Optimization calculation method for lightning protection shunt strip spacing based on lightning breakdown and flashover effect

Abstract

This invention discloses an optimized calculation method for the spacing of lightning protection shunt strips based on lightning breakdown and flashover effects, specifically as follows: Step 1: Determine the spacing H from the lightning origin to the radome housing; Step 2: Determine the minimum distance d between the protected device and the radome housing; Step 3: Determine the thickness t of the radome housing; Step 4: Determine the breakdown field strength of the radome housing material and the flashover field strength along the surface of the radome housing based on the material properties of the radome housing. E surface Step 5: Calculate the shunt bar spacing under the condition that lightning directly strikes the shunt bars; Step 6: Calculate the shunt bar spacing under the condition that lightning strikes the shunt bars after a surface flashover; Step 7: Establish a dual-condition constraint model for the shunt bar spacing. This method can ensure that lightning current can flash onto the shunt bars under both conditions, avoiding or reducing lightning damage to the composite material radome housing.

Description

Technical Field

[0001] This invention belongs to the field of lightning protection technology, specifically relating to an optimization calculation method for the spacing of lightning protection shunt bars based on lightning breakdown and flashover effects. Background Technology

[0002] Traditional designs for shunt bar spacing often fail to adequately consider the structural relationship between the protected object (typically a metal antenna structure) and the composite radome housing, as well as the coupling effects of surface flashover and direct breakdown. Differences in radome housing material and the spacing between the radome housing and the protected object both affect lightning interception performance.

[0003] In the lightning protection design system for aerospace vehicle radomes, shunt strip lightning interception methods include two types, such as... Figure 1 As shown, the first type is a direct lightning strike to the shunt bar. When lightning, in a complex electromagnetic environment, travels along the most vulnerable path with its immense energy, it may strike the shunt bar directly. In this case, the straight-line distance between the lightning's origin and the shunt bar becomes the preferred path for the lightning current. Due to the special structural design and electrical performance of the shunt bar, it can effectively disperse the enormous energy of the lightning, preventing the energy from accumulating locally and causing severe damage to the equipment. The second type is where lightning first originates from the lightning's origin and adheres to the surface of the radome housing. Then, before penetrating the radome housing, a surface flashover occurs, striking the shunt bar. In this case, the lightning's energy first acts on the surface of the radome housing. Although the radome housing has insulation and protective functions, under the strong electric field of lightning, charge accumulation and uneven distribution may occur on the surface of the radome housing. When this charge distribution and accumulation reach a certain level, a surface flashover will occur. A surface flashover is a special discharge phenomenon that conducts along the surface of the radome housing rather than directly penetrating it. The surface flashover path of lightning along the radome housing can be affected by various factors, including the material, roughness, and humidity of the radome housing surface. Once a surface flashover occurs, the conducted energy is highly likely to strike the shunt strip. The shunt strip then plays a crucial role in dispersing energy and preventing direct lightning strikes to the equipment, ensuring the safety and stability of the protected device under lightning strikes.

[0004] Direct lightning strike has its unique characteristics, and the surface flashover also has corresponding rules. The two lightning diversion strip connection methods have mutual influence. However, the traditional design ignores this joint action, so that the design is insufficient when dealing with complex situations, and finally leads to the difficulty of reaching the expected protection range. And in the current research and application in the related field, there is no quantitative spacing calculation model based on the insulating strength of the antenna cover shell material and the air breakdown field strength. This may lead to a lack of scientific and precise basis for setting the air gap spacing of the lightning diversion strip in practical operation, and it is impossible to effectively determine the appropriate spacing by combining the specific values of the material and air field strength, which may affect the safety and stability of the overall system. SUMMARY

[0005] The purpose of the present application is to provide a lightning protection diversion strip spacing optimization calculation method based on lightning breakdown and flashover effect, and to give a diversion strip spacing calculation method under the coupling conditions of direct lightning strike and surface flashover, to ensure that lightning current can be struck to the diversion strip under the two conditions, and to avoid or reduce the lightning damage of the composite antenna cover shell.

[0006] The technical solution adopted by the present application is a lightning protection diversion strip spacing optimization calculation method based on lightning breakdown and flashover effect, which is as follows:

[0007] Step 1: Determine the distance H from the lightning starting point to the antenna cover shell;

[0008] Step 2: Determine the minimum distance d between the protected device and the antenna cover shell;

[0009] Step 3: Determine the thickness t of the antenna cover shell;

[0010] Step 4: Determine the breakdown field strength of the antenna cover shell material according to the material properties of the antenna cover shell And the field strength of the surface flashover along the antenna cover shell E surface ;

[0011] Step 5: Calculate the diversion strip spacing under the condition of lightning directly striking the diversion strip ;

[0012] Step 6: Calculate the diversion strip spacing under the condition of lightning striking the diversion strip after surface flashover ;

[0013] Step 7: Establish a double-condition constraint model for the diversion strip spacing.

