CN115825584A - Lightning positioning optimization method and system for correcting influence of terrain and geological parameters on lightning electromagnetic wave transmission and medium - Google Patents
Lightning positioning optimization method and system for correcting influence of terrain and geological parameters on lightning electromagnetic wave transmission and medium Download PDFInfo
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Abstract
The method comprises the steps of gridding the peripheral area of a thunder detection station participating in thunder positioning, and calculating the time delay correction value and the parameter correction coefficient of the thunder electromagnetic wave waveform transmitted from the thunder initial position to the thunder detection station under the conditions of not considering the terrain and the geological parameters and considering the terrain and the geological parameters when each grid point is used as the thunder initial position by utilizing ground and ionized layer electromagnetic wave transmission model simulation; and when the closest lattice points are respectively found in the time delay correction tables and the parameter correction coefficient tables corresponding to the lightning detection stations participating in positioning as lightning strike points, the time delay correction values and the parameter correction coefficients corresponding to the lightning detection stations respectively correct the participating lightning detection stations to obtain corrected waveform arrival time and corrected characteristic parameters corresponding to the lightning detection stations, and lightning accurate positions and lightning accurate characteristic parameters are calculated.
Description
Technical Field
The invention relates to the technical field of lightning location, in particular to a lightning location optimization method, a lightning location optimization system and a medium for correcting influences of topographic and geological parameters on lightning electromagnetic wave propagation.
Background
Thunder and lightning is a phenomenon of short-time and strong atmospheric discharge existing in the nature, which can cause forest fires and building destruction, and prevent the normal operation of industry departments such as electric power, communication, petroleum, chemical engineering and the like. The lightning strikes an overhead high-voltage transmission line or an iron tower to generate overvoltage, so that the tripping or the outage of a power transmission system is a serious meteorological disaster faced by China and even the global power industry, and accidents caused by the disaster can account for more than 40% of power grid accidents in China. The frequency band of the lightning electromagnetic wave generated in the primary lightning process covers from Extremely Low Frequency (ELF) to Ultra High Frequency (UHF), and the propagation characteristics of the electromagnetic wave in different frequency bands are different. At present, the electric power department in China generally constructs a lightning positioning system for monitoring lightning stroke power grid accidents so as to rapidly inspect and analyze the accidents and avoid catastrophic consequences of power failure in a larger area caused by expansion of the accidents.
The lightning location technology adopted by the electric power department in China at present is to construct a lightning detection network to collect lightning electromagnetic waves through a detection device of a VLF/LF frequency band, and to realize the determination of lightning positions and the inversion of lightning parameters through a multi-station location algorithm by means of electromagnetic wave waveform parameters. Due to the influences of factors such as geographic environment, system hardware conditions, survey station layout and algorithm and the like, the lightning location accuracy and the parameter inversion accuracy of the lightning location network in each area are different. The lightning electromagnetic wave is influenced by factors such as irregular topographic features with fluctuation, limited soil conductivity, soil anisotropy and the like in the process of propagating along the ground surface, so that the waveform peak value and the position, the rising edge time, the half-peak time and the like of the electromagnetic wave are changed.
However, the existing lightning location algorithm basically assumes that electromagnetic waves in VLF/LF frequency band are transmitted on a standard earth ellipsoid model, and does not consider the influence of ground relief topography and finite conductivity on the transmission of the electromagnetic waves, especially in complex terrain environments such as Chuanzang areas in China, the waveform change of the lightning electromagnetic waves is more obvious, and more obvious errors are introduced to lightning location positions and inversion parameters.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a thunder and lightning positioning optimization method, a thunder and lightning positioning optimization system and a thunder and lightning positioning optimization medium for correcting the influence of terrain and geological parameters on the transmission of thunder and lightning electromagnetic waves.
In order to achieve the purpose, the invention designs a lightning positioning optimization method for correcting the influence of topographic and geological parameters on the transmission of lightning electromagnetic waves, which is characterized by comprising the following steps:
Further, in step 1, the specific step of establishing the ground and ionosphere electromagnetic wave propagation model is
Step 1-1, assuming that the lightning electromagnetic wave is transmitted on a two-dimensional plane r-z plane under a cylindrical coordinate system, wherein the r direction is along the earth surface direction, the z direction is the height direction,
the direction is the direction meeting the right-hand rule with the r direction and the z direction,
the gradient in the direction is constant to 0, a Maxwell rotation equation set of a vertical electric field and a horizontal magnetic field of VLF/LF lightning electromagnetic waves propagating between the ground and an ionized layer r-z plane is deduced from a Maxwell original equation set, and the propagation of the lightning electromagnetic waves from a lightning preliminary position to a lightning detection station is solved by the Maxwell rotation equation set;
step 1-2, applying a lightning current excitation source at a lightning preliminary position, wherein the lightning current excitation source is a lightning current strike-back channel and is placed on a symmetrical axis of a two-dimensional cylindrical coordinate system, assuming that a base current at the bottom of the strike-back discharge channel is I (0, t), the lightning current gradually develops upwards from the ground, the propagation speed is v, the amplitude of the lightning current attenuates along with the height z according to the f (z) rule, the current distribution at the height z of the channel at the time t is I (z, t), and the current distribution at the height z of the channel at the time t is I (z, t) expressed as an expression
Step 1-3, carrying out differential dispersion on a Maxwell rotation equation set, carrying out dispersion on E and H components in an electromagnetic field in a space and time alternative sampling mode, namely, four corresponding H and E field components surround each E and H field component, converting the Maxwell rotation equation set containing time variables into a Maxwell dispersion equation set through the dispersion mode, and gradually updating and advancing through a leapfrog format on a time domain to solve a space electromagnetic field, adopting Yee cells in a space format distribution under a cylindrical coordinate system, setting the lattice point of the Yee cells as (i, j, k), namely (i, j, k) representing that the r direction is i, the phi direction is j, and the z direction is k, connecting a plurality of same Yee cells together to form the whole calculation domain, and staggering the electric field and the magnetic field on a time step, namely, the updating of the electric field and the magnetic field has half time step difference;
1-4, receiving a lightning vertical electric field E from a lightning detection station under the consideration of topographic and geological parameter factors z Wave-shaped or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform a And characteristic parameter Pr a (ii) a Lightning vertical electric field E received by lightning detection station without considering terrain and geological parameter factors z Wave-shaped or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform b And characteristic parameter Pr b (ii) a The formula of the time delay correction value is delta t = t a -t b The formula of the parameter correction coefficient is k = Pr a /Pr b 。
Further, in step 1-1, the Maxwell original equation set is
In the above-mentioned formula, the compound has the following structure,
e is a vector of the electric field intensity in the propagation of the electric wave,
b is the magnetic induction vector in the propagation of the electric wave,
p is the free charge and is the free charge,
ε 0 which is the dielectric constant in a vacuum, is,
j is the conduction current density vector, j = σ E,
sigma is the electrical conductivity of the steel,
μ 0 is magnetic permeability;
further, in step 1-1, the Maxwell rotation equation set based on the vertical electric field and the horizontal magnetic field of the lightning discharge channel is as follows
Wherein,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
Further, in step 1-2, the Heidler double exponential function is used to construct the ground bounce back bottom base current I (0, t), and the expression of the ground bounce back bottom base current I (0, t) is
Wherein,
I 01 which is representative of the breakdown current of the transistor,
I 02 which is representative of the peak value of the corona current,
eta represents a breakdown current correction factor,
τ 1 the rise time of the waveform representing the breakdown current,
τ 2 the waveform fall time representing the breakdown current,
τ 3 representing the rise time of the waveform of the corona current,
τ 4 representing the waveform fall time of the corona current.
Further, in step 1-2, an MTLE engineering model is used as a current back-striking model, the base current decays exponentially in the upward development process, and the current distribution at the channel height z at the time t is represented by I (z, t)
I(z,t)＝e -z/λ I(0,t-z/v)
Wherein,
i (z, t) is the current at the z-height of the channel at time t,
z is the height of the strike-back discharge channel,
e -z/λ in order that the lightning current amplitude decays exponentially with the height z,
the x is a decay factor of the optical fiber,
v is the propagation velocity of the lightning current.
