CN107179462A - Fan blade based on lightning physics is dynamically hit away from the construction method with electric geometry method - Google Patents
Fan blade based on lightning physics is dynamically hit away from the construction method with electric geometry method Download PDFInfo
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Abstract
The invention discloses a kind of fan blade based on lightning physics dynamically hit away from electric geometry method construction method, based on the physical model that lightning leader develops, dynamically hit away from method using fan blade, ensure diverse location on fan blade have it is different hit away from, and the change and changing of fan blade present position hit away from, give blade dynamically hit away from distribution characteristics.Assuming that thunder and lightning descending leader develops straight down, it will dynamically hit away from being combined with traditional electric geometry method, set up the electric geometrical analysis model for fan blade.Improved electric geometry method proposed by the present invention not only can provide theoretical foundation for the lightning Protection Design of fan blade with assessing, and provide thinking for the ground object lightning protection calculation with labyrinth.
Description
Technical field
Dynamically hit away from the construction method with electric geometry method the present invention relates to a kind of fan blade based on lightning physics.
Background technology
Wind-powered electricity generation is as the important component of clean energy resource, and its extensive development is the weight for promoting China's energy system reform
Want technical support.However, in view of environment and its own special construction residing for blower fan, is easily struck by lightning by air.Lightning strike accident
The damage of Leaf accounts for more than the 40% of lightning damage sum, and most for unrepairable damage.The cost of fan blade,
The high costs such as lifting, maintenance have badly influenced the economic stability operation of wind power plant.Therefore, a reliable method is found to comment
Estimate the efficiency of fan blade lightning-protection system, the sustainable development of lightning Protection Design and promotion wind-powered electricity generation to fan blade has important meaning
Justice.
Current fan blade lightning Protection Design is to be based on experimental study mostly, in the distribution of blade surrounding electric field, arrester protection
Certain achievement is achieved in terms of effect.But the running environment of the environment in laboratory and actual blower fan has differences unavoidably, its with
The equivalence of actual conditions also remains to be discussed, and is required for carrying out repeating examination for the fan blade of varying environment, different model
Test, consume substantial amounts of manpower and materials, need badly and develop a kind of appraisal procedure of blade lightning protection efficiency.
In the 1960s, domestic and foreign scholars first connect the geometry of the electric parameter of lightning current and circuit
The shielding problem of transmission line of electricity is studied, the classics that transmission line of electricity is proposed on the basis of many experiments are observed and are calculated are electrically several
What model, huge advance is achieved relative to legacy procedures method.Hereafter people are carried out to hitting in electric geometric method away from formula
Improve to adapt to different environment, but hitting to remain unchanged away from formula has physics concept obfuscation, the poor shortcoming of versatility, and can not
Embody ground object diverse location, different structure to hit away from change, it is difficult to apply in the complex rotation knot as fan blade
Structure.Meanwhile, the research of part prior art is mainly by the calculating repeatedly of pilot model, to the lightning protection properties index of specified point
Analyzed, the overall lightning protection efficiency calculation method of blade is not provided.
The content of the invention
The present invention is in order to solve the above problems, it is proposed that a kind of fan blade based on lightning physics dynamically hit away from it is electric
Electric method of geometry is combined by the construction method of geometrical model, the present invention with the physical process that lightning leader develops, it is proposed that
For the electric geometrical analysis model of fan blade.By introduce fan blade dynamically hit away from concept and analysis method so that
Hit away from physical significance become apparent from, and further derived the computational methods of blade lightning-protection system efficiency.Followed by the mould
The type analysis influence factor of actual size fan blade lightning-protection system efficiency, and tested based on fan blade long gap breakdown test
The validity of this method is demonstrate,proved.The fan blade electric geometry method of proposition, can be carried for the lightning Protection Design of fan blade with assessment
For theoretical foundation.
To achieve these goals, the present invention is adopted the following technical scheme that：
A kind of fan blade based on lightning physics is dynamically hit away from the construction method with electric geometry method, with lightning leader
Based on the physical model of development, and with negative polarity thunderbolt description lightning stroke process, negative polarity thunderbolt is divided into three phases, it is descending
Guide is developed downwards, upward leader starting, up-downgoing guide's connection procedure, it is assumed that thunder and lightning descending leader develops straight down, when
The streamer of uplink and downlink guide is struck by lightning when meeting, the height on upward leader streamer head when being struck by lightning is set to hit away from, according to
This calculates fan blade and dynamically hit away from having different hit away from and fan blade to embody diverse location on fan blade
The change of present position and changing is hit away from assuming that lightning current numerical value is downwards on the premise of development, being hit according to dynamic away from setting up pin
To the electric geometry method of fan blade.
Closed according to the geometry of exposure arc, shielding arc and the fan blade anglec of rotation in fan blade electric geometry method
System, calculates fan blade electric geometry method exposed range, and then obtain fan blade lightning-protection system efficiency.
The electric geometry method of fan blade lightning protection includes the hitting away from hitting that, blade and blade is in of blade arrester
Away from, exposure arc and shielding arc.
