AU2023331397A1 - Lightning positioning optimization method and system by correcting impacts of terrain and geological parameter on propagation of lightning electromagnetic wave, and medium - Google Patents
Lightning positioning optimization method and system by correcting impacts of terrain and geological parameter on propagation of lightning electromagnetic wave, and medium Download PDFInfo
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Abstract
The present disclosure provides a lightning positioning optimization method and system by
correcting impacts of a terrain and a geological parameter on propagation of a lightning
electromagnetic wave, and a medium. The method meshes a surrounding region of a lightning
detection station participating in lightning positioning, and uses a ground and ionospheric
electromagnetic wave propagation model to perform simulation calculation to obtain a delay
correction value and a parameter correction coefficient of a waveform of a lightning
electromagnetic wave propagating from an initial lightning location to the lightning detection
station without considering a terrain and a geological parameter when each grid point is used as
the initial lightning location. When a closest grid point is separately found as a lightning strike
point in a delay correction table and a parameter correction coefficient table that are
corresponding to the lightning detection station participating in the lightning positioning, based
on a delay correction value and a parameter correction coefficient that are corresponding to each
lightning detection station, each participating lightning detection station is corrected separately
to obtain corrected waveform arrival time and characteristic parameter that are corresponding to
the lightning detection station. Then an accurate lightning location and an accurate lightning
characteristic parameter are calculated.
ABSTRACT FIGURE
Establish a ground and ionospheric electromagnetic wave
propagation model, and obtain a delay correction value and a
parameter correction coefficient for propagation of a lightning
electromagnetic wave from an initial lightning location to a lightning
detection station
Mesh a target region of a lightning detection station participating in
lightning positioning, calculate a delay correction value and a
parameter correction coefficient of each grid point in a corresponding
region of each lightning detection station, and create a corresponding
delay correction table and a parameter correction coefficient table as
an information index
Calculate initial lightning occurrence time, an initial lightning
location, and an initial lightning characteristic parameter by using an
existing lightning positioning method
Find a grid point closest to the initial lightning location on an
equidistant circle corresponding to each lightning detection station,
and determine a corresponding delay correction value and parameter
correction coefficient of each lightning detection station when using
the closest grid point as a lightning strike point
Separately perform delay correction and character parameter
correction on the lightning detection station participating in the
lightning positioning to obtain corresponding corrected waveform
arrival time and a corresponding corrected characteristic parameter
of each lightning detection station, and calculate an accurate
lightning location and an accurate lightning characteristic parameter
FIG. I
Description
Establish a ground and ionospheric electromagnetic wave propagation model, and obtain a delay correction value and a parameter correction coefficient for propagation of a lightning electromagnetic wave from an initial lightning location to a lightning detection station
Mesh a target region of a lightning detection station participating in lightning positioning, calculate a delay correction value and a parameter correction coefficient of each grid point in a corresponding region of each lightning detection station, and create a corresponding delay correction table and a parameter correction coefficient table as an information index
Calculate initial lightning occurrence time, an initial lightning location, and an initial lightning characteristic parameter by using an existing lightning positioning method
Find a grid point closest to the initial lightning location on an equidistant circle corresponding to each lightning detection station, and determine a corresponding delay correction value and parameter correction coefficient of each lightning detection station when using the closest grid point as a lightning strike point
Separately perform delay correction and character parameter correction on the lightning detection station participating in the lightning positioning to obtain corresponding corrected waveform arrival time and a corresponding corrected characteristic parameter of each lightning detection station, and calculate an accurate lightning location and an accurate lightning characteristic parameter
[0001] The present disclosure relates to the technical field of lightning positioning, and specifically, to a lightning positioning optimization method and system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, and a medium.
[0002] Lightning is a short-term strong atmospheric discharge phenomenon in nature, which can cause forest fires, destroy buildings, and hinder normal operation of power, communications, petroleum, chemical engineering, and other industries. A trip or a shutdown of a transmission system due to an overvoltage generated by a lightning strike on an overhead high-voltage transmission line or a tower is a serious meteorological disaster faced by power industries in China and even in the world. Accidents caused by such a disaster can account for more than 40% of power grid accidents in China. A frequency band of a lightning electromagnetic wave generated in a lightning process ranges from an extremely low frequency (ELF) to an ultra-high frequency (UHF), and electromagnetic waves in different frequency bands have different propagation characteristics. At present, the power sector in China has generally built a lightning positioning system to monitor a lightning strike on a power grid, in order to quickly inspect and analyze the accident, and avoid a catastrophic consequence such as a widespread power outage caused by expansion of the accident.
[0003] At present, a lightning positioning technology adopted by the power sector in China is to use a detection device of a very low frequency (VLF)/low frequency (LF) band to construct a lightning detection network to collect the lightning electromagnetic wave. With the help of a waveform parameter of the electromagnetic wave, a multi-station positioning algorithm is used to determine a lightning location and invert a lightning parameter. Due to geographical environments, system hardware conditions, station layouts, algorithms, and other factors, lightning positioning accuracy and parameter inversion accuracy of lightning positioning networks in different regions are different. Because the lightning electromagnetic wave is affected by various factors such as an irregular terrain, limited soil conductivity, and soil anisotropy during propagation along an earth's surface, a waveform peak and its position, rising edge time, and half peak time of the electromagnetic wave are altered.
[0004] However, existing lightning positioning algorithms mostly assume that the electromagnetic wave in the VLF/LF band is propagated on a standard earth ellipsoid model, without considering impacts of an undulant terrain and limited conductivity on the propagation of the electromagnetic wave. Especially in a complex terrain environment, such as the Sichuan Tibet region of China, the waveform of the lightning electromagnetic wave changes more obviously, which introduces significant errors in determining the lightning location and performing parameter inversion.
[0005] In response to the shortcomings in the prior art, the present disclosure provides a lightning positioning optimization method and system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, and a medium. By considering impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave in a lightning positioning method, a quantitative correction method is proposed to more accurately calculate a lightning location and a lightning parameter.
[0006] To achieve the above objective, the present disclosure designs a lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, including following steps:
[0007] step 1: establishing a ground and ionospheric electromagnetic wave propagation model, calculating, based on waveform arrival time considering a terrain and a geological parameter, and waveform arrival time without considering the terrain and the geological parameter, a delay correction value for propagation of a lightning electromagnetic wave from an initial lightning location to a lightning detection station, and calculating, based on a waveform characteristic parameter considering the terrain and the geological parameter, and a waveform characteristic parameter without considering the terrain and the geological parameter, a parameter correction coefficient for the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station;
[0008] step 2: drawing n corresponding equidistant circles respectively centered on lightning detection stations participating in lightning positioning, drawing an equiangular ray that passes through a corresponding circle center and has a preset azimuth on each of the equidistant circles, where an intersection point of each of the equidistant circles and the corresponding equiangular ray is a grid point within a region of the corresponding lightning detection station, taking each grid point within a region of each of the lightning detection stations as the initial lightning location, calculating a delay correction value and a parameter correction coefficient that are corresponding to each grid point within the region of each of the lightning detection stations, creating a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient, and taking the delay correction table and the parameter correction coefficient table that are corresponding to each of the lightning detection stations as an information index of the lightning detection station;
[0009] step 3: assuming that the earth is a standard ellipsoid model, calculating initial lightning occurrence time and the initial lightning location by using an existing lightning positioning method based on waveform arrival time of a lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; and then calculating an initial lightning characteristic parameter based on a waveform characteristic parameter extracted from a waveform of the lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning;
[0010] step 4: based on the initial lightning location and information of the lightning detection stations participating in the lightning positioning, finding a corresponding grid point closest to the corresponding initial lightning location on each of the equidistant circles corresponding to the corresponding lightning detection stations; and based on the information index of each of the lightning detection stations, determining a corresponding delay correction value and parameter correction coefficient of each of the lightning detection stations when using each closest grid point as a lightning strike point; and
[0011] step 5: performing delay correction on each of the participating lightning detection stations to obtain corresponding corrected waveform arrival time of each of the lightning detection stations, and then calculating accurate lightning occurrence time and an accurate lightning location by using the lightning positioning method; and performing parameter correction on each of the participating lightning detection stations to obtain a corresponding corrected characteristic parameter of each of the lightning detection stations, and then calculating an accurate lightning characteristic parameter.
