Power transmission line lightning stroke transient calculation model construction method considering non-transverse electromagnetic wave characteristics

Abstract

The invention discloses a power transmission line lightning stroke transient calculation model construction method considering non-transverse electromagnetic wave characteristics. The method comprises the following steps: 1) constructing a power transmission tower wave impedance expression; 2) simulating the attenuation process of the lightning current along the power transmission tower, and calculating the propagation constant of the lightning current attenuated along the power transmission tower; and 3) replacing a frequency domain wave impedance and a propagation constant in the Jmarti model by using the transmission tower wave impedance expression in the step 1) and the propagation constant of the lightning current attenuating along the transmission tower in the step 2) so as to correct the Jmarti model, and taking the corrected Jmarti model as a transmission line lightning stroke transient calculation model so as to realize transmission line lightning stroke transient calculation. According to the method, the time-varying characteristic of tower wave impedance and the attenuation process along a tower are simulated through a Jmarti frequency-varying parameter line model in an electromagnetic transient analysis program, the coupling delay process between a lightning conductor and a wire is simulated through a controlled voltage source, and modeling of the model in the electromagnetic transient analysis program is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection for power transmission lines, and in particular to a method for constructing a lightning transient calculation model for power transmission lines taking into account non-transverse electromagnetic wave characteristics. Background Art

[0002] With the advancement of the construction of ultra-high and extra-high voltage transmission lines in my country, the number of multi-circuit transmission lines on the same tower and high towers such as crossing towers has increased year by year, which has greatly increased the risk of lightning strikes on high-voltage transmission lines. At the same time, lightning activity observation data show that the lightning parameters and discharge characteristics of multiple lightning strikes are significantly different from those of single lightning strikes, and the impact on the lightning resistance performance of transmission lines is essentially different. Compared with the first lightning strike, the significant feature of subsequent lightning strikes is that the steepness is extremely high, which leads to the possibility that subsequent lightning strikes with low current amplitudes may form lightning overvoltages exceeding the first lightning strike. However, the current regulations do not consider the threat of subsequent lightning strikes when evaluating the lightning resistance performance of transmission lines.

[0003] At present, the methods used for calculating lightning transients of transmission lines are mainly divided into two categories, electromagnetic calculation methods and calculation methods based on circuit theory. The advantage of the electromagnetic calculation method is that it does not require simplification and additional assumptions on the configuration of the transmission line or tower, but directly solves the Maxwell equations numerically, so it has high calculation accuracy. However, the modeling process of the electromagnetic calculation method is very complicated, and the solution process requires a lot of computing resources, making it difficult for such methods to be widely used in scenarios that require a lot of calculations, such as transmission line design and lightning resistance performance evaluation. Therefore, the current designers and researchers are most commonly using simulation calculation methods based on circuit theory when calculating lightning transients of transmission lines. Such methods simplify the complex tower and line structure into concentrated circuit elements or distributed parameter circuit models, and then solve the circuit model to avoid a lot of spatial electromagnetic field calculations. However, the circuit theory calculation method based on the assumption of transverse electromagnetic waves cannot reflect the non-transverse electromagnetic wave characteristics in the initial stage after the lightning strike, which will cause serious errors in the calculation of lightning transients of transmission lines, especially the calculation results of the lightning resistance level of subsequent lightning strikes with extremely short wave head time. Summary of the invention

[0004] The object of the present invention is to provide a method for constructing a lightning transient calculation model for a power transmission line taking into account the characteristics of non-transverse electromagnetic waves, comprising the following steps:

[0005] 1) Considering the non-transverse electromagnetic wave characteristics after lightning strike, the wave impedance expression of the transmission tower is constructed;

[0006] 2) Simulate the attenuation process of lightning current along the transmission tower and calculate the propagation constant of lightning current attenuation along the transmission tower;

[0007] 3) Considering the characteristics of transverse electromagnetic waves, the coupling delay between the lightning conductor and the phase conductor is modeled to simulate the insulator voltage under time delay, and the insulator voltage under time delay is used as the output at the node where the insulator string is located;

[0008] 4) The frequency domain wave impedance and propagation constant in the Jmarti model are replaced by the transmission tower wave impedance expression in step 1) and the propagation constant of the lightning current attenuation along the transmission tower in step 2), so as to modify the Jmarti model, and the modified Jmarti model is used as the transmission line lightning transient calculation model, so as to realize the transmission line lightning transient calculation.

