CN106707040B - A method of lightning parameter is obtained using actual measurement lightning vertical electric field - Google Patents
A method of lightning parameter is obtained using actual measurement lightning vertical electric field Download PDFInfo
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Abstract
The present invention proposes a kind of method for obtaining lightning parameter using actual measurement lightning vertical electric field, belongs to the lightning monitoring technical field of electrical field.This method passes through artificially triggered lightning method first and obtains remote actual measurement lightning vertical electric field data, and carries out smoothing denoising to actual measurement lightning vertical electric field data, eliminates the noise signal in actual measurement lightning vertical electric field data, obtains actual measurement lightning vertical electric field segment；The reflex of soil, is determined soil attenuation function after the expression formula of time domain, is searched for obtain optimal lightning substrate current and Return stroke speed using particle swarm algorithm where considering electric field measurement point；The distribution of charge density in lightning channel is finally calculated.The present invention overcomes lightning substrate currents directly to measure, and Return stroke speed and lightning channel charge density directly measure and is difficult to obtain this deficiency, applied widely, facilitates electric system using more effective lightning protection safeguard procedures.
Description
Technical field
It is the invention belongs to the lightning monitoring technical field of electrical field, in particular to a kind of to utilize actual measurement lightning vertical electric field
The method for obtaining lightning parameter.
Background technique
Thunder and lightning is one of ten the Nature disasters.High current, high voltage and the strong-electromagnetic field that its moment generates, not only result in
People and animals' injures and deaths, the material goods that natural resources for the survival of mankind and the mankind are created rich in huge destruction, but also
Often to the installations and facilities of the sectors of the national economy such as electric power, communication, petrochemical industry, aerospace, railway traffic or even financial instrument
Bring damage.Therefore, atmospheric electrical phenomena, lightning physics, Lightning Warning and the problems such as protection, are still atmospheric electricity, electric system, put
The hot research problem in the fields such as electric physics.
Lightning substrate current (also known as thunder and lightning substrate current) refers to the lightning current of lightning channel lowermost end, lightning substrate current
It is the high current as caused by lightning, is to influence the major source of building and electronic equipment, therefore understand lightning substrate current
Characteristic is the basis of lightning protection.Generally there are two types of methods for the acquisition of lightning substrate current: 1) directly measuring；2) method of inversion.Directly survey
Amount just refers to, generated lightning base when lightning is hit on this high tower is directly measured using the current sensor being mounted on high tower
Bottom electric current.Due to lightning launch a surprise attack be a little it is random, if launch a surprise attack a little not on high tower if lightning substrate current is not measured, so
The scope of application of kind method is little.The method of inversion just refers to, counter to push away by computation model using electromagnetic field caused by lightning
To lightning substrate current, M.Izadia was in article " the Estimation of Lightning Current and at him in 2014
Return Stroke Velocity Profile Using Measured Electromagnetic Fields " in propose
A method of lightning substrate current and Return stroke speed being obtained using short distance lightning electromagnetic field Inversion Calculation, but his method is only
Lightning electromagnetic field feature under considering closely needs to consider not in view of lightning electromagnetic field is in remote transmission
Attenuation of the soil to lightning electromagnetic field.Since the charge density distribution in lightning channel is difficult to actual measurement, therefore can only lead to
It crosses round-about way and determines its distribution.
Lightning occur when, it will generate electric field in space, wherein electric field is vector, it be decomposed into for ground level
Parallel horizontal component of electric field and vertical electric field perpendicular to the ground, it is vertically electric that vertical electric field perpendicular to the ground is referred to as lightning
?.
When lightning phenomenon occurs between cloud and ground, such lightning dodges with being referred to as.Ground, which dodges, is usually accompanied by charge
The electric discharge that cloud is rushed at by ground, referred to as fights back, and the discharge path passed through in counterattack is referred to as lightning channel, referred to as dodges
Road.Return stroke speed refers to that charge is rushed at the speed in cloud by ground, therefore Return stroke speed can be different with the difference of height.Lightning is logical
Refer to charge Density Distribution situation in lightning channel when road charge density distribution.
Prior art relevant to the content of present invention is described as follows:
Lightning substrate current NCBC current model, expression formula are as follows:
In formula, i is thunder and lightning substrate current, and t is time, intermediate parameterstmWhen being the corresponding peak value of peak value lightning current
Between, ImIt is peak point current, a and bi(i=1,2 ..., n) is respectively wave head parameter and wave rear parameter, ciFor weight parameter, n is wave rear adjustable parameter.