When amplitude of lightning current increase, exposure arc can continue to reduce until disappearing, blade is shielded completely, now corresponding
Amplitude of lightning current may connect the maximum lightning current that mishap loses for blade.
Thunder and lightning descending leader uses leader channel charge distribution model.
Using fan blade electric geometry method, analysis angle of fan leaves, amplitude of lightning current and arrester arrangement are to anti-
The influence of thunder system effectiveness, is finally based on the validity that breakdown test under fan blade long gap demonstrates the model.
Fan blade dynamically hit away from computational methods include：
1) according to thundercloud and descending leader position, the background potential around blower fan is obtained, the electricity that space ionization is produced is calculated
Lotus number, judges corona starting, if corona is not originated, descending leader further develops downwards；
2) after corona starting, potential curve calculates corona region electric charge around blower fan, is set when corona region electric charge is more than
Streamer is converted to guide during definite value, and otherwise descending leader further develops downwards；
3) after guide's starting, it is assumed that an initial leader length, upward leader is calculated according to current potential distortion curve and developed
Journey, when the average field-strength between up-downgoing guide head is EstrWhen determine connect sudden strain of a muscle, finally try to achieve the development of upward leader and streamer
Highly.
When blower fan tower height, amplitude of lightning current fix when, blade hit away from the position on blade and the anglec of rotation
It is relevant.
Blower fan lightning-protection system efficiency is：
Wherein, EsFor blade lightning-protection system classification efficiency, amplitude of lightning current is I, IminAnd ImaxRespectively lightning current is minimum
And maximum amplitude, blade is at angle theta, and f (I) is the probability function on amplitude of lightning current, lMN(I, θ) represents the total of exposed range
With lMO(I, θ) represents overall area distance.
When stormy weather blower fan is stopped transport, it is to avoid have fan blade close to level, make blade straight up.Increase blade
During arrester, the screen effect between arrester is considered.
Compared with prior art, beneficial effects of the present invention are：
1) present invention propose fan blade dynamically hit away from concept and analysis method.Pass through the physics of thunder and lightning upward leader
Progressions model, give blade dynamically hit away from distribution characteristics, find hitting away from significantly increasing at arrester, and the analysis
Method provides thinking for the ground object lightning protection with labyrinth；
2) present invention dynamically hit based on fan blade away from concept, the model develops electric method of geometry and lightning leader
Physical process be combined, give the computational methods of blade lightning-protection system efficiency, the assessment for blade lightning-protection system provides reason
By foundation, while devising the validity that fan blade long gap breakdown test demonstrates the model；
3) using the model analysis lightning-protection system efficiency of fan blade built, it is found that amplitude of lightning current is smaller, blade
Efficiency closer to horizontal blade lightning-protection system is lower, when stormy weather blower fan is stopped transport, it is to avoid have fan blade close to water
It is flat, make a wherein blade straight up.The lightning protection efficiency of blade can effectively be improved by setting up blade arrester.
Brief description of the drawings
The Figure of description for constituting the part of the application is used for providing further understanding of the present application, and the application's shows
Meaning property embodiment and its illustrate be used for explain the application, do not constitute the improper restriction to the application.
Fig. 1 (a), Fig. 1 (b) are dynamically hit away from schematic diagram for the fan blade of the present invention；
Fig. 2 is fan blade lightning protection electric geometry method schematic diagram of the invention；
Fig. 3 is thundercloud charge distributed model schematic diagram of the invention；
Fig. 4 is leader development model schematic diagram of the invention；
Dynamically hit away from curve synoptic diagram when Fig. 5 is I=30kA of the invention；
Fig. 6 is blade lightning-protection system thunder and lightning intercepting efficiency analysis chart of the invention；
Fig. 7 is exposed range mathematics computing model schematic diagram of the invention；
Fig. 8 is different amplitude of lightning current lower blade lightning-protection system crash rate schematic diagrames of the invention；
Dynamically hit away from curve synoptic diagram when Fig. 9 is I=20kA of the invention；
Figure 10 (a), Figure 10 (b) are respectively the present invention in dash current 15kA, 7.5kA lower blade material damage figure；
Figure 11 is the different arrester quantity lower blade lightning-protection system crash rate schematic diagrames of the present invention；
Figure 12 is experimental principle figure of the invention；
Figure 13 is discharge path observed result schematic diagram of the invention；
Figure 14 is calculated value of the invention and experiment value comparison diagram.
Embodiment：
The invention will be further described with embodiment below in conjunction with the accompanying drawings.
It is noted that described further below is all exemplary, it is intended to provide further instruction to the application.Unless another
Indicate, all technologies and scientific terminology that the present invention is used have logical with the application person of an ordinary skill in the technical field
The identical meanings understood.
It should be noted that term used herein above is merely to describe embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singulative
It is also intended to include plural form, additionally, it should be understood that, when in this manual using term "comprising" and/or " bag
Include " when, it indicates existing characteristics, step, operation, device, component and/or combinations thereof.