[0009] Furthermore, the expression of the transmission tower wave impedance in the time domain is as follows:

[0010] Z T (t) = Z0(1-e -t / τ )(1)

[0011] In the formula, Z T is the time domain wave impedance of the tower, Z0 is the wave impedance under the assumption of transverse electromagnetic wave, τ is the time constant, and t is the time.

[0012] Furthermore, the expression of the transmission tower wave impedance in the frequency domain is as follows:

[0013]

[0014] Where h is the tower height, c0 is the speed of light; Z T (s) Frequency domain wave impedance of the tower; s is the frequency domain parameter; τ is the coefficient.

[0015] Further, in step 2), the step of calculating the propagation constant of the lightning current attenuation along the transmission tower includes:

[0016] 2.1) Divide the tower into K sections and construct the propagation constant expression of the lightning current attenuation along each section of the transmission tower, that is:

[0017]

[0018] In the formula, h T is the transmission tower height, l k is the height of each section of the transmission tower, k is the current section number; 1, 2, ..., K; P Tk (s) is the propagation constant of lightning current attenuation along k-section transmission tower;

[0019] Among them, the impulse response of the tower's traveling wave is P T (s) are as follows:

[0020]

[0021] p Ta =0.8(5)

[0022] β Ta =0.5h U / c0(6)

[0023] β Tb =20h L / c0(7)

[0024] In the formula, h U and h L are the heights of the upper and lower ends of the transmission tower, respectively; c0 is the speed of light; L{p T (t)} represents the T (t) perform Laplace transform; p Ta is a constant; β Ta , β Tb is the intermediate coefficient;

[0025] The step current response of the traveling wave along the tower T (t) is as follows:

[0026]

[0027] 2.2) Using the pade approximation method in the s domain, when s = π / β Tb The attenuation constant is converted into a rational fraction to obtain the propagation constant of the lightning current attenuation along the tower, that is:

[0028]

[0029] In the formula, p Tk1 、p Tk2 、p Tk3 , β Tk1 , β Tk2 , β Tk3 is the constant obtained when the attenuation constant is decomposed into a rational fraction expression after PAD approximation.

[0030] Furthermore, in step 3), the step of modeling the coupling delay between the lightning conductor and the phase conductor is: adding a controlled voltage source between the insulator and the conductor, and simulating the insulator voltage under time delay by controlling the controlled voltage source.

[0031] Further, the controlled voltage source is controlled by a transfer function G(s);

[0032] The transfer function G(s) is shown below:

[0033]

[0034] In the formula, h Tis the transmission tower height. g is the coefficient.

[0035] Further, in step 4), the Jmarti model is a frequency-dependent transmission line model in the EMTP software.

[0036] Furthermore, the Jmarti model simulates the tower in the form of an equivalent circuit.

[0037] The technical effect of the present invention is unquestionable. The present invention proposes a lightning transient calculation model for transmission lines that takes into account non-transverse electromagnetic wave characteristics. The lightning transient modeling calculation of transmission lines that takes into account the delay in the formation of transverse electromagnetic waves after lightning strikes needs to consider three non-transverse electromagnetic wave characteristics: the wave impedance of the tower gradually increases over time; the time delay of the coupling of the transmission line corresponding to the spatial distance; and the significant attenuation of the lightning traveling wave propagating along the tower. The Jmarti frequency-varying parameter line model in the electromagnetic transient analysis program is used to simulate the time-varying characteristics of the tower wave impedance and the attenuation process along the tower. The controlled voltage source is used to simulate the coupling delay process between the lightning arrester and the conductor, so as to realize the modeling of the model in the electromagnetic transient analysis program. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a multi-wave impedance model in an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of the transmission line coupling delay modeling process in an embodiment of the present invention;