Further, in steps 1-3, the Maxwell discrete equations are set as
Wherein,
at represents a step of time that is,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
μ represents the magnetic permeability and,
ε represents a dielectric constant.
Further, in steps 1-4, the waveform arrival time is extracted based on a waveform peak point, a half-peak point of a waveform rising edge, or a maximum point of a waveform rising edge derivative, and the characteristic parameters include a waveform peak value, a wave head time, a wave tail time, a waveform half-peak width, and an electric field amplitude.
Further, in step 5, the lightning detection station S involved in lightning location 1 、S 2 、S 3 、…、S n The arrival time of the waveforms of the lightning electromagnetic waves received by the lightning electromagnetic waves is T 1 、T 2 、T 3 、…、T n And with the closest lattice point A 1 、A 2 、A 3 、…、A n As lightning strike points, lightning detection stations S 1 、S 2 、S 3 、…、S n The corresponding delay correction value is divided into Δ t 1 ′、Δt 2 ′、Δt 3 ′…、Δt n ', then lightning detection station S 1 、S 2 、S 3 、…、S n The arrival times of the corresponding corrected waveforms are respectively T 1 -Δt 1 ′、T 21 -Δt 2 ′、T 31 -Δt 3 ′、…、T n1 -Δt n ′。
Further, in step 5, a lightning detection station S involved in lightning location 1 、S 2 、S 3 、…、S n The characteristic parameters of the lightning electromagnetic waves received by the lightning electromagnetic waves are respectively Pr 1 、Pr 2 、Pr 3 、…、Pr n And with the closest lattice point A 1 、A 2 、A 3 、…、A n As lightning strike points, lightning detection stations S 1 、S 2 、S 3 、…、S n The corresponding parameter correction coefficients are respectively k 1 ′、k 2 ′、k 3 ′…、k n ', then lightning detection station S 1 、S 2 、S 3 、…、S n The corresponding corrected characteristic parameters are respectively 1/k 1 ′×Pr 1 、1/k 2 ′×Pr 2 、1/k 3 ′×Pr 3 、…、1/k n ′×Pr n 。
Furthermore, in step 4, the method for finding the closest lattice point closest to the corresponding lightning preliminary position includes calculating a distance R and a preset azimuth angle θ of the lightning preliminary position relative to each lightning detection station, and finding the lattice point closest to both the distance R and the preset azimuth angle θ in the equidistant circle corresponding to each lightning detection station as the closest lattice point closest to the lightning preliminary position.
Furthermore, in step 2, the radii of the equally spaced circles are R respectively 1 、R 2 、R 3 、…、R a ，R 1 、R 2 、R 3 、…、R a Are all 6-15 km, wherein R a Wherein a takes a value of 20 to 50; the preset azimuth angle of the equiangular ray is theta 1 、θ 2 、θ 3 、…、θ b ，θ 1 、θ 2 、θ 3 、…、θ b Are all 1 to 3 degrees, wherein theta b The value of b is floor (360/theta), which represents the rounding operation.
Furthermore, in step 3, the lightning location method is to obtain the initial lightning occurrence time t by solving the minimum value of the cost function formed by the nonlinear equation system initial Lightning preliminary position P (x) initial ，y initial )，(x initial ，y initial ) Longitude and latitude representing a lightning strike point; the set of non-linear equations comprises a lightning detection station S i The arrival time T of the received thunder and lightning electromagnetic wave i And the lightning preliminary position P (x) initial ，y initial ) And a lightning detection station S i Measured azimuth angle β of i The system of nonlinear equations is
β i ＝β Pi +ε Ai
Wherein,
T i for a participating lightning detection station S i The arrival time of the lightning electromagnetic wave is received,
t is the time of occurrence of the lightning,
S Pi for lightning strikes P (x, y) to a participating lightning detection station S i Distance of (S) Pi It needs to be calculated on the ellipsoid surface,
c is the propagation speed of the electromagnetic wave,
ε Ti in order to measure the error in time,
β i for a participating lightning detection station S i The measured azimuth angle of the lightning electromagnetic wave is received,
β Pi for lightning strikes P (x, y) to a participating lightning detection station S i Is calculated as azimuth angle, beta Pi It needs to be calculated on the ellipsoid surface,
ε Ai in order to measure the error in the angle,
S i is known as (x) i ,y i ) Wherein i =1,2,3 \ 8230n;
the system of nonlinear equations is described as the following simple form
r i ＝F i (t,x,y)+ε i
Wherein,
r i in order to observe the quantity of the object,
F i (t，x l and y) is a function of the unknown number,
ε i to measure the error.
Further, in step 3, in a simple form of the system of nonlinear equations, when ε i Cost function minimum of simple form of the system of nonlinear equations when =0
Namely the preliminary thunder and lightning occurrence time t initial Lightning preliminary position P (x) initial ，y initial )。
A computer-readable storage medium storing a computer program, characterized in that: the computer program, when being executed by a processor, carries out the steps of the lightning localization optimization method as described above.
The invention has the advantages that:
1. according to the lightning detection method, in a ground and ionized layer electromagnetic wave propagation model, firstly, electromagnetic wave propagation numerical calculation simulation is performed, lightning electromagnetic wave waveforms considering terrain, geological parameters and terrain and geological parameters are calculated, time delay correction values and parameter correction coefficients of each lightning detection station corresponding to a lightning preliminary position are obtained, and real terrain fluctuation and real soil conductivity are considered in the electromagnetic wave propagation numerical simulation, so that the lightning positioning optimization effect can be greatly improved, and the lightning positioning accuracy and the parameter inversion accuracy are improved;
2. the method comprises the steps of meshing a target area of participating lightning detection stations, namely drawing a plurality of equidistant circles by taking each lightning detection station as a center, drawing isoangle rays which pass through corresponding circle centers and have preset azimuth angles on each equidistant circle, wherein intersection points of each isoangle circle and each isoangle ray are grid points in the target area, and calculating time delay correction values and parameter correction coefficients of all grid points in the area of each lightning detection station participating in lightning location by using a ground and ionosphere electromagnetic wave propagation model;
3. the method comprises the steps of manufacturing time delay correction values and parameter correction coefficients of all grid points in a self area corresponding to lightning detection stations participating in lightning positioning into corresponding time delay correction tables and parameter correction coefficient tables, and taking the time delay correction tables and the parameter correction coefficient tables corresponding to the lightning detection stations as information indexes of the lightning detection stations, namely carrying out numerical simulation of time consumption in advance, only needing to inquire the information indexes of the lightning detection stations in actual service application, and greatly improving the efficiency of lightning positioning optimization;
4. according to the method, the closest lattice points closest to the primary lightning position are respectively found on equidistant circles corresponding to the lightning detection stations participating in lightning positioning according to the primary lightning position, and the time delay correction values and the parameter correction coefficients corresponding to the lightning detection stations when the closest lattice points are used as lightning points are determined according to respective information indexes of the lightning detection stations participating in lightning positioning;
5. according to the method, the corrected waveform arrival time of the lightning electromagnetic waves received by the participating lightning detection stations is calculated through the time delay correction values of the participating lightning detection stations corresponding to the respective closest lattice points, and the accurate lightning occurrence time and the accurate lightning position are obtained through recalculation by utilizing the existing lightning positioning method; calculating corrected characteristic parameters of lightning electromagnetic waves received by the participating lightning detection stations respectively through the parameter correction coefficients of the participating lightning detection stations corresponding to the respective closest grid points, and recalculating to obtain accurate lightning characteristic parameters;
the invention relates to a thunder and lightning positioning optimization method, a thunder and lightning positioning optimization system and a thunder and lightning positioning optimization medium for correcting influences of landform and geological parameters on thunder and lightning electromagnetic wave propagation, which are characterized in that a ground and ionosphere electromagnetic wave propagation model is established, time delay correction values and parameter correction coefficients of the thunder and lightning electromagnetic waves propagated from a lightning primary position to a thunder and lightning detection station under the condition of considering the landform and the geological parameters and not considering the landform and the geological parameters are calculated in a simulation mode, a target area of the thunder and lightning detection station participating in the thunder and lightning positioning is meshed, a time delay correction table and a parameter correction coefficient table of all grid points in the area corresponding to the participating thunder and lightning positioning are calculated, and according to the corresponding thunder and lightning primary occurrence time, thunder and lightning primary position and thunder primary characteristic parameters of the thunder and lightning detection station participating in the thunder positioning and the closest grid point serving as a lightning strike point, the corresponding time delay correction values and lightning primary position and lightning characteristic parameters of the participating thunder detection station are recalculated.