As background technology is introduced, blower fan has badly influenced wind power plant by the high cost caused by being struck by lightning
Economic stability is run, and finds the efficiency that a reliable method assesses fan blade lightning-protection system, and the lightning protection to fan blade is set
The sustainable development of meter and promotion wind-powered electricity generation is significant.Existing experimental technique and simulation model are not all suitable for blower fan and answered
Miscellaneous structure and its revolving property, the overall lightning protection efficiency calculation method of blade are not provided yet, in order to solve as above
Technical problem, dynamically hits away from the structure side with electric geometry method present applicant proposes a kind of fan blade based on lightning physics
Electric method of geometry is combined by method, the present invention with the physical process that lightning leader develops, it is proposed that for the electricity of fan blade
Gas geometrical analysis model.By introduce fan blade dynamically hit away from concept and analysis method so that hit away from physical significance more
Plus it is clear, and further derived the computational methods of blade lightning-protection system efficiency.The actual size followed by the model analysis
The influence factor of (1.5MW) fan blade lightning-protection system efficiency, and the party is demonstrated based on fan blade long gap breakdown test
The validity of method.The fan blade electric geometry method newly proposed, can provide theory for the lightning Protection Design of fan blade with assessing
Foundation.
In a kind of typical embodiment of the application, electric geometric method can be by lightning current parameter with studied object
Geometry is connected, and draws thunder ability away from description ground object using hitting, it is believed which thing thunder and lightning descending leader first reaches
Body is hit away from just to which object discharge.Hit away from the pilot discharge passage head earthward developed for thundercloud of physical significance reach
Hit the critical striking distance of object.In hitting away from calculating for conventional electrical geometric method, mainly counted according to service data, or
Only determine to hit away from the lightning stroke process gap with reality is larger by the field strength around ground object.What is be widely used at present hits
Only it is the function of lightning current away from formula, and the rotational structure of actual fan blade is to be embedded with one or more to connect sudden strain of a muscle on blade
Device, therefore, space computing method can not embody fan blade arrester and blade (no arrester part) is hit away from not for traditional hitting
Together, can not consider in addition the blade anglec of rotation to hit away from influence, be not particularly suited for the lightning protection calculation of fan blade.
To set up the electric geometry method of fan blade, dynamically hit present invention introduces fan blade away from concept, it is " dynamic
State " mainly includes two layers of meaning：First, on fan blade diverse location (such as arrester and blade) have it is different hit away from；The
Two, the change of fan blade present position (such as angle and height), can also cause hit away from change.The dynamic of fan blade hit away from
With distribution characteristics, not only exist at arrester hit away from, also have at blade it is corresponding hit away from, simply blade is hit away from shorter,
It can regard as in the plane of blade apart from blade surface certain distance, the less non-circular arc of curvature.Fig. 1 (a), Fig. 1 (b) give not
With diverse location in angle and blade hit away from situation of change.When blade non-vertical is upward, two flank attacks are not away from being Striking symmetry
, downside hit away from (such as Fig. 1 (a) shown in) be slightly less than upside hit away from.When assuming that thunder and lightning develops straight down, lower flank attack away from
Do not interfere with and connect sudden strain of a muscle, it is contemplated that the rotational symmetry of blade, by flank attack on blade away from downside is symmetric on axis of runner blade, be easy to
The numerical computations of model.
Hit according to the dynamic of above-mentioned fan blade away from concept, the electric geometry method of fan blade lightning protection can be derived,
As illustrated in fig. 2, it is assumed that thunder and lightning descending leader develops straight down.Wherein, RpFor hitting away from R for blade arresterbFor blade blade
Place is hit away from θ is fan blade and the angle of horizontal direction, is taken counterclockwise as just.When amplitude of lightning current is I, blade
Hit away from corresponding to arcWherein arcTo expose arc,For shielding arc, A points (can be studied blade-section
Be blade a part) correspondence hit the starting point away from envelope.When thunder and lightning descending leader reaches exposure arcWhen, then it represents that leaf
Body is struck by lightning, and lightning-protection system connects mishap and lost.
With the increase of lightning current, RpAnd RbAlso increase therewith, when lightning current increases to ImWhen, hit increases to away from scopeIt can be seen that exposure arcExposure arc during relative to lightning current I It is obviously reduced, when
Amplitude of lightning current continues to increase, and exposure arc be may proceed to be decreased to disappear, and blade is shielded completely, now corresponding lightning current
Amplitude is that blade may meet the maximum lightning current I that mishap losesmax.When the amplitude of lightning current is more than ImaxWhen, the lightning-protection system of blade
Can be to the complete shielding of blade, ImaxIt is mainly relevant with the design of blade present position and blade lightning-protection system.For one
Designed fan blade lightning-protection system, the amplitude range of its lightning current that can not effectively shield is Imin<I<Imax, wherein Imin
The injury-free maximum amplitude of lightning current of material, I during to puncture blademinMainly have with blade material therefor and processing technology
Close.If the protective capacities of blade lightning-protection system design is sufficiently strong so that Imax<Imin, then the blade lightning-protection system can be to all
The lightning current of amplitude is effectively shielded.