[0040] Figure 3 Schematic diagram of the modeling and calculation process of the Jmarti model in an embodiment of the present invention;. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0042] Embodiment 1:

[0043] See also Figures 1 to 3 , a method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics includes the following steps:

[0044] 1) Considering the non-transverse electromagnetic wave characteristics after lightning strike, the wave impedance expression of the transmission tower is constructed;

[0045] 2) Simulate the attenuation process of lightning current along the transmission tower and calculate the propagation constant of lightning current attenuation along the transmission tower;

[0046] 3) Considering the characteristics of transverse electromagnetic waves, the coupling delay between the lightning conductor and the phase conductor is modeled to simulate the insulator voltage under time delay, and the insulator voltage under time delay is used as the output at the node where the insulator string is located;

[0047] 4) The frequency domain wave impedance and propagation constant in the Jmarti model are replaced by the transmission tower wave impedance expression in step 1) and the propagation constant of the lightning current attenuation along the transmission tower in step 2), so as to modify the Jmarti model, and the modified Jmarti model is used as the transmission line lightning transient calculation model, so as to realize the transmission line lightning transient calculation.

[0048] The present invention constructs a modified Jmarti model that takes into account the characteristics of non-transverse electromagnetic waves, and introduces a controlled source to correct the insulator voltage, thereby realizing the lightning transient calculation of the transmission line, thereby outputting the cross-arm voltage and insulator voltage of the tower, wherein the cross-arm voltage is used as the output at the node where the insulator string is located.

[0049] The expression of the transmission tower wave impedance in the time domain is as follows:

[0050] Z T (t) = Z0(1-e -t / τ )(1)

[0051] In the formula, Z T is the time domain wave impedance of the tower, Z0 is the wave impedance under the assumption of transverse electromagnetic wave, τ is the time constant, and t is the time.

[0052] The expression of the transmission tower wave impedance in the frequency domain is as follows:

[0053]

[0054] Where h is the tower height, c0 is the speed of light; Z T (s) Frequency domain wave impedance of the tower; s is the frequency domain parameter; τ is the coefficient.

[0055] In step 2), the step of calculating the propagation constant of the lightning current attenuation along the transmission tower includes:

[0056] 2.1) Divide the tower into K sections and construct the propagation constant expression of the lightning current attenuation along each section of the transmission tower, that is:

[0057]

[0058] In the formula, h T is the transmission tower height, l k is the height of each section of the transmission tower, k is the current section number; 1, 2, ..., K; P Tk (s) is the propagation constant of lightning current attenuation along k-section transmission tower;

[0059] Among them, the impulse response of the tower's traveling wave is P T (s) are as follows:

[0060]

[0061] p Ta =0.8(5)

[0062] β Ta =0.5h U / c0(6)

[0063] β Tb =20h L / c0(7)

[0064] In the formula, h U and h L are the heights of the upper and lower ends of the transmission tower, respectively; c0 is the speed of light; L{p T (t)} represents the T (t) perform Laplace transform; p Ta is a constant; β Ta , β Tb is the intermediate coefficient;

[0065] The step current response of the traveling wave along the tower T (t) is as follows:

[0066]

[0067] 2.2) Using the pade approximation method in the s domain, when s = π / β Tb The attenuation constant is converted into a rational fraction to obtain the propagation constant of the lightning current attenuation along the tower, that is:

[0068]

[0069] In the formula, p Tk1 、p Tk2 、p Tk3 , β Tk1 , β Tk2 , β Tk3 is the constant obtained when the attenuation constant is decomposed into a rational fraction expression after PAD approximation.