Drawings
FIG. 1 is a flow chart of the lightning location optimization method for correcting the influence of topographic and geological parameters on the transmission of lightning electromagnetic waves;
FIG. 2 is a schematic diagram of the principles of the present invention;
FIG. 3 is a spatial format distribution diagram under a cylindrical coordinate system according to the present invention;
FIG. 4a is an integral diagram of electric field waveforms received by a lightning detection station in the Tibet region of China when the terrain and geological parameters are taken into consideration and the terrain and geological parameters are not taken into consideration;
FIG. 4b is a partial enlarged view of the electric field waveform of FIG. 4 a;
FIG. 5 is a schematic diagram of the target area meshing of a lightning detection station according to the present invention;
FIG. 6 is a schematic diagram of a method for finding the closest lattice point to the preliminary location of lightning in the present invention;
FIG. 7a is a distribution diagram of altitude within 300km of a lightning detection station in FIGS. 4 a-4 b;
FIG. 7b is a diagram showing a distribution of conductivity of soil in a range of 300km around a lightning detection station in FIGS. 4 a-4 b;
FIG. 7c is a distribution diagram of the lightning electric field amplitude correction coefficient within a range of 300km around a lightning detection station in FIGS. 4 a-4 b;
FIG. 7d is a distribution diagram of the lightning electric field time delay correction values within 300km around a lightning detection station in FIGS. 4 a-4 b;
FIG. 8 is a position distribution diagram of a lightning strike point and 7 detection stations involved in positioning in an embodiment of the present invention;
FIG. 8a is a cross-sectional view of the terrain between the detection station number 1 and the lightning strike point of FIG. 8;
FIG. 8b is a cross-sectional view of the terrain between the detection station number 2 and the lightning strike point of FIG. 8;
FIG. 8c is a cross-sectional view of the terrain between the detection station # 3 and the lightning strike point of FIG. 8;
FIG. 8d is a cross-sectional view of the terrain between the detection station number 4 and the lightning strike point of FIG. 8;
FIG. 8e is a cross-sectional view of the terrain between the detection station No. 5 and the lightning strike point of FIG. 8;
FIG. 8f is a cross-sectional view of the terrain between the probing station number 6 and the lightning strike point of FIG. 8;
FIG. 8g is a cross-sectional view of the terrain between the detection station # 7 and the lightning strike point of FIG. 8;
FIG. 9a is a waveform diagram of a vertical electric field (Ez) of the No. 1 detecting station in FIG. 8a when the terrain and geological parameters are considered and the terrain and geological parameters are not considered;
FIG. 9b is a graph of vertical electric field (Ez) waveforms for the detection station # 2 of FIG. 8b, with and without consideration of terrain and geological parameters;
FIG. 9c is a graph of vertical electric field (Ez) waveforms for the station No. 3 of FIG. 8c, with and without consideration of terrain and geological parameters;
FIG. 9d is a graph of vertical electric field (Ez) waveforms for the station No. 4 of FIG. 8d with and without consideration of terrain and geological parameters;
FIG. 9e is a graph of vertical electric field (Ez) waveforms for the detection station # 5 in FIG. 8e with and without consideration of terrain and geological parameters;
FIG. 9f is a graph of vertical electric field (Ez) waveforms for the station No. 6 of FIG. 8f, with and without consideration of terrain and geological parameters;
FIG. 9g is a graph of vertical electric field (Ez) waveforms for the station No. 7 of FIG. 8g, with and without consideration of terrain and geological parameters;
FIG. 10 is a block diagram of a lightning localization optimization system for correcting the influence of topographic and geological parameters on the propagation of lightning electromagnetic waves in accordance with the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the invention.
As shown in FIG. 1, the lightning positioning optimization method for correcting the influence of topographic and geological parameters on lightning electromagnetic wave propagation comprises the following steps:
In the ground and ionosphere electromagnetic wave propagation model, the ground is taken as an irregular ground surface with topographic relief and geological parameter change, the ionosphere is taken as a layer of medium with the conductivity sigma changing along with the height, and the thunder electromagnetic wave is propagated to a detection station from a thunder electromagnetic wave excitation source under a cylindrical coordinate system, and the schematic diagram of the principle is shown in fig. 2.
Step 1-1, assuming that the lightning electromagnetic wave is transmitted on a two-dimensional plane r-z plane under a cylindrical coordinate system, wherein the r direction is along the earth surface direction, the z direction is the height direction,
the direction is the direction meeting the right-hand rule with the r direction and the z direction,
the gradient of the direction is constant 0, a Maxwell rotation equation set of a vertical electric field and a horizontal magnetic field of VLF/LF lightning electromagnetic waves propagating on the ground and an ionized layer r-z plane is deduced from a Maxwell original equation set, and the Maxwell rotation equation set is used for solving the lightning electromagnetic waves from a lightning preliminary position P (x) initial ，y initial ) Propagation to the lightning detection station S.
Specifically, the Maxwell original equation set is
In the above formula, the first and second carbon atoms are,
e is a vector of electric field strength in propagation of the electric wave,
b is the magnetic induction vector in the propagation of the electric wave,
p is the free charge and is the free charge,
ε 0 which is the dielectric constant in a vacuum, is,
j is the conduction current density vector, j = σ E,
sigma is the electric conductivity of the alloy, and the electric conductivity of the alloy,
μ 0 is magnetic permeability.
For a wide-area lightning positioning system, the vertical electric field and the horizontal magnetic field of a lightning discharge channel are mainly detected, and the Maxwell rotation equation system based on the vertical electric field and the horizontal magnetic field of the lightning discharge channel is
Wherein,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
Step 1-2, at the preliminary position P (x) of thunder and lightning initial ，y initial ) Applying a lightning current excitation source which is a lightning current return channel and is placed on a symmetrical axis of a two-dimensional cylindrical coordinate system, and assuming that the base current at the bottom of the return discharge channel is I (0, t), the lightning current is from the groundThe surface starts to gradually develop upwards, the propagation speed is v, the lightning current amplitude is attenuated along the height z according to the f (z) rule, the current distribution at the channel height z at the time t is I (z, t), wherein the current distribution at the channel height z at the time t is I (z, t), the expression is I (z, t)
Then according to the lightning electromagnetic wave propagation equation set in the step 1-1, obtaining the lightning preliminary position P (x) under the cylindrical coordinate system initial ，y initial ) And (4) transmitting the lightning electromagnetic wave excitation source to the lightning detection station S.
Specifically, the bottom base current I (0, t) of the ground snapback is constructed by using a Heider bi-exponential function, and then the bottom base current I (0, t) of the ground snapback is expressed as
Wherein,
wherein,
I 01 representing the breakdown current, and taking 9.9kA,
I 02 representing the peak value of the corona current, and taking 7.5kA,
eta represents the breakdown current correction factor, takes the value of 0.845,
τ 1 the waveform rise time representing the breakdown current is 0.072 mus,
τ 2 the waveform falling time representing the breakdown current is 5 mus,
τ 3 representing the waveform rise time of the corona current, taking 100 mus,
τ 4 the waveform falling time of the corona current is 6 mus.