[0014] The present application is also characterized by:

[0015] In step 1, the distance H is specifically solved by an empirical formula, which is as follows:

[0016] (1)

[0017] Wherein, E is the lightning discharge amplitude obtained according to the actual meteorological monitoring; k is the needle plate breakdown coefficient, which is positively correlated with the size of the radome shell, , ; is the air breakdown field strength, and is ; M is the maximum side length of the radome shell, and the unit is cm; m is the boundary allowance of the radome shell, which reduces the influence of the boundary effect, , and the unit is cm.

[0018] Step 2 is specifically:

[0019] According to the three-dimensional structure model of the lightning protection object composed of the radome shell and the protected device, the key protection position is determined; in the three-dimensional structure model of the lightning protection object, the position of the radome shell closest to the protected device is taken as the key protection position, and the vertical distance between the key protection position and the protected device is the minimum distance d between the protected device and the radome shell.

[0020] Step 3 is specifically:

[0021] The three-dimensional software is used to measure the three-dimensional structure model of the lightning protection object, and the thickness t of the radome shell is obtained.

[0022] In step 5:

[0023] The condition for lightning directly hitting the shunt strip is that the total air breakdown voltage drop between the lightning starting point and the shunt strip is less than or equal to the voltage drop from the lightning starting point to the protected device, which is equal to the sum of the air breakdown voltage drop from the lightning starting point to the radome shell, the breakdown voltage drop of the radome shell material, and the air breakdown voltage drop from the radome shell to the protected device .

[0024] According to the condition for directly hitting the shunt strip, the relationship between the total air breakdown voltage drop between the lightning starting point and the shunt strip and the voltage drop from the lightning starting point to the protected device is constructed, which is specifically as follows:

[0025] (2)

[0026] Wherein: is the air breakdown field strength; is the straight-line distance from the lightning starting point to the nearest shunt strip; H is the distance between the lightning starting point and the radome shell; is the breakdown field strength of the radome shell material; is the thickness of the radome shell; This is the minimum distance between the protected device and the antenna housing.

[0027] In formula (2), the straight-line distance from the lightning origin to the nearest shunt strip is... The expression is:

[0028] (3)

[0029] Substituting formula (3) into formula (2), the spacing between the shunt bars under the condition of direct lightning strike is calculated. Satisfy the following expression:

[0030] (4).

[0031] In step 6:

[0032] The condition for a lightning strike to hit the shunt bar after a surface flashover is: when lightning strikes but does not penetrate the radome housing, the insulation breakdown voltage drop required for air breakdown along the distance from the flashover point on the radome housing surface to the shunt bar is... It must be less than the breakdown voltage drop of the radome housing material. ;

[0033] Based on the conditions under which a lightning flashover occurs and then strikes the shunt bar, the insulation breakdown voltage drop of the radome housing material is constructed. The insulation breakdown voltage drop required for air breakdown along the distance from the flash point on the radome housing to the shunt strip. The relationship between the two insulation breakdown voltage drops is used to ensure that the two insulation breakdown voltage drops satisfy formula (5), as follows:

[0034] (5)

[0035] in: E surface This represents the electric field strength during surface flashover. d surface = / 2 represents the path length from the surface of the radome housing to the shunt strip; The breakdown field strength of the radome housing material; The thickness of the radome housing;

[0036] Will d surface = Substituting / 2 into formula (5), we obtain the shunt bar spacing under the condition that lightning strikes the shunt bar after a surface flashover. The details are as follows:

[0037] (6).

[0038] In step 7: the established shunt strip spacing double condition constraint model is specifically shown in formula (7):

[0039] (7)

[0040] Wherein: S is the safety factor value.

[0041] In step 7: the safety factor value S is determined according to the lightning partition, when in 1A area, S is 0.3, and S is 0.5 in other lightning partitions.