The expression formula of Return stroke speed model is as follows:
V (z)=v1(z+z0) 1≤z≤H
In formula, z is height, avAnd yiFor adjustment parameter, zmFor the height corresponding to maximum Return stroke speed, H is lightning channel
Length, v1And z0For speed intermediate variable, v is Return stroke speed, vmFor Return stroke speed maximum value, w1And w2For weight parameter,
The return-stroke model of continuity equation method calculating lightning vertical electric field:
Wherein E (d, t) is the lightning vertical electric field of ideal big underground, and t is the time, and c is the spread speed of light in a vacuum,
It is highly the current segment of z away from the distance of electric field measurement point that R (z), which is in lightning channel, and calculation formula is as follows:
In formula, d is horizontal distance of the electric field measurement point apart from lightning channel.I (z, t-R (z)/c) is in lightning channel
Electric current, expression formula are as follows:
In formula, v is Return stroke speed, and i (0, t) is lightning substrate current, and H is the total length of lightning channel.ρ*(z, t) refers to
It is highly the lightning channel local charge density of z, calculation formula is as follows under t moment:
In formula, Q (z, t) refers under t moment, is highly the lightning channel total charge dosage of z.
Finally, lightning vertical electric field expression formula when considering soil reflex are as follows:
The calculation method of soil attenuation function:
Lightning electric field in long-distance communications, the influence for the effects of will receive the reflection and absorption of soil and decay, we
Attenuation of the soil to lightning electric field is expressed as a function, referred to as soil attenuation function, expression formula such as formula (0-9) institute
Show:
Wherein WstrIt is soil attenuation function, ρ is horizontal distance of the measurement point away from lightning channel, and ω is angular frequency, and erfc is
Complex value error function (also referred to as Gauss error function), p are intermediate parameters, and the calculation formula of p is as follows:
ε1=εr1ε0 (0-18)
ε2=εr2ε0
Wherein, μ0It is space permeability, ε0It is permittivity of vacuum, εr1,εr2It is opposite Jie of soil 1 and soil 2 respectively
Electric constant, h1It is the thickness of first layer soil, remaining parameter is intermediate parameters needed for calculating p.
The expression formula in the soil attenuation function of frequency domain can be calculated by formula (0-9)-(0-18), then pass through Fu
In the available soil attenuation function in time domain of leaf inverse transformation expression formula.
Particle swarm algorithm:
Particle swarm algorithm is earliest by social psychology doctor Kennedy and electronic engineering doctor Eberhart in nineteen ninety-five
It proposes, in particle swarm algorithm model, the oneself state of each particle is by one group of position and speed vector description, difference table
Show the feasible solution and its direction of motion in search space of problem.Particle is optimal by constantly learning the group that it is found
Solution and neighbours' optimal solution realize global optimum's search.The location updating equation of the speed of particle is the core of PSO algorithm, respectively
It is described by following two formula:
vij(k+1)=w (k) vij(k)+c1r1(pbestij(k)-xij(k))+c2r2(gbestj(k)-xij
(k)) (0-19)
xij(k+1)=xij(k)+vij(k+1) (0-20)
Wherein, c1, c2For Studying factors, r1, r2For the random number of [0,1], w (k) is evolution adjustment parameter, in this patent
Take w (k)=1-k/kmax, kmaxIt is maximum number of iterations.vij(k) indicate particle i evolve to k for when jth tie up flying speed
Component.xij(k) indicate particle i evolve to k for when jth tie up location components, pbestij(k) indicate that particle i is evolving to k
For when jth tie up personal best particle pbestiComponent, gbestj(k) indicate to evolve to k for when entire population optimal location
The jth of gbest ties up component.
Summary of the invention
It is an object of the invention to overcome the shortcoming of prior art, provides a kind of utilize and survey lightning vertical electric field
The method for obtaining lightning parameter.The present invention overcomes lightning substrate currents directly to measure, and Return stroke speed and lightning channel charge are close
Degree directly measurement is difficult to obtain this deficiency, applied widely, facilitates electric system and is arranged using more effective lightning protection protection
It applies.