In addition, an MTLE (modified Transmission line models with explicit decay of the current with height) engineering model is adopted as a current attack model, the base current decays in an exponential form in the upward development process, and the current distribution at the channel height z at the time t is represented by I (z, t) and represented by I (z, t)
I(z,t)＝e -z/λ I(0,t-z/v)
Wherein,
i (z, t) is the current at the z-height of the channel at time t,
z is the height of the back-striking discharge channel, with a maximum of 7500m,
e -z/λ in order that the lightning current amplitude decays exponentially with the height z,
lambda is attenuation factor, the value of which is 2000m,
v is the propagation velocity of lightning current and takes 1.5 multiplied by 10 8 m/s。
Step 1-3, carrying out differential dispersion on the Maxwell rotation equation set, dispersing E and H components in an electromagnetic field in a space and time alternative sampling mode, namely, surrounding each E and H field component by four corresponding H and E field components, converting the Maxwell rotation equation set containing time variables into the Maxwell dispersion equation set in the dispersion mode, gradually updating and advancing in a time domain through a leapfrogue format to solve the space electromagnetic field, adopting Yee cells in a space format distribution under a cylindrical coordinate system, setting the lattice point of the Yee cells as (i, j, k), namely, (i, j, k) represents that r direction is i, phi direction is j, and z direction is k, the whole calculation domain is formed by connecting a plurality of same Yee cells, and the electric field and the magnetic field are staggered in a time step, namely, the updating of the electric field and the magnetic field are different by half of time step.
The Maxwell discrete equation set is
Wherein,
at represents a step of time that is,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
μ represents the magnetic permeability and,
ε represents a dielectric constant.
Considering that the computer is limited in capability, the numerical solution of the maxwell discrete equation set can be performed only in a limited area, and in order to simulate the open-domain electromagnetic wave propagation process, an absorption boundary condition must be given at the boundary of the calculation area.
Magnetic field component B of electromagnetic wave propagating in medium φ Split into two subcomponents B φr And B φz And B is φ ＝B φr +B φz Thus, maxwell's rotation equation will be rewritten as:
wherein σ is the electric conductivity, and u is the magnetic conductivity; when σ is r ＝σ z ＝u r ＝u z If =0, the equation degenerates to maxwell's equation for free space; when the electric conductivity and the magnetic permeability are not 0, the medium becomes a lossy medium, and the electromagnetic wave is attenuated in the medium.
In addition, in the steps 1-3, the terrain elevation data is obtained through digital elevation model data, and the geological parameters are represented through soil conductivity.
1-4, receiving a lightning vertical electric field by a lightning detection station under the consideration of topographic and geological parameter factorsE z Wave-shaped or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform a And characteristic parameter Pr a (ii) a Thunder and lightning vertical electric field E received by thunder and lightning detection station under the condition of not considering terrain and geological parameter factors z Wave-shaped or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform b And characteristic parameter Pr b (ii) a The formula of the time delay correction value is delta t = t a -t b The formula of the parameter correction coefficient is k = Pr a /Pr b 。
Specifically, the waveform arrival time is extracted based on a waveform peak point, a half-peak point of a waveform rising edge or a maximum point of a waveform rising edge derivative, and the characteristic parameters include a waveform peak value, a wave head time, a wave tail time, a waveform half-peak width and an electric field amplitude.
Specifically, the influence of topographic and geological parameters is not considered, i.e. a flat, lossless ground; the effects of terrain and geological parameters, i.e. heaving, lossy ground, are taken into account.
In the embodiment, a place in the Tibet region of China is used as a lightning detection station, and the received electric field waveform of the lightning detection station is shown in figures 4 a-4 b when the terrain and geological parameters are considered and the terrain and geological parameters are not considered. And (3) electric field waveforms obtained under flat, lossless ground and undulating, lossy ground conditions assuming that a lightning current as represented by the current distribution expression in the above step 1-2 occurs at 300km just west of the lightning detection station, wherein fig. 4a is an overall view of the electric field waveforms and fig. 4b is a partially enlarged view of the electric field waveforms. The relief surface model of FIGS. 4 a-4 b uses the global terrain model ETOPO1 with a resolution of 1'× 1' promulgated by the national oceanics and atmospheric administration, and has a spatial resolution of about 1.6km × 1.6km; soil texture type data is derived from the World Soil Database (HWSD), which contains the required Soil conductivity information.
According to the lightning detection method, the ground and ionized layer electromagnetic wave propagation models are subjected to electromagnetic wave propagation numerical calculation simulation, the lightning electromagnetic wave waveform with the terrain and geological parameters and without the terrain and geological parameters is calculated, the time delay correction value and the parameter correction coefficient of each lightning detection station corresponding to the primary lightning position are obtained, and the real terrain fluctuation and the real soil conductivity are considered in the electromagnetic wave propagation numerical simulation, so that the lightning positioning optimization effect can be greatly improved, and the lightning positioning accuracy and the parameter inversion accuracy are improved.
Step 2, respectively using thunder and lightning detection stations S participating in thunder and lightning positioning 1 、S 2 、S 3 、…、S n As a center, a radius R is plotted 1 、R 2 、R 3 、…、R a The equal-spacing circles (equal-spacing circles: the spacing between two adjacent circles) are drawn on each equal-spacing circle, and the circle passes through the corresponding circle center and has a preset azimuth angle theta 1 、θ 2 、θ 3 、…、θ b The equal angle rays (equal angle rays: the angles between the adjacent rays are equal), and the intersection point of the equal spacing circle and the equal angle rays is the corresponding lightning detection station S 1 、S 2 、S 3 、…、S n Grid points within the region; station for detecting lightning 1 、S 2 、S 3 、…、S n All lattice points in the area are respectively used as lightning primary positions P (x) initial ，y initial ) Calculating the lightning detection station S 1 、S 2 、S 3 、…、S n Time delay correction values and parameter correction coefficients corresponding to all grid points in the area per se are made into corresponding time delay correction tables and parameter correction coefficient tables by each lightning detection station corresponding to all grid points in the area per se, and the time delay correction tables and the parameter correction coefficient tables corresponding to each lightning detection station are used as information indexes of the lightning detection station; steps 1-1 to 1-4 can be performed on the target area in advance, and the delay correction table and the parameter correction coefficient table of the area are obtained in advance.
Specifically, the invention carries out target area gridding display on the lightning detection stationSee figure 5 for an intent. In addition, the equidistant radii are each R 1 、R 2 、R 3 、…、R a ，R 1 、R 2 、R 3 、…、R a Are all 6-15 km, wherein R a Wherein a takes a value of 20 to 50; the preset azimuth angle of the equiangular ray is theta 1 、θ 2 、θ 3 、…、θ b ，θ 1 、θ 2 、θ 3 、…、θ b Are all 1 to 3 degrees, wherein theta b The value of b is floor (360/theta), which represents the rounding operation.
The invention carries out target area gridding on the thunder and lightning detection stations participating in thunder and lightning positioning, namely, each thunder and lightning detection station is taken as the center to draw a radius R 1 、R 2 、R 3 、…、R a Is equally spaced, and a predetermined azimuth angle theta is drawn 1 、θ 2 、θ 3 、…、θ b The intersection points of the circular arcs and the rays are grid points in the target area, time delay correction values and parameter correction coefficients of all the grid points in the area corresponding to the participating lightning detection stations are calculated, the method can greatly reduce the workload of simulation calculation, and the lightning electromagnetic wave waveform of each grid point along the isoangle ray can be obtained by carrying out one-time simulation calculation on one isoangle ray.
And 3, assuming the earth as a standard ellipsoid model, and detecting the lightning through the involved lightning detection station S 1 、S 2 、S 3 、…、S n The waveform arrival time T of each received thunder and lightning electromagnetic wave 1 、T 2 、T 3 、…、T n Calculating to obtain the preliminary thunder occurrence time t by utilizing the conventional thunder positioning method initial Lightning preliminary position P (x) initial ，y initial ) (ii) a Then through the participating lightning detection station S 1 、S 2 、S 3 、…、S n Waveform characteristic parameter Pr extracted from waveforms of respective received lightning electromagnetic waves 1 、Pr 2 、Pr 3 、…、Pr n Calculating to obtain the primary characteristic parameter Pr of the thunder and lightning initial 。
Existing lightning location methods include time difference methods or grid search methods by assuming the earth as a standard ellipsoidal model (e.g., WGS-84 model).