[0070] In step 3), the steps of modeling the coupling delay between the lightning conductor and the phase conductor are: adding a controlled voltage source between the insulator and the conductor, and simulating the insulator voltage under time delay by controlling the controlled voltage source.

[0071] The controlled voltage source is controlled by a transfer function G(s);

[0072] The transfer function G(s) is shown below:

[0073]

[0074] In the formula, h T is the transmission tower height. g is the coefficient.

[0075] In step 4), the Jmarti model is a frequency-dependent transmission line model in the EMTP software.

[0076] The Jmarti model simulates the tower in the form of an equivalent circuit.

[0077] Embodiment 2:

[0078] The method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics includes the following steps:

[0079] 1) Considering the non-transverse electromagnetic wave characteristics after lightning strike, the wave impedance expression of the transmission tower is constructed;

[0080] 2) Simulate the attenuation process of lightning current along the transmission tower and calculate the propagation constant of lightning current attenuation along the transmission tower;

[0081] 3) Considering the characteristics of transverse electromagnetic waves, the coupling delay between the lightning conductor and the phase conductor is modeled to simulate the insulator voltage under time delay, and the insulator voltage under time delay is used as the output at the node where the insulator string is located;

[0082] 4) using the transmission tower wave impedance expression in step 1) and the propagation constant of the lightning current attenuation along the transmission tower in step 2) to replace the frequency domain wave impedance and propagation constant in the Jmarti model, so as to modify the Jmarti model;

[0083] 5) Taking the insulator voltage under time delay as the lightning strike voltage, the updated Jmarti model is used to simulate the lightning strike process of the transmission line.

[0084] Embodiment 3:

[0085] The method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics has the same technical content as Example 2. Furthermore, the expression of the transmission tower wave impedance in the time domain is as follows:

[0086] Z T (t) = Z0(1-e -t / τ )(1)

[0087] In the formula, Z T is the time domain wave impedance of the tower, Z0 is its wave impedance under the assumption of transverse electromagnetic wave, and τ is the time constant.

[0088] Embodiment 4:

[0089] A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, the technical content is the same as any one of Embodiments 2-3, and further, the expression of the transmission tower wave impedance in the frequency domain is as follows:

[0090]

[0091] Where h is the tower height and c0 is the speed of light.

[0092] Embodiment 5:

[0093] A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, the technical content of which is the same as any one of Embodiments 2-4, further, in step 2), the step of calculating the propagation constant of the lightning current attenuation along the transmission tower includes:

[0094] 2.1) Divide the tower into K sections and construct the propagation constant expression of the lightning current attenuation along each section of the transmission tower, that is:

[0095]

[0096] In the formula, h T is the transmission tower height, l k is the height of each section of the transmission tower, k is the current section number; 1, 2, ..., K;

[0097] Among them, the impulse response of the tower's traveling wave is P T (s) are as follows:

[0098]

[0099] p Ta =0.8(5)

[0100] β Ta =0.5h U / c0(6)

[0101] β Tb =20h L / c0(7)

[0102] In the formula, h U and h L are the heights of the upper and lower ends of the transmission tower, respectively; c0 is the speed of light; L{p T (t)} represents the T (t) perform Laplace transform; p Ta is a constant; β Ta , β Tb is the intermediate coefficient;

[0103] The step current response of the traveling wave along the tower T (t) is as follows:

[0104]

[0105] 2.2) Using the pade approximation method in the s domain, when s = π / β Tb The attenuation constant is converted into a rational fraction to obtain the propagation constant of the lightning current attenuation along the tower, that is:

[0106]

[0107] In the formula, p Tk1 、p Tk2 、p Tk3 , β Tk1 , β Tk2 , β Tk3 is the constant obtained when the attenuation constant is decomposed into a rational fraction expression after PAD approximation.