A kind of method obtaining lightning parameter using actual measurement lightning vertical electric field proposed by the present invention, wherein lightning parameter
It include: lightning substrate current, Return stroke speed and lightning channel charge density distribution, which is characterized in that this method includes following step
It is rapid:
1) remote actual measurement lightning vertical electric field data are obtained using artificially triggered lightning method, and to actual measurement lightning vertical electric field
Data carry out smoothing denoising, eliminate the noise signal in actual measurement lightning vertical electric field data, obtain actual measurement lightning vertical electric field piece
Section；Specific step is as follows:
Electric-field sensor 1-1) is installed in the distant place that artificially triggered lightning bar bottom level distance is d, d > 10km, d are electric field
Horizontal distance of the measurement point apart from lightning channel；
1-2) when successfully carrying out artificially triggered lightning test, using electric-field sensor, measurement obtain artificially channel braided
Vertical electric field caused by remote, to obtain actual measurement lightning vertical electric field data；From actual measurement lightning vertical electric field data
The waveform segment of N number of sampled point is intercepted, start-stop point is denoted as [j, j+199] respectively, and wherein j point is electric field when artificially channel braided occurs
Start occur changing first zero point at first；
1-3) by step 1-2) interception obtain actual measurement the N number of groups of samples of lightning vertical electric field data at electric field waveform
Section carries out smoothing denoising processing, eliminates the noise signal in actual measurement lightning vertical electric field waveform segment data, obtains actual measurement lightning and hangs down
Straight electric field segment Emeasure；
2) reflex of soil, determines soil attenuation function in the expression formula of time domain where considering electric field measurement point；Tool
Body the following steps are included:
2-1) determine the basic parameter of soil attenuation function, comprising: the conductivityσ of first layer soil1, second layer soil
Conductivityσ2, the relative dielectric constant ε of first layer soilr1, the relative dielectric constant ε of second layer soilr2And first layer soil
Thickness h1；
2-2) soil attenuation function represents soil to the attenuation of lightning electric field, shown in expression formula such as formula (1):
In formula, WstrIt is soil attenuation function, ω is angular frequency, and erfc is complex value error function, and p is intermediate parameters, p's
Calculation formula is as follows:
In formula, μ0It is space permeability, ε0It is permittivity of vacuum, remaining parameter is intermediate parameters needed for calculating p；
The expression formula W in the soil attenuation function of frequency domain is calculated by formula (1)-(10)str(d, j ω), then passes through
Fourier inversion obtains the expression formula w in the soil attenuation function of time domainstr(d,t)；
3) it searches for obtain optimal lightning substrate current and Return stroke speed using particle swarm algorithm；Specifically include following step
It is rapid:
Particle swarm algorithm 3-1) is used, each particle in particle swarm algorithm is enabled to represent and lightning substrate current and Return stroke speed
Relevant one group of parameter, comprising: Im, tm, a, bi, ci, n, vm,av,zm,y1,y2,w1,w2,z0；Wherein, ImIt is peak point current, tmIt is
The corresponding time to peak of peak value lightning current, vmFor Return stroke speed maximum value, a and biRespectively wave head parameter and wave rear parameter, i=
1,2 ..., n, ciFor weight parameter,N is wave rear adjustable parameter, av、y1And y2For adjustment parameter, zmFor corresponding to most
The height of big Return stroke speed, w1And w2For weight parameter,z0For speed intermediate variable；
3-2) utilize the N obtained at the kth iterationpA particle value, NpThe particle total number for representing population, according to formula
(11) and lightning substrate current and Return stroke speed corresponding to each particle value is calculated in formula (12), and is counted according to formula (13)
It calculates and obtains the lightning vertical electric field of the big underground of ideal corresponding to each particle value:
In formula, i (0, t) is lightning substrate current, and t is time, intermediate parameters
V (z)=v1(z+z0)1≤z≤H
In formula, z is height, yiFor adjustment parameter, H is the length of lightning channel, v1For speed intermediate variable, v is to fight back speed
Degree；
In formula, E (d, t) is the lightning vertical electric field of ideal big underground, and c is the spread speed of light in a vacuum, and R (z) is
It is highly the current segment of z in lightning channel away from the distance of electric field measurement point, calculation formula is as follows:
I (z, t-R (z)/c) is the electric current in lightning channel, and expression formula is as follows:
3-3) the expression formula w for the soil attenuation function in time domain for combining step 2) to obtainstr(d, t) is calculated and is considered soil
Lightning vertical electric field when reflex, expression formula are as follows:
3-4) lightning substrate current corresponding to each particle value that step 3-2) is calculated and Return stroke speed substitute into
Lightning vertical electric field E corresponding to each particle value is calculated in formula (13) and (16)calculate, and obtained with step 1-3)
Survey lightning vertical electric field segment EmeasureIt is compared, calculates error amount between the two using formula (17) and is determined,
Obtain optimal lightning substrate current and Return stroke speed；
In formula, N is the total number of measured data sequence；
If 3-4-1) NpThe minimum error values er in all error amounts that a particle uses formula (17) to be calculatedmin< ζ, ζ
