Lightning current modeling method and system in lightning intrusion wave overvoltage simulation

Abstract

The invention provides a lightning current modeling method in lightning intrusion wave overvoltage simulation, which comprises the following steps of: in preset simulation software, simulating a lightning current calculation model under multiple lightning strokes of a transformer substation by wave impedance and n + 1 oblique angle wave current sources; the oblique angle wave current source and the wave impedance are connected in parallel, and a time delay module is arranged between the adjacent oblique angle wave current source and the wave impedance and comprises a current main discharge source for representing active discharge of lightning current and n current return stroke sources for representing secondary return stroke after active discharge of the lightning current; according to the voltage class of the transformer substation and the discharge type of lightning current, in a lightning current calculation model, setting the value of n, the current amplitude, wave head time and wave head gradient values of lightning current on a current main discharge source and n current return stroke sources, the values of delay time on n delay modules, and the impedance value of wave impedance. By implementing the method, the problem of lightning current modeling under multiple lightning strokes can be solved, and accurate data support is provided for subsequent lightning intruding wave overvoltage simulation.

Description

Technical Field

[0001] The present invention relates to the technical field of computer simulation, and particularly to a method and system for modeling lightning current in the simulation of lightning intrusion overvoltage. Background Art

[0002] At present, when studying the simulation of lightning intrusion overvoltage at home and abroad, lightning current modeling is a very important step. In the past, it was basically single-stroke lightning modeling. For example, in simulation calculations, the lightning intrusion wave is generally represented by an oblique-angle wave current source (the wavefront time is generally taken as 2.6 μs, and the wave tail is taken as 50 μs) or a double-exponential wave current source, and the wave impedance of the lightning channel in parallel with it, as Figure 1 shown. Among them, when calculating the counterattack lightning intrusion wave, the counterattack lightning current can be selected according to the lightning protection reliability requirements of the substation at a certain cumulative probability; when calculating the shielding failure lightning intrusion wave, the shielding failure lightning current can be obtained by the electrical geometric model method; the wave impedance of the lightning channel is taken as 300 Ω during counterattack and 800 Ω during shielding failure.

[0003] However, there is a lack of a method for modeling lightning current under multiple lightning strokes in the prior art. Therefore, it is urgent to solve the problem of modeling lightning current under multiple lightning strokes to provide accurate data support for subsequent lightning intrusion overvoltage simulation. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a method and system for modeling lightning current in the simulation of lightning intrusion overvoltage, which can solve the problem of modeling lightning current under multiple lightning strokes and provide accurate data support for subsequent lightning intrusion overvoltage simulation.

[0005] To solve the above technical problem, an embodiment of the present invention provides a method for modeling lightning current in the simulation of lightning intrusion overvoltage, and the method includes the following steps:

[0006] In a preset simulation software, a lightning current calculation model of a substation under multiple lightning strokes is constructed; wherein, the lightning current calculation model is simulated by a wave impedance and n + 1 oblique-angle wave current sources, and the wave impedance is connected in parallel with each oblique-angle wave current source; a delay module is provided between adjacent two oblique-angle wave current sources; among the n + 1 oblique-angle wave current sources, the one oblique-angle wave current source farthest from the wave impedance is a current main discharge source for characterizing the active discharge of the lightning current, and the other n oblique-angle wave current sources are n current return stroke sources for characterizing the n times of return strokes after the active discharge of the lightning current; n is a positive integer greater than or equal to 1;

[0007] According to the voltage level of the substation and the type of lightning current discharge, in the lightning current calculation model, set the value of n, and further set the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the main current discharge source, the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the n current return stroke sources, the values of the delay times on the n delay modules, and the impedance value of the wave impedance; wherein, the voltage level of the substation is 110 kV or 220 kV; the type of lightning current discharge is shielding failure lightning or back flashover lightning.

[0008] Among them, the values of the current amplitude and wavefront time of the lightning current on the main current discharge source are set based on the voltage level of the substation and the type of lightning current discharge; the value of the wavefront steepness of the lightning current on the main current discharge source is calculated from the value of its current amplitude and the value of the wavefront time.

[0009] The values of the current amplitude of the lightning current on the n current return stroke sources are calculated based on the preset Log-Logistic distribution formula for the current amplitude of the lightning current on the main current discharge source; or, set according to a predetermined amplitude change rule; or, set according to the maximum shielding failure lightning current in the limit condition or the maximum back flashover lightning current.