[0042] The beneficial effects of the application are:

[0043] The method of the application gives the shunt strip spacing calculation method under the two coupling conditions of direct hit and surface flashover under the condition of fully considering the relationship between the metal antenna structure and the composite antenna radome shell, ensures that the lightning current can be connected to the shunt strip under the two conditions, avoids or reduces the lightning damage of the composite antenna radome shell. The method can accurately analyze the electric field characteristics, and determine the optimal lightning shunt strip arrangement strategy according to the electric field breakdown principle. Its application scenarios are very wide, and it is especially suitable for composite antenna radome shell structures that need lightning protection, such as aerospace vehicles, buildings, etc. In the field of aerospace, flight safety can be ensured; in the field of building, the internal personnel and facilities can be effectively protected. The effectiveness of lightning protection is significantly improved through the innovative method. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a schematic diagram of two lightning shunt modes of lightning shunt strip;

[0045] Figure 2 It is a schematic diagram of lightning directly hitting the shunt strip;

[0046] Figure 3 It is a schematic diagram of lightning surface flashover to the shunt strip;

[0047] Figure 4 It is a schematic diagram of lightning connection.

[0048] In the figure, 1 is the lightning starting point, 2 is the lightning direct breakdown path, 3 is the lightning surface flashover path, 4 is the shunt strip, 5 is the antenna radome shell, 6 is the protected device, and 7 is the lightning current. DETAILED DESCRIPTION

[0049] The application will be described in detail below in combination with the drawings and specific embodiments.

[0050] The application provides a lightning protection shunt strip spacing optimization calculation method based on lightning breakdown and flashover effect, which is specifically as follows:

[0051] Step 1: determine the distance H from the lightning starting point 1 to the antenna radome shell 5, and the specific solution formula is as follows:

[0052] (1)

[0053] wherein E is the lightning discharge amplitude obtained according to actual meteorological monitoring, E = 1000 kV; k is the needle plate breakdown coefficient, which is positively correlated with the size of the radome shell 5, , ; is the air breakdown field strength, which is ; M is the maximum side length of the radome shell 5, with the unit of cm; m is the boundary allowance of the radome shell 5, which reduces the influence of the boundary effect, , with the unit of cm.

[0054] Step 2: Determine the minimum distance d between the protected device 6 and the radome shell 5, specifically as follows:

[0055] According to the three-dimensional structure model of the lightning protection object composed of the radome shell 5 and the protected device 6, determine the key protection position; in the three-dimensional structure model of the lightning protection object, the position of the radome shell 5 closest to the protected device 6 is taken as the key protection position, and the vertical distance between the key protection position and the protected device 6 is the minimum distance d between the protected device 6 and the radome shell 5;

[0056] Step 3: Determine the thickness t of the radome shell 5, specifically as follows:

[0057] Measure the three-dimensional structure model of the lightning protection object by using three-dimensional software (such as CATIA, etc.), and obtain the thickness t of the radome shell 5;

[0058] Step 4: Determine the radome shell material breakdown field strength and the field strength along the surface flashover of the radome shell E surface ;

[0059] Step 5: Calculate the shunt strip spacing under the condition that lightning directly hits the shunt strip 4;

[0060] In Step 5:

[0061] The condition that lightning directly hits the shunt strip 4 is that the total air breakdown voltage drop between the lightning starting point 1 and the shunt strip 4 is less than or equal to the voltage drop from the lightning starting point 1 to the protected device 6 (such as the distance between the radome shell 5 and the protected device 6 is 65 mm), which is equal to the air breakdown voltage drop from the lightning starting point 1 to the radome shell 5 , the radome shell material breakdown voltage drop and the air breakdown voltage drop from the radome shell 5 to the protected device 6 The operating trajectory of the lightning current 7 is the lightning direct strike path 2 as shown in Figures 1-2 .

[0062] The total voltage drop of the air breakdown between the lightning inception point 1 and the shunt bar 4 under the condition of direct strike of the shunt bar 4 is , and the relationship between the voltage drop of the lightning inception point 1 and the protected device 6 is as follows:

[0063] (2)

[0064] Wherein: is the air breakdown field strength; is the straight-line distance from the lightning inception point 1 to the nearest shunt bar 4; H is the distance from the lightning inception point 1 to the radome shell 5 (1m-3m); is the breakdown field strength of the radome shell material; is the thickness of the radome shell 5; is the minimum distance between the protected device 6 and the radome shell 5;

[0065] In formula (2), the expression of the straight-line distance from the lightning inception point 1 to the nearest shunt bar 4 is:

[0066] (3)

[0067] The shunt bar distance under the condition of direct strike of the shunt bar 4 is calculated by bringing formula (3) into formula (1) as , which satisfies the following expression:

[0068] (4).

[0069] Step 6: Calculate the shunt bar distance under the condition of strike of the shunt bar 4 after the lightning surface flashover occurs .