Specifically, the existing lightning location method obtains the initial lightning occurrence time t by solving the minimum value of a cost function formed by a nonlinear equation set initial Lightning preliminary position P (x) initial ，y initial )，(x initial ，y initial ) Longitude and latitude representing a lightning strike point; the set of non-linear equations comprises a lightning detection station S i The arrival time T of the received thunder and lightning electromagnetic wave i And the lightning preliminary position P (x) initial ，y initial ) And a lightning detection station S i Measured azimuth angle beta therebetween i The system of nonlinear equations is
β i ＝β Pi +ε Ai
Wherein,
T i for a participating lightning detection station S i The arrival time of the lightning electromagnetic wave is received,
t is the time of occurrence of the lightning,
S Pi for lightning strikes P (x, y) to a participating lightning detection station S i Distance of (S) Pi It is necessary to calculate on an ellipsoid surface,
c is the propagation speed of the electromagnetic wave,
ε Ti in order to measure the error in time,
β i for a participating lightning detection station S i The measured azimuth angle of the lightning electromagnetic wave is received,
β Pi for lightning strikes P (x, y) to a participating lightning detection station S i Is calculated as azimuth angle, beta Pi It needs to be calculated on the ellipsoid surface,
ε Ai in order to measure the error in the angle,
S i coordinates of (2)Known as (x) i ,y i ) Wherein i =1,2,3 \ 8230n.
The system of nonlinear equations is described as the following simple form
r i ＝F i (t,x,y)+ε i
Wherein,
r i in order to observe the quantity of the object,
F i (t，x l and y) is a function of the unknown number,
ε i to measure the error.
The lightning location calculation aims at solving the optimal estimation value of the target position by using the observed quantity containing errors. When the observed error is small and obeys a normal distribution, then the distribution of the unknown quantities also obeys a multidimensional normal distribution, where the error ε is omitted, i.e., when ε is i Cost function minimum of simple form of the system of nonlinear equations when =0
Namely the preliminary thunder occurrence time t initia Lightning preliminary position P (x) initial ，y initial )。
According to the method, the time delay correction values and the parameter correction coefficients of all grid points in the area corresponding to the participating lightning detection stations are made into the time delay correction tables and the parameter correction coefficient tables, the time delay correction tables and the parameter correction coefficient tables corresponding to each lightning detection station are used as the information indexes of the lightning detection stations, namely, numerical simulation of the time consumption is carried out in advance, only the information indexes of each lightning detection station need to be inquired in practical service application, and the efficiency of lightning positioning optimization is greatly improved.
Specifically, the closest lightning preliminary position P (x) is found initial ，y initial ) The most similar lattice point A 1 、A 2 、A 3 、…、A n The method comprises calculating a lightning initial position P (x) initial ，y initial ) At the lightning detection station S, with respect to the distance R and the preset azimuth theta of each lightning detection station 1 、S 2 、S 3 、…、S n Finding the lattice points closest to the distance R and the preset azimuth theta in the corresponding equidistant circles to be the closest lightning primary position P (x) initial ，y initial ) The most similar lattice point A 1 、A 2 、A 3 、…、A n 。
According to the method, the closest lattice points closest to the primary lightning detection stations are respectively found on equidistant circles corresponding to the participating lightning detection stations according to the primary lightning positions, and then the time delay correction values and the parameter correction coefficients corresponding to the participating lightning detection stations are determined when the closest lattice points are taken as lightning strike points according to respective information indexes of the participating lightning detection stations, so that the retrieval efficiency can be improved, and the method is easy to realize in service;
fig. 6 is a schematic diagram of the method for finding the closest lattice point closest to the preliminary location of lightning in the present invention. As can be seen from FIG. 6, drawing equally spaced circles centering on the two lightning detection stations S1 and S2, the lightning preliminary location is at point P (x) initial ，y initial ) Calculating the distance R of the point P relative to the lightning detection station S1 A1 And a predetermined azimuth angle theta A1 Distance R relative to lightning detection station S2 A2 And a predetermined azimuth angle theta A2 . And comparing in the information index of the lightning detection station S1 to obtain the most similar lattice point A1, and comparing in the information index of the lightning detection station S2 to obtain the most similar lattice point A2.
FIGS. 7a to 7d are distribution diagrams showing the altitude, the soil conductivity, and the corresponding lightning electric field amplitude correction coefficient and lightning electric field time delay correction value within a range of 300km around a lightning detection station in the Tibet region of China in the above embodiments. It can be seen from fig. 7a to 7d that the lightning current amplitude parameter is strongly correlated with the terrain factor, taking the lightning detection station as an example, when the altitude of the lightning detection station is close to the surrounding, the lightning current amplitude ratio fluctuates around 1, the altitude of the whole area of the lightning detection station is above 4000m, the lightning current amplitude ratio of most areas is around 0.8-1.2, the altitude difference of only the south area is large, the altitude is around 2000m, and the fluctuation of the lightning current amplitude ratio of the area is large and fluctuates between 0.5-1.5.
The effect of the method for optimizing the lightning location, which corrects the influence of the topographic and geological parameters on the propagation of the lightning electromagnetic waves, is explained below in combination with a lightning stroke detected by the grid lightning location system 2022, 6 months, and 20 days.
After inquiring an existing power grid lightning positioning system, the lightning strike position at the moment is 907m away from a certain pole tower of the extra-high voltage power transmission line, the lightning current intensity is-15.5 kA, the lightning strike position is matched with the fault position, but the lightning current intensity is low, so that the extra-high voltage line cannot be tripped.
Fig. 8 shows the position distribution diagram of the above-mentioned one lightning strike point and 7 lightning detection stations involved in the positioning, and the topographic map of each lightning detection station to the lightning strike point. Wherein FIG. 8a is a topographical cross-sectional view between a number 1 detection station and a lightning strike point; FIG. 8b is a topographical cross-sectional view between the number 2 detection station and the lightning strike point; FIG. 8c is a topographical profile view between the number 3 detection station and the lightning strike point; FIG. 8d is a topographical profile view between the number 4 detection station and the lightning strike point; FIG. 8e is a topographical cross-sectional view between the number 5 detection station and the lightning strike point; FIG. 8f is a cross-sectional view of the terrain between the number 6 detection station and the lightning strike point; fig. 8g is a topographical profile between the number 7 detection station and the lightning strike point.
As can be seen from fig. 8a to 8g, the height difference of partial propagation paths is up to 1000m, such as 2 stations, 7 stations, etc. The lightning electric field waveform is received at each lightning detection station by applying a lightning current excitation source as described in step 2-2 above at the point of lightning strike. FIGS. 9 a-9 g show the vertical electric fields (E) of 7 participating lightning detection stations with and without consideration of terrain and geological parameters, respectively Z ) And (4) waveform. Vertical electric field (E) from FIGS. 9a to 9g Z ) Waveform characteristic parameters (peak amplitude) and waveform arrival time under the condition of considering terrain and geological parameters, and waveform characteristic parameters (including peak amplitude) and waveform arrival time under the condition of not considering terrain and geological parameters are respectively extracted from the waveform, and time delay correction values and amplitude correction coefficients shown in the table 1 are obtained by calculation, namely parameters required for correcting the position of the lightning stroke point.
TABLE 1 delay correction values and amplitude correction coefficients for participating lightning detection stations
According to the step 5, on the basis that the waveform arrival time of the lightning electromagnetic waves received by the 7 lightning detection stations respectively is reduced by the time delay correction value obtained by simulation, and then the existing lightning positioning method in the step 1 is adopted for recalculation to obtain the accurate lightning occurrence time t final Lightning accurate position P' (x) final ，y final )。
According to the step 5, on the basis that the 7 lightning detection stations respectively receive the peak amplitude of the lightning electromagnetic wave, the amplitude correction coefficient obtained through simulation is divided, then the peak amplitude is extracted through the waveforms of the lightning electromagnetic wave received by the 7 lightning detection stations respectively, and the accurate peak amplitude Pr of the lightning is obtained through calculation final . After correction, the optimized lightning stroke position is 328m away from a certain pole tower of the extra-high voltage transmission line, and the error is smaller; the current intensity of the lightning stroke is improved to-36.1 kA and exceeds the lightning shielding failure insulation level of the extra-high voltage line, and data support is provided for fault study, judgment and analysis.
