two towers. The cross-sectional area can be divided into 5 cases:

[0124] 1) When I > I At time 1, the highest point of the arc surface of the lower-level line protection is lower than the grounding distance of the upper-level line, and at this time the lower-level line has no lightning shielding effect on the upper-level line.

[0125] 2) When I < I At time 1, the highest point of the arc surface of the lower-level line's protective arc is higher than the grounding distance of the upper-level line. At this time, the lower-level line provides lightning shielding for the upper-level line. When the lightning current amplitude... I < I At time 2, the protective arc surface of the lower-level line intersects with the lowest exposed arc surface of the upper-level line.

[0126] 3) When I 2< I < I At 3 o'clock, the highest point of the lower-level line's protective arc surface is higher than the lowest exposed arc surface of the upper-level line. At this time, the lightning shielding effect will simultaneously shield the middle and lower exposed surfaces.

[0127] 4) When I 3< I < I At time 4, the highest point of the protective arc surface of the lower line is higher than the middle exposed arc surface of the upper line. At this time, the protective arc surface of the lower line will partially intersect with the protective arc surface of the upper line, so only the remaining part can shield the exposed surface.

[0128] 5) When I 4< I < I At time 1, the highest point of the lower-level line's protective arc surface is higher than the uppermost exposed arc surface of the upper-level line. At this time, the lightning shielding effect will simultaneously shield all exposed surfaces.

[0129] Crossover cases such as Figure 7As shown.

[0130] in: I 1 represents the lightning current when the highest point of the lower line protection arc is at the same height as the grounding distance of the upper line. I 2 represents the lightning current when the highest point of the protective arc of the lower line is at the same height as the highest point of the exposed arc surface of the lowest layer of the upper line. I 3 represents the lightning current when the highest point of the lower-level line's protective arc is at the same height as the highest point of the exposed arc surface of the upper-level line's intermediate arc. I 4 represents the lightning current when the highest point of the lower-level protective arc is at the same height as the highest point of the uppermost exposed arc surface of the upper-level line. The calculation formula is as follows:

[0131] ;

[0132] ;

[0133] In the formula, q Take 2, 3, and 4 respectively; h 5 and h 1 represents the height of the lightning protection wires above the ground for the lower and upper lines, respectively, in meters (m). h 5 and h 1 corresponds to Figure 5 and Figure 3 The height of the lightning protection wire above the ground at point A.

[0134] C 2. C 3 and C 4 represents the maximum lightning strike current when the bottom, middle, and top exposed arc surfaces are completely shielded, and the calculation formulas are shown below:

[0135] ;

[0136] In the formula, n Take 1, 2, and 3 respectively. m By taking values ​​of 2, 3, and 4 respectively, and then using the strike distance formula, the maximum winding current can be calculated.

[0137] This invention considers that the protective arc surface of the lower line is completely within the span. When the lightning current is small, the crossing situation is as shown in Figure 6(a). This situation can be calculated according to the following formula:

[0138] ;

[0139] ;

[0140]

[0141]

[0142] ;

[0143] ;

[0144] ;

[0145] In the formula, h 5. h 6. d 5 and d 6 represents the height of the lightning protection wire and conductor above ground and the length of the crossarm in the lower-level line, in meters; h 4 and d 4 represents the ground height and crossarm length of the lowest conductor in the upper-level line, respectively, in meters.

[0146] This invention approximately will S △AEF and S △AFC The sum of the areas is used as S AEC The area of ​​the line is then used to calculate the entrapment rate using the following formula:

[0147] ;

[0148] ;

[0149] When the lightning current increases, the cross-sectional area of ​​the intersecting lines can also be divided in this way, and then the cross-sectional area of ​​the intersecting lines under the action of each lightning current can be calculated in a cyclical analysis, so as to calculate the tripping rate of the crossing lines.

[0150] Specific calculation example:

[0151] Taking a specific crossing line as an example, where the upper line consists entirely of double-circuit towers on the same tower, and the lower line consists entirely of single-circuit towers, the crossing section is as follows: Figure 7 As shown.

[0152] The structural parameters of the towers crossing the line sections are shown in Table 2:

[0153]

[0154] The tripping rates of the crossing lines before and after considering the lightning shielding effect are calculated separately and are shown in Table 3:

[0155]

[0156] As shown in Table 3, without considering the lightning shielding effect, the tripping rate of a double-circuit line section on the same tower due to lightning strikes is 0.9602 times / 100 (unit: km·a). Considering the lightning shielding effect, the tripping rate due to lightning strikes is 0.8525 times / 100 (unit: km·a), which is 0.1077 times / 100 (unit: km·a) less than that without considering the lightning shielding effect, accounting for 11.21%.

