CN104361216B - A kind of insulator contamination method for early warning based on change power analytic hierarchy process (AHP) - Google Patents

Abstract

The invention discloses a kind of based on the insulator contamination method for early warning for becoming power analytic hierarchy process (AHP), comprise the following steps：（1）, quantitatively evaluating is carried out to the intrinsic factor of insulator, the intrinsic factor of described insulator includes retting-flax wastewater, insulator hydrophobicity, the Ageing of Insulators degree；（2）, using become power analytic hierarchy process (AHP) be calculated the intrinsic factor index of insulatorm；Pollution severity of insulators level index is calculated according to atmospheric environmental parameters and meteorological conditionP _f ；（3）According to the intrinsic factor index of insulatormWith pollution severity of insulators level indexP _f Product judge insulator contamination comprehensive pre-warning indexR, determine advanced warning grade.This method can provide the comprehensive pre-warning index of region insulator and issue advanced warning grade, realize the insulator pollution flashover early warning of science, so as to effectively improve power supply reliability, reduce the economic loss of power network, improve the reliability service ability of power network.

Description

A kind of insulator contamination method for early warning based on change power analytic hierarchy process (AHP)

Technical field

It is based on the present invention relates to the insulator contamination early warning field prevented and reduced natural disasters in a kind of power system, more particularly to one kind Become the insulator contamination method for early warning of power analytic hierarchy process (AHP).

Background technology

At present, in power system, insulator is the important portion for being mechanically connected with each other the different electric conductor of current potential Part, the good and bad safe operation to whole transmission system of its performance plays very crucial effect.Especially run out of doors Insulator, in addition to the mechanical performance that should have certain electrical insulation properties and some strength, should also possess tolerance nature The invasion and attack of environment and pollution etc. are ensureing the condition of safe power supply.With the fast development of national economy, various types of pollutions Thing is more and more, and the bad weather such as haze, sandstorm is also increasingly severe, has when power circuit and equipment large area pollution flashover accident Occur, caused harm is also increasing.According to statistics, with the exacerbation that transmission line of electricity pollutes, insulation pollution flashover accident is only second to Thunderbolt, accounts for the 2nd of power grid accident sum, and loss is 10 times of lightning strike accident, therefore research and strick precaution pollution flashover Just into a current key subjects.

Deposited on each insulator surface due to being uneven along the Electric Field Distribution of insulator chain, therefore in insulator chain The degree of dust is also different, and continuous contamination can make the close continuous increase of the equivalent attached salt of equipment, once experience a thick fog or drouth after During the weathers such as drizzle, when pollution layer is sufficiently humidified so as to and progressively extension forms the conductive layer of insulator surface, will produce and let out Leakage current, causes external insulation to change along surface-potential gradient, forms local brush electric discharge；And the electric-field intensity between electric arc is with electric arc electricity Stream increases and weakens, and Shi Shiwu areas field intensity is raised, and produces intermittence electric discharge, and repeats to develop.When field intensity change exceedes critical value When, there is flashover over the ground through whole insulator chain surface in electric arc.

Current existing insulator on-line monitoring early warning system, although can gather the state parameter of insulator, such as leaks Electric current, working voltage grade and insulator model etc., but the analysis prediction treatment of system background is substantially delayed, is only input into Each value of consult volume, it is impossible to administrative staff is judged analysis to filthy state, therefore effective pollution flashover prevention cannot be implemented. And power system possesses countless multiple insulators, detection means is installed on a large scale unrealistic.

Because insulator pollution flashover occurs to need two conditions filthy and moistening, thus how to consider insulator contamination and The influence of weather conditions combines with insulator contamination, just into this area technical issues that need to address.

The content of the invention

It is an object of the invention to provide a kind of based on the insulator contamination method for early warning for becoming power analytic hierarchy process (AHP), can be directed to Deficiencies of the prior art, this method can effectively improve power supply reliability, reduce the economic loss of power network, improve electricity The reliability service ability of net.