The invention relates to a thunder and lightning positioning optimization method for correcting the influence of landform and geological parameters on the transmission of thunder and lightning electromagnetic waves, which comprises the steps of establishing a ground-ionosphere electromagnetic wave transmission model, carrying out simulation calculation on a time delay correction value and a parameter correction coefficient of the transmission of the thunder and lightning electromagnetic waves from a lightning stroke preliminary position to a thunder and lightning detection station under the condition of considering the landform and the geological parameters and not considering the landform and the geological parameters, carrying out gridding on a target area of the thunder and lightning detection station participating in the thunder and lightning positioning, calculating a time delay correction table and a parameter correction coefficient table of all grid points in the area corresponding to the lightning positioning, recalculating the accurate lightning occurrence time, the accurate lightning position and the accurate lightning characteristic parameter according to the initial lightning occurrence time, the initial lightning position and the initial characteristic parameter corresponding to the participating lightning detection stations when the closest grid point is taken as a lightning stroke point.
As shown in fig. 10, a lightning location optimization system for correcting the influence of topographic and geological parameters on lightning electromagnetic wave propagation comprises a time delay correction value and parameter correction coefficient calculation module, an information index establishment module, a lightning preliminary position and preliminary characteristic parameter calculation module, a time delay correction value and parameter correction coefficient determination module for the closest lattice point, and a lightning accurate position and accurate characteristic parameter calculation module;
the time delay correction value and parameter correction coefficient calculation module is used for establishing a ground and ionized layer electromagnetic wave propagation model, and calculating the time delay correction value of the lightning electromagnetic wave from the lightning preliminary position to the lightning detection station according to the waveform arrival time under the condition of considering the terrain and geological parameter factors and the waveform arrival time under the condition of not considering the terrain and geological parameter factors; calculating a parameter correction coefficient of the lightning electromagnetic wave transmitted from the lightning primary position to the lightning detection station according to the waveform characteristic parameters under the condition of considering the terrain and geological parameter factors and the waveform characteristic parameters under the condition of not considering the terrain and geological parameter factors;
the information index establishing module is used for drawing corresponding n equidistant circles by taking each lightning detection station participating in lightning positioning as a center, drawing isoangle rays passing through corresponding circle centers and having preset azimuth angles on each isoangle circle, and setting intersection points of each isoangle circle and the corresponding isoangle ray as grid points in the corresponding lightning detection station area; respectively taking all grid points in each lightning detection station area as lightning preliminary positions, calculating a time delay correction value and a parameter correction coefficient of each lightning detection station corresponding to all grid points in the area per se, manufacturing the time delay correction value and the parameter correction coefficient into a corresponding time delay correction table and a corresponding parameter correction coefficient table, and taking the time delay correction table and the corresponding parameter correction coefficient table of each lightning detection station as information indexes of the lightning detection station;
the lightning preliminary position and preliminary characteristic parameter calculation module is used for assuming the earth as a standard ellipsoid model, and calculating the lightning preliminary generation time and the lightning preliminary position by utilizing the existing lightning positioning method through the waveform arrival time of the lightning electromagnetic waves received by the lightning detection stations participating in lightning positioning; then waveform characteristic parameters extracted from the waveforms of the lightning electromagnetic waves received by the lightning detection stations participating in lightning positioning are used for calculating lightning preliminary characteristic parameters;
the time delay correction value and parameter correction coefficient determining module of the closest lattice point is used for respectively finding out the corresponding closest lattice point closest to the corresponding lightning preliminary position on each equidistant circle corresponding to the corresponding lightning detection station according to the lightning preliminary position and the information of the lightning detection station participating in lightning positioning; determining a time delay correction value and a parameter correction coefficient corresponding to each thunder and lightning detection station when each closest grid point is taken as a lightning stroke point according to respective information indexes of the thunder and lightning detection stations;
the lightning accurate position and accurate characteristic parameter calculation module is used for respectively carrying out time delay correction on lightning detection stations participating in lightning positioning to obtain corrected waveform arrival time corresponding to each lightning detection station, and then calculating lightning accurate occurrence time and lightning accurate position by using a lightning positioning method; and respectively correcting the characteristic parameters of the involved lightning detection stations to obtain corrected characteristic parameters corresponding to each lightning detection station, and then calculating accurate lightning characteristic parameters.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such modifications are intended to be included in the scope of the present invention.
Claims (16)
1. A lightning positioning optimization method for correcting the influence of topographic and geological parameters on lightning electromagnetic wave propagation is characterized by comprising the following steps:
step 1, establishing a ground and ionized layer electromagnetic wave propagation model, and calculating a time delay correction value of the lightning electromagnetic wave from a lightning initial position to a lightning detection station according to the waveform arrival time under the condition of considering terrain and geological parameter factors and the waveform arrival time under the condition of not considering terrain and geological parameter factors; calculating a parameter correction coefficient of the lightning electromagnetic wave transmitted from the lightning primary position to the lightning detection station according to the waveform characteristic parameters under the condition of considering the terrain and geological parameter factors and the waveform characteristic parameters under the condition of not considering the terrain and geological parameter factors;
step 2, drawing corresponding n equidistant circles by respectively taking each lightning detection station participating in lightning positioning as a center, drawing isoangle rays which pass through corresponding circle centers and have preset azimuth angles on each equidistant circle, wherein intersection points of each isoangle circle and the corresponding isoangle ray are grid points in the area of the corresponding lightning detection station; respectively taking all grid points in each lightning detection station area as lightning preliminary positions, calculating a time delay correction value and a parameter correction coefficient of each lightning detection station corresponding to all grid points in the area per se, manufacturing the time delay correction value and the parameter correction coefficient into a corresponding time delay correction table and a corresponding parameter correction coefficient table, and taking the time delay correction table and the corresponding parameter correction coefficient table of each lightning detection station as information indexes of the lightning detection station;
step 3, assuming the earth as a standard ellipsoid model, calculating the primary lightning occurrence time and the primary lightning position by using the existing lightning positioning method through the waveform arrival time of the lightning electromagnetic waves received by the lightning detection stations participating in lightning positioning; then waveform characteristic parameters extracted from the waveforms of the lightning electromagnetic waves received by the lightning detection stations participating in lightning positioning are used for calculating lightning preliminary characteristic parameters;
step 4, respectively finding out the corresponding closest lattice points closest to the corresponding lightning preliminary positions on the equidistant circles corresponding to the corresponding lightning detection stations according to the lightning preliminary positions and the information of the lightning detection stations participating in lightning positioning; determining a time delay correction value and a parameter correction coefficient corresponding to each lightning detection station when each closest lattice point is taken as a lightning strike point according to the respective information index of the lightning detection station;
step 5, respectively carrying out time delay correction on the lightning detection stations participating in lightning positioning to obtain corrected waveform arrival time corresponding to each lightning detection station, and then calculating accurate lightning occurrence time and accurate lightning positions by using a lightning positioning method; and respectively correcting the characteristic parameters of the involved lightning detection stations to obtain corrected characteristic parameters corresponding to each lightning detection station, and then calculating accurate lightning characteristic parameters.
2. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 1, characterized in that: in step 1, the specific steps of establishing the ground and ionosphere electromagnetic wave propagation model are
Step 1-1, assuming that the lightning electromagnetic wave is transmitted on a two-dimensional plane r-z plane under a cylindrical coordinate system, wherein the r direction is along the earth surface direction, the z direction is the height direction,
the direction is the direction meeting the right-hand rule with the r direction and the z direction,
the gradient in the direction is constant to 0, a Maxwell rotation equation set of a vertical electric field and a horizontal magnetic field of VLF/LF lightning electromagnetic waves propagating between the ground and an ionized layer r-z plane is deduced from a Maxwell original equation set, and the propagation of the lightning electromagnetic waves from a lightning preliminary position to a lightning detection station is solved by the Maxwell rotation equation set;
step 1-2, applying a lightning current excitation source at a lightning preliminary position, wherein the lightning current excitation source is a lightning current strike-back channel and is placed on a symmetrical axis of a two-dimensional cylindrical coordinate system, assuming that a base current at the bottom of the strike-back discharge channel is I (0, t), the lightning current gradually develops upwards from the ground, the propagation speed is v, the amplitude of the lightning current attenuates along with the height z according to the f (z) rule, the current distribution at the height z of the channel at the time t is I (z, t), and the current distribution at the height z of the channel at the time t is I (z, t) expressed as an expression
Step 1-3, carrying out differential dispersion on a Maxwell rotation equation set, carrying out dispersion on E and H components in an electromagnetic field in a space and time alternative sampling mode, namely, four corresponding H and E field components surround each E and H field component, converting the Maxwell rotation equation set containing time variables into a Maxwell dispersion equation set through the dispersion mode, and gradually updating and advancing through a leapfrog format on a time domain to solve a space electromagnetic field, adopting Yee cells in a space format distribution under a cylindrical coordinate system, setting the lattice point of the Yee cells as (i, j, k), namely (i, j, k) representing that the r direction is i, the phi direction is j, and the z direction is k, connecting a plurality of same Yee cells together to form the whole calculation domain, and staggering the electric field and the magnetic field on a time step, namely, the updating of the electric field and the magnetic field has half time step difference;
1-4, receiving a lightning vertical electric field E from a lightning detection station under the consideration of topographic and geological parameter factors z Wave-shaped or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform a And characteristic parameter Pr a (ii) a Lightning vertical electric field E received by lightning detection station without considering terrain and geological parameter factors z Wave or horizontal magnetic field
Respectively extracting the arrival time t of the waveform from the waveform b And characteristic parameter Pr b (ii) a The formula of the time delay correction value is delta t = t a -t b The formula of the parameter correction coefficient is k = Pr a /Pr b 。
3. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 2, characterized in that: in step 1-1, the Maxwell original equation set is
In the above formula, the first and second carbon atoms are,
e is a vector of the electric field intensity in the propagation of the electric wave,
b is the magnetic induction vector in the propagation of the electric wave,
p is the free charge and is the free charge,
ε 0 which is the dielectric constant in a vacuum, is,
j is the conduction current density vector, j = σ E,
sigma is the electric conductivity of the alloy, and the electric conductivity of the alloy,
μ 0 is magnetic permeability.
4. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 3, characterized in that: in step 1-1, the Maxwell rotation equation set based on the vertical electric field and the horizontal magnetic field of the lightning discharge channel is
Wherein,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
5. The method for optimizing lightning localization to correct the influence of topographic and geological parameters on the propagation of lightning electromagnetic waves according to claim 4, wherein the method comprises the following steps: in step 1-2, a Heideler double exponential function is adopted to construct the ground-lightning-back base current I (0, t), and the expression of the ground-lightning-back base current I (0, t) is shown as
Wherein,
I 01 which represents the breakdown current of the semiconductor device,
I 02 which is representative of the peak value of the corona current,
eta represents a breakdown current correction factor,
τ 1 the rise time of the waveform representing the breakdown current,
τ 2 the waveform fall time representing the breakdown current,
τ 3 representing the rise time of the waveform of the corona current,
τ 4 representing the waveform fall time of the corona current.
6. The method for optimizing lightning localization to correct the influence of topographic and geological parameters on the propagation of lightning electromagnetic waves according to claim 5, wherein the method comprises the following steps: in the step 1-2, an MTLE engineering model is used as a current attack model, the base current decays in an exponential mode in the upward development process, and the current distribution at the channel height z at the time t is represented by an expression I (z, t)
I(z,t)＝e -z/λ I(0,t-z/v)
Wherein,
i (z, t) is the current at the z-height of the channel at time t,
z is the height of the strike-back discharge channel,
e -z/λ in order that the lightning current amplitude decays exponentially with the height z,
the lambda is the attenuation factor of the light beam,
v is the propagation velocity of the lightning current.
7. The method for optimizing lightning location according to claim 6, wherein the method is characterized in that the method comprises the following steps: in step 1-3, the Maxwell discrete equation set is
Wherein,
at represents a step of time that is,
E r representing the component of the electric field strength E in the direction r,
E z representing the component of the electric field strength E in the z direction,
μ represents the magnetic permeability and,
ε represents a dielectric constant.
8. The method for optimizing lightning location according to claim 7, wherein the method is used for correcting the influence of topographic and geological parameters on lightning electromagnetic wave propagation, and is characterized in that: in the steps 1-4, the waveform arrival time is extracted based on a waveform peak point, a half-peak point of a waveform rising edge or a maximum point of a waveform rising edge derivative, and the characteristic parameters comprise a waveform peak value, wave head time, wave tail time, waveform half-peak width and electric field amplitude.
9. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 2, characterized in that: in step 5, a lightning detection station S participating in lightning location 1 、S 2 、S 3 、…、S n The arrival time of the waveforms of the lightning electromagnetic waves received by the lightning electromagnetic waves is T 1 、T 2 、T 3 、…、T n And with the closest lattice point A 1 、A 2 、A 3 、…、A n As lightning strike points, lightning detection stations S 1 、S 2 、S 3 、…、S n The corresponding delay correction value is divided into Δ t 1 ′、Δt 2 ′、Δt 3 ′…、Δt n ', then lightning detection station S 1 、S 2 、S 3 、…、S n The arrival times of the corresponding corrected waveforms are respectively T 1 -Δt 1 ′、T 21 -Δt 2 ′、T 31 -Δt 3 ′、…、T n1 -Δt n ′。
10. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 2, characterized in that: in step 5, a lightning detection station S participating in lightning location 1 、S 2 、S 3 、…、S n The characteristic parameters of the lightning electromagnetic waves received by the lightning electromagnetic waves are respectively Pr 1 、Pr 2 、Pr 3 、…、Pr n And with the closest lattice point A 1 、A 2 、A 3 、…、A n As lightning strike point, lightning detecting station S 1 、S 2 、S 3 、…、S n The corresponding parameter correction coefficients are respectively k 1 ′、k 2 ′、k 3 ′…、k n ', then lightning detection station S 1 、S 2 、S 3 、…、S n The corresponding corrected characteristic parameters are respectively 1/k 1 ′×Pr 1 、1/k 2 ′×Pr 2 、1/k 3 ′×Pr 3 、…、1/k n ′×Pr n 。
11. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 1, characterized in that: in the step 4, the method for finding out the closest corresponding lattice point closest to the corresponding lightning preliminary position includes calculating the distance R and the preset azimuth angle theta of the lightning preliminary position relative to each lightning detection station, and finding out the lattice point closest to both the distance R and the preset azimuth angle theta in the equidistant circle corresponding to each lightning detection station as the closest corresponding closest lattice point to the lightning preliminary position.
12. The lightning localization optimization method for correcting the influence of the topographic and geological parameters on the lightning electromagnetic wave propagation according to claim 1, characterized in that: in step 2, the radii of the equidistant circles are R respectively 1 、R 2 、R 3 、…、R a ，R 1 、R 2 、R 3 、…、R a Are all 6-15 km, wherein R a Wherein a takes a value of 20 to 50; the preset azimuth angle of the equiangular ray is theta 1 、θ 2 、θ 3 、…、θ b ，θ 1 、θ 2 、θ 3 、…、θ b Are all 1 to 3 degrees, wherein theta b The value of b is floor (360/theta), which represents the rounding operation.
13. The method for optimizing lightning localization to correct the influence of topographic and geological parameters on the propagation of lightning electromagnetic waves according to claim 1, wherein the method comprises the following steps: in step 3, the lightning location method is to obtain the initial lightning occurrence time t by solving the minimum value of a cost function formed by a nonlinear equation set initial Lightning preliminary position P (x) initial ，y initial )，(x initial ，y initial ) Longitude and latitude representing a lightning strike point; the set of non-linear equations comprises a lightning detection station S i The arrival time T of the received thunder and lightning electromagnetic wave i And the lightning preliminary position P (x) initial ，y initial ) And a lightning detection station S i Measured azimuth angle beta therebetween i The system of non-linear equations is
β i ＝β Pi +ε Ai
Wherein,
T i for a participating lightning detection station S i The arrival time of the lightning electromagnetic wave is received,
t is the time of occurrence of the lightning,
S Pi for lightning strikes P (x, y) to a participating lightning detection station S i Distance of (S) Pi It needs to be calculated on the ellipsoid surface,
c is the propagation speed of the electromagnetic wave,
ε Ti in order to measure the error in time,
β i for a participating lightning detection station S i The measured azimuth angle of the lightning electromagnetic wave is received,
β Pi for lightning strikes P (x, y) to a participating lightning detection station S i Is calculated as azimuth angle, beta Pi It needs to be calculated on the ellipsoid surface,
ε Ai in order to measure the error in the angle,
S i is known as (x) i ,y i ) Wherein i =1,2,3 \ 8230n;
the system of nonlinear equations is described as the following simple form
r i ＝F i (t,x,y)+ε i
Wherein,
r i in order to observe the quantity of the object,
F i (t，x l and y) is a function of an unknown number,
ε i to measure the error.