Claims

1. A method for calculating the tripping rate of crossing lines considering multiple factors, characterized in that... Includes the following steps: Step 1: Based on the obtained transmission line and tower parameters, determine the three-dimensional electrical geometry model and obtain lightning activity parameters; Step 2: Based on the three-dimensional electrical geometry model in Step 1, considering the terrain tilt angle and the lightning incident angle respectively, an improved electrical geometry model considering the terrain tilt angle and an improved electrical geometry model considering the lightning incident angle were constructed. Step 3: Based on the improved electrical geometry model considering the terrain tilt angle in Step 2, calculate the ground strike distance after considering the terrain tilt angle; based on the improved electrical geometry model considering the lightning incident angle in Step 2, calculate the tilted projected area. Step 4: Based on the ground strike distance and tilted projected area calculated in Step 3, and considering the lightning shielding effect between crossing lines, calculate the intersection area under different lightning currents according to the intersection of the arc surfaces of the two electrical geometric models. ； Step 5: Based on the oblique projection area calculated in Step 3 and the intersecting cross-sectional area calculated in Step 4, calculate the tripping rate of each line segment of the transmission line. In step 3, when considering the terrain slope angle, the impact is on the ground impact distance. The changes in the ground impact distance after considering the terrain slope angle are calculated as follows: ； ； ； In the formula, h 3. h 4. b 3. b 4 represents the height of the two conductors above the ground and the length of the crossarm, respectively; r g1 To account for the ground strike distance after considering the terrain slope, β The slope angle of the terrain; This refers to the ground impact distance without considering other factors. In step 3, the probability distribution formula for the lightning incident angle and the formula for calculating the line projected area after considering the lightning incident angle are as follows: ； ； In the formula, The probability distribution of the lightning incident angle; λ The angle of incidence of lightning; This refers to the height of the lightning protection wire above the ground. r gmax The ground fault distance under the maximum winding current; K The height of the highest point of the protective arc surface of the lightning protection wire and the exposed arc surface of the conductor above the ground; r s This refers to the line distance.

2. The method for calculating the tripping rate of crossing lines considering multiple factors as described in claim 1, characterized in that: In step 1, the transmission line parameters include the spatial location of the conductors and ground wires; the tower parameters include the tower type, tower height, and crossarm length; and the lightning activity parameters include the ground flash density and the lightning current amplitude distribution function.

3. The method for calculating the tripping rate of crossing lines considering multiple factors as described in claim 1, characterized in that: In step 4, the two electrical geometric models include: the electrical geometric model of a double-circuit line on the same tower and the electrical geometric model of a single-circuit line.

4. The method for calculating the tripping rate of crossing lines considering multiple factors as described in claim 3, characterized in that: The cross-sectional area is calculated based on the positional relationship of the electrical geometry model formed by the two towers. The cross-sectional area can be divided into 5 cases: 1) When I > I At time 1, the highest point of the arc surface of the lower line protection is lower than the grounding distance of the upper line, and at this time the lower line has no lightning shielding effect on the upper line. 2) When I < I At time 1, the highest point of the arc surface of the lower-level line's protective arc is higher than the grounding distance of the upper-level line. At this time, the lower-level line provides lightning shielding for the upper-level line; when the lightning current amplitude... I < I At time 2, the protective arc surface of the lower-level line intersects with the lowest exposed arc surface of the upper-level line; 3) When I 2< I < I At 3 o'clock, the highest point of the lower-level line's protective arc surface is higher than the lowest exposed arc surface of the upper-level line; at this time, the lightning shielding effect will simultaneously shield the middle and lower exposed surfaces. 4) When I 3< I < I At 4 o'clock, the highest point of the protective arc surface of the lower line is higher than the middle exposed arc surface of the upper line. At this time, the protective arc surface of the lower line will partially intersect with the protective arc surface of the upper line, so only the remaining part can shield the exposed surface. 5) When I 4< I < I At time 1, the highest point of the lower line's protective arc surface is higher than the uppermost exposed arc surface of the upper line. At this time, the lightning shielding effect will simultaneously shield all exposed surfaces. in: I 1 represents the lightning current when the highest point of the lower line protection arc is at the same height as the grounding distance of the upper line; I 2 represents the lightning current when the highest point of the protective arc of the lower line is at the same height as the highest point of the exposed arc surface of the lowest layer of the upper line; I 3 represents the lightning current when the highest point of the lower-level line's protective arc is at the same height as the highest point of the exposed arc surface in the middle of the upper-level line; I 4 represents the lightning current when the highest point of the lower-level line's protective arc is at the same height as the highest point of the uppermost exposed arc surface of the upper-level line.

5. The method for calculating the tripping rate of crossing lines considering multiple factors as described in claim 1, characterized in that: In step 4, the calculation formulas for double-circuit sections on the same tower and cross-span sections are as follows: P 同塔双回 = S 暴露面积 / ( S 暴露面积 + S 保护面积 ) P 交叉跨越 =( S 暴露面积 - S ) / ( S 暴露面积 + S 保护面积 ) ； In the formula, P 同塔双回 For double-circuit lines on the same tower, the swerving rate is... P 交叉跨越 This refers to the bypass rate of a double-circuit line on the same tower when an intersection occurs. S 暴露面积 and S 保护面积 These are the exposed projection area of ​​the conductor and the protected projection area of ​​the lightning protection wire, respectively. S is the intersection area of ​​the two electrical geometric models when a crossover occurs.

6. The method for calculating the tripping rate of crossing lines considering multiple factors as described in claim 1, characterized in that: In step 5, the formula for calculating the tripping rate is as follows: ； In the formula, The line's tripping rate due to backlash. The line's skewing rate, For the maximum winding current, The critical flashover current, d Exposure distance is calculated using the following formula: ； In the formula, h 1 and h 4 represents the ground elevation at points A and D, respectively; f ( I () is the probability density function of lightning current. η For the arc-building rate; The calculation formula is as follows: ； ； In the formula, E The average operating voltage gradient of the insulator string, in kV / m; Given the magnitude of the lightning current, This is a variable representing the amplitude of the lightning current.

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