The electric geometry method of fan blade is dynamically hit away from being wind by hitting away from thunder ability is drawn describe blade each position
A characteristic parameter in machine blade electric geometry method, is also the basis of final quantitatively characterizing fan blade lightning protection efficiency.Will
Want characterize dynamic hit away from variation characteristic, it is necessary to consider the distortion situation of blade diverse location space potential, be further incorporated into
Lightning leader development physical mechanism so that solve dynamic hit away from computational problem.
It is struck by lightning in evolution, background potential is mainly made up of thundercloud and descending leader two parts current potential.The present invention is used
Analogue charge method is asked for background potential and is distributed, and the charge distribution model of thundercloud and descending leader is as shown in Figure 3.
Nature thunder and lightning is based on negative polarity thunder and lightning, and its thundercloud typically has 2~3 charge-sites, and the superiors gather greatly
Positive charge is measured, lower floor is negative electrical charge, and bottommost has one or more weak positive charge areas sometimes.Uman and Rakov is using circle
Post electric charge heap model simulates thundercloud charge, can really reflect thundercloud charge distribution and space potential characteristic.
Amorouso and Lattarulo researchs find that when charge density is more uniform in thundercloud cylinder electric charge heap can use disk
To simplify, as shown in Figure 3.The representative value of each parameter is taken as in modulus type in model：ρp=3nC/m3, ρn=-0.9nC/m3, hp=
10km, hb=5.5km, hn=1.5km.By electric-field intensity near the ground on calculating axis about between 10~20kV/m.
Thunder and lightning descending leader uses the leader channel charge distribution model that Cooray is proposed, the model has good with measured value
Charge density is in good identical property, guide：
Wherein ρ (ζ) is descending leader channel charge density, C/m；ζ is the point of certain in leader channel away from guide's head distance, m；
IpFor amplitude of lightning current, kA；HcIt is thundercloud to ground level, Hc=hn=1500m；HiFor guide head height off the ground, m；Each coefficient
For a0=1.476 × 10-5, a=4.857 × 10-5, b=3.9097 × 10-6, c=0.522, d=3.73 × 10-3。
As negative polarity descending leader develops downwards, ground object surface field increase, due to ionization by collision and attachment work
With positive polarity space charge region is generated, initial corona is produced when positive polarity space charge is more than certain value：
α and η are respectively impact ionization coefficient and attachment coefficient, R in formula0For electrode curvature radius, R is ionization by collision area side
Boundary, x is electron avalanche head to electrode distance, NcriIt can be taken as 0.55 × 108。
After initial corona is produced, streamer area can be formed in discharging gap, the free electron that streamer area is produced is pooled to stream
The root of note, free electron collides in root with gas molecule, passes to gas molecule energy (translation energy, rotational energy, electricity
Sub- excitation energy and vibrational energy etc.), the portion of energy will be 10-5S~10-3Translation energy H is converted in st(Th), ThFor gas molecule
Translation energy temperature.If assuming gas molecule constant mass in streamer area, translation energy equation is met：
F in formulat、fr、feThe respectively conversion coefficient of translation energy, rotational energy, electronic excitation energy, ft+fr+fe=0.07, k are
Boltzmann constant, nhFor density of gas molecules, rstem, E, I be respectively streamer bottom radius, field strength and the electric current passed through, Tv
For molecular vibrational energy temperature, τvtThe time constant of translation energy, W are converted into for vibrational energyv(T) it is gas molecule vibrational energy, vibration
The equilibrium equation of energy is represented by：
ε in formulavFor nitrogen molecule vibration ground state excitation energy, about 0.28eV, fvFor the transformation ratio of vibrational energy, ft+fr+fe
+fv=1.When streamer bottom temp reaches 1500K, electrical conductivity is significantly increased, and guide initially forms.Streamer bottom temp and stream
The electron number for noting region generation is relevant, according to the kinetic energy balancing equation of above-mentioned gas molecule, when the space charge in streamer region
During more than 1 μ C, it is believed that meet the temperature conditionss that streamer is converted to guide.
After upward leader starting, it is believed that descending leader is with the stepped downward development of certain speed, corresponding upward leader
Evolution is as shown in Figure 4.The current potential on upward leader head is：
E in formula∞For quasistatic guide's field strength steady-state value, 3 × 104V/m；EstrIt is similar to steady state value for streamer area electric field,
4.5×105V/m；x0For length factor, 0.75m.