[0010] The values of the wavefront time of the lightning current on the n current return stroke sources are set according to a predetermined wavefront time change rule.

[0011] The values of the wavefront steepness of the lightning current on the n current return stroke sources are calculated from the values of their respective current amplitudes and their corresponding wavefront times.

[0012] The values of the delay times on the n delay modules are all set to the same constant.

[0013] The impedance value of the wave impedance is set based on the type of lightning current discharge.

[0014] Among them, when the type of lightning current discharge is shielding failure lightning, take the current amplitude of the lightning current on the main current discharge source as the first value, the wavefront time as the first fixed time value, and the wavefront steepness as the quotient obtained by dividing the first value by the first time value.

[0015] When the type of lightning current discharge is back flashover lightning, if the voltage level of the substation is 110 kV, then take the current amplitude of the lightning current on the main current discharge source as the second value, the wavefront time as the second fixed time value, and the wavefront steepness as the quotient obtained by dividing the second value by the second time value.

[0016] When the lightning current discharge type is back-stroke lightning, if the voltage level of the substation is 220 kV, the current amplitude of the lightning current on the main current discharge source is taken as the third value, the wave front time is taken as the third time constant, and the wave front steepness is the quotient obtained by dividing the third value by the third time constant.

[0017] Among them, the predetermined amplitude change rule is the calculation rule that the current amplitude of the lightning current on the current lightning strike source is 1 / 3 of the current amplitude of the lightning current on the previous lightning strike source; among them, if the current lightning strike source is adjacent to the main current discharge source, the value of the current amplitude of its lightning current is 1 / 3 of the value of the current amplitude of the lightning current on the main current discharge source.

[0018] Among them, the predetermined wave front time change rule is the calculation rule that the wave front time of the lightning current discharged by the current lightning strike source is 1 / 2 of the wave front time of the lightning current discharged by the previous lightning strike source; among them, if the current lightning strike source is adjacent to the main current discharge source, the wave front time of its lightning current is fixed as the fourth time constant.

[0019] Among them, the wave front steepness values of the lightning currents on the n lightning strike sources are all the quotients obtained by dividing the values of the current amplitudes of their respective lightning currents by the values of the corresponding wave front times.

[0020] Among them, when the lightning current discharge type is shielding failure lightning, the impedance value of the wave impedance is the first impedance constant; when the lightning current discharge type is back-stroke lightning, the impedance value of the wave impedance is the second impedance constant; among them, the first impedance constant is less than the second impedance constant.

[0021] The embodiment of the present invention also provides a lightning current modeling system in the simulation of lightning intrusion overvoltage, including:

[0022] A lightning current calculation model construction unit, configured to construct a lightning current calculation model of a substation under multiple lightning strikes in a preset simulation software; among them, the lightning current calculation model is simulated by a wave impedance and n + 1 ramp wave current sources, and the wave impedance is connected in parallel with each ramp wave current source; a delay module is provided between adjacent two ramp wave current sources; among the n + 1 ramp wave current sources, the ramp wave current source farthest from the wave impedance is the main current discharge source for characterizing the active discharge of the lightning current, and the other n ramp wave current sources are n lightning strike sources for characterizing the n times of back strikes after the active discharge of the lightning current; n is a positive integer greater than or equal to 1;

[0023] A model parameter value setting unit is used to set the value of n in the lightning current calculation model according to the voltage level of the substation and the lightning current discharge type, and further set the values of the lightning current amplitude, wavefront time, and wavefront steepness of the lightning current released by the main current source, the values of the lightning current amplitude, wavefront time, and wavefront steepness of the lightning current released by the n current return stroke sources, the values of the delay times on the n delay modules, and the impedance value of the wave impedance; wherein, the voltage level of the substation is 110 kV or 220 kV; the lightning current discharge type is shielding failure lightning or back flashover lightning.

[0024] Among them, the values of the lightning current amplitude and wavefront time on the main current source are set based on the voltage level of the substation and the lightning current discharge type; the value of the wavefront steepness of the lightning current on the main current source is calculated from the value of its lightning current amplitude and the value of the wavefront time.

[0025] The values of the lightning current amplitudes of the lightning currents on the n current return stroke sources are calculated based on a preset Log-Logistic distribution formula for the lightning current amplitude of the main current source; or, set according to a predetermined amplitude change rule; or, set according to the maximum shielding failure lightning current under extreme conditions or the maximum back flashover lightning current.