[0070] In step 6:

[0071] The condition of strike of the shunt bar 4 after the lightning surface flashover occurs is that when the lightning strikes but does not break down the radome shell 5, the insulation breakdown voltage drop required for the air breakdown of the striking point on the radome shell 5 along the distance from the surface of the radome shell 5 to the shunt bar 4 needs to be less than the breakdown voltage drop of the radome shell material , and the operating trajectory of the lightning current 7 is the lightning surface flashover path 3 as shown in Figure 1 and Figure 3 .

[0072] The relationship between the air breakdown insulation breakdown voltage drop of the distance from the lightning striking point on the antenna housing 5 to the shunt bar 4 and the breakdown insulation breakdown voltage drop of the antenna housing material is established, and the two breakdown insulation breakdown voltage drops satisfy formula (5) as follows:

[0073] (5)

[0074] Wherein: E surface is the field strength of the surface flashover; d surface is the path length from the surface of the antenna housing 5 to the shunt bar 4; is the breakdown field strength of the antenna housing material; is the thickness of the antenna housing 5;

[0075] d surface is substituted into formula (5) to obtain the shunt bar spacing under the condition that the lightning surface flashover occurs and hits the shunt bar 4 , which is as follows:

[0076] (6)

[0077] Step 7: Establish a double-condition constraint model of the shunt bar spacing to determine the final spacing of the shunt bar 4 , avoid the risk of edge electric field distortion, and ensure that the lightning current 7 strikes the shunt bar, as shown in Figure 4 , and as shown in formula (7):

[0078] (7)

[0079] Wherein: S is the safety factor value; the safety factor value S is determined according to the lightning zoning, and when in the 1A zone, S is 0.3, and in other lightning zones, S is 0.5;

[0080] Example 1

[0081] The lightning shunt bar spacing optimization calculation method based on lightning breakdown and flashover effect is as follows:

[0082] Step 1: Determine the spacing H of the lightning starting point 1 to the test piece;

[0083] ​​​​​According to the provisions of the lightning protection test method in SAE ARP 5416A or GJB 3567A-2023 standard, the electrode of the simulated lightning source is hung above the test piece, and the distance between the electrode and the test piece should not be less than 1m, the distance between the electrode and the test piece is determined according to the size of the test piece, and the distance is 1m-3m; the lightning starting point 1 is equivalent to the position of the electrode of the simulated lightning source in SAE ARP 5416A or GJB 3567A-2023 standard, the test piece is equivalent to the antenna cover shell 5, and the voltage generator is used to simulate lightning;

[0084] The specific method is as follows:

[0085] The test piece (equivalent to the antenna cover shell 5) is a 1000mm*1000mm flat plate structure, according to the provisions of the lightning protection test method in standard SAE ARP 5416A or GJB 3567A-2023, and the following empirical formula is calculated:

[0086] (1)

[0087] Wherein, E is the discharge amplitude of the voltage generator to simulate the actual lightning discharge amplitude obtained by meteorological monitoring, E=1000kV; k is the needle plate breakdown coefficient, ; The air breakdown field strength is ; M is the maximum side length of the test piece, M=100cm, unit: cm; m is the boundary allowance of the test piece, m=10cm.

[0088] After calculation, H=0.92m, and according to the standard SAE ARP 5416A, the minimum value of H is 1m, so the H of the present example is 1m.

[0089] Step 2: determine the minimum distance d between the protected device 6 and the test piece, the specific method is as follows:

[0090] According to the three-dimensional structure model of the lightning protection object composed of the test piece and the protected device 6, the position of the test piece closest to the protected device 6 is taken as the key protection position, and the vertical distance between the key protection position and the protected device 6 is the minimum distance d between the protected device 6 and the test piece, the minimum distance d between the present test piece and the protected device 6 is 65mm;

[0091] Step 3: determine the thickness t of the test piece, the specific method is as follows:

[0092] The three-dimensional software CATIA is used to measure the three-dimensional structure model of the lightning protection object, and the thickness t of the test piece is 4.8mm;

[0093] Step 4: the material of the present test piece is glass fiber reinforced plastic, and its breakdown field strength and the field strength along the radome shell surface to flashover E surface 12.8 kV / mm, 140 kV / m, respectively.