For setting minimal error allowed band or the number of iterations k > maximum number of iterations MaxStep when, then stop particle swarm algorithm
Search exports minimum error values particle value corresponding with its in population, lightning substrate current corresponding to the particle value with
Return stroke speed is optimal lightning substrate current and Return stroke speed；
If 3-4-2) minimum error values ermin>=ζ and the number of iterations k≤MaxStep are then right using formula (18)-(19)
The particle value and velocity amplitude of each particle are updated, the number of iterations k=k+1, continue particle swarm algorithm search, until searching
Rope obtains the lightning vertical electric field E so that being calculatedcalculateVertical electric field E is surveyed with lightningmeasureBetween error amount exist
Error amount particle value corresponding with its within allowed band, lightning substrate current and Return stroke speed corresponding to the particle value are
For optimal lightning substrate current and Return stroke speed；
vij(k+1)=w (k) vij(k)+c1r1(pbestij(k)-xij(k))+c2r2(gbestj(k)-xij
(k)) (18)
xij(k+1)=xij(k)+vij(k+1) (19)
In formula, c1, c2For Studying factors, r1, r2For the random number of [0,1], w (k) is evolution adjustment parameter, w (k)=1-
k/kmax, kmaxIt is maximum number of iterations MaxStep, vij(k) indicate particle i evolve to k for when jth dimension flying speed point
Amount, xij(k) indicate particle i evolve to k for when jth tie up location components, pbestij(k) indicate that particle i is evolving to k generation
When jth tie up personal best particle pbestiComponent, gbestj(k) indicate to evolve to k for when entire population optimal location
The jth of gbest ties up component；
4) the optimal lightning substrate electricity that local charge density formula and step 3) in continuity equation method obtain is utilized
Stream and Return stroke speed, are calculated the distribution of charge density in lightning channel；Specific step is as follows:
The optimal lightning for 4-1) utilizing local charge density formula (20) and step 3) in continuity equation method to obtain
The distribution of charge density in lightning channel is calculated in substrate current and Return stroke speed；
ρ*(z, t) refers under t moment, is highly the lightning channel local charge density of z, calculation formula is as follows:
Wherein:
In formula, it is highly the lightning channel total charge dosage of z that Q (z, t), which refers under t moment,.
The features of the present invention and the utility model has the advantages that
The present invention is based on the calculating lightning electromagnetic field return-stroke models under particle swarm algorithm and soil reflex, utilize actual measurement
Lightning vertical electric field realizes the indirect acquisition to lightning substrate current, Return stroke speed and lightning channel charge density distribution, more
Lightning substrate current, Return stroke speed and lightning channel charge density distribution has been mended to be difficult to directly measure this deficiency.Due to lightning
The vertical electric field of generation is easier to obtain in space, so kind method is applied widely, can assist in lightning channel
Characteristic parameter, to help electric system using more effective lightning protection safeguard procedures.
Detailed description of the invention
Fig. 1 is the flow diagram of the method for the present invention.
Fig. 2 is that the lightning substrate current that optimizing obtains in the embodiment of the present invention is illustrated compared with surveying lightning substrate current
Figure.
Fig. 3 is the Return stroke speed schematic diagram that optimizing obtains in the embodiment of the present invention.
Fig. 4 is actual measurement lightning vertical electric field and the comparison schematic diagram for calculating both vertical electric fields in the embodiment of the present invention.
Fig. 5 is close for the charge inscribed in lightning channel in t=H/v+R (H)/c being calculated in the embodiment of the present invention
Spend distribution map.
Specific embodiment
It is proposed by the present invention it is a kind of using actual measurement lightning vertical electric field obtain lightning parameter method, with reference to the accompanying drawing and
Specific embodiment is further described as follows.
A kind of method obtaining lightning parameter using actual measurement lightning vertical electric field proposed by the present invention, wherein lightning parameter
It include: lightning substrate current, Return stroke speed and lightning channel charge density distribution.This method overall procedure is as shown in Figure 1, include
Following steps:
1) remote actual measurement lightning vertical electric field data are obtained using artificially triggered lightning method and (while also obtains actual measurement lightning base
Bottom current data), and smoothing denoising is carried out to actual measurement lightning vertical electric field data, it eliminates in actual measurement lightning vertical electric field data
Noise signal obtains actual measurement lightning vertical electric field segment；Specific step is as follows:
Current sensor 1-1) is installed in artificially triggered lightning bar bottom, current sensor generally uses Rogowski coil, this
Example measures lightning current using Rogowski coil, and range is ± 50kA, sample frequency 10MHz.In distance electricity
Electric-field sensor is installed in the distant place (usual d > 10km, this example d=32.7km) that the horizontal distance of flow sensor is d, and (d is electricity
Horizontal distance of the field measurement point apart from lightning channel), the electric-field sensor that the present embodiment uses can produce lightning for speed antenna
Raw speed electric field measures, wherein the time constant of fast antenna is 2ms, bandwidth is 1kHz~2MHz, the time of slow antenna
Constant is 6s, and bandwidth is 0.1Hz~3MHz.