[0026] The values of the wavefront times of the lightning currents on the n current return stroke sources are set according to a predetermined wavefront time change rule.

[0027] The values of the wavefront steepnesses of the lightning currents on the n current return stroke sources are calculated from the values of their respective lightning current amplitudes and their corresponding wavefront times.

[0028] The values of the delay times on the n delay modules are all set to the same constant.

[0029] The impedance value of the wave impedance is set based on the lightning current discharge type.

[0030] Among them, when the lightning current discharge type is shielding failure lightning, the lightning current amplitude on the main current source is taken as the first value, the wavefront time is taken as the first time constant value, and the wavefront steepness is the quotient obtained by dividing the first value by the first time constant value.

[0031] When the lightning current discharge type is back flashover lightning, if the voltage level of the substation is 110 kV, the lightning current amplitude on the main current source is taken as the second value, the wavefront time is taken as the second time constant value, and the wavefront steepness is the quotient obtained by dividing the second value by the second time constant value.

[0032] When the lightning current discharge type is back-stroke lightning, if the voltage level of the substation is 220 kV, the current amplitude of the lightning current on the main current source is taken as the third value, the wavefront time is taken as the third time constant, and the wavefront steepness is the quotient obtained by dividing the third value by the third time constant.

[0033] Implementing the embodiments of the present invention has the following beneficial effects:

[0034] The present invention constructs a lightning current calculation model for a substation under multiple lightning strikes through simulation software, and sets the model parameter values according to the voltage level of the substation and the lightning current discharge type, so as to quickly evaluate the measured value of the lightning current under multiple lightning strikes, thereby solving the problem of lightning current modeling under multiple lightning strikes and providing accurate data support for subsequent lightning intrusion wave overvoltage simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0036] Figure 1 It is a lightning current calculation model diagram under single lightning strike in the prior art;

[0037] Figure 2 It is a flowchart of a lightning current modeling method in lightning intrusion wave overvoltage simulation provided by an embodiment of the present invention;

[0038] Figure 3 It is a lightning current calculation model diagram under multiple lightning strikes in the application scenario of a lightning current modeling method in lightning intrusion wave overvoltage simulation provided by an embodiment of the present invention;

[0039] Figure 4 It is a structural schematic diagram of a lightning current modeling system in lightning intrusion wave overvoltage simulation provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] As Figure 2 shown, in an embodiment of the present invention, a lightning current modeling method in lightning intrusion wave overvoltage simulation is provided, and the method includes the following steps:

[0042] Step S1: In a preset simulation software, construct a lightning current calculation model for a substation under multiple lightning strikes. Among them, the lightning current calculation model is simulated by a wave impedance and n + 1 ramp wave current sources, and the wave impedance is connected in parallel with each ramp wave current source; a delay module is provided between adjacent two ramp wave current sources; among the n + 1 ramp wave current sources, the ramp wave current source farthest from the wave impedance is the main current source for characterizing the active discharge of the lightning current, and the other n ramp wave current sources are n current return sources for characterizing the n - time subsequent strokes after the active discharge of the lightning current; n is a positive integer greater than or equal to 1.

[0043] Step S2: According to the voltage level of the substation and the type of lightning current discharge, in the lightning current calculation model, set the value of n, further set the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the main current source, the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the n current return sources, the value of the delay time on the n delay modules, and the impedance value of the wave impedance. Among them, the voltage level of the substation is 110 kV or 220 kV; the type of lightning current discharge is a shielding failure lightning strike or a back - flashover lightning strike.

[0044] Specifically, in step S1, using the electromagnetic transient simulation calculation program ATP - EMTP, construct a lightning current calculation model for a substation under multiple lightning strikes obtained by simulating a wave impedance and n + 1 ramp wave current sources, as Figure 3 shown. Among them, the icon represents a ramp wave current source, the icon represents a wave impedance, the icon represents the delay module provided between adjacent two ramp wave current sources, and the left - most ramp wave current source is set as the main current source for characterizing the active discharge of the lightning current, and the other n ramp wave current sources except the left - most ramp wave current source are n current return sources for characterizing the n - time subsequent strokes after the active discharge of the lightning current.