[0094] Step 5: Calculate the shunt strip spacing under the condition that lightning directly hits the shunt strip 4 ;

[0095] According to the condition of directly hitting the shunt strip 4, the total voltage drop of air breakdown between the lightning starting point 1 and the shunt strip 4 is constructed And the relationship between the voltage drop of the lightning starting point 1 to the protected device 6 is as follows:

[0096] (2)

[0097] Wherein: 3 kV / mm is the air breakdown field strength; is the straight-line distance from the lightning starting point 1 to the nearest shunt strip 4; H is the distance from the lightning starting point 1 to the test piece; is the breakdown field strength of the radome shell material; is the thickness of the test piece; is the minimum distance between the protected device 6 and the test piece;

[0098] In formula (2), the expression of the straight-line distance from the lightning starting point 1 to the nearest shunt strip 4 is:

[0099] (3)

[0100] The formula (3) is brought into the formula (2) to calculate the shunt strip spacing under the condition that lightning directly hits the shunt strip 4 Satisfy the following expression:

[0101] (4).

[0102] The parameter values obtained in steps 1 to 4 are brought into the above formula:

[0103] =844.4mm

[0104] Step 6: Calculate the shunt strip spacing under the condition that lightning hits the shunt strip 4 after the surface flashover occurs ;

[0105] Ensure that the following formula is satisfied:

[0106] (5)

[0107] Wherein: Esurface The field strength of the surface flashover; d surface = 877.7mm The path length from the surface of the test piece to the shunt 4; The breakdown field strength of the radome shell material; The thickness of the test piece;

[0108] The parameters obtained in steps 3 and 4 are brought into formula (6): d surface = 877.7mm The shunt spacing under the condition that lightning surface flashover occurs and hits the shunt 4 is obtained by bringing into formula (5), as follows:

[0109] (6);

[0110] The parameter values obtained in steps 3 and 4 are brought into formula (6):

[0111] = 877.7mm

[0112] Step 7: Establish a double-condition-constrained model of shunt spacing, as shown in formula (7): Determine the final spacing of the shunt 4, avoid the risk of edge electric field distortion, and ensure that the lightning current strikes the shunt;

[0113] (7)

[0114] Since the lightning division of the test piece is 1A zone, the safety factor value is 0.3. The calculation results obtained in steps 5 and 6 are brought into formula (7) to obtain :

[0115] = 253mm;

[0116] According to the calculation result of step 7, arrange the lightning shunt on the test piece, and carry out verification test according to the method TL101 (initial leader attachment test) in the standard GJB3576A-2023. First, carry out the test piece verification test of the radome plate level, and arrange four parallel and equal-spaced shunts on the surface of the test piece (the spacing between adjacent two shunts is ), the four shunt strips are named in turn as: first shunt strip, second shunt strip, third shunt strip and fourth shunt strip, and the test result statistics are shown in Table 1, a total of 6 tests, 3 times of positive and negative polarity of lightning (simulating the actual lightning situation), the lightning current generated by the voltage generator in the 6 tests is directly connected to the lightning shunt strip, and no damage is caused to the composite plate test piece. Then, an initial leader attachment test is carried out on a certain type of antenna cover, nine shunt strips are arranged on the certain type of antenna cover, which are parallel to each other and have equal spacing (the spacing between adjacent two shunt strips is ), the nine shunt strips are named in turn as: fifth shunt strip, sixth shunt strip, seventh shunt strip, eighth shunt strip, ninth shunt strip, tenth shunt strip, eleventh shunt strip, twelfth shunt strip and thirteenth shunt strip, and the test results are shown in Table 2, a total of 12 tests, 6 times of positive and negative polarity of lightning (simulating the actual lightning situation), the lightning current generated by the voltage generator in the 12 tests is connected to the lightning shunt strip, and no breakdown, ablation and other damage are caused in the antenna cover itself. Therefore, the spacing of the lightning shunt strip calculated by the present application meets the lightning protection of the antenna cover.

[0117] Table 1 Test results of plate-level test piece

[0118]

[0119] Table 2 Test results of a certain type of antenna cover

[0120]

[0121] Example 2

[0122] The lightning shunt strip spacing optimization calculation method based on lightning breakdown and flashover effect is as follows:

[0123] Step 1: Determine the spacing H of the lightning starting point 1 to the antenna cover shell 5;

[0124] Step 2: Determine the minimum distance d between the protected device 6 and the antenna cover shell 5;

[0125] Step 3: Determine the thickness t of the antenna cover shell 5;

[0126] Step 4: Determine the lightning cover shell material breakdown field strength and the field strength of the lightning cover shell surface flashover E surface ;

[0127] Step 5: Calculate the shunt strip spacing under the condition that the lightning directly hits the shunt strip 4;

[0128] Step 6: Calculate the shunt strip spacing under the condition that lightning hits the shunt strip 4 after the occurrence of surface flashover ;

[0129] Step 7: Establish a double-condition constraint model for shunt strip spacing.