[0108] Embodiment 6:

[0109] A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, the technical content of which is the same as any one of Examples 2-5. Furthermore, in step 3), the step of modeling the coupling delay between the lightning conductor and the phase conductor is: adding a controlled voltage source between the insulator and the conductor, and simulating the insulator voltage under time delay by controlling the controlled voltage source.

[0110] Embodiment 7:

[0111] A method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics, the technical content of which is the same as any one of Embodiments 2-6, and further, the controlled voltage source is controlled by a transfer function G(s);

[0112] The transfer function G(s) is shown below:

[0113]

[0114] In the formula, h T is the transmission tower height.

[0115] Embodiment 8:

[0116] A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, the technical content of which is the same as any one of embodiments 2-7, and further, in step 4), the Jmarti model is a frequency-dependent transmission line model in the EMTP software.

[0117] Embodiment 9:

[0118] A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, the technical content of which is the same as any one of Examples 2-8, and further, the Jmarti model simulates the tower in the form of an equivalent circuit.

[0119] Embodiment 9:

[0120] The construction method of the lightning transient calculation model for transmission lines considering the characteristics of non-transverse electromagnetic waves is as follows:

[0121] (1) Tower wave impedance approximation method

[0122] After the lightning strikes the tower, the lightning electromagnetic field will slowly transition from the transverse magnetic wave structure to a structure similar to a transverse electromagnetic wave. During this period, the wave impedance of the tower will gradually rise and converge to its stable wave impedance under the assumption of transverse electromagnetic waves. Under current injection, before the negative reflection wave from the bottom of the tower reaches the top of the tower, the wave impedance of the tower is approximately a logarithmically rising function, so the wave impedance of the tower is set to the following form:

[0123] Z T (t) = Z0(1-e -t / τ )

[0124] In the formula, Z T is the time domain wave impedance of the tower, Z0 is its wave impedance under the assumption of transverse electromagnetic wave, and τ is the time constant.

[0125] By performing Laplace transform on it, we can get its wave impedance expression in the frequency domain:

[0126]

[0127] Where h is the tower height and c0 is the speed of light.

[0128] The above expression can realize the approximate logarithmic growth of wave impedance in the time domain, and it is easy to implement in electromagnetic transient calculation programs based on circuit calculation methods such as ATP-EMTP. When performing actual modeling, the value of the wave impedance steady-state value Z0 will affect the accuracy of the calculation. The wave impedance calculation formula can adopt the wave impedance formula of Hara's multi-wave impedance tower model.

[0129] Hara equates a typical transmission tower to Figure 1 The cascade segmented model shown in the figure has a tower body divided into four segments, with heights of h k (k=1,2,3,4), the conductor spacing is J Tk (k=1,2,3,4), the radius of the diagonal conductor is r Tk (k=1,2,3,4), the cross arm radius is r Ak(k=1, 2, 3, 4), for the tower body, its wave impedance can be calculated by the following formula:

[0130]

[0131] In the above formula, r ek is the effective radius of the main body, we have:

[0132]

[0133] The measured data show that the wave impedance with the inclined material is about 90% of the wave impedance without the inclined material, so the wave impedance of the inclined material can be obtained as:

[0134] Z LK =9Z TK (k=1,2,3,4)

[0135] For the cross arm, its wave impedance can be calculated by the following formula:

[0136]

[0137] where r Ak It is 1 / 4 of the width of the connection between the cross arm and the tower.

[0138] (2) Calculation and simulation method of tower propagation constant

[0139] Even if the conductor is a perfect conductor, the current propagating upward along a vertical cylinder or cone will be significantly attenuated due to the tangential electric field boundary conditions on the conductor surface. The waves propagating upward and downward along the vertical cylinder are not transverse electromagnetic waves, so they will be attenuated during the propagation process in these two directions. The attenuation characteristics of the current along the tower should be considered in the tower model. The step current response of the traveling wave along the tower can be expressed as follows:

[0140]

[0141] in

[0142] p Ta =0.8

[0143] β Ta =0.5h U / c0

[0144] β Tb =20h L / c0

[0145] Where h U and h L are the heights of the upper and lower ends of this section of the tower respectively;.