When descending leader develops into i-1 steps, when not considering streamer regional space electric charge, background potential is U1 i-1, it is considered to flow
It is U to note current potential distortion after area's space charge2 i-1.When descending leader develops into i steps, it is assumed that upward leader does not develop, background
Current potential is changed into Ui, now in view of the space charge of the i-th -1 step, current potential distortion is UT i.In pilot head portion from li-1Develop into li's
During, l is developed on streamer heads i, the current potential in streamer region is changed into U2 i.Shaded area can represent newly to produce during this in Fig. 4
Raw electric charge Δ Qi, approximately can be calculated with following formula：
K in formulaQFor envirment factor, value is 3.5 × 10-11C/(V·m).The increment of next step guide is represented by：
Q in formulaLFor meet streamer to guide convert when, the electricity required for unit length guide, for nature thunder and lightning
Value is about 65 × 10-6C/m.Then next step upward leader head position is：
li+1=li+Δli (8)
By above-mentioned guide's development mechanism, it is believed that the streamer of uplink and downlink guide is struck by lightning when meeting.Therefore, leaf during calculating
On piece the dynamic of certain point hit away from be defined as when descending leader be in the point directly over, upward leader streamer head when being struck by lightning
Relative to the height of the research point.Determine to hit away from more conforming to actual lightning stroke process using pilot model.
In calculating, the parameter of blower fan model is the high 70m of tower, the long 40m of blade, downlead radius 0.01m, tower in blade
Radius 2.5m.Fan blade dynamically hits as follows away from calculation process：
1) according to thundercloud and descending leader position, the background potential around blower fan is obtained, space ionization is calculated using formula (2)
The charge number of generation, judges corona starting, if corona is not originated, descending leader further develops downwards；
2) after corona starting, potential curve calculates corona region electric charge Δ Q around blower fan, as Δ Q>During 1 μ C streamer to
Guide converts, and otherwise descending leader further develops downwards；
3) after guide's starting, it is assumed that initial leader length 0.05m, upward leader hair is calculated according to current potential distortion curve (8)
Exhibition process, when the average field-strength between up-downgoing guide head is EstrWhen determine to connect sudden strain of a muscle, finally try to achieve upward leader and streamer
Development height.
The present invention is to reduce amount of calculation in calculating, it is believed that upward leader length>2m can form stable upward leader.Up-downgoing
The bulk velocity ratio of guide's development is 1:4~1:Change between 1, for the such overlength gap discharge of nature thunderbolt, calculate
It was found that its bulk velocity ratio is closer to 1:4.When being originated by upward leader is stable descending leader to ground level, can with reference to speed ratio
Provide dynamic hit away from approximation.By pilot model, when lightning current is 30kA, descending leader step-length is 10m, and speed ratio takes 1:4
When obtain the dynamic of fan blade and hit as shown in Figure 5 away from curve, it can be seen that when tower height, amplitude of lightning current are fixed, leaf
Piece is hit away from relevant with the position on blade and the anglec of rotation.
The dynamic of fan blade is hit away from curve as shown in figure 5, can be divided into three regions, is existed in point effect area obvious
Upwarp, this is that caused by blade tip arrester point effect, the space potential distortion around arrester is serious, it is easier in generation
Row guide, so it is hit away from significantly greater than blade.Blade region is hit away from reducing with the increase away from vane tip distance, can be near
Seemingly represent that blade is hit away from R with a straight line obliquelyb(l), l is represented away from blade tip distance, as shown in broken line in fig. 5.Dotted line
Angle with abscissa direction is θ ', is dynamically hit we term it blade away from fitting angle, is negative value.In screen effect area, due to
Blower fan tower barrel screen effect, hits and accelerates away from decrease speed, and the phenomenon is more obvious when blade angle is closer to level.IEEE according to
A large amount of hitting for field operational datas recommendation are widely used away from formula in ground object lightning protection, but it is perpendicular to provide fan blade
It is straight upwards when blade tip arrester hit away from calculating blade tip arrester using IEEE recommended formulas and hit away from for 72.9m, hit with the present invention
Blade tip arrester is obtained away from model hitting away from 67m relatively, it was demonstrated that the present invention hits the reliability away from model.
Electric geometric method have passed through since the proposition and update, and IEEE working groups are based on long-term data statistics within 1993
And research, it is proposed that the intercepting efficiency of lightning-protection system is calculated using the method for exposed range, this method also assumes that descending elder generation
Lead and develop straight down, it is consistent with the hypothesis that the present invention had previously been done.Wherein exposed range refers to expose the water between arc two-end-point
Flat distance, as shown in Figure 6.
Blower fan lightning-protection system efficiency E calculation formula is proposed in IEC 61400-24：
E=Ei×Es (9)
E in formulaiFor the intercepting efficiency of fan blade, EsFor blade lightning-protection system classification efficiency.
When amplitude of lightning current is I, when blade is at angle theta, the intercepting efficiency E of blade is obtained according to exposed range methodi：
As amplitude of lightning current Imin<I<Imax, when obtaining fan blade and horizontal direction at angle theta by formula (9), formula (10),
Blade lightning-protection system efficiency is：
F (I) is the probability function on amplitude of lightning current in formula；For having the fan blade of many arresters, lMNRepresent sudden and violent
Reveal the summation of distance.
In actual fan operation, each distance that fan blade is in continuous rotation status, formula (11) is not only I letter
Number, is also θ function.Thunderbolt is more subject at 0-180 ° in view of blower fan rotary course and blade, makes formula (11) in 0-
Geometrical mean is used as operation fan blade lightning-protection system efficiency in 180 °：
Herein it is considered that lightning-protection system aerial drainage capacity is sufficiently large, successfully blade will not then be caused as long as arrester connects to dodge
Damage, then EsValue is 1.