[0012] Further, in the step 1, specific steps of establishing the ground and ionospheric electromagnetic wave propagation model are as follows:
[0013] step 1-1: assuming that the lightning electromagnetic wave is planarly propagated in a two-dimensional plane r-z in a cylindrical coordinate system, where an r direction is a direction along an earth's surface, a z direction is a height direction, a p direction satisfies a right-hand rule with respect to the r and z directions, and a gradient of the p direction is always 0, deriving, based on Maxwell's original equations, Maxwell's curl equations for a vertical electric field and a horizontal magnetic field of a VLF/LF lightning electromagnetic wave propagating on the ground and ionospheric plane r-z, and solving the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station based on the Maxwell's curl equations;
[0014] step 1-2: applying a lightning current excitation source at the initial lightning location, where the lightning current excitation source is a lightning current return stroke channel, which is placed on a symmetry axis of the two-dimensional cylindrical coordinate system; and assuming that a base current at a bottom of a return discharge channel is 1(0, t), a lightning current gradually develops upwards from the ground, with a propagation speed of v, and an amplitude of the lightning current is attenuated with a height z according to an f (z) rule, a current distribution at the channel height z at at a time pointt is I(z,t), where the current distribution at the channel height z at the time point t is expressed as I(z, t):
I(z, t) = f(z)xI (0, t - 3)
[0015] step 1-3: performing differential discretization on the Maxwell's curl equations, transforming the Maxwell's curl equations with a time variable into Maxwell's discrete equations by discretizing E and H components in an electromagnetic field in space and time through alternate sampling to ensure that each E-field component is surrounded by four corresponding H components and each H-field component is surrounded by four corresponding E-field components, and gradually performing update and advancing based on a leap-frog scheme in a time domain to solve a spatial electromagnetic field, where in the cylindrical coordinate system, a spatial format distribution adopts a Yee cell, a grid point of the Yee cell is set to (i, j, k), which is a grid point with i in the r direction, j in the (p direction, and k in the z direction, an entire computational domain includes many identical Yee cells connected to each other, and the electric field and the magnetic field are also staggered in terms of a time step, meaning that updates of the electric field and the magnetic field differ by half a time step; and
[0016] step 1-4: separately extracting waveform arrival time ta and a characteristic parameter Pra from a waveform of lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are considered; and separately extracting waveform arrival time tb and a characteristic parameter Prb from a waveform of the lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are not considered, where a formula for the delay correction value is At = ta - tb, and a formula for the parameter correction coefficient is k=Pra/Prb.
[0017] Further, in the step 1-1, the Maxwell's original equations are as follows: aB p V x E =-E at E0 aE V x B = poj + E p - V-B=O
[0018] where
[0019] E represents an electric field intensity vector in radio wave propagation;
[0020] B represents a magnetic induction intensity vector in the radio wave propagation;
[0021] p represents a free charge;
[0022] co represents a dielectric constant in vacuum;
[0023] j represents a conduction current density vector, where j = oE;
[0024] 1 represents conductivity; and
[0025] o represents magnetic permeability.
[0026] Further, in the step 1-1, the Maxwell's curl equations based on a vertical electric field and a horizontal magnetic field of a lightning discharge channel are as follows: aEr 1 aH at E 0 aZ aEz 11 a -=(rHO) < at E 0 rar aH, 1 (aEz aEr at p'o ar az
[0027] where
[0028] Er represents a component of electric field intensity E in the r direction;
[0029] Ez represents a component of the electric field intensity E in the z direction; and
[0030] H, represents a component of magnetic field intensity B in the p direction.
[0031] Further, in the step 1-2, if a Heidler double exponential function is used to construct a base current 1(0, t) at a bottom of a cloud-to-ground return stroke, the base current at the bottom of the cloud-to-ground return stroke is expressed as follows:
I(0, t) = I77 2e -t/T2 + 02 (e t/T3- et/T4 (t+1
[0032] where
[0033] Ioi represents a breakdown current;
[0034] 102 represents a peak corona current;
[0035] 1i represents a correction factor of the breakdown current;
[0036] 1T represents waveform rise time of the breakdown current;
[0037] T2 represents waveform fall time of the breakdown current;
[0038] 1T3 represents waveform rise time of a corona current; and
[0039] T4 represents waveform fall time of the corona current.
[0040] Further, in the step 1-2, if a modified transmission line model with exponential decay of the current with height (MTLE) is used as a current return stroke model, and the base current is attenuated exponentially as the base current develops upwards, the current distribution at the channel height z at the time point t is I(z, t), which is expressed as follows: I(z,t) = e-z/XI(0,t - z/v)
[0041] where
[0042] I(z, t) represents a current at the channel height z at the time point t;
[0043] z represents a height of the return discharge channel;
[0044] e/- represents that the amplitude of the lightning current is attenuated exponentially with the height z;
[0045] represents an attenuation factor; and
[0046] v represents the propagation speed of the lightning current.
[0047] Further, in the step 1-3, the Maxwell's discrete equations are as follows: 1t 1I i
Er lijk= Er1 lij- El~ i+, At r| H,|i+1k+1 r| _ H1|- 1 2 2' 2i2 ik+- i,k+ E i,k+A En+1 2' 2 -2
22
-Ez Al+1k+±!- EzI k+1
H l - HAt Ar i+ ,k+- 22 i+',k+l 2' 2 l i+1+ - pli+-k± ErI ++ Er- l i+j 2' 22'2 ErI i1kk Az
[0048] where
[0049] i represents an ith grid point in the r direction;
[0050] k represents a kth grid point in the z direction;
[0051] N represents a total quantity of differential solving steps;
[0052] Az represents a step in the z direction;
[0053] Ar represents a step in the r direction;
[0054] At represents a time step;
[0055] Er represents the component of the electric field intensity E in the r direction;
[0056] Ez represents the component of the electric field intensity E in the z direction;
[0057] Hcp represents a component of magnetic field intensity H in the p direction;
[0058] p represents the magnetic permeability; and
[0059] 1 represents a dielectric constant.
[0060] Further, in the step 1-4, the waveform arrival time is extracted based on a peak point of the waveform, a half-peak point of a rising edge of the waveform, or a maximum derivative point of the rising edge of the waveform, and the characteristic parameter includes a waveform peak, front time, time to half value, a waveform half-peak width, and an electric field amplitude.
[0061] Further, in the step 5, waveform arrival time of lightning electromagnetic waves received by lightning detection stations Si, S2, S3, . . , and Sn participating in the lightning positioning is Ti, T 2, T 3 , ... , and Tn respectively, and when closest grid points Ai, A 2 , A 3 , ... , and An are used as lightning strike points, if delay correction values corresponding to the lightning detection stations
Si, S2, S3, ... , and Sn are Ati', At 2 , At3 ', ... , and Atn' respectively, corrected waveform arrival time corresponding to the lightning detection stations Si, S2, S3, ... , and S, is Ti-Ati', T21-At2', T31-At3', ..., and Tni-Atn' respectively.
[0062] Further, in the step 5, characteristic parameters of lightning electromagnetic waves received by lightning detection stations Si, S2, S3, ... , and Sn participating in the lightning positioning are Pri, Pr2, Pr3, ... , and Prn respectively, and when closest grid points Ai, A 2, A 3 , ...
, and An are used as lightning strike points, if parameter correction coefficients corresponding to the lightning detection stations Si, S2, S3, .., and Sn are ki', k2, k3 ', ... , and kn' respectively, corrected characteristic parameters corresponding to the lightning detection stations Si, S 2 , S3, and Sn are 1/ki'xPri, 1/k2'xPr2 , 1/k3'xPr 3 , ... , and 1/kn'xPrn respectively.
[0063] Further, in the step 4, the corresponding grid point closest to the corresponding initial lightning location is found as follows: calculating a distance R and a preset azimuth 0 of the initial lightning location relative to each of the lightning detection stations, and finding a grid point that is closest to both the distance R and the preset azimuth 0 in the corresponding equidistant circle of each of the lightning detection stations as the corresponding grid point closest to the initial lightning location.
[0064] Further, in the step 2, radii of the equidistant circles are RI, R2 , R3, ... , and Ra respectively, and the RI, the R2 , the R3 , ... , and the Ra are all 6 kilometers to 15 kilometers, where a value of a in the Ra ranges from 20 to 50; and the preset azimuths for the equiangular rays are 01, 02, 03, ..., and O, and the 01, the 02, the 03, ..., and the Ob are all 1 to 3, where a value of b in theOb is floor (360/0), and floor(-) represents a rounding operation.
[0065] Further, in the step 3, the lightning positioning method solves a minimum value of a cost function including nonlinear equations, to obtain the initial lightning occurrence time tinitia1 and the initial lightning location P(Xinitia, yinitia), where the (Xinitia, yinitiai) represents a longitude and a latitude of the lightning strike point; the nonlinear equations include an observation equation for arrival time Ti of a lightning electromagnetic wave received by a lightning detection station Si, and an observation equation for a measurement azimuth Pi between the initial lightning location P(Xinitial, yinitiai) and the lightning detection station Si; and the nonlinear equations are as follows:
Ti=t+ - +E' C
i =PPi +-Ai
[0066] where
[0067] Ti represents the arrival time of the lightning electromagnetic wave received by the participating lightning detection station Si;
[0068] t represents lightning occurrence time;
[0069] Spi represents a distance from a lightning strike location P(x, y) to the participating lightning detection station Si, and needs to be calculated on an ellipsoidal surface;
[0070] c represents a propagation speed of an electromagnetic wave;
[0071] ETi represents a time measurement error;
[0072] Pi represents the measurement azimuth of the lightning electromagnetic wave received by the participating lightning detection station Si;
[0073] pi represents a calculation azimuth from the lightning strike location P(x, y) to the participating lightning detection station Si, and needs to be calculated on the ellipsoidal surface;
[0074] EAi represents an angle measurement error;
[0075] coordinates of the Si are known, namely, (xi, yi), where i = 1,2,3 --- n; and
[0076] the nonlinear equations are denoted as a following simple form: ri = F(t,x,y) + Ei
[0077] where
[0078] ri represents an observed quantity;
[0079] Fi(t, x, y) represents an unknown function; and
[0080] 1i represents a measurement error.