[0146] In order to calculate the cross-arm voltage and insulator voltage of the tower, the above formula is divided into four parts according to Hara's multi-wave impedance tower structure. The above formula is Laplace transformed and the result is divided by 1 / s to obtain its impulse response:

[0147]

[0148] In order to calculate the cross-arm voltage and insulator voltage, the tower must be divided into four parts. Considering the length of the four parts of the tower, the attenuation constant of each part is obtained:

[0149]

[0150] In the formula, h T is the tower height, l k is the height of each section of the tower, and k is the number of the section. Using the pade approximation method in the s domain, when s = π / β Tb Convert the above function to rational fraction form:

[0151]

[0152] (3) Modeling method of coupling delay between lightning arrester and phase conductor

[0153] When considering the non-transverse electromagnetic wave characteristics in the initial stage after the lightning strike, it is necessary to consider the transmission line coupling delay in the electromagnetic wave formation process, that is, before the spatial electromagnetic field formed by the lightning strike reaches the phase conductor position, no coupling overvoltage should be generated on the phase conductor. Based on this characteristic, a controlled voltage source is used to consider the insulator lightning overvoltage when the transverse electromagnetic wave formation delay occurs, as follows: the line model is not directly modified during the calculation, and the Jmarti frequency-variable parameter line model is still used. Therefore, the actual coupling voltage generated on the conductor is the same as that under the transverse electromagnetic wave assumption. According to the coupling voltage on the conductor and the coupling coefficient related only to the physical structure and spatial position of the lightning rod and the conductor, a controlled voltage source is added between the insulator and the conductor. By controlling the voltage, the insulator voltage under the delay in the formation of the transverse electromagnetic wave can be reproduced. The transfer function G(s) is used to correct the potential on the phase conductor.

[0154]

[0155] The specific calculation process is as follows Figure 2 shown.

[0156] (4) Implementation of the model in EMTP

[0157] The Jmarti model is a frequency-dependent transmission line model commonly used in EMTP software. It simulates the propagation and attenuation of electromagnetic waves on the conductor by approximating the wave impedance and transmission constant of the line. Its workflow in EMTP is as follows: Figure 3 shown.

[0158] The main steps of the Jmarti frequency-variable parameter line model are as follows: ① First, calculate the theoretical circuit parameters based on the input line physical parameters and conductor structure, such as the inductance per unit length L, capacitance to ground C, etc. ② Based on the above calculation results, the theoretical wave impedance and frequency characteristics of the propagation constant Z of the line can be calculated. c (s) and A1(s). ③ Use the broken line to approximate the theoretical characteristics and obtain the approximate wave impedance and propagation constant Z eq (s) and P1(s).

[0159]

[0160] The following conditions must be met: the poles and zeros are all negative real numbers, that is, z i 、p i are all greater than 0, i = 1, 2, ..., n; H is a positive real number. When s = 0, the DC wave impedance

[0161] Z eq (0) = H (z1z2…z n ) / (p1p2…p n )>0. ③The number of poles and zeros is equal, both n.

[0162] Transform into the form of a sum of partial fractions:

[0163]

[0164] in

[0165] k0=H

[0166]

[0167] The network expressed in the above equation can be realized by a series of series circuit elements or a combination of elements. The calculation process of the propagation constant P1(s) is similar to Z eq (s) is similar, except that P1(s) requires that the numerator order in the approximate result is less than the denominator order. Based on the above approximate results, the corresponding parameters can be obtained, which can be directly used for the calculation of EMTP.