Exposed range lMNIt is the important parameter for obtaining fan blade lightning-protection system efficiency.Below will be sudden and violent with two arrester blades
Exemplified by dew distance is calculated, illustrate fan blade exposed range computational methods.Because the rotation of blade has rotational symmetry, calculate
Middle θ values are 0-90 °.
Blade hit when there is side arrester away from envelope scope it is as shown in Figure 7.l1、l2Two arresters are represented respectively and connect sudden strain of a muscle
Device is to the distance between studied blade starting point；Shield arcRespectively using blade tip arrester and blade arrester as circle
The heart, two arresters are hit away from Rp1、Rp2For the circular arc of radius；Exposure arcTo vertical range the hitting for blade of blade
Away from Rb(l), exposed range is A1、B1And C1、D1The sum of horizontal range.Studied blade starting point O blade is hit away from for Rb(l1+
l2), make A1Point coordinates is (x1,y1), then have：
Blade the same side exposure arc is (such as) can be approximately considered on same straight line, A1、B1、C1、D1Place
Straight line be：
θ ' is that blade is dynamically hit away from fitting angle (being provided in Fig. 5) in formula.O1、O2Coordinate be：
Then O1、O2Place circle equation be：
Simultaneous formula (14), formula (16) can be in the hope of coordinate B1(x2,y2)、C1(x3,y3)、D1(x4,y4) numerical value, according to leaf
Piece is dynamically hit away from making electric geometry method figure, it may be determined that various point locations.For there is a situation where that two ends expose arc shown in Fig. 7,
Need to give up one group of maximum solution of x values and have x2<x3<x4.Then exposed range lMNFor：
lMN=x4-x3+x2-x1 (17)
The corresponding overall area l of studied blade-sectionMOFor：
Formula (17), formula (18) are substituted into the operation lightning protection that formula (12) (or formula (11)) can obtain studied fan blade part
System effectiveness E (or fixed angle lightning-protection system efficiency Eθ)。
It is described before fan parameter, according to fan blade electric geometry method, obtain 30kA lightning currents, only blade tip arrester
Blade, the lightning-protection system efficiency E under 0 °, 30 °, 60 °, 90 ° of Typical anglesθ.Lost to more intuitively provide blade lightning protection
The situation of effect, the present invention depicts the lightning-protection system failure rate characteristic (1-E in 0-180 ° according to blade rotational symmetryθ),
As shown in Figure 8.Polar angle represents blade anglec of rotation θ in figure, and radius represents blade lightning-protection system crash rate 1-Eθ。
In amplitude of lightning current 30kA, the blade anglec of rotation is closer to horizontal line, and lightning-protection system crash rate is bigger.Work as angle
For 0 ° when, crash rate is 40% or so, when blade angle is gone to during 30 °, and crash rate declines rapidly close to 0.This be by
Bigger in blade angle, more obvious, the easier starting upward leader of space potential distortion at blade tip arrester tip causes and connects sudden strain of a muscle
Hitting away from increase for device, exposes arc length degree and reduces rapidly, blade is in the protective range of blade tip arrester.
Pass through the research to blower fan angle, it is proposed that when stormy weather blower fan is stopped transport, it is to avoid have fan blade close to water
It is flat, a blade can be made straight up, blade lightning-protection system efficiency can be effectively improved.
Change amplitude of lightning current (30kA, 20kA, 10kA), and ensure that other specification is constant, research amplitude of lightning current is to leaf
The influence of piece lightning protection efficiency, different amplitude of lightning current lower blade lightning-protection system crash rates are as shown in Figure 8.As lightning current 20kA, θ=
At 30 °, crash rate is reduced to as 0 when crash rate is 17%, θ=60 °；As lightning current 10kA, during θ=30 °, crash rate is
Its crash rate is 15% when 53%, θ=60 °.It was found that with the reduction of amplitude of lightning current, the lightning protection efficiency of blade declines substantially,
And the angle that blade is protected completely also reduces therewith.Therefore lightning current is smaller, blade is more subject to thunderbolt.
This is due to that the change of lightning current causes the hitting away from changing of blade, and have impact on the lightning protection efficiency of blade.Thunder and lightning
Dynamically hit away from curve during stream 20kA as shown in figure 9, comparison diagram 5 is found, hitting at vane tip and blade significantly subtracts away from having
It is small, and arrester point effect decrease so that shielding arc scope diminishes, and causes blade to connect the unsuccessful probability increase of sudden strain of a muscle.
For blade porous interlayer material, it can just cause irreversible ablation to damage under 10kA electric currents, leave safety
Hidden danger.As shown in Figure 10, it is degree of impairment of the fan blade sandwich material (PET, 10cm × 10cm) under dash current, in electricity
Material ablation is serious when flowing 15kA, and only in electric arc, a pocket has carbonization phenomenon around during 7.5kA, therefore advises Imin
Value is less than 10kA.