[0130] Example 3

[0131] The lightning protection shunt strip spacing optimization calculation method based on lightning breakdown and flashover effect is as follows:

[0132] Step 1: Determine the distance H from the lightning starting point 1 to the antenna cover shell 5;

[0133] In step 1, the distance H is specifically solved by an empirical formula, which is as follows:

[0134] (1)

[0135] Wherein, E is the lightning discharge amplitude obtained according to the actual meteorological monitoring, E = 1000 kV; k is the needle plate breakdown coefficient, which is positively correlated with the size of the antenna cover shell 5, , ; The air breakdown field strength is ; M is the maximum side length of the antenna cover shell 5, with unit of cm; m is the boundary allowance of the antenna cover shell 5, which reduces the influence of boundary effect, , with unit of cm.

[0136] Step 2: Determine the minimum distance d between the protected device 6 and the antenna cover shell 5;

[0137] Step 3: Determine the thickness t of the antenna cover shell 5;

[0138] Step 4: Determine the antenna cover shell material breakdown field strength and the field strength of surface flashover along the antenna cover shell E surface ;

[0139] Step 5: Calculate the shunt strip spacing under the condition that lightning directly hits the shunt strip 4 ;

[0140] Step 6: Calculate the shunt strip spacing under the condition that lightning hits the shunt strip 4 after the occurrence of surface flashover ;

[0141] Step 7: Establish a double-condition constraint model for shunt strip spacing.

[0142] Example 4

[0143] The optimization calculation method for the spacing of lightning protection shunt bars based on lightning breakdown and flashover effects is as follows:

[0144] Step 1: Determine the distance H from the lightning origin 1 to the antenna housing 5;

[0145] In step 1, the spacing H is specifically calculated using an empirical formula, as follows:

[0146] (1)

[0147] Where E is the lightning discharge amplitude obtained from actual meteorological monitoring, E=1000kV; k is the needle-plate breakdown coefficient, which is positively correlated with the size of the antenna radome housing 5. , ; For air breakdown field strength, for M represents the maximum side length of the radome housing 5, in cm; m represents the boundary margin of the radome housing 5, which reduces the impact of boundary effects. The unit is cm.

[0148] Step 2: Determine the minimum distance d between the protected device 6 and the antenna housing 5;

[0149] Step 2 is as follows:

[0150] Based on the three-dimensional structural model of the lightning protection object consisting of the antenna housing 5 and the protected device 6, the critical protection position is determined. In the three-dimensional structural model of the lightning protection object, the position of the antenna housing 5 closest to the protected device 6 is taken as the critical protection position. The vertical distance between the critical protection position and the protected device 6 is the minimum distance d between the protected device 6 and the antenna housing 5.

[0151] Step 3: Determine the thickness t of the radome housing 5;

[0152] Step 4: Determine the breakdown field strength of the radome housing material based on the material properties of the radome housing 5. and the field strength of flashover along the surface of the radome housing E surface ;

[0153] Step 5: Calculate the spacing between shunt bars 4 under the condition that lightning directly strikes shunt bar 4. ;

[0154] Step 6: Calculate the shunt bar spacing under the condition that a lightning flashover occurs along the surface and strikes shunt bar 4. ;

[0155] Step 7: Establish a dual-condition constraint model for the spacing of the flow dividers.

[0156] Example 5

[0157] The lightning protection shunt strip spacing optimization calculation method based on lightning breakdown and flashover effect is as follows:

[0158] Step 1: Determine the spacing H from the lightning starting point 1 to the antenna cover shell 5.

[0159] In step 1, the spacing H is specifically solved by an empirical formula, as follows:

[0160] (1)

[0161] Wherein, E is the lightning discharge amplitude obtained according to the actual meteorological monitoring, E = 1000 kV; k is the needle plate breakdown coefficient, which is positively correlated with the size of the antenna cover shell 5, , ; is the air breakdown field strength, which is ; M is the maximum side length of the antenna cover shell 5, with the unit of cm; m is the boundary allowance of the antenna cover shell 5, which reduces the influence of boundary effect, , with the unit of cm.

[0162] Step 2: Determine the minimum distance d between the protected device 6 and the antenna cover shell 5.

[0163] Step 2 is as follows:

[0164] According to the three-dimensional structure model of the lightning protection object composed of the antenna cover shell 5 and the protected device 6, the key protection position is determined; in the three-dimensional structure model of the lightning protection object, the position of the antenna cover shell 5 closest to the protected device 6 is taken as the key protection position, and the vertical distance between the key protection position and the protected device 6 is the minimum distance d between the protected device 6 and the antenna cover shell 5.