[0081] Further, in the step 3, in the simple form of the nonlinear equations, when Ei=O, the minimumvalue minxlF(t,x,y) - r||2 of the cost function of the simple form of the nonlinear equations is the initial lightning occurrence time tinitia1 and the initial lightning location P(initial, initiall.
[0082] A computer-readable storage medium is provided. The computer-readable storage medium stores a computer program. The computer program is executed by a processor to implement the steps of the lightning positioning optimization method described above.
[0083] The present disclosure has following advantages:
[0084] 1. In a ground and ionospheric electromagnetic wave propagation model, through numerical calculation and simulation of electromagnetic wave propagation, the present disclosure first calculates a waveform of a lightning electromagnetic wave when a terrain and a geological parameter are considered, and a waveform of the lightning electromagnetic wave when the terrain and the geological parameter are not considered, to obtain a delay correction value and a parameter correction coefficient that are of each lightning detection station and are corresponding to an initial lightning location. In the numerical simulation of the electromagnetic wave propagation, a real terrain undulation and real soil conductivity are considered. This can greatly improve an effect of lightning positioning optimization, and improve lightning stroke positioning accuracy and parameter inversion accuracy.
[0085] 2. The present disclosure meshes target regions of participating lightning detection stations by drawing a plurality of equidistant circles respectively centered on the lightning detection stations, and then drawing an equiangular ray that passes through a corresponding circle center and has a preset azimuth on each equidistant circle. An intersection point of each equidistant circle and the corresponding equiangular ray is a grid point in the target region. Then, the ground and ionospheric electromagnetic wave propagation model is used to calculate a delay correction value and a parameter correction coefficient of each grid point in a region corresponding to the lightning detection station participating in lightning positioning. This method can greatly reduce a simulation calculation workload. A single equiangular ray only needs to undergo simulation calculation once to obtain a waveform of a lightning electromagnetic wave of each grid point along the equiangular ray.
[0086] 3. The present disclosure creates a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient of each grid point in the region corresponding to the lightning detection station participating in the lightning positioning, and uses a delay correction table and a parameter correction coefficient table that are corresponding to each lightning detection station as an information index of the lightning detection station, which means that time-consuming numerical simulation is carried out in advance. In a practical business application, only an information index of each lightning detection station needs to be queried, thereby greatly improving efficiency of the lightning positioning optimization.
[0087] 4. According to the present disclosure, based on the initial lightning location, a grid point closest to the initial lightning location is found on the corresponding equidistant circle of the lightning detection station participating the lightning positioning. Then, based on the information index of each lightning detection station, a corresponding delay correction value and parameter correction coefficient of each lightning detection station when the closest grid point is used as a lightning strike point are determined. This method can improve retrieval efficiency and can be easily implemented in a business.
[0088] 5. Based on a delay correction value corresponding to a closest grid point of each participating lightning detection station, the present disclosure calculates corrected waveform arrival time of a lightning electromagnetic wave received by each participating lightning detection station, and recalculates accurate lightning occurrence time and an accurate lightning location by using an existing lightning positioning method. Based on a parameter correction coefficient corresponding to the closest grid point of each participating lightning detection station, the present disclosure calculates a corrected characteristic parameter of the lightning electromagnetic wave received by each participating lightning detection station, and recalculates an accurate lightning characteristic parameter.
[0089] According to the lightning positioning optimization method and system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, and the medium in the present disclosure, the ground and ionospheric electromagnetic wave propagation model is established, and the simulation calculation is separately performed to obtain a delay correction value and a parameter correction coefficient of a lightning electromagnetic wave propagating from an initial location of a lightning strike to the lightning detection station when the terrain and the geological parameter are considered and when the terrain and the geological parameter are not considered. In addition, the target region of the lightning detection station participating in the lightning positioning is meshed, and the delay correction table and the parameter correction coefficient table of each grid point in the region corresponding to the participating lightning detection station are calculated. Based on initial lightning occurrence time, the initial lightning location, and an initial lightning characteristic parameter of each lightning detection station participating in the lightning positioning, as well as the delay correction value and the parameter correction coefficient that are corresponding to the participating lightning detection station when the closest grid point is used as the lightning strike point, the accurate lightning occurrence time, lightning location, and lightning characteristic parameter are recalculated.
[0090] FIG. 1 is a flowchart of a lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to the present disclosure;
[0091] FIG. 2 is a schematic diagram of the present disclosure;
[0092] FIG. 3 shows a spatial format distribution under a cylindrical coordinate system according to the present disclosure;
[0093] FIG. 4a shows overall electric field waveforms received by a lightning detection station in the Tibet region of China when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0094] FIG. 4b illustrates a partially enlarged view of the electric field waveforms in FIG. 4a;
[0095] FIG. 5 is a schematic diagram of meshing a target region of a lightning detection station according to the present disclosure;
[0096] FIG. 6 is a schematic diagram of a method for finding a grid point closest to an initial lightning location according to the present disclosure;
[0097] FIG. 7a shows an altitude distribution within 300 km with a certain lightning detection station in FIG. 4a and FIG. 4b as a circle center;
[0098] FIG. 7b shows a soil conductivity distribution within 300 km with a certain lightning detection station in FIG. 4a and FIG. 4b as a circle center;
[0099] FIG. 7c shows a distribution of an amplitude correction coefficient of a lightning electric field within 300 km with a certain lightning detection station in FIG. 4a and FIG. 4b as a circle center;
[0100] FIG. 7d shows a distribution of a delay correction value of a lightning electric field within 300 km with a certain lightning detection station in FIG. 4a and FIG. 4b as a circle center;
[0101] FIG. 8 shows a location distribution of a lightning strike point and seven detection stations participating in positioning according to an embodiment of the present disclosure;
[0102] FIG. 8a shows a profile of a terrain between No.1 detection station and the lightning strike point in FIG. 8;
[0103] FIG. 8b shows a profile of a terrain between No.2 detection station and the lightning strike point in FIG. 8;
[0104] FIG. 8c shows a profile of a terrain between No.3 detection station and the lightning strike point in FIG. 8;
[0105] FIG. 8d shows a profile of a terrain between No.4 detection station and the lightning strike point in FIG. 8;
[0106] FIG. 8e shows a profile of a terrain between No.5 detection station and the lightning strike point in FIG. 8;
[0107] FIG. 8f shows a profile of a terrain between No.6 detection station and the lightning strike point in FIG. 8;
[0108] FIG. 8g shows a profile of a terrain between No.7 detection station and the lightning strike point in FIG. 8;
[0109] FIG. 9a shows waveforms of No. 1 detection station in FIG. 8a in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0110] FIG. 9b shows waveforms of No. 2 detection station in FIG. 8b in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0111] FIG. 9c shows waveforms of No. 3 detection station in FIG. 8c in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0112] FIG. 9d shows waveforms of No. 4 detection station in FIG. 8d in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0113] FIG. 9e shows waveforms of No. 5 detection station in FIG. 8e in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0114] FIG. 9f shows waveforms of No. 6 detection station in FIG. 8f in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered;
[0115] FIG. 9g shows waveforms of No. 7 detection station in FIG. 8g in a vertical electric field (Ez) when a terrain and a geological parameter are considered and when the terrain and the geological parameter are not considered; and
[0116] FIG. 10 is a block diagram of a lightning positioning optimization system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to the present disclosure.
[0117] The present disclosure is described in further detail below with reference to the accompanying drawings and specific embodiments.
[0118] In the description of the present disclosure, it should be understood that orientations or position relationships indicated by terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", and the like are based on the orientations or position relationships shown in the accompanying drawings. These terms are just used to facilitate the description of the present disclosure and simplify the description, but not to indicate or imply that the mentioned device or elements must have a specific orientation and must be established and operated in a specific orientation, and thus these terms cannot be understood as a limitation to the present disclosure.
[0119] As shown in FIG. 1, a lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to the present disclosure includes following steps:
[0120] Step 1: Establish a ground and ionospheric electromagnetic wave propagation model, and obtain a delay correction value and a parameter correction coefficient for propagation of a lightning electromagnetic wave from an initial lightning location P(initial, yinitia) to a lightning detection station S.