1-2) when successfully carrying out artificially triggered lightning test, using current sensor and electric-field sensor, measurement obtains artificial
It triggers the substrate current of lightning and in remote generated vertical electric field, surveys lightning substrate current data and reality to obtain
Lightning vertical electric field data are surveyed, wherein actual measurement lightning substrate current data are the lightning bases being calculated for verifying context of methods
Whether bottom electric current is correct, and the sample frequency of current sensor and electric-field sensor is 10MHz.Then from actual measurement lightning substrate electricity
Intercepting N respectively in flow data and actual measurement lightning vertical electric field data, (usual value range is [100,1000], the present embodiment value
For the waveform segment of 200) a sampled point, start-stop point is denoted as [j, j+199] respectively, and wherein j point is artificially channel braided respectively
When substrate current and electric field start occur changing first zero point at first, obtain the waveform segment actual measurement lightning substrate current segment
Imeasure；
1-3) by step 1-2) interception obtain actual measurement lightning vertical electric field data N (usual value range be [100,
1000], the present embodiment value be 200) a groups of samples at electric field waveform segment, carry out smoothing denoising processing, eliminate actual measurement dodge
Noise signal in electric vertical electric field waveform segment data obtains actual measurement lightning vertical electric field segment Emeasure；
2) consider soil reflex, determine soil attenuation function in the expression formula of time domain, specifically includes the following steps:
2-1) determining the basic parameter of soil attenuation function, soil is considered as the soil of two layers of horizontal slice by the present invention, the
One layer of soil is one layer of soil on most closely surface, and second layer soil is one layer of soil under first layer soil.Soil is basic
Parameter includes: the conductivityσ of first layer soil1, the conductivityσ of second layer soil2, the relative dielectric constant of first layer soil
εr1, the relative dielectric constant ε of second layer soilr2And the thickness h of first layer soil1；Due to soil parameters and thickness of soil with
It measures the difference in vertical electric field data place and different, therefore is considered as the practical soil regime of measurement point when its value, this implementation
The corresponding each parameter value difference of example is as follows: σ1=0.002；σ2=0.1；εr1=5；εr2=81；h1=14.55；
The influence for the effects of 2-2) lightning electric field is in long-distance communications, will receive the reflection and absorption of soil and decay,
Attenuation of the soil to lightning electric field is expressed as a function, referred to as soil attenuation function, shown in expression formula such as formula (1):
In formula, WstrIt is soil attenuation function, d is horizontal distance of the electric field measurement point away from lightning channel, and ω is angular frequency,
Erfc is complex value error function (also referred to as Gauss error function), and p is intermediate parameters, and the calculation formula of p is as follows:
In formula, μ0It is space permeability, ε0It is permittivity of vacuum, εr1,εr2It is first layer soil and second layer soil respectively
The relative dielectric constant of earth, h1It is the thickness of first layer soil, remaining parameter is intermediate parameters needed for calculating p.
The expression formula W in the soil attenuation function of frequency domain can be calculated by formula (1)-(10)str(d, j ω), then
Pass through the expression formula w of the available soil attenuation function in time domain of Fourier inversionstr(d,t)。
3) it searches for obtain optimal lightning substrate current and Return stroke speed using particle swarm algorithm, specifically includes following step
It is rapid:
Particle swarm algorithm 3-1) is used, each particle in particle swarm algorithm is enabled to represent and lightning substrate current and Return stroke speed
Relevant one group of parameter, comprising: Im, tm, a, bi, ci, n, vm,av,zm,y1,y2,w1,w2,z0；Wherein, ImIt is peak point current, tmIt is
The corresponding time to peak of peak value lightning current, vmFor Return stroke speed maximum value, a and bi(i=1,2 ..., n) be respectively wave head parameter and
Wave rear parameter, ciFor weight parameter,N is wave rear adjustable parameter, av、y1And y2For adjustment parameter, zmFor corresponding to most
The height of big Return stroke speed, w1And w2For weight parameter,z0For speed intermediate variable；
3-2) utilize the N obtained at the kth iterationpA particle value, NpThe particle total number for representing population, according to formula
(11) and lightning substrate current and Return stroke speed corresponding to each particle value is calculated in formula (12), and is counted according to formula (13)
It calculates and obtains the lightning vertical electric field of the big underground of ideal corresponding to each particle value:
In formula, i (0, t) is lightning substrate current, and t is time, intermediate parameterstmIt is that peak value lightning current is corresponding
Time to peak, ImIt is peak point current, a and bi(i=1,2 ..., n) is respectively wave head parameter and wave rear parameter, ciFor weight parameter,N is wave rear adjustable parameter.