[0165] Step 3: Determine the thickness t of the antenna cover shell 5.

[0166] Step 3 is as follows:

[0167] The three-dimensional software is used to measure the three-dimensional structure model of the lightning protection object to obtain the thickness t of the antenna cover shell 5.

[0168] Step 4: According to the material properties of the antenna cover shell 5, determine the antenna cover shell material breakdown field strength and the field strength of the antenna cover shell surface flashover E surface ;

[0169] Step 5: Calculate the shunt strip spacing under the condition that the lightning directly hits the shunt strip 4.

[0170] Step 6: Calculate the shunt bar spacing under the condition that lightning surface flashover hits the shunt bar 4 ;

[0171] Step 7: Establish a double-condition constraint model for shunt bar spacing.

[0172] Example 6

[0173] The lightning protection shunt bar spacing optimization calculation method based on lightning breakdown and flashover effect is as follows:

[0174] Step 1: Determine the distance H from the lightning starting point 1 to the antenna cover shell 5;

[0175] In step 1, the distance H is specifically solved by an empirical formula, which is as follows:

[0176] (1)

[0177] Wherein, E is the lightning discharge amplitude obtained according to the actual meteorological monitoring, E=1000kV; k is the needle plate breakdown coefficient, which is positively correlated with the size of the antenna cover shell 5, , ; The air breakdown field strength is ; M is the maximum side length of the antenna cover shell 5, with unit of cm; m is the boundary allowance of the antenna cover shell 5, which reduces the influence of boundary effect, , with unit of cm.

[0178] Step 2: Determine the minimum distance d between the protected device 6 and the antenna cover shell 5;

[0179] Step 2 is as follows:

[0180] According to the three-dimensional structure model of the lightning protection object composed of the antenna cover shell 5 and the protected device 6, the key protection position is determined; in the three-dimensional structure model of the lightning protection object, the position of the antenna cover shell 5 closest to the protected device 6 is taken as the key protection position, and the vertical distance between the key protection position and the protected device 6 is the minimum distance d between the protected device 6 and the antenna cover shell 5.

[0181] Step 3: Determine the thickness t of the antenna cover shell 5;

[0182] Step 3 is as follows:

[0183] The three-dimensional software is used to measure the three-dimensional structure model of the lightning protection object to obtain the thickness t of the antenna cover shell 5.

[0184] Step 4: Determine the antenna cover shell material breakdown field strength and the field strength of surface flashover along the antenna cover shellE surface ;

[0185] Step 5: Calculate the shunt strip spacing under the condition that lightning directly hits the shunt strip 4 ;

[0186] In Step 5:

[0187] The condition that lightning directly hits the shunt strip 4 is that the total air breakdown voltage drop between the lightning starting point 1 and the shunt strip 4 is less than or equal to the voltage drop from the lightning starting point 1 to the protected device 6, which is equal to the sum of the air breakdown voltage drop from the lightning starting point 1 to the radome housing 5 , the breakdown voltage drop of the radome housing material , and the air breakdown voltage drop from the radome housing 5 to the protected device 6 ;

[0188] According to the condition of directly hitting the shunt strip 4, the relationship between the total air breakdown voltage drop between the lightning starting point 1 and the shunt strip 4 and the voltage drop from the lightning starting point 1 to the protected device 6 is constructed, specifically as follows:

[0189] (2)

[0190] Where: is the air breakdown field strength; is the straight-line distance from the lightning starting point 1 to the nearest shunt strip 4; H is the distance from the lightning starting point 1 to the radome housing 5; is the breakdown field strength of the radome housing material; is the thickness of the radome housing 5; is the minimum distance between the protected device 6 and the radome housing 5;

[0191] In formula (2), the expression for the straight-line distance from the lightning starting point 1 to the nearest shunt strip 4 is:

[0192] (3)

[0193] Substituting formula (3) into formula (2) gives the shunt strip spacing under the condition that lightning directly hits the shunt strip 4 satisfies the following expression:

[0194] (4).

[0195] Step 6: Calculate the shunt strip spacing under the condition that lightning hits the shunt strip 4 after surface flashover occurs ;

[0196] Step 7: Establish the double conditional constraint model of the distance between the shunt bars.