[0045] At this time, Figure 3 in the lightning current calculation model in

[0046]

[0047] , the wave impedance is connected in parallel with each ramp wave current source, and the ramp wave current source will generate a lightning current containing active discharge, the 1st stroke, the 2nd stroke, the 3rd stroke, the 4th stroke, the 5th stroke, the 6th stroke,..., the nth stroke. In step S2, according to the voltage level of the substation and the type of lightning current discharge, set the model parameters in the lightning current calculation model for subsequent simulation and evaluation of the measured lightning current values.At this time, in the lightning current calculation model, the values of the current amplitude and the wavefront time of the lightning current on the main current source are set based on the voltage level of the substation and the lightning current discharge type; the value of the wavefront steepness of the lightning current on the main current source is calculated from the values of its current amplitude and wavefront time.

[0048] For example, when the lightning current discharge type is a side flash, the current amplitude of the lightning current on the main current source is taken as the first value (such as 30 kA), the wavefront time is taken as the first fixed time value (such as 2.6 μs), and the wavefront steepness is the quotient obtained by dividing the first value by the first time value;

[0049] When the lightning current discharge type is a back flash, if the voltage level of the substation is 110 kV, the current amplitude of the lightning current on the main current source is taken as the second value (such as 100 kA), the wavefront time is taken as the second fixed time value (such as 2.6 μs), and the wavefront steepness is the quotient obtained by dividing the second value by the second time value;

[0050] When the lightning current discharge type is a back flash, if the voltage level of the substation is 220 kV, the current amplitude of the lightning current on the main current source is taken as the third value (such as 150 kA), the wavefront time is taken as the third fixed time value (such as 2.6 μs), and the wavefront steepness is the quotient obtained by dividing the third value by the third time value.

[0051] In an example, when calculating the intrusion wave of a side flash (i.e., the lightning current discharge type is a side flash), the current amplitude of the lightning current on the main current source takes a value within [20 kA, 40 kA] as the first value.

[0052] When calculating the intrusion wave of a back flash (i.e., the lightning current discharge type is a back flash), in the case where the voltage level of the substation is 110 kV, the current amplitude of the lightning current on the main current source takes 100 kA as the second value; in the case where the voltage level of the substation is 220 kV, the current amplitude of the lightning current on the main current source takes 150 kA as the third value.

[0053] In any case of the voltage level of the substation and the lightning current discharge type, the wavefront time of the lightning current on the main current source takes the same value of 2.6 μs, and the value of the wavefront steepness is the current amplitude of the corresponding lightning current / the wavefront time of the lightning current.

[0054] At this time, in this lightning current calculation model, the values of the current amplitudes of the lightning currents on the n current return stroke sources are calculated based on the preset Log-Logistic distribution formula for the current amplitude of the lightning current on the main current discharge source; or set according to a predetermined amplitude change rule; or set according to the maximum shielding failure lightning current in the extreme condition or the maximum counterattack lightning current; where the predetermined amplitude change rule is that the current amplitude of the lightning current on the current current return stroke source is 1 / 3 of the current amplitude of the lightning current on the previous current return stroke source; if the current current return stroke source is adjacent to the main current discharge source, the value of the current amplitude of its lightning current is 1 / 3 of the value of the current amplitude of the lightning current on the main current discharge source.

[0055] The values of the front time of the lightning currents on the n current return stroke sources are set according to a predetermined front time change rule; where the predetermined front time change rule is that the front time of the lightning current discharged by the current current return stroke source is 1 / 2 of the front time of the lightning current discharged by the previous current return stroke source; if the current current return stroke source is adjacent to the main current discharge source, the front time of its lightning current is fixed at the fourth time constant (such as 0.5 μs).

[0056] The values of the front steepness of the lightning currents on the n current return stroke sources are calculated from the values of their respective current amplitudes and the values of their corresponding front times; where the values of the front steepness of the lightning currents on the n current return stroke sources are all the quotients obtained by dividing the values of the current amplitudes of their respective lightning currents by the values of the corresponding front times.

[0057] For example, the inventor found that the ratio of the current amplitude of the subsequent return stroke lightning current to the main discharge lightning current is close to the Log-Logistic distribution and decreases with the increase of the subsequent return stroke order. The Log-Logistic distribution is a continuous probability distribution, and its distribution function is: 1 / f(x) = exp[-(x - α) / β]. Where α and β are the two parameters of the distribution, α is called the scale function, which determines the shape of the distribution; β is called the shape parameter, which determines the tail decay rate of the distribution. When α = 0 and β = 1, the standard logistic distribution is obtained. The distribution function is shown in Equation (1):

[0058] 1 / f(x) = exp(-x), that is, f(x) = 1 / exp(-x) (1);

[0059] Therefore, according to formula (1), the values of the current amplitudes of the lightning currents on the subsequent n current return stroke sources can be calculated from the current amplitude of the lightning current on the main current discharge source.