Influence for research blade arrester to blade protection, is adding a blade arrester at vane tip 7m,
The 30kA lightning currents blade lightning-protection system crash rates is obtained as shown in Figure 11 curves.An arrester situation is contrasted, when blade level
When, lightning-protection system intercepts crash rate and is down to 25% by 41%, and the blade arrester of addition can effectively increase the scope of shielding arc,
So as to improve blade lightning-protection system efficiency.
Due to there is screen effect between arrester, when two arresters are closer to the distance, blade tip arrester is more original to be hit
Away from that can decline, when calculating discovery blade arrester away from blade tip arrester 1m or so, blade tip arrester is hit away from decline about 2m.
So when arranging arrester position, it is necessary to the discharge of arrester be determined according to blade electric geometry method, to reach blade
The requirement of lightning protection efficiency, it is impossible to simply increase arrester quantity, otherwise it is possible that increase arrester quantity is instead resulted in
The phenomenon that blade lightning protection efficiency declines.
The scope of arc and shielding arc is clearly exposed, is the basis that the electric geometric method of blade is calculated.For the effective of checking model
Property, the actual process for being struck by lightning fan blade is simplified, entity fan blade has been carried out in DianKeYuan Shahe, North China experiment station
Large air gap discharge experiment, find exposure arc and shielding arc boundary position.Experimental principle figure as shown in figure 12, adopt by fan blade
With first five rice (only blade tip arrester) of sinoma45.2B-1.5MW blades, the angle theta with ground is about 30 °, using bar-shaped
Top electrode simulates thunder and lightning descending leader, is along the direction of arrow in the figure that step-length is moved since blade tip surface with 0.75 meter,
Find 50% and connect sudden strain of a muscle rate Top electrode position, this position is regarded as exposing arc and shielding arc boundary.Surge voltage uses 250/
2500 μ s negative polarity operate ripple.Digital camera records discharge path using long Exposure mode, to judge that blade lightning-protection system connects sudden strain of a muscle
Success and failure, successfully launch a surprise attack middle arrester, such as figure wherein connecing and dodging including hitting blade tip arrester tip, arrester side and cunning
Shown in 13 (a), (b), (c)；Connect mishap to lose to hit blade, not by arrester aerial drainage, shown in such as Figure 13 (d).
Carry out 20 discharge tests in each Top electrode position, statistical experiment data and to draw its matched curve such as Figure 14 green
Shown in color curve, if taking the intersection at probability 50% for shielding arc and exposure arc, its value is about 2.3m.Using present invention introduction
Fan blade electric geometry method, obtain the boundary of exposure arc and shielding arc in the case of this kind 1.8125m at, both mistakes
Difference is 0.4875m, relative to the relative error δ of experiment value：
δ=| lc-le|/le× 100%=21%
Wherein lc、leRespectively calculated value and experimental fit value.
(0~1.8m) and experimental fit curve worst error are about 19% in the range of the shielding arc calculated, but flat
Equal error only has 3% or so.In the range of exposure arc (>1.8m), model will connect sudden strain of a muscle success rate less than certain value as completely not
Can protective treatment, it is ensured that the protected field degree of blade electric geometry method, but have in transitional region certain error.
See on the whole, calculated curve is approached with experimental fit curve shape, with certain protected field degree, only in mistake
Cross region and there is certain error.Experiment demonstrates the validity of fan blade electric geometry method of the present invention.
It should be noted that, there are difference, experiment and actual conditions unavoidably in the thunderbolt environment of experiment condition and true blower fan
Equivalence stills need checking, but designed experiment demonstrates the reliability of the inventive method to a certain extent.
The preferred embodiment of the application is the foregoing is only, the application is not limited to, for the skill of this area
For art personnel, the application can have various modifications and variations.It is all within spirit herein and principle, made any repair
Change, equivalent substitution, improvement etc., should be included within the protection domain of the application.
Although above-mentioned the embodiment of the present invention is described with reference to accompanying drawing, not to present invention protection model
The limitation enclosed, one of ordinary skill in the art should be understood that on the basis of technical scheme those skilled in the art are not
Need to pay various modifications or deform still within protection scope of the present invention that creative work can make.
Claims (10)
1. a kind of fan blade based on lightning physics is dynamically hit away from the construction method with electric geometry method, it is characterized in that：With
Based on the physical model of lightning leader development, and with negative polarity thunderbolt description lightning stroke process, negative polarity thunderbolt is divided into three
Stage, descending leader develops downwards, upward leader starting, up-downgoing guide's connection procedure, it is assumed that thunder and lightning descending leader it is vertical to
Lower development, is struck by lightning when the streamer of uplink and downlink guide meets, and the height on upward leader streamer head when being struck by lightning is determined
For hit away from, calculate accordingly fan blade dynamically hit away from, with embody diverse location on fan blade have it is different hit away from, and
The change of fan blade present position and changing is hit away from assuming that lightning current numerical value downwards on the premise of development, is hit according to dynamic
Away from electric geometry method of the foundation for fan blade.
2. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：According in fan blade electric geometry method exposure arc, shielding arc and the fan blade anglec of rotation it is several
What relation, calculates fan blade electric geometry method exposed range, and then obtain fan blade lightning-protection system efficiency.
3. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：Hitting including blade arrester is in away from, blade and blade on the electric geometry method of fan blade lightning protection
Hit away from, exposure arc and shielding arc, it is determined that during studied blade-section lightning protection efficiency, blade clear and definite first hit away from it is corresponding cruelly
Reveal the starting point of arc and shielding arc envelope.
4. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：When amplitude of lightning current increase, exposure arc be may proceed to be decreased to disappear, and blade is shielded completely, now institute
Corresponding amplitude of lightning current is that blade may connect the maximum lightning current that mishap loses.
5. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：Thunder and lightning descending leader uses leader channel charge distribution model.
6. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：Utilize fan blade electric geometry method, analysis angle of fan leaves, amplitude of lightning current and arrester cloth
The influence to lightning-protection system efficiency is put, the validity that breakdown test under fan blade long gap demonstrates the model is finally based on.
7. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：Fan blade dynamically hit away from computational methods include：
1) according to thundercloud and descending leader position, the background potential around blower fan is obtained, the charge number that space ionization is produced is calculated,
Judge corona starting, if corona is not originated, descending leader further develops downwards；
2) after corona starting, potential curve calculates corona region electric charge around blower fan, when corona region electric charge is more than setting value
When streamer converted to guide, otherwise descending leader further develops downwards；
3) after guide's starting, it is assumed that an initial leader length, upward leader evolution is calculated according to current potential distortion curve, when
Average field-strength between up-downgoing guide head is EstrWhen determine to connect sudden strains of a muscle, finally try to achieve the development of upward leader and streamer highly.
8. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：When blower fan tower height, amplitude of lightning current fix when, blade hit away from the position on blade and rotation
Gyration is relevant.
9. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Method, it is characterized in that：Blower fan lightning-protection system efficiency is：
<mrow>
<mi>E</mi>
<mo>=</mo>
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<mn>1</mn>
<mi>&pi;</mi>
</mfrac>
<msubsup>
<mo>&Integral;</mo>
<mn>0</mn>
<mi>&pi;</mi>
</msubsup>
<msubsup>
<mo>&Integral;</mo>
<msub>
<mi>I</mi>
<mi>min</mi>
</msub>
<msub>
<mi>I</mi>
<mi>max</mi>
</msub>
</msubsup>
<mfrac>
<mrow>
<msub>
<mi>l</mi>
<mrow>
<mi>M</mi>
<mi>O</mi>
</mrow>
</msub>
<mrow>
<mo>(</mo>
<mi>I</mi>
<mo>,</mo>
<mi>&theta;</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msub>
<mi>l</mi>
<mrow>
<mi>M</mi>
<mi>N</mi>
</mrow>
</msub>
<mrow>
<mo>(</mo>
<mi>I</mi>
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<mi>&theta;</mi>
<mo>)</mo>
</mrow>
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<mo>)</mo>
</mrow>
<mi>d</mi>
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<mi>&theta;</mi>
</mrow>
Wherein, EsFor blade lightning-protection system classification efficiency, amplitude of lightning current is I, IminAnd ImaxRespectively lightning current minimum and maximum
Amplitude, blade is at angle theta, and f (I) is the probability function on amplitude of lightning current, lMN(I, θ) represents the summation of exposed range, lMO
(I, θ) represents overall area distance.
10. a kind of fan blade based on lightning physics as claimed in claim 1 is dynamically hit away from the structure with electric geometry method
Construction method, it is characterized in that：When stormy weather blower fan is stopped transport, it is to avoid have fan blade close to level, make blade straight up；
When increasing blade arrester, the screen effect between arrester is considered.
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| CN107729680A (en) * | 2017-11-03 | 2018-02-23 | 华北电力大学 | Fan blade lightning strike probability appraisal procedure |
| CN109541409A (en) * | 2018-11-30 | 2019-03-29 | 国家电网有限公司 | Distribution line flashover strike innovatory algorithm based on electric geometry method |
| CN107179462B (en) * | 2017-06-27 | 2019-06-14 | 山东大学 | Fan blade dynamic based on lightning physics is hit away from the construction method with electric geometry method |
| CN110197048A (en) * | 2019-06-18 | 2019-09-03 | 国网山西省电力公司大同供电公司 | A kind of distribution line lightning protection measures configuration method based on electric field and damage to crops caused by thunder analysis |
| CN112796958A (en) * | 2020-12-30 | 2021-05-14 | 中国电力科学研究院有限公司 | Method for improving optimal design of lightning protection system of wind turbine generator |
| CN117390368A (en) * | 2023-12-07 | 2024-01-12 | 云南电投绿能科技有限公司 | Lightning probability calculation method, device and equipment for wind turbine and storage medium |
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| CN117390368A (en) * | 2023-12-07 | 2024-01-12 | 云南电投绿能科技有限公司 | Lightning probability calculation method, device and equipment for wind turbine and storage medium |
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