The present invention uses following technical proposals：A kind of insulator contamination method for early warning based on change power analytic hierarchy process (AHP), bag Include following steps：

(1), the intrinsic factor to insulator carries out quantitatively evaluating, and the intrinsic factor of described insulator is included climbs electric ratio Away from, insulator hydrophobicity, the Ageing of Insulators degree, calculate insulator retting-flax wastewater index k₁, insulator hydrophobicity index k₂, absolutely Edge Ageing Index k₃, obtain the intrinsic factor index vector K=(k of insulator₁, k₂, k₃)：

Wherein insulator retting-flax wastewater index k₁Computational methods are：

In formula, λ is insulator retting-flax wastewater, λ_maxIt is insulator maximum retting-flax wastewater, λ_minFor insulator minimum climbs electric ratio Away from；

Wherein insulator hydrophobicity index k₂It is to be determined by way of scoring, and grading system D is taken at normalization Reason, the insulator hydrophobicity index k after normalized₂For：

In formula, D is insulator hydrophobicity grading system；Wherein the Ageing of Insulators index k₃It is to be described using Weibull distribution , the failure density function of Weibull distribution is defined as：

In formula, t is insulator run time, and β is form parameter, and α is scale parameter, and γ is location parameter；

The Ageing of Insulators index k₃Directly represented with the accumulative failure function of insulator, i.e.,：

In formula, t is insulator run time, and β is form parameter, and α is scale parameter；

(2) the intrinsic factor index m of insulator, is calculated using change power analytic hierarchy process (AHP)；Specifically include following steps：

2.1), according to power analytic hierarchy process (AHP) comparing two-by-two to the intrinsic factor relative importance of insulator is become, insulated Shown in sub intrinsic factor index comparator matrix A such as formulas (5), the element value of comparator matrix A is：

Element a on diagonal_ii=1；The i-th row j column elements a on off-diagonal_ijRepresent i factors to the important of j factors Degree, it is of equal importance to take 1, it is somewhat important to take 3, it is relatively important by force to take 5, it is strongly important to take 7, extremely important 9, in two adjacent judgements Between value desirable 2,4,6,8, now, a_ji=1/a_ij；

2.2) initial weight vector, is calculated by specification column average methodI.e.：

Obtain initial weight：

2.3) it is, vectorial using power analytic approach calculating variable weight is becomeThe intrinsic factor index of insulator Any one Zhi Guo big city makes insulator be in danger level, i.e. their weight should increase and increase with desired value, therefore Stimulable type should be selected to become power, become weight coefficient a ＞ 1, its become power formula into：

2.4) the intrinsic factor index m of insulator, is calculated：

In formula, m is the intrinsic factor index of insulator；k₁It is insulator retting-flax wastewater index；k₂For insulator hydrophobicity refers to Mark；k₃It is the Ageing of Insulators index；

(3), the SO provided according to environmental administration₂、NO₂, PM10 concentration measurement datas and weather bureau issue weather forecast letter Breath, calculates pollution severity of insulators level index P_f, specifically include following steps：

3.1) air quality index P and insulator equivalent salt density value ρ, is calculated：

The SO that environmental administration is provided₂、NO₂, PM10 concentration measurement datas substitute into formula (10) calculate air quality index P, so The P values obtained by calculating are substituted into equivalent salt density value afterwards and calculates insulator equivalent salt density value ρ with air quality index empirical formula (11)：

ρ=- 0.015+0.0806P (11)

In formula：U is the monthly measured concentration of pollutant, mg/m³；B is pollutant evaluation criterion value, mg/m³；SO₂、NO₂、 The evaluation criterion value of PM10 takes 0.06mg/m respectively³, 0.05mg/m³, 0.1mg/m³；

U in formula_PM10/B_PM10Independent entry can be converted, and chosen area influences most prominent factor；

The development trend of insulator contamination is predicted using air quality index P, insulator surface equivalent salt density value is controlled, closed Reason arranges to clean plan；When the equivalent salt density value of insulator has larger nargin with permissible value, cleaning period can be extended；When clear Sweep after the completion of work, system insulation sublist face equivalent salt density value resets, if the time of clearing was at of that month t days, the end of month after resetting Equivalent salt density value be

In formula, ρ_mIt is the moon accumulation equivalent salt density value calculated by air quality index；

3.2) pollution severity of insulators level