[0060] In addition, it can also be taken as 1 / 3 of the first time, which is an empirical value; and, taken according to the maximum shielding failure lightning current in the extreme condition.

[0061] As shown in Table 1 below, six ways of obtaining the current amplitude of lightning current on the current return stroke sources are listed; among them, I m is the value of the lightning current amplitude on the main lightning current source:

[0062] Table 1

[0063]

[0064] At this time, the comparison of the values of the lightning current amplitude, wavefront time, and wavefront steepness on the above six current return stroke sources and the main lightning current source is shown in Table 2 below:

[0065] Table 2

[0066]

[0067] At this time, in this lightning current calculation model, the values of the delay times on the n delay modules are all set to the same constant, such as ΔT1, ΔT2, ΔT3, ΔT4, ΔT5, ΔT6,..., ΔTn, and can all be taken as 60 ms on average.

[0068] At this time, in this lightning current calculation model, the impedance value of the wave impedance is set based on the lightning current discharge type. Among them, when the lightning current discharge type is a shielding failure strike, the impedance value of the wave impedance is the first impedance fixed value; when the lightning current discharge type is a back flashover strike, the impedance value of the wave impedance is the second impedance fixed value; among them, the first impedance fixed value is less than the second impedance fixed value. For example, in the case of a back flashover strike, the first impedance fixed value is generally taken as 300 Ω; in the case of a shielding failure strike, the second impedance fixed value is generally taken as 800 Ω.

[0069] As Figure 4 shown, in the embodiment of the present invention, a lightning current modeling system in lightning intrusion overvoltage simulation is provided, including:

[0070] A lightning current calculation model construction unit 110, configured to construct a lightning current calculation model of a substation under multiple lightning strikes in a preset simulation software; wherein, the lightning current calculation model is simulated by a wave impedance and n + 1 ramp wave current sources, and the wave impedance is connected in parallel with each ramp wave current source; a delay module is provided between adjacent two ramp wave current sources; among the n + 1 ramp wave current sources, a ramp wave current source farthest from the wave impedance is a main lightning current source for characterizing the active discharge of lightning current, and the other n ramp wave current sources are n current return stroke sources for characterizing the n - time return strokes after the active discharge of lightning current; n is a positive integer greater than or equal to 1;

[0071] The model parameter value setting unit 120 is used to set the value of n in the lightning current calculation model according to the voltage level of the substation and the lightning current discharge type, and further set the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the main current discharge source, the values of the current amplitude, wavefront time, and wavefront steepness of the lightning current released by the n current return stroke sources, the values of the delay times on the n delay modules, and the impedance value of the wave impedance; wherein, the voltage level of the substation is 110 kV or 220 kV; the lightning current discharge type is shielding failure lightning or back flashover lightning.

[0072] Among them, the values of the current amplitude and wavefront time of the lightning current on the main current discharge source are set based on the voltage level of the substation and the lightning current discharge type; the value of the wavefront steepness of the lightning current on the main current discharge source is calculated from the value of its current amplitude and the value of the wavefront time;

[0073] The values of the current amplitudes of the lightning currents on the n current return stroke sources are calculated based on a preset Log-Logistic distribution formula for the current amplitude of the lightning current on the main current discharge source; or, set according to a predetermined amplitude change rule; or, set according to the maximum shielding failure lightning current under extreme conditions or the maximum back flashover lightning current.

[0074] The values of the wavefront times of the lightning currents on the n current return stroke sources are set according to a predetermined wavefront time change rule;

[0075] The values of the wavefront steepnesses of the lightning currents on the n current return stroke sources are calculated from the values of their respective current amplitudes and their corresponding wavefront times;

[0076] The values of the delay times on the n delay modules are all set to the same constant;

[0077] The impedance value of the wave impedance is set based on the lightning current discharge type.