Claims

1. A lightning protection shunt strip spacing optimization calculation method based on lightning breakdown and flashover effect, characterized in that, Specific as follows: Step 1: determine the distance H from the lightning starting point to the radome shell; Step 2: determine the minimum distance d between the protected device and the radome shell; Step 3: determine the thickness t of the radome shell; Step 4: Determine the radome shell material breakdown field strength based on the material properties of the radome shell and the field strength along the radome shell surface flashover E surface ; Step 5: Calculate the down conductor spacing under the condition of a direct lightning strike to the down conductor ; Step 6: Calculate the shunt strip spacing for the condition where a lightning surface flash strikes a shunt strip ; Step 7: establish a shunt strip spacing double condition constraint model.

2. The lightning arcing and flashover effect based lightning shunt strip spacing optimization calculation method of claim 1, wherein, In step 1, the distance H is specifically solved by an empirical formula, as follows: （1） Where E is the lightning discharge amplitude obtained from actual meteorological monitoring; k is the needle-plate breakdown coefficient. , ; For air breakdown field strength, for M represents the maximum side length of the radome housing, in cm; m represents the boundary margin of the radome housing. The unit is cm.

3. The lightning strike and flashover effect based lightning diverter strip spacing optimization calculation method according to claim 1, characterized in that, Step 2 is specifically: According to the three-dimensional structure model of the lightning protection object composed of the radome shell and the protected device, the key protection position is determined; in the three-dimensional structure model of the lightning protection object, the position of the radome shell closest to the protected device is taken as the key protection position, and the vertical distance between the key protection position and the protected device is the minimum distance d between the protected device and the radome shell.

4. The lightning strike and flashover effect based lightning diverter strip spacing optimization calculation method of claim 1, wherein, Step 3 is specifically: The three-dimensional structure model of the lightning protection object is measured by using three-dimensional software, and the thickness t of the radome shell is obtained.

5. The method for lightning strike and flashover effect based lightning shunt strip spacing optimization calculation of claim 1, wherein, In step 5: The condition for a direct lightning strike to the diverter bar is that the total air breakdown voltage drop between the lightning inception point and the diverter bar is less than or equal to the voltage drop from the lightning inception point to the protected device, which is equal to the air breakdown voltage drop from the lightning inception point to the radome housing , the breakdown voltage drop of the radome housing material and the air breakdown voltage drop from the radome housing to the protected device ; The total voltage drop of the air breakdown between the lightning inception point and the diverter bar is constructed according to the conditions of the direct hit of the diverter bar and the voltage drop between the lightning inception point and the protected device, specifically as follows: （2） wherein: is the air breakdown field strength; is the straight-line distance from the lightning inception point to the nearest shunt; H is the distance from the lightning inception point to the radome housing; is the breakdown field strength of the radome housing material; is the thickness of the radome housing; is the minimum distance between the protected device and the radome housing; In formula (2), the linear distance from the lightning starting point to the nearest shunt strip is expressed as: （3） The formula (3) is brought into the formula (2) to calculate the shunt bar spacing under the condition of lightning directly hitting the shunt bar satisfies the following expression: （4）。 6. The method for lightning strike and flashover effect based lightning shunt strip spacing optimization calculation of claim 1, wherein, In step 6: The condition for lightning surface flashover to hit the shunt bar is that when lightning hits but does not break through the antenna cover shell, the insulation breakdown voltage drop required for air breakdown of the distance from the lightning striking point on the antenna cover shell to the shunt bar along the surface of the antenna cover shell is less than the breakdown voltage drop of the antenna cover shell material ; Based on the conditions under which a lightning flashover occurs and then strikes the shunt bar, the insulation breakdown voltage drop of the radome housing material is constructed. The insulation breakdown voltage drop required for air breakdown from the flash point on the radome housing along the distance from the radome housing surface to the shunt strip. The relationship between the two insulation breakdown voltage drops is used to ensure that the two insulation breakdown voltage drops satisfy formula (5), as follows: （5） wherein: E surface is the field strength for surface flashover; d surface = is the path length from the surface of the radome housing to the shunt strip; is the breakdown field strength of the radome housing material; is the thickness of the radome housing; Will d surface = Substituting / 2 into formula (5), we obtain the shunt bar spacing under the condition that lightning strikes the shunt bar after a surface flashover. The details are as follows: （6）。 7. The method for lightning strike and flashover effect based lightning shunt strip spacing optimization calculation of claim 1, wherein, In step 7: the established shunt strip spacing double condition constraint model is specifically shown in formula (7): （7） Where: S is the safety factor value.

8. The lightning strike and flashover effect based lightning diverter strip spacing optimization calculation method according to claim 7, characterized in that, In step 7: according to the lightning zoning, the safety factor value S is determined, when in 1A zone, S is 0.3, and in other lightning zones, S is 0.5.

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