14. The method for optimizing lightning location according to claim 10, wherein the method is characterized by comprising the following steps: in step 3, in a simple form of the system of nonlinear equations, when ε i Cost function minimum of simple form of the system of nonlinear equations when =0
Namely the preliminary thunder occurrence time t initial Lightning preliminary position P (x) initial ，y initial )。
15. A thunder and lightning positioning optimization system for correcting the influence of landform and geological parameters on the propagation of thunder and lightning electromagnetic waves is characterized by comprising a time delay correction value and parameter correction coefficient calculation module, an information index establishment module, a thunder and lightning preliminary position and preliminary characteristic parameter calculation module, a time delay correction value and parameter correction coefficient determination module of the closest lattice point and a thunder and lightning accurate position and accurate characteristic parameter calculation module;
the time delay correction value and parameter correction coefficient calculation module is used for establishing a ground and ionized layer electromagnetic wave propagation model, and calculating the time delay correction value of the lightning electromagnetic wave from the lightning preliminary position to the lightning detection station according to the waveform arrival time under the condition of considering the terrain and geological parameter factors and the waveform arrival time under the condition of not considering the terrain and geological parameter factors; calculating a parameter correction coefficient of the lightning electromagnetic wave transmitted from the lightning primary position to the lightning detection station according to the waveform characteristic parameters under the condition of considering the terrain and geological parameter factors and the waveform characteristic parameters under the condition of not considering the terrain and geological parameter factors;
the information index establishing module is used for drawing corresponding n equidistant circles by taking each lightning detection station participating in lightning positioning as a center, drawing isoangle rays passing through corresponding circle centers and having preset azimuth angles on each isoangle circle, and setting intersection points of each isoangle circle and the corresponding isoangle ray as grid points in the corresponding lightning detection station area; respectively taking all grid points in each lightning detection station area as lightning preliminary positions, calculating a time delay correction value and a parameter correction coefficient of each lightning detection station corresponding to all grid points in the area per se, manufacturing the time delay correction value and the parameter correction coefficient into a corresponding time delay correction table and a corresponding parameter correction coefficient table, and taking the time delay correction table and the corresponding parameter correction coefficient table of each lightning detection station as information indexes of the lightning detection station;
the lightning preliminary position and preliminary characteristic parameter calculation module is used for assuming the earth as a standard ellipsoid model, and calculating the lightning preliminary generation time and the lightning preliminary position by utilizing the existing lightning positioning method through the waveform arrival time of the lightning electromagnetic waves received by the lightning detection stations participating in lightning positioning; then waveform characteristic parameters extracted from the waveforms of the lightning electromagnetic waves are received by the lightning detection stations participating in lightning positioning, and lightning preliminary characteristic parameters are calculated;
the time delay correction value and parameter correction coefficient determining module of the closest lattice point is used for respectively finding out the corresponding closest lattice point closest to the corresponding lightning preliminary position on each equidistant circle corresponding to the corresponding lightning detection station according to the lightning preliminary position and the information of the lightning detection station participating in lightning positioning; determining a time delay correction value and a parameter correction coefficient corresponding to each lightning detection station when each closest lattice point is taken as a lightning strike point according to the respective information index of the lightning detection station;
the lightning accurate position and accurate characteristic parameter calculation module is used for respectively carrying out time delay correction on lightning detection stations participating in lightning positioning to obtain corrected waveform arrival time corresponding to each lightning detection station, and then calculating lightning accurate occurrence time and lightning accurate position by using a lightning positioning method; and respectively correcting the characteristic parameters of the involved lightning detection stations to obtain corrected characteristic parameters corresponding to each lightning detection station, and then calculating accurate lightning characteristic parameters.
16. A computer-readable storage medium storing a computer program, characterized in that: which computer program, when being executed by a processor, carries out the steps of the method as set forth in claims 1 to 14.
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| PCT/CN2023/138799 WO2024094225A1 (en) | 2022-11-04 | 2023-12-14 | Lightning locating optimization method that corrects effect of topological and geological parameters on lightning electromagnetic wave propagation, system, and medium |
| AU2023331397A AU2023331397A1 (en) | 2022-11-04 | 2023-12-14 | Lightning positioning optimization method and system by correcting impacts of terrain and geological parameter on propagation of lightning electromagnetic wave, and medium |
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| CN116087726A (en) * | 2023-04-11 | 2023-05-09 | 国网四川省电力公司电力科学研究院 | Device and method for measuring critical breakdown distance of flame channel |
| CN117054755A (en) * | 2023-10-13 | 2023-11-14 | 宁波麦思捷科技有限公司武汉分公司 | Method and system for analyzing magnetic field change caused by lightning |
| WO2024094225A1 (en) * | 2022-11-04 | 2024-05-10 | 国网电力科学研究院武汉南瑞有限责任公司 | Lightning locating optimization method that corrects effect of topological and geological parameters on lightning electromagnetic wave propagation, system, and medium |
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| JP2723929B2 (en) * | 1988-10-14 | 1998-03-09 | 株式会社日立製作所 | Lightning strike location system |
| JP3752463B2 (en) * | 2002-03-29 | 2006-03-08 | 東京電力株式会社 | Lightning strike location method, apparatus, system and program |
| CN103116083B (en) * | 2013-01-23 | 2014-12-10 | 华中科技大学 | Very low frequency (VLF) / low frequency (LF) frequency range ground lightening detection positioning system |
| CN107037272A (en) * | 2017-06-20 | 2017-08-11 | 云南电网有限责任公司昆明供电局 | Lightning Location Method based on thunder and lightning multivariate data peak-seeking Shicha algorithm |
| CN107765102B (en) * | 2017-09-13 | 2019-11-22 | 广东电网有限责任公司江门供电局 | A kind of lightning parameter Inversion Calculation optimization method |
| CN108519523B (en) * | 2018-03-14 | 2020-04-21 | 南京中科九章信息技术有限公司 | Lightning positioning method, system, electronic device and storage medium |
| CN108828332B (en) * | 2018-06-07 | 2020-11-06 | 国网电力科学研究院武汉南瑞有限责任公司 | Method for calculating detection efficiency of lightning positioning system |
| CN113238099A (en) * | 2021-06-02 | 2021-08-10 | 湖北省防雷中心 | Lightning positioning system-based ground lightning grade division method |
| CN113901689A (en) * | 2021-10-12 | 2022-01-07 | 云南电网有限责任公司电力科学研究院 | Mountain area lightning stroke positioning method and device |
| CN115825584A (en) * | 2022-11-04 | 2023-03-21 | 国网电力科学研究院武汉南瑞有限责任公司 | Lightning positioning optimization method and system for correcting influence of terrain and geological parameters on lightning electromagnetic wave transmission and medium |
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| WO2024094225A1 (en) * | 2022-11-04 | 2024-05-10 | 国网电力科学研究院武汉南瑞有限责任公司 | Lightning locating optimization method that corrects effect of topological and geological parameters on lightning electromagnetic wave propagation, system, and medium |
| CN116087726A (en) * | 2023-04-11 | 2023-05-09 | 国网四川省电力公司电力科学研究院 | Device and method for measuring critical breakdown distance of flame channel |
| CN116087726B (en) * | 2023-04-11 | 2023-06-27 | 国网四川省电力公司电力科学研究院 | Device and method for measuring critical breakdown distance of flame channel |
| CN117054755A (en) * | 2023-10-13 | 2023-11-14 | 宁波麦思捷科技有限公司武汉分公司 | Method and system for analyzing magnetic field change caused by lightning |
| CN117054755B (en) * | 2023-10-13 | 2023-12-22 | 宁波麦思捷科技有限公司武汉分公司 | Method and system for analyzing magnetic field change caused by lightning |
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