[0121] In the ground and ionospheric electromagnetic wave propagation model, the ground is used as an irregular earth's surface with a terrain undulation and a geological parameter change, while an ionosphere is used as a medium layer with conductivity a varying with a height. The lightning electromagnetic wave is propagated from a lightning electromagnetic wave excitation source to the detection station in a cylindrical coordinate system. A schematic diagram is shown in FIG. 2.
[0122] Step 1-1: Assuming that the lightning electromagnetic wave is planarly propagated in a two-dimensional plane r-z in the cylindrical coordinate system, where an r direction is a direction along the earth's surface, a z direction is a height direction, a p direction satisfies a right-hand rule with respect to the r and z directions, and a gradient of the P direction is always 0, derive, based on Maxwell's original equations, Maxwell's curl equations for a vertical electric field and a horizontal magnetic field of a VLF/LF lightning electromagnetic wave propagating on the ground and ionospheric plane r-z, and solve the propagation of the lightning electromagnetic wave from the initial lightning location P(xinitial, yinitia) to the lightning detection station S based on the Maxwell's curl equations.
[0123] Specifically, the Maxwell's original equations are as follows: aB p Vx E = -E- at E0 aE V x B = poj + Eo p - V-B=0
[0124] In the above formula:
[0125] E represents an electric field intensity vector in radio wave propagation;
[0126] B represents a magnetic induction intensity vector in the radio wave propagation;
[0127] p represents a free charge;
[0128] 1c represents a dielectric constant in vacuum;
[0129] j represents a conduction current density vector, where j = oE;
[0130] 1 represents the conductivity; and
[0131] po represents magnetic permeability.
[0132] For a wide-area lightning positioning system, a vertical electric field and a horizontal magnetic field of a lightning discharge channel are mainly detected. The Maxwell's curl equations based on the vertical electric field and the horizontal magnetic field of the lightning discharge channel are as follows: aEr 1 aH at E0 aZ aEz 11 a -=(rHO) < at E 0 rar aH, 1 (aEz aEr at p'o ar az
[0133] In the above formula:
[0134] Er represents a component of electric field intensity E in the r direction;
[0135] Ez represents a component of the electric field intensity E in the z direction; and
[0136] H, represents a component of magnetic field intensity B in the (p direction.
[0137] Step 1-2: Apply a lightning current excitation source at the initial lightning location P(xiitia1, yiitia), where the lightning current excitation source is a lightning current return stroke channel, which is placed on a symmetry axis of the two-dimensional cylindrical coordinate system; and assuming that a base current at a bottom of a return discharge channel is 1(0, t), a lightning current gradually develops upwards from the ground, with a propagation speed of v, and an amplitude of the lightning current is attenuated with a height z according to an f (z) rule, a current distribution at the channel height z at a time point t is I(z, t), where the current distribution at the channel height z at the time point t is expressed as I(z, t):
I(z, t) = f(z)xI (0,t -
[0138] Then, propagation equations of the lightning electromagnetic wave in the step 1-1 are followed to obtain a model of the propagation from the lightning electromagnetic wave excitation source at the initial lightning location P(Xinitial, yinitia) to the lightning detection station S in the cylindrical coordinate system.
[0139] Specifically, if a Heidler double exponential function is used to construct a base current 1(0, t) at a bottom of a cloud-to-ground return stroke, the base current 1(0, t) at the bottom of the cloud-to-ground return stroke is expressed as follows:
I(0,t)= e(/ + I0 2 (e tT3- e
[0140] In the above formula:
[0141] Ioi represents a breakdown current, which is set to 9.9 kA;
[0142] 102represents a peak corona current, which is set to 7.5 kA;
[0143] 1i represents a correction factor of the breakdown current, which is set to 0.845;
[0144] 1T represents waveform rise time of the breakdown current, which is set to 0.072 [s;
[0145] T2 represents waveform fall time of the breakdown current, which is set to 5 s;
[0146] 1T3 represents waveform rise time of a corona current, which is set to 100 [s; and
[0147] T4 represents waveform fall time of the corona current, which is set to 6 s.
[0148] In addition, if an MTLE is used as a current return stroke model, and the base current is attenuated exponentially as it develops upwards, the current distribution at the channel height z at the time point t is I(z, t), which is expressed as follows: I(z,t) = e-z/XI(0,t - z/v)
[0149] In the above formula:
[0150] I(z, t) represents a current at the channel height z at the time point t;
[0151] z represents a height of the return discharge channel, and its maximum value is 7500 m;
[0152] e/- represents that the amplitude of the lightning current is attenuated exponentially with the height z;
[0153] 1 represents an attenuation factor, which is set to 2000 m; and
[0154] v represents the propagation speed of the lightning current, which is set to 1.5x108 m/s.
[0155] Step 1-3: Perform differential discretization on the Maxwell's curl equations, transform the Maxwell's curl equations with a time variable into Maxwell's discrete equations by discretizing E and H components in an electromagnetic field in space and time through alternate sampling to ensure that each E-field component is surrounded by four corresponding H components and each H-field component is surrounded by four corresponding E-field components, as shown in FIG. 3, and gradually perform update and advancing based on a leap-frog scheme in a time domain to solve a spatial electromagnetic field, where in the cylindrical coordinate system, a spatial format distribution adopts a Yee cell, a grid point of the Yee cell is set to (i, j, k), which is a grid point with i in the r direction, j in the (p direction, and k in the z direction, an entire computational domain includes many identical Yee cells connected to each other, and the electric field and the magnetic field are also staggered in terms of a time step, meaning that updates of the electric field and the magnetic field differ by half a time step.
[0156] The Maxwell's discrete equations are as follows:
1+ 1 _
Er 1 = Er|"1 - at~~ HAi+k+ H]i0 i+{,k ,k ii+,k k, Az
[ Oni-- 11 _r i1O n En+1 n n2 At i+{H |i+10k+- 2' 2 rH|i- 2 k+{2 Ezi,k+ 2 Ez2 i,k+{ + EEliki- ii+rI IA 2
EzI7+l,k+- Ezik+{ 2 2 At A H In -12 H 1'2±+ 2' 2r i ,k+ i+ ,k+ pik+ Er, - ErI+{ 2' 2 Az
[0157] In the above formula:
[0158] i represents an ith grid point in the r direction;
[0159] k represents a kth grid point in the z direction;
[0160] N represents a total quantity of differential solving steps;
[0161] Az represents a step in the z direction;
[0162] Ar represents a step in the r direction;
[0163] At represents a time step;
[0164] Er represents the component of the electric field intensity E in the r direction;
[0165] Ez represents the component of the electric field intensity E in the z direction;
[0166] Hcp represents a component of magnetic field intensity H in the p direction;
[0167] p represents the magnetic permeability; and
[0168] represents a dielectric constant.
[0169] Considering a limited capability of a computer, numerical solution of the Maxwell's discrete equations mentioned above can only be carried out in a finite region. To simulate electromagnetic wave propagation in an open domain, an absorption boundary condition must be provided at a boundary of a computational region.
[0170] A magnetic-field component B of an electromagnetic wave propagating in a medium is split into two sub-components Bor and Bez, and Be=Bor+B z. Therefore, a Maxwell's curl
equation will be rewritten as follows:
dEr 2 (2 (Bepr + BOz) azEr = c I ___ at az Eo
dEr (2 (Bepr + BOz) arEz = c 2 -_ __
at dr F-0 Ber_ dEz ItrBpr at dr po HB z_ dEr I zBpr at az po
[0171] In the above equation, c represents a propagation speed of the electromagnetic wave, a represents the conductivity, u represents the magnetic permeability, or represents a component of the conductivity in the r direction, az represents a component of the conductivity in the z direction, ur represents a component of the magnetic permeability in the r direction, and uz represents a component of the magnetic permeability in the z direction. When or = az = Ur = uz = 0, this equation is degenerated into a Maxwell's equation in free space. When the conductivity and the magnetic permeability are not 0, the medium becomes a lossy medium, and the electromagnetic wave is attenuated in the medium.
[0172] In addition, in the step 1-3, terrain altitude data is obtained based on digital elevation model data, and the geological parameter is characterized by the soil conductivity.
[0173] Step 1-4: Separately extract waveform arrival time ta and a characteristic parameter Pra from a waveform of lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are considered; and separately extract waveform arrival time tb and a characteristic parameter Prb from a waveform of the lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are not considered, where a formula for the delay correction value is At = ta - tb, and a formula for the parameter correction coefficient is k=PrJPrb.
[0174] Specifically, the waveform arrival time is extracted based on a peak point of the waveform, a half-peak point of a rising edge of the waveform, or a maximum derivative point of the rising edge of the waveform, and the characteristic parameter includes a waveform peak, front time, time to half value, a waveform half-peak width, and an electric field amplitude.
[0175] Specifically, when impacts of the terrain and the geological parameter are not considered, the ground is flat and lossless. When the impacts of the terrain and the geological parameter are considered, the ground is undulating and lossy.
[0176] In this embodiment, a place in the Tibet region of China is used as the lightning detection station. Electric field waveforms received by the lightning detection station when the terrain and the geological parameter are considered and when the terrain and the geological parameter are not considered are shown in FIG. 4a and FIG. 4b. Assuming that the lightning current expressed by the current distribution expression in the step 1-2 occurs at 300 km on a west side of the lightning detection station, electric field waveforms in the case of the flat and lossless ground and in the case of the undulating and lossy ground are obtained. FIG. 4a shows an overall electric field waveform, and FIG. 4b shows a locally enlarged electric field waveform. An undulating surface model in FIG. 4a and FIG. 4b adopts the global terrain model ETOPO1 with a resolution of 'x1' and published by the National Oceanic and Atmospheric Administration of the United States. The global terrain model ETOPO1 has a spatial resolution of approximately 1.6 kmx1.6 km. Soil texture type data is sourced from the Harmonized World Soil Database (HWSD), which contains required soil conductivity information.
[0177] In the ground and ionospheric electromagnetic wave propagation model, through numerical calculation and simulation of electromagnetic wave propagation, the present disclosure first calculates a waveform of the lightning electromagnetic wave when the terrain and the geological parameter are considered, and a waveform of the lightning electromagnetic wave when the terrain and the geological parameter are not considered, to obtain a delay correction value and a parameter correction coefficient that are of each lightning detection station and are corresponding to the initial lightning location. In the numerical simulation of the electromagnetic wave propagation, a real terrain undulation and real soil conductivity are considered. This can greatly improve an effect of lightning positioning optimization, and improve lightning positioning accuracy and parameter inversion accuracy.
[0178] Step 2: Draw equidistant circles with radii respectively being R 1, R2 , R3 , ..., and Ra and respectively centered on lightning detection stations Si, S2, S3, . . , and Sn participating in the lightning positioning (the equidistant circles mean that a distance between any two adjacent circles is the same), and then draw equiangular rays that pass through corresponding circle centers and respectively have preset azimuths 01, 02, 03, . . , and Ob on the equidistant circles (the equiangular rays mean that an angle between any two adjacent rays is the same), where an intersection point of the equidistant circle and the equiangular ray is a corresponding grid point in a region of each of the lightning detection stations Si, S2, S3, ..., and Sn; and take each grid point in the region of each of the lightning detection stations Si, S2, S3, . . , and Sn as the initial lightning location P(Xinitiai, yinitial), calculate a delay correction value and a parameter correction coefficient that are corresponding to each grid point in the region of each of the lightning detection stations Si, S2, S3, . . , and Sn, create a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient of each grid point in the region of each of the lightning detection stations, and take the corresponding delay correction table and parameter correction coefficient table of each of the lightning detection stations as an information index of the lightning detection station, where the steps 1-1 to 1-4 can be performed for a target region in advance to obtain a delay correction table and a parameter correction coefficient table of the region.
[0179] Specifically, a schematic diagram of meshing the target region of the lightning detection station according to the present disclosure is shown in FIG. 5. In addition, the radii of the equidistant circles are R1, R2, R3 , ... , and Ra respectively, and the R1, the R2, the R3 , ... , and the Ra are all 6 kilometers to 15 kilometers, where a value of a in the Ra ranges from 20 to 50. The preset azimuths for the equiangular rays are 01, 02, 03, ..., and Ob, and the 01, the 02, the 03, ...
, and the Ob are all 1 to 3, where a value of b in the Ob is floor (360/0), and floor(-) represents a rounding operation.
[0180] The present disclosure meshes the target region of the lightning detection station participating in the lightning positioning by drawing the equidistant circles with the radii respectively being the R1, R2, R3 , ..., and Ra and centered on the lightning detection stations, and then drawing the equiangular rays that have the preset azimuths 01, 02, 03, ..., and Ob respectively. An intersection point of an arc and the ray is a grid point in the target region. Then, the delay correction value and the parameter correction coefficient of each grid point in the region corresponding to each participating lightning detection station are calculated. This method can greatly reduce a simulation calculation workload. A single equiangular ray only needs to undergo simulation calculation once to obtain a waveform of a lightning electromagnetic wave of each grid point along the equiangular ray.
[0181] Step 3: Assuming that the earth is a standard ellipsoid model, calculate initial lightning occurrence time tinitiai and the initial lightning location P(initiai, yinitiai) by using an existing lightning positioning method based on waveform arrival time T1, T 2 , T 3 , ..., and Tn of lightning electromagnetic waves received by the participating lightning detection stations Si, S2, S3, ... ,
and Sn; then, extract waveform characteristic parameters Pri, Pr2, Pr3, ..., and Prn from waveforms of the lightning electromagnetic waves received by the participating lightning detection stations Si, S2, S3, ... , and S, and calculate an initial lightning characteristic parameter Prinitiai.
[0182] The existing lightning positioning method assumes that the earth is the standard ellipsoid model (such as the WGS-84 model), and includes a time difference method or a grid search method.
[0183] Specifically, the existing lightning positioning method solves a minimum value of a cost function including nonlinear equations, to obtain the initial lightning occurrence time tinitia1 and the initial lightning location P(xinitia, yinitiai), where the initiala, yinitiai) represents a longitude and a latitude of the lightning strike point. The nonlinear equations include an observation equation for arrival time Ti of a lightning electromagnetic wave received by a lightning detection station Si, and an observation equation for a measurement azimuth Pi between the initial lightning location P(Xinitial, yinitiai) and the lightning detection station Si; and the nonlinear equations are as follows:
Ti=t+ +E'pi C
i Pi +Ai
[0184] In the above nonlinear equations:
[0185] Ti represents the arrival time of the lightning electromagnetic wave received by the participating lightning detection station Si;
[0186] t represents lightning occurrence time;
[0187] Si represents a distance from a lightning strike location P(x, y) to the participating lightning detection station Si, and needs to be calculated on an ellipsoidal surface;
[0188] c represents the propagation speed of the electromagnetic wave;
[0189] ETi represents a time measurement error;
[0190] Pi represents the measurement azimuth of the lightning electromagnetic wave received by the participating lightning detection station Si;
[0191] 1i represents a calculation azimuth from the lightning strike location P(x, y) to the participating lightning detection station Si, and needs to be calculated on the ellipsoidal surface;
[0192] EAi represents an angle measurement error; and
[0193] coordinates of the Si are known, namely, (xi, yi), where i = 1,2,3 --- n.
[0194] The nonlinear equations are denoted as a following simple form: ri = Fj(t,x,y) + Ej
[0195] In the above nonlinear equations:
[0196] ri represents an observed quantity;
[0197] Fi(t, xi, y) represents an unknown function; and
[0198] 1i represents a measurement error.
[0199] Lightning positioning calculation is intended to obtain an optimal estimate of a target location based on an observed quantity with an error. When an observation error is small and obeys a normal distribution, a distribution of an unknown quantity also obeys a multi-dimensional normal distribution. In this case, an error E is omitted, that is, when Ei=O, the minimum value minxlF(t,x,y) - r||I of the cost function of the simple form of the nonlinear equations is the initial lightning occurrence time tinitia and the initial lightning location P(xinitia, yiitiai), where r represents a vector composed of each ri.
[0200] Step 4: Based on the initial lightning location P(initial, yinitia) and information of the participating lightning detection station, find grid points Ai, A 2, A 3 , ... , and An closest to the initial lightning location P(initial, yinitiai) on the corresponding equidistant circles and orientations of the corresponding lightning detection stations Si, S2, S3, ... , and Sn; and then based on information indexes of the lightning detection stations Si, S2, S3, ... , and Sn, determine corresponding delay correction values At', At 2', At, ... , and Atn' and corresponding parameter correction coefficients ki', k 2', k3'..., and kn' for the lightning detection stations Si, S2, S3, ... , and
Sn when the closest grid points Ai, A 2, A 3 , ... , and An are used as lightning strike points.
[0201] The present disclosure creates the delay correction table and the parameter correction coefficient table based on the delay correction value and the parameter correction coefficient of each grid point in the region corresponding to the participating lightning detection station, and uses the delay correction table and the parameter correction coefficient table that are corresponding to each lightning detection station as the information index of the lightning detection station, which means that time-consuming numerical simulation is carried out in advance. In a practical business application, only an information index of each lightning detection station needs to be queried, thereby greatly improving efficiency of the lightning positioning optimization.
[0202] Specifically, a method for finding the grid points Ai, A2 , A 3 , ... , and An closest to the initial lightning location P(xinitial, yinitiai) is to calculate a distance R and a preset azimuth 0 of the initial lightning location P(xinitial, yinitiai) relative to each lightning detection station, and find a grid point that is closest to both the distance R and the preset azimuth 0 in the corresponding equidistant circle of each of the lightning detection stations Si, S2, S3, ... , and Sn, namely, the
grid points Ai, A 2, A 3 , . . , and An closest to the initial lightning location P(xinitial, yinitial).
[0203] According to the present disclosure, on the corresponding equidistant circle of the participating lightning detection station, the grid point closest to the initial lightning location is found based on the initial lightning location. Then, based on the information index of each participating lightning detection station, the corresponding delay correction value and parameter correction coefficient of the participating lightning detection station when the closest grid point is used as the lightning strike point are determined. This method can improve retrieval efficiency and can be easily implemented in a business.
[0204] FIG. 6 is a schematic diagram of the method for finding the grid point closest to the initial lightning location according to the present disclosure. From FIG. 6, it can be seen that equidistant circles respectively centered on lightning detection stations Si and S2 are drawn. The initial lightning location is at the point P(xinitiai, yinitiai). A distance RAi and a preset azimuth 0A1 Of the point P relative to the lightning detection station Si, and a distance RA2 and a preset azimuth OA2 of the point P relative to the lightning detection station S2 are calculated. In an information index of the lightning detection station S, a closest grid point Al is found through comparison. In an information index of the lightning detection station S2, a closest grid point A2 is found through comparison.
[0205] Step 5: Correct the lightning detection stations Si, S2, S3, ... , and Sn participating in the lightning positioning, such that corrected waveform arrival time of the lightning detection stations is Ti-Ati, T21-At2, T 3 1-At 3 ', . . , and Tni-Atn' respectively, and then perform calculation again by using the existing lightning positioning method, to obtain accurate lightning occurrence time tfinai and an accurate lightning location P'(x final, y final); and calculate an accurate lightning waveform characteristic parameter Prfinai based on corrected waveform characteristic parameters 1/ki'xPri, 1/k2 'xPr 2 , 1/k3'xPr 3 , ... , and 1/kn'xPrn of the lightning electromagnetic waves received by the lightning detection stations Si, S2, S3, ... , and Sn participating in the lightning positioning.
[0206] FIG. 7a to FIG. 7d respectively show distributions of an altitude, soil conductivity, an amplitude correction coefficient of a corresponding lightning electric field, and a delay correction value of the lightning electric field within 300 km with a certain lightning detection station in the Tibet region of China as a circle center in the above embodiment. In FIG. 7a to FIG. 7d, a horizontal axis represents a longitude, and a vertical axis represents a latitude. From FIG. 7a to FIG. 7d, it can be seen that there is a strong correlation between the lightning current amplitude and the terrain. Taking the lightning detection station as an example, when the altitude of the lightning detection station is close to a surrounding altitude, a lightning current amplitude ratio fluctuates around 1. An overall altitude of the lightning detection station is above 4000 m, and lightning current amplitude ratios in most regions of the lightning detection station are around 0.8 to 1.2. A southern region of China has a significant difference in altitude, with an altitude of around 2000 m, and a lightning current amplitude ratio in this region fluctuates greatly in a range of 0.5 to 1.5.
[0207] Based on a lightning strike detected by a power grid thunder and lightning positioning system on June 20, 2022, the following describes an effect of the lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave in the present disclosure.
[0208] At 19:08:28:785 on June 20, 2022, a lightning strike caused a trip on a certain ultra-high voltage transmission line of the State Grid. The existing power grid thunder and lightning positioning system is checked, and it is found that the lightning strike occurs 907 m away from a certain tower of the ultra-high voltage transmission line, with a lightning current intensity of 15.5 kA. A location of the lightning strike matches a fault location, but the lightning current intensity is too low to cause the trip on the ultra-high voltage line.
[0209] FIG. 8 shows a location distribution of the above lightning strike point and seven detection stations participating in positioning, and a topographic map from each lightning detection station to the lightning strike point. FIG. 8a shows a profile of a terrain between No.1 detection station and the lightning strike point; FIG. 8b shows a profile of a terrain between No.2 detection station and the lightning strike point; FIG. 8c shows a profile of a terrain between No.3 detection station and the lightning strike point; FIG. 8d shows a profile of a terrain between No.4 detection station and the lightning strike point; FIG. 8e shows a profile of a terrain between No.5 detection station and the lightning strike point; FIG. 8f shows a profile of a terrain between No.6 detection station and the lightning strike point; FIG. 8g shows a profile of a terrain between No.7 detection station and the lightning strike point.
[0210] From FIG. 8a to FIG. 8g, it can be seen that some propagation paths have a height difference of up to 1000 m, such as No.2 detection station and No.7 detection station. By applying the lightning current excitation source as described in the step 2-2 at the lightning strike point, a waveform of the lightning electric field is received at each lightning detection station. FIG. 9a to FIG. 9g show waveforms of the seven participating lightning detection stations in the vertical electric field (Ez) when the terrain and the geological parameter are considered and when the terrain and the geological parameter are not considered. Waveform characteristic parameters (peak amplitudes) and waveform arrival time when the terrain and the geological parameter are considered, as well as waveform characteristic parameters (including peak amplitudes) and waveform arrival time when the terrain and the geological parameter are not considered are extracted from the waveforms of the vertical electric field (Ez) in FIG. 9a to FIG. 9g. Delay correction values and amplitude correction coefficients shown in Table 1 are calculated, which are required for correcting the location of the lightning strike point.
[0211] Table 1 Delay correction values and amplitude correction coefficients of the participating lightning detection stations Considering the terrain Not considering the Lightning and the geological terrain and the geological Delay detection parameter parameter correction Amplid correction station Waveform Waveform value coefficient SN Amplitude arrival time Amplitude arrival time (ps) (V/m) (ps) (V/m) (ps) 4 4.3366 201.54 4.1863 201.32 0.22 1.0359 5 2.8474 374.04 3.0229 374.04 0 0.9419 7 1.1936 619.76 2.3302 619.52 0.24 0.5122 3 2.2622 633.38 2.3039 633.38 0.2 0.9819 6 2.1630 646.30 2.2813 645.72 0.58 0.9481 2 1.0519 781.08 2.0707 780.72 0.36 0.508 1 1.9866 891.84 1.9359 891.52 0.32 1.0262
[0212] According to the step 5, the delay correction value obtained through simulation is subtracted from the waveform arrival time of the lightning electromagnetic wave received by each of the seven lightning detection stations. Then, calculation is performed again by using the existing lightning positioning method in the step 1 to obtain accurate lightning occurrence time tfinaland an accurate lightning location P'(xfinal,y final).
[0213] According to the step 5, the peak amplitude of the lightning electromagnetic wave received by each of the seven lightning detection stations is divided by the amplitude correction coefficient obtained through the simulation, and then the peak amplitude is extracted from a waveform of the lightning electromagnetic wave received by each of the seven lightning detection stations to calculate an accurate lightning peak Prfinal. After correction and optimization, the location of the lightning strike is 328 m away from the tower of the ultra-high voltage transmission line, with a smaller error. The current intensity of the lightning strike increased to 36.1 kA, which exceeds an insulation level of lightning shielding of the ultra-high voltage line, and provides data support for fault diagnosis and analysis.
[0214] According to the lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave in the present disclosure, the ground and ionospheric electromagnetic wave propagation model is established, and the simulation calculation is separately performed to obtain a delay correction value and a parameter correction coefficient of a lightning electromagnetic wave propagating from an initial location of a lightning strike to the lightning detection station when the terrain and the geological parameter are considered and when the terrain and the geological parameter are not considered. In addition, the target region of the lightning detection station participating in the lightning positioning is meshed, and the delay correction table and the parameter correction coefficient table of each grid point in the region corresponding to the participating lightning detection station are calculated. Based on the initial lightning occurrence time, the initial lightning location, and the initial lightning characteristic parameter of each participating lightning detection station, as well as the delay correction value and the parameter correction coefficient that are corresponding to the participating lightning detection station when the closest grid point is used as the lightning strike point, the accurate lightning occurrence time, lightning location, and lightning characteristic parameter are recalculated.
[0215] As shown in FIG. 10, a lightning positioning optimization system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave includes a delay correction value and parameter correction coefficient calculation module, an information index establishment module, an initial lightning location and characteristic parameter calculation module, a module for determining a delay correction value and a parameter correction coefficient of a closest grid point, and an accurate lightning location and characteristic parameter calculation module.
[0216] The delay correction value and parameter correction coefficient calculation module is configured to: establish a ground and ionospheric electromagnetic wave propagation model, calculate, based on waveform arrival time considering a terrain and a geological parameter, and waveform arrival time without considering the terrain and the geological parameter, a delay correction value for propagation of a lightning electromagnetic wave from an initial lightning location to a lightning detection station, and calculate, based on a waveform characteristic parameter considering the terrain and the geological parameters, and a waveform characteristic parameter without considering the terrain and the geological parameter, a parameter correction coefficient for the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station.
[0217] The information index establishment module is configured to: draw n corresponding equidistant circles respectively centered on lightning detection stations participating in lightning positioning, draw an equiangular ray that passes through a corresponding circle center and has a preset azimuth on each of the equidistant circles, where an intersection point of each of the equidistant circles and the corresponding equiangular ray is a grid point within a region of the corresponding lightning detection station, take each grid point within a region of each of the lightning detection stations as an initial lightning location, calculate a delay correction value and a parameter correction coefficient that are corresponding to each grid point within the region of each of the lightning detection stations, create a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient, and take the delay correction table and the parameter correction coefficient table that are corresponding to each of the lightning detection stations as an information index of the lightning detection station.
[0218] The initial lightning location and characteristic parameter calculation module is configured to: assuming that the earth is a standard ellipsoid model, calculate initial lightning occurrence time and the initial lightning location by using an existing lightning positioning method based on waveform arrival time of a lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; and then calculate an initial lightning characteristic parameter based on a waveform characteristic parameter extracted from a waveform of the lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning.
[0219] The module for determining the delay correction value and the parameter correction coefficient of the closest grid point is configured to: based on the initial lightning location and information of the lightning detection stations participating in the lightning positioning, find a corresponding grid point closest to the corresponding initial lightning location on each of the equidistant circles corresponding to the corresponding lightning detection stations; and based on the information index of each of the lightning detection stations, determine a corresponding delay correction value and parameter correction coefficient of each of the lightning detection stations when using each closest grid point as a lightning strike point.
[0220] The accurate lightning location and characteristic parameter calculation module is configured to: perform delay correction on each of the lightning detection stations participating in the lightning positioning to obtain corresponding corrected waveform arrival time of each of the lightning detection stations, and then calculate accurate lightning occurrence time and an accurate lightning location by using the lightning positioning method; and perform characteristic parameter correction on each of the participating lightning detection stations to obtain a corresponding corrected characteristic parameter of each of the lightning detection stations, and then calculate an accurate lightning characteristic parameter.
[0221] The above embodiments are preferred implementations of the present disclosure. However, the implementations of the present disclosure are not limited by the above embodiments. Any change, modification, substitution, combination, and simplification made without departing from the spiritual essence and principle of the present disclosure should be an equivalent replacement manner, and all are included in the protection scope of the present disclosure.
Claims (16)
- CLAIMS: 1. A lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, comprising following steps: step 1: establishing a ground and ionospheric electromagnetic wave propagation model, calculating, based on waveform arrival time considering a terrain and a geological parameter, and waveform arrival time without considering the terrain and the geological parameter, a delay correction value for propagation of a lightning electromagnetic wave from an initial lightning location to a lightning detection station, and calculating, based on a waveform characteristic parameter considering the terrain and the geological parameter, and a waveform characteristic parameter without considering the terrain and the geological parameter, a parameter correction coefficient for the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station; step 2: drawing n corresponding equidistant circles respectively centered on lightning detection stations participating in lightning positioning, drawing an equiangular ray that passes through a corresponding circle center and has a preset azimuth on each of the equidistant circles, wherein an intersection point of each of the equidistant circles and the corresponding equiangular ray is a grid point within a region of the corresponding lightning detection station, taking each grid point within a region of each of the lightning detection stations as the initial lightning location, calculating a delay correction value and a parameter correction coefficient that are corresponding to each grid point within the region of each of the lightning detection stations, creating a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient, and taking the delay correction table and the parameter correction coefficient table that are corresponding to each of the lightning detection stations as an information index of the lightning detection station; step 3: assuming that the earth is a standard ellipsoid model, calculating initial lightning occurrence time and the initial lightning location by using an existing lightning positioning method based on waveform arrival time of a lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; and then calculating an initial lightning characteristic parameter based on a waveform characteristic parameter extracted from a waveform of the lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; step 4: based on the initial lightning location and information of the lightning detection stations participating in the lightning positioning, finding a corresponding grid point closest to the corresponding initial lightning location on each of the equidistant circles corresponding to the corresponding lightning detection stations; and based on the information index of each of the lightning detection stations, determining a corresponding delay correction value and parameter correction coefficient of each of the lightning detection stations when using each closest grid point as a lightning strike point; and step 5: performing delay correction on each of the lightning detection stations participating in the lightning positioning to obtain corresponding corrected waveform arrival time of each of the lightning detection stations, and then calculating accurate lightning occurrence time and an accurate lightning location by using the lightning positioning method; and performing characteristic parameter correction on each of the participating lightning detection stations to obtain a corresponding corrected characteristic parameter of each of the lightning detection stations, and then calculating an accurate lightning characteristic parameter.
- 2. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 1, wherein in the step 1, specific steps of establishing the ground and ionospheric electromagnetic wave propagation model are as follows: step 1-1: assuming that the lightning electromagnetic wave is planarly propagated in a two-dimensional plane r-z in a cylindrical coordinate system, wherein an r direction is a direction along an earth's surface, a z direction is a height direction, a p direction satisfies a right-hand rule with respect to the r and z directions, and a gradient of the p direction is always 0, deriving, based on Maxwell's original equations, Maxwell's curl equations for a vertical electric field and a horizontal magnetic field of a very low frequency (VLF)/low frequency (LF) lightning electromagnetic wave propagating on the ground and ionospheric plane r-z, and solving the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station based on the Maxwell's curl equations; step 1-2: applying a lightning current excitation source at the initial lightning location, wherein the lightning current excitation source is a lightning current return stroke channel, which is placed on a symmetry axis of the two-dimensional cylindrical coordinate system; and assuming that a base current at a bottom of a return discharge channel is 1(0, t), a lightning current gradually develops upwards from the ground, with a propagation speed of v, and an amplitude of the lightning current is attenuated with a height z according to an f (z) rule, a current distribution at the channel height z at a time pointt is I(z,t), wherein the current distribution at the channel height z at the time point t is expressed as I(z, t):I (z, t) = f(z)xI1 (0, t- 0 step 1-3: performing differential discretization on the Maxwell's curl equations, transforming the Maxwell's curl equations with a time variable into Maxwell's discrete equations by discretizing E and H components in an electromagnetic field in space and time through alternate sampling to ensure that each E-field component is surrounded by four corresponding H components and each H-field component is surrounded by four corresponding E-field components, and gradually performing update and advancing based on a leap-frog scheme in a time domain to solve a spatial electromagnetic field, wherein in the cylindrical coordinate system, a spatial format distribution adopts a Yee cell, a grid point of the Yee cell is set to (i, j, k), which is a grid point with i in the r direction, j in the (p direction, and k in the z direction, an entire computational domain comprises many identical Yee cells connected to each other, and the electric field and the magnetic field are also staggered in terms of a time step, meaning that updates of the electric field and the magnetic field differ by half a time step; and step 1-4: separately extracting waveform arrival time ta and a characteristic parameter Pra from a waveform of lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are considered; and separately extracting waveform arrival time t and a characteristic parameter Prb from a waveform of the lightning received by the lightning detection station in the vertical electric field Ez or a waveform of the lightning received by the lightning detection station in the horizontal magnetic field H 9 when the terrain and the geological parameter are not considered, wherein a formula for the delay correction value is At = ta - tb, and a formula for the parameter correction coefficient is k=Pra/Prb.
- 3. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 2, wherein in the step 1-1, the Maxwell's original equations are as follows:V-E- p aB V x E = B at E0aE V X B = oj + E0- V-B=0wherein E represents an electric field intensity vector in radio wave propagation; B represents a magnetic induction intensity vector in the radio wave propagation; p represents a free charge; so represents a dielectric constant in vacuum; j represents a conduction current density vector, wherein j = oE; a represents conductivity; and to represents magnetic permeability.
- 4. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 3, wherein in the step 1-1, the Maxwell's curl equations based on a vertical electric field and a horizontal magnetic field of a lightning discharge channel are as follows: aEr 1 aHq at E0 aZ aEz 11 a at E 0 rar aH, 1 (aE aEr) at p'o ar az wherein Er represents a component of electric field intensity E in the r direction; Ez represents a component of the electric field intensity E in the z direction; and H, represents a component of magnetic field intensity B in the (p direction.
- 5. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 4, wherein in the step 1-2, if a Heidler double exponential function is used to construct a base current 1(0, t) at a bottom of a cloud-to-ground return stroke, the base current at the bottom of the cloud-to-ground return stroke is expressed as follows:I(0, t) = e- + 02 (et - et/T4wherein Ioi represents a breakdown current; 102 represents a peak corona current; i represents a correction factor of the breakdown current; Ti represents waveform rise time of the breakdown current; T2 represents waveform fall time of the breakdown current; T3 represents waveform rise time of a corona current; and T4 represents waveform fall time of the corona current.