[0078] Among them, when the lightning current discharge type is shielding failure lightning, the current amplitude of the lightning current on the main current discharge source is taken as the first value, the wavefront time is taken as the first time constant, and the wavefront steepness is the quotient obtained by dividing the first value by the first time constant;

[0079] When the lightning current discharge type is back flashover lightning, if the voltage level of the substation is 110 kV, the current amplitude of the lightning current on the main current discharge source is taken as the second value, the wavefront time is taken as the second time constant, and the wavefront steepness is the quotient obtained by dividing the second value by the second time constant;

[0080] When the lightning current discharge type is back-strike lightning, if the voltage level of the substation is 220 kV, the current amplitude of the lightning current on the main discharge source is taken as the third value, the wavefront time is taken as the third time constant, and the wavefront steepness is the quotient obtained by dividing the third value by the third time constant.

[0081] Implementing the embodiments of the present invention has the following beneficial effects:

[0082] The present invention constructs a lightning current calculation model of a substation under multiple lightning strikes through simulation software, and sets the model parameter values according to the voltage level of the substation and the lightning current discharge type, so as to quickly evaluate the measured value of the lightning current under multiple lightning strikes, thereby solving the problem of lightning current modeling under multiple lightning strikes and providing accurate data support for subsequent lightning intrusion wave overvoltage simulation.

[0083] It should be noted that in the above system embodiments, the included system modules are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of the functional modules are only for easy distinction from each other and do not limit the protection scope of the present invention.

[0084] Those of ordinary skill in the art can understand that all or part of the steps in implementing the above method embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disc, etc.

[0085] The above-disclosed are only the preferred embodiments of the present invention, and of course cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A lightning current modeling method in lightning intrusion wave overvoltage simulation, characterized in that: The method comprises the following steps: In the preset simulation software, a lightning current calculation model of the substation under multiple lightning strikes is constructed; wherein the lightning current calculation model is simulated by wave impedance and n+1 oblique wave current sources, and the wave impedance is connected in parallel with each oblique wave current source; a delay module is provided between two adjacent oblique wave current sources; among the n+1 oblique wave current sources, the oblique wave current source farthest from the wave impedance is a main current discharge source for characterizing active discharge of lightning current, and the other n oblique wave current sources are n current return stroke sources for characterizing n return strokes after active discharge of lightning current; n is a positive integer greater than or equal to 1; According to the voltage level of the substation and the type of lightning current discharge, in the lightning current calculation model, the value of n is set, and the current amplitude, wave front time and wave front steepness of the lightning current released by the current main discharge source, the current amplitude, wave front time and wave front steepness of the lightning current released by the n current return stroke sources, the values ​​of the delay time on the n delay modules, and the impedance value of the wave impedance are further set; wherein the voltage level of the substation is 110kV or 220kV; and the lightning current discharge type is bypass lightning or counter-strike lightning.

2. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 1, characterized in that: The current amplitude and wave front time of the lightning current on the main current discharge source are set based on the voltage level and lightning current discharge type of the substation; the wave front steepness of the lightning current on the main current discharge source is calculated by the current amplitude and the wave front time; The current amplitudes of the lightning currents on the n current return stroke sources are calculated based on a preset Log-Logistic distribution formula for the current amplitudes of the lightning currents on the current main discharge source; or, are set according to a predetermined amplitude variation rule; or, are set according to the maximum shielding lightning current taking the limit condition or the maximum back-stroke lightning current; The value of the wave front time of the lightning current on the n current return stroke sources is set according to the predetermined wave front time variation law; The values ​​of the wave front steepness of the lightning current on the n current return stroke sources are calculated by the values ​​of the respective current amplitudes and the values ​​of their corresponding wave front times; The values ​​of the delay time on the n delay modules are all set to the same constant; The impedance value of the wave impedance is set based on the lightning current discharge type.

3. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 2, characterized in that: When the lightning current discharge type is a lightning strike, the current amplitude of the lightning current on the current main discharge source is taken as a first value, the wave front time is taken as a first time constant, and the wave front steepness is taken as a quotient obtained by dividing the first value by the first time constant; When the lightning current discharge type is counter-strike lightning, if the voltage level of the substation is 110 kV, the current amplitude of the lightning current on the current main discharge source is taken as the second value, the wave front time is taken as the second time constant, and the wave front steepness is taken as the quotient obtained by dividing the second value by the second time constant; When the lightning current discharge type is strike back lightning, if the voltage level of the substation is 220kV, the current amplitude of the lightning current on the current main discharge source is taken as the third value, the wave front time is the third time constant, and the wave front steepness is the quotient obtained by dividing the third value by the third time constant.

4. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 2, characterized in that: The predetermined amplitude change rule is a calculation rule that the current amplitude of the lightning current on the current return stroke source is 1 / 3 of the current amplitude of the lightning current on its previous current return stroke source; wherein, if the current current return stroke source is adjacent to the current main discharge source, then the current amplitude of its lightning current is 1 / 3 of the current amplitude of the lightning current on the current main discharge source.

5. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 3, characterized in that: The predetermined wave front time variation rule is a calculation rule that the wave front time of the lightning current released by the current current return stroke source is 1 / 2 of the wave front time of the lightning current released by the previous current return stroke source; wherein, if the current current return stroke source is adjacent to the current main discharge source, the wave front time of its lightning current is fixed to the fourth time constant.

6. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 3, characterized in that: The values ​​of the wave front steepness of the lightning current on the n current return stroke sources are all quotients obtained by dividing the values ​​of the current amplitudes of the respective lightning currents by the values ​​of the corresponding wave front time.

7. The lightning current modeling method in lightning intrusion wave overvoltage simulation according to claim 3, characterized in that: When the lightning current discharge type is a lightning strike, the impedance value of the wave impedance is a first impedance constant; when the lightning current discharge type is a lightning strike, the impedance value of the wave impedance is a second impedance constant; wherein the first impedance constant is less than the second impedance constant.

8. A lightning current modeling system in lightning intrusion wave overvoltage simulation, characterized in that: include: A lightning current calculation model construction unit is used to construct a lightning current calculation model of a substation under multiple lightning strikes in a preset simulation software; wherein the lightning current calculation model is simulated by a wave impedance and n+1 oblique wave current sources, and the wave impedance is connected in parallel with each oblique wave current source; a delay module is provided between two adjacent oblique wave current sources; among the n+1 oblique wave current sources, the oblique wave current source farthest from the wave impedance is a main current discharge source for characterizing active discharge of lightning current, and the other n oblique wave current sources are n current return stroke sources for characterizing n return strokes after active discharge of lightning current; n is a positive integer greater than or equal to 1; The model parameter value setting unit is used to set the value of n in the lightning current calculation model according to the voltage level of the substation and the type of lightning current discharge, and further set the current amplitude, wave front time and wave front steepness of the lightning current released by the current main discharge source, the current amplitude, wave front time and wave front steepness of the lightning current released by the n current return stroke sources, the values ​​of the delay time on the n delay modules, and the impedance value of the wave impedance; wherein the voltage level of the substation is 110kV or 220kV; and the lightning current discharge type is bypass lightning or counter-strike lightning.

9. The lightning current modeling system in lightning intrusion wave overvoltage simulation according to claim 8, characterized in that: The current amplitude and wave front time of the lightning current on the main current discharge source are set based on the voltage level and lightning current discharge type of the substation; the wave front steepness of the lightning current on the main current discharge source is calculated by the current amplitude and the wave front time; The current amplitudes of the lightning currents on the n current return stroke sources are calculated based on a preset Log-Logistic distribution formula for the current amplitudes of the lightning currents on the current main discharge source; or, are set according to a predetermined amplitude variation rule; or, are set according to the maximum shielding lightning current taking the limit condition or the maximum back-stroke lightning current; The value of the wave front time of the lightning current on the n current return stroke sources is set according to the predetermined wave front time variation law; The values ​​of the wave front steepness of the lightning current on the n current return stroke sources are calculated by the values ​​of the respective current amplitudes and the values ​​of their corresponding wave front times; The values ​​of the delay time on the n delay modules are all set to the same constant; The impedance value of the wave impedance is set based on the lightning current discharge type.

10. The lightning current modeling system in lightning intrusion wave overvoltage simulation according to claim 9, characterized in that: When the lightning current discharge type is a lightning strike, the current amplitude of the lightning current on the current main discharge source is taken as a first value, the wave front time is taken as a first time constant, and the wave front steepness is taken as a quotient obtained by dividing the first value by the first time constant; When the lightning current discharge type is counter-strike lightning, if the voltage level of the substation is 110 kV, the current amplitude of the lightning current on the current main discharge source is taken as the second value, the wave front time is taken as the second time constant, and the wave front steepness is taken as the quotient obtained by dividing the second value by the second time constant; When the lightning current discharge type is strike back lightning, if the voltage level of the substation is 220kV, the current amplitude of the lightning current on the current main discharge source is taken as the third value, the wave front time is the third time constant, and the wave front steepness is the quotient obtained by dividing the third value by the third time constant.

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