[0168] The proposed tower model considering the delay of transverse electromagnetic wave formation is based on the above principles, and the frequency domain expressions of tower wave impedance and propagation constant are given, namely P1(s) and Z mentioned above. eq(s), by replacing the frequency domain wave impedance and propagation constant of the transmission line with the calculation results of the above formula, the Jmarti frequency-variable parameter line model in EMTP can be directly used to simulate the tower.

Claims

1. A method for constructing a lightning transient calculation model for a transmission line considering non-transverse electromagnetic wave characteristics, characterized in that: The following steps are involved: 1) Considering the non-transverse electromagnetic wave characteristics after lightning strike, the wave impedance expression of the transmission tower is constructed; 2) Simulate the attenuation process of lightning current along the transmission tower and calculate the propagation constant of lightning current attenuation along the transmission tower. 3) Considering the characteristics of transverse electromagnetic waves, the coupling delay between the lightning conductor and the phase conductor is modeled to simulate the insulator voltage under time delay, and the insulator voltage under time delay is used as the output at the node where the insulator string is located; 4) The frequency domain wave impedance and propagation constant in the Jmarti model are replaced by the transmission tower wave impedance expression in step 1) and the propagation constant of the lightning current attenuation along the transmission tower in step 2), so as to modify the Jmarti model, and the modified Jmarti model is used as the transmission line lightning transient calculation model, so as to realize the transmission line lightning transient calculation.

2. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 1, characterized in that: The expression of the transmission tower wave impedance in the time domain is as follows: Z T (t)=Z0(1-e -t / τ ) (1) In the formula, Z T is the time domain wave impedance of the tower, Z0 is its wave impedance under the assumption of transverse electromagnetic wave, τ is the time constant; t is time.

3. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 1, characterized in that: The expression of the transmission tower wave impedance in the frequency domain is as follows: Where h is the tower height, c0 is the speed of light; Z T (s) Frequency domain wave impedance of the tower; s is the frequency domain parameter; τ is the coefficient.

4. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 1, characterized in that: In step 2), the step of calculating the propagation constant of the lightning current attenuation along the transmission tower includes: 2.1) Divide the tower into K sections and construct the propagation constant expression of the lightning current attenuation along each section of the transmission tower, that is: In the formula, h T is the transmission tower height, l k is the height of each section of the transmission tower, k is the current section number; 1, 2, ..., K; P Tk (s) is the propagation constant of lightning current attenuation along k-section transmission tower; Among them, the impulse response of the tower's traveling wave is P T (s) are as follows: p Ta ＝0.8(5) b Ta =0.5h U / c0(6) b Tb =20h L / c0(7) In the formula, h U and h L are the heights of the upper and lower ends of the transmission tower, respectively; c0 is the speed of light; L{p T (t)} represents the T (t) perform Laplace transform; p Ta is a constant; β Ta , β Tb is the intermediate coefficient; The step current response of the traveling wave along the tower T (t) is as follows: 2.2) Using the pade approximation method in the s domain, when s = π / β Tb The attenuation constant is converted into a rational fraction to obtain the propagation constant of the lightning current attenuation along the tower, that is: In the formula, p Tk1 、p Tk2 、p Tk3 , β Tk1 , β Tk2 , β Tk3 is the constant obtained when the attenuation constant is decomposed into a rational fraction expression after pade approximation.

5. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 1, characterized in that: In step 3), the steps of modeling the coupling delay between the lightning conductor and the phase conductor are: adding a controlled voltage source between the insulator and the conductor, and simulating the insulator voltage under time delay by controlling the controlled voltage source.

6. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 5, characterized in that: The controlled voltage source is controlled by a transfer function G(s); The transfer function G(s) is shown below: In the formula, h T is the transmission tower height; τ g is the coefficient.

7. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 1, characterized in that: In step 4), the Jmarti model is a frequency-dependent transmission line model in the EMTP software.

8. The method for constructing a lightning transient calculation model for a power transmission line considering non-transverse electromagnetic wave characteristics according to claim 7, characterized in that: The Jmarti model simulates the tower in the form of an equivalent circuit.

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