V (z)=v1(z+z0) 1≤z≤H
In formula, z is height, avAnd yiFor adjustment parameter, zmFor the height corresponding to maximum Return stroke speed, H is lightning channel
Length, v1And z0For speed intermediate variable, v is Return stroke speed, w1And w2For weight parameter,
In formula, E (d, t) is the lightning vertical electric field of ideal big underground, and t is the time, and c is the propagation speed of light in a vacuum
Degree, it is highly the current segment of z away from the distance of electric field measurement point that R (z), which is in lightning channel, and calculation formula is as follows:
I (z, t-R (z)/c) is the electric current in lightning channel, and expression formula is as follows:
In formula, v is Return stroke speed, and i (0, t) is lightning substrate current；
3-3) the expression formula w for the soil attenuation function in time domain for combining step 2) to obtainstr(d, t) is calculated and is considered soil
Lightning vertical electric field when reflex, expression formula are as follows:
3-4) lightning substrate current corresponding to each particle value that step 3-2) is calculated and Return stroke speed substitute into
Lightning vertical electric field E corresponding to each particle value is calculated in formula (13) and (16)calculate, and obtained with step 1-3)
Survey lightning vertical electric field segment EmeasureIt is compared, calculates error amount between the two using formula (17) and is determined,
Obtain optimal lightning substrate current and Return stroke speed；
In formula, N is the total number of measured data sequence；
If 3-4-1) NpThe minimum error values er in all error amounts that a particle uses formula (17) to be calculatedmin< ζ, ζ
For the minimal error allowed band (value range of ζ is depending on the circumstances, and the present embodiment takes ζ=0.001) of setting, or repeatedly
(value range of maximum number of iterations MaxStep is usually [50,500] to generation number k > MaxStep, and the present embodiment takes MaxStep
=100) when, then stop particle swarm algorithm search, export minimum error values particle value corresponding with its in population, the particle
The corresponding lightning substrate current of value and Return stroke speed are optimal lightning substrate current and Return stroke speed；
If 3-4-2) minimum error values ermin>=ζ and the number of iterations k≤MaxStep are then right using formula (18)-(19)
The particle value and velocity amplitude of each particle are updated, the number of iterations k=k+1, continue particle swarm algorithm search, until searching
Rope obtains the lightning vertical electric field E so that being calculatedcalculateVertical electric field E is surveyed with lightningmeasureBetween error amount exist
Error amount particle value corresponding with its within allowed band, lightning substrate current and Return stroke speed corresponding to the particle value are
For optimal lightning substrate current and Return stroke speed；
vij(k+1)=w (k) vij(k)+c1r1(pbestij(k)-xij(k))+c2r2(gbestj(k)-xij
(k)) (18)
xij(k+1)=xij(k)+vij(k+1) (19)
In formula, c1, c2For Studying factors, r1, r2For the random number of [0,1], w (k) is evolution adjustment parameter, w (k)=1-
k/kmax, kmaxIt is maximum number of iterations MaxStep, vij(k) indicate particle i evolve to k for when jth dimension flying speed point
Amount, xij(k) indicate particle i evolve to k for when jth tie up location components, pbestij(k) indicate that particle i is evolving to k generation
When jth tie up personal best particle pbestiComponent, gbestj(k) indicate to evolve to k for when entire population optimal location
The jth of gbest ties up component；
4) the optimal lightning substrate electricity that local charge density formula and step 3) in continuity equation method obtain is utilized
Stream and Return stroke speed, are calculated the distribution of charge density in lightning channel；Specific step is as follows:
The optimal lightning for 4-1) utilizing local charge density formula (20) and step 3) in continuity equation method to obtain
The distribution of charge density in lightning channel is calculated in substrate current and Return stroke speed；
ρ*(z, t) refers under t moment, is highly the lightning channel local charge density of z, calculation formula is as follows:
Wherein:
In formula, it is highly the lightning channel total charge dosage of z that Q (z, t), which refers under t moment,.
Lightning substrate current (the corresponding particle value: I that this method optimizing obtainsm=14.44kA, tm=0.5641 μ s, a
=1.1723, b1=0.0207, b2=0.1460, b3=0, c1=0.6028, c2=0.2598, c3=0.1374, n=3) and return
Hit speed (corresponding particle value: vm=2.1 × 108M/s, zm=667m, av=5, w1=0.4379, w2=0.5621, y1=
8.8815 y2=0.4203, z0=488m) result is as shown in Figures 2 and 3.Fig. 2 is the sudden strain of a muscle that optimizing obtains in the embodiment of the present invention
The comparison schematic diagram of electric substrate current and actual measurement lightning substrate current.Horizontal axis is the time in Fig. 2, and unit μ s, the longitudinal axis is lightning base
Bottom electric current, unit kA, solid line are the substrate current that actual measurement obtains, and dotted line is the lightning substrate current that optimizing obtains, from Fig. 2
As can be seen that the lightning substrate current that this method is calculated is consistent with actual measurement lightning substrate current, this method is demonstrated
Correctness, and formula (17) are utilized, the lightning substrate current mean error of actual measurement lightning substrate current and calculating is calculated
It is 0.0018.