- 6. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 5, wherein in the step 1-2, if a modified transmission line model with exponential decay of the current with height (MTLE) is used as a current return stroke model, and the base current is attenuated exponentially as the base current develops upwards, the current distribution at the channel height z at the time point t is I(z, t), which is expressed as follows: I(z,t) = e-z/XI(0,t - z/v) wherein I(z, t) represents a current at the channel height z at the time point t; z represents a height of the return discharge channel; e-Z represents that the amplitude of the lightning current is attenuated exponentially with the height z; X represents an attenuation factor; and v represents the propagation speed of the lightning current.
- 7. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 6, wherein in the step 1-3, the Maxwell's discrete equations are as follows:n+1 n a +},+j 0 In+},k 2 12 E1n+1 i+- i,k E,k + AZ 2'At r| OH1i+1 k+ r| _H Hi+ - 1 11t 2 Ein t r d ik2 k 2 Elik±! rIjAr 2-EzIn±k! EzInk± 2 2 Arersnts at tim step;~ k At A 2 2 ' 12 Ik1 +rI - ErIni 2' 222AZ wherein At represents atime step; Errepresents the component of the electric field intensity Ein the rdirection;Ez represents the component of the electric field intensity E in the z direction; Hqp represents a component of magnetic field intensity H in the p direction; p represents the magnetic permeability; and , represents a dielectric constant.
- 8. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 7, wherein in the step 1-4, the waveform arrival time is extracted based on a peak point of the waveform, a half-peak point of a rising edge of the waveform, or a maximum derivative point of the rising edge of the waveform, and the characteristic parameter comprises a waveform peak, front time, time to half value, a waveform half-peak width, and an electric field amplitude.
- 9. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 2, wherein in the step 5, waveform arrival time of lightning electromagnetic waves received by lightning detection stations Si, S2, S3, . . , and Sn participating in the lightning positioning is Ti, T 2 , T 3 , . . , and Tn respectively, and when closest grid points Ai, A 2, A 3 , . . , and An are used as lightning strike points, if delay correction values corresponding to the lightning detection stations Si, S2, S3, ..., and Sn are Ati', At 2', At 3 ', ..., and Atn' respectively, corrected waveform arrival time corresponding to the lightning detection stations Si, S2, S3, ..., and S, is Ti-Ati', T21-At2', T31-At3', ..., and Tni-Atn' respectively.
- 10. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 2, wherein in the step 5, characteristic parameters of lightning electromagnetic waves received by lightning detection stations Si, S 2 , S3, . . , and Sn participating in the lightning positioning are Pri, Pr2, Pr3, . . , and Prn respectively, and when closest grid points Ai, A 2, A 3 , . . , and An are used as lightning strike points, if parameter correction coefficients corresponding to the lightning detection stations Si, S2, S3, ..., and Sn are ki', k2', k 3', ..., and kn' respectively, corrected characteristic parameters corresponding to the lightning detection stations Si, S 2 , S3, . . , and S, are 1/ki'xPri, 1/k 2'xPr 2, 1/k 3'xPr 3 , ... , and 1/kn'xPrn respectively.
- 11. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 1, wherein in the step 4, the corresponding grid point closest to the corresponding initial lightning location is found as follows: calculating a distance R and a preset azimuth 0 of the initial lightning location relative to each of the lightning detection stations, and finding a grid point that is closest to both the distance R and the preset azimuth 0 in the corresponding equidistant circle of each of the lightning detection stations as the corresponding grid point closest to the initial lightning location.
- 12. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 1, wherein in the step 2, radii of the equidistant circles are RI, R2, R3, ... , and Ra respectively, and the R1, the R2 , the R3, ... , and the Ra are all 6 kilometers to 15 kilometers, wherein a value of a in the Ra ranges from 20 to 50; and the preset azimuths for the equiangular rays are 01, 02, 03, ..., and O, and the 01, the 02, the 03, ... , and the Ob are all 1 to 3, wherein a value of b in the Ob is floor (360/0), and floor(-) represents a rounding operation.
- 13. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 1, wherein in the step 3, the lightning positioning method solves a minimum value of a cost function comprising nonlinear equations, to obtain the initial lightning occurrence time tinitia1 and the initial lightning location P(Xinitia, yinitiai), wherein the initiala, yinitiai) represents a longitude and a latitude of the lightning strike point; the nonlinear equations comprise an observation equation for arrival time Ti of a lightning electromagnetic wave received by a lightning detection station Si, and an observation equation for a measurement azimuth Pi between the initial lightninglocation P(Xinitial, yinitiai) and the lightning detection station Si; and the nonlinear equations are asfollows:Ti=t+ +E'pi Ci Pi +Ai wherein Ti represents the arrival time of the lightning electromagnetic wave received by the participating lightning detection station Si; t represents lightning occurrence time; Spi represents a distance from a lightning strike location P(x, y) to the participating lightningdetection station Si, and is calculated on an ellipsoidal surface; c represents a propagation speed of an electromagnetic wave;Eri represents a time measurement error; Pi represents the measurement azimuth of the lightning electromagnetic wave received by the participating lightning detection station Si; Ppi represents a calculation azimuth from the lightning strike location P(x, y) to the participating lightning detection station Si, and is calculated on the ellipsoidal surface; eAi represents an angle measurement error; coordinates of the Si are known, namely, (xi, yi), wherein i = 1,2,3 --- n; and the nonlinear equations are denoted as a following simple form: ri = F(t,x,y) + Ej wherein ri represents an observed quantity; Fi(t, xi, y) represents an unknown function; andEi represents a measurement error.
- 14. The lightning positioning optimization method by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave according to claim 10, wherein in the step 3, in the simple form of the nonlinear equations, whenEi=, the minimum value minx||F(t,x,y) - r||2 of the cost function of the simple form of the nonlinear equations is the initial lightning occurrence time tiitia1 and the initial lightning location P(initial, initiall.
- 15. A lightning positioning optimization system by correcting impacts of a terrain and a geological parameter on propagation of a lightning electromagnetic wave, comprising a delay correction value and parameter correction coefficient calculation module, an information index establishment module, an initial lightning location and characteristic parameter calculation module, a module for determining a delay correction value and a parameter correction coefficient of a closest grid point, and an accurate lightning location and characteristic parameter calculation module, wherein the delay correction value and parameter correction coefficient calculation module is configured to: establish a ground and ionospheric electromagnetic wave propagation model, calculate, based on waveform arrival time considering a terrain and a geological parameter, and waveform arrival time without considering the terrain and the geological parameter, a delay correction value for propagation of a lightning electromagnetic wave from an initial lightning location to a lightning detection station, and calculate, based on a waveform characteristic parameter considering the terrain and the geological parameters, and a waveform characteristic parameter without considering the terrain and the geological parameter, a parameter correction coefficient for the propagation of the lightning electromagnetic wave from the initial lightning location to the lightning detection station; the information index establishment module is configured to: draw n corresponding equidistant circles respectively centered on lightning detection stations participating in lightning positioning, draw an equiangular ray that passes through a corresponding circle center and has a preset azimuth on each of the equidistant circles, wherein an intersection point of each of the equidistant circles and the corresponding equiangular ray is a grid point within a region of the corresponding lightning detection station, take each grid point within a region of each of the lightning detection stations as an initial lightning location, calculate a delay correction value and a parameter correction coefficient that are corresponding to each grid point within the region of each of the lightning detection stations, create a corresponding delay correction table and parameter correction coefficient table based on the delay correction value and the parameter correction coefficient, and take the delay correction table and the parameter correction coefficient table that are corresponding to each of the lightning detection stations as an information index of the lightning detection station; the initial lightning location and characteristic parameter calculation module is configured to: assuming that the earth is a standard ellipsoid model, calculate initial lightning occurrence time and the initial lightning location by using an existing lightning positioning method based on waveform arrival time of a lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; and then calculate an initial lightning characteristic parameter based on a waveform characteristic parameter extracted from a waveform of the lightning electromagnetic wave received by each of the lightning detection stations participating in the lightning positioning; the module for determining the delay correction value and the parameter correction coefficient of the closest grid point is configured to: based on the initial lightning location and information of the lightning detection stations participating in the lightning positioning, find a corresponding grid point closest to the corresponding initial lightning location on each of the equidistant circles corresponding to the corresponding lightning detection stations; and based on the information index of each of the lightning detection stations, determine a corresponding delay correction value and parameter correction coefficient for each of the lightning detection stations when using each closest grid point as a lightning strike point; and the accurate lightning location and characteristic parameter calculation module is configured to: perform delay correction on each of the lightning detection stations participating in the lightning positioning to obtain corresponding corrected waveform arrival time of each of the lightning detection stations, and then calculate accurate lightning occurrence time and an accurate lightning location by using the lightning positioning method; and perform characteristic parameter correction on each of the participating lightning detection stations to obtain a corresponding corrected characteristic parameter of each of the lightning detection stations, and then calculate an accurate lightning characteristic parameter.
- 16. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the method according to 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 |
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| 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 |
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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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