Fig. 3 is the Return stroke speed schematic diagram that optimizing obtains in the embodiment of the present invention.Horizontal axis is logical away from lightning bottom in Fig. 3
Road height, unit m, the longitudinal axis are Return stroke speed, unit 108M/s, solid line is that the Return stroke speed of different channel heights is distributed, through counting
It calculates, the average value of the Return stroke speed is 1.3 × 108M/s, meeting Return stroke speed range in document is described in c/3~2c/3.
The vertical electric field and reality being calculated using lightning substrate current obtained in Fig. 2 and Fig. 3 and Return stroke speed result
The comparison for surveying vertical electric field is as shown in Figure 4.Fig. 4 is to survey lightning vertical electric field in the embodiment of the present invention and vertical electricity is calculated
The comparison schematic diagram of both fields.Horizontal axis is the time in Fig. 4, and unit μ s, the longitudinal axis is vertical electric field, and unit V/m, solid line is that actual measurement is dodged
Electric vertical electric field, dotted line are the vertical electric field being calculated, from fig. 4, it can be seen that the vertical electric field that is calculated of this method with
Actual measurement vertical electric field is consistent, and demonstrates the correctness of this method, and the average mistake of the two is calculated using formula (17)
Difference is 0.0015.
Fig. 5 inscribes the charge density distribution figure in lightning channel when being t=H/v+R (H)/c.In Fig. 5, horizontal axis is away from lightning
The channel height of bottom, unit m, the longitudinal axis are charge density, unit 10-3C/m, solid line are the charge density distribution of different height,
Charge density calculated result in Fig. 5 is integrated in height, the total electrical charge in available lightning channel at this time is
0.5403 coulomb, meet in document described in 0.38 coulomb~2 coulombs.
Claims (1)
1. a kind of method for obtaining lightning parameter using actual measurement lightning vertical electric field, wherein lightning parameter includes: lightning substrate electricity
Stream, Return stroke speed and lightning channel charge density distribution, which is characterized in that method includes the following steps:
1) remote actual measurement lightning vertical electric field data are obtained using artificially triggered lightning method, and to actual measurement lightning vertical electric field data
Smoothing denoising is carried out, the noise signal in actual measurement lightning vertical electric field data is eliminated, obtains actual measurement lightning vertical electric field segment；Tool
Steps are as follows for body:
Electric-field sensor 1-1) is installed in the distant place that artificially triggered lightning bar bottom level distance is d, d > 10km, d are electric field measurement
Horizontal distance of the point apart from lightning channel；
1-2) when successfully carrying out artificially triggered lightning test, using electric-field sensor, measurement obtain artificially channel braided in long distance
From generated vertical electric field, to obtain actual measurement lightning vertical electric field data；N is intercepted from actual measurement lightning vertical electric field data
The waveform segment of a sampled point, start-stop point are denoted as [j, j+199] respectively, wherein j point be artificially channel braided occur when electric field at first
Start occur changing first zero point；
1-3) by step 1-2) interception obtain actual measurement the N number of groups of samples of lightning vertical electric field data at electric field waveform segment, into
The noise signal in actual measurement lightning vertical electric field waveform segment data is eliminated in the processing of row smoothing denoising, and it is vertically electric to obtain actual measurement lightning
Field segment Emeasure；
2) reflex of soil, determines soil attenuation function in the expression formula of time domain where considering electric field measurement point；Specific packet
Include following steps:
2-1) determine the basic parameter of soil attenuation function, comprising: the conductivityσ of first layer soil1, the conductance of second layer soil
Rate σ2, the relative dielectric constant ε of first layer soilr1, the relative dielectric constant ε of second layer soilr2And the thickness of first layer soil
Spend h1；
2-2) soil attenuation function represents soil to the attenuation of lightning electric field, shown in expression formula such as formula (1):
In formula, WstrIt is soil attenuation function, ω is angular frequency, and erfc is complex value error function, and p is intermediate parameters, the calculating of p
Formula is as follows:
In formula, μ0It is space permeability, ε0It is permittivity of vacuum, remaining parameter is intermediate parameters needed for calculating p；
The expression formula W in the soil attenuation function of frequency domain is calculated by formula (1)-(10)str(d, j ω), then by Fu
Leaf inverse transformation obtains the expression formula w in the soil attenuation function of time domainstr(d,t)；
3) it searches for obtain optimal lightning substrate current and Return stroke speed using particle swarm algorithm；Specifically includes the following steps:
Particle swarm algorithm 3-1) is used, enables each particle representative in particle swarm algorithm related to lightning substrate current and Return stroke speed
One group of parameter, comprising: Im, tm, a, bi, ci, n, vm,av,zm,y1,y2,w1,w2,z0；Wherein, ImIt is peak point current, tmIt is peak value
The corresponding time to peak of lightning current, vmFor Return stroke speed maximum value, a and biRespectively wave head parameter and wave rear parameter, i=1,
2 ..., n, ciFor weight parameter,N is wave rear adjustable parameter, av、y1And y2For adjustment parameter, zmFor corresponding to maximum
The height of Return stroke speed, w1And w2For weight parameter,z0For height intermediate variable；
3-2) utilize the N obtained at the kth iterationpA particle value, NpThe particle total number for representing population, according to formula (11)
Lightning substrate current and Return stroke speed corresponding to each particle value is calculated with formula (12), and is calculated according to formula (13)
To the lightning vertical electric field of the big underground of ideal corresponding to each particle value:
In formula, i (0, t) is lightning substrate current, and t is time, intermediate parameters
In formula, z is height, yiFor adjustment parameter, H is the length of lightning channel, v1For speed intermediate variable, v is Return stroke speed；
In formula, E (d, t) is the lightning vertical electric field of ideal big underground, and c is the spread speed of light in a vacuum, and R (z) is lightning
It is highly the current segment of z in channel away from the distance of electric field measurement point, calculation formula is as follows:
I (z, t-R (z)/c) is the electric current in lightning channel, and expression formula is as follows:
3-3) the expression formula w for the soil attenuation function in time domain for combining step 2) to obtainstr(d, t) is calculated and is considered soil reflection
Lightning vertical electric field when effect, expression formula are as follows:
3-4) lightning substrate current corresponding to each particle value that step 3-2) is calculated and Return stroke speed substitute into formula
(13) and (16) lightning vertical electric field E corresponding to each particle value, is calculatedcalculate, and the reality obtained with step 1-3)
Survey lightning vertical electric field segment EmeasureIt is compared, calculates error amount between the two using formula (17) and is determined, obtained
To optimal lightning substrate current and Return stroke speed；
In formula, N is the total number of measured data sequence；
If 3-4-1) NpThe minimum error values er in all error amounts that a particle uses formula (17) to be calculatedmin< ζ, ζ are setting
Minimal error allowed band or when the number of iterations k > maximum number of iterations MaxStep, then stop particle swarm algorithm search,
Export minimum error values particle value corresponding with its in population, lightning substrate current corresponding to the particle value and counterattack speed
Degree is optimal lightning substrate current and Return stroke speed；
If 3-4-2) minimum error values ermin>=ζ and the number of iterations k≤MaxStep, then using formula (18)-(19) to each
The particle value and velocity amplitude of particle are updated, the number of iterations k=k+1, continue particle swarm algorithm search, until searching for
To so that the lightning vertical electric field E being calculatedcalculateVertical electric field E is surveyed with lightningmeasureBetween error amount allowing
Within the scope of error amount particle value corresponding with its, lightning substrate current and Return stroke speed corresponding to the particle value are most
Excellent lightning substrate current and Return stroke speed；
vij(k+1)=w (k) vij(k)+c1r1(pbestij(k)-xij(k))+c2r2(gbestj(k)-xij(k)) (18)
xij(k+1)=xij(k)+vij(k+1) (19)
In formula, c1, c2For Studying factors, r1, r2For the random number of [0,1], w (k) is evolution adjustment parameter, w (k)=1-k/kmax,
kmaxIt is maximum number of iterations MaxStep, vij(k) indicate particle i evolve to k for when jth tie up flying speed component, xij
(k) indicate particle i evolve to k for when jth tie up location components, pbestij(k) indicate particle i evolve to k for when jth
Tie up personal best particle pbestiComponent, gbestj(k) indicate to evolve to k for when entire population optimal location gbest the
J ties up component；
4) using in continuity equation method local charge density formula and the obtained optimal lightning substrate current of step 3) and
The distribution of charge density in lightning channel is calculated in Return stroke speed；Specific step is as follows:
The optimal lightning substrate for 4-1) utilizing local charge density formula (20) and step 3) in continuity equation method to obtain
The distribution of charge density in lightning channel is calculated in electric current and Return stroke speed；
ρ*(z, t) refers under t moment, is highly the lightning channel local charge density of z, calculation formula is as follows:
Wherein:
In formula, it is highly the lightning channel total charge dosage of z that Q (z, t), which refers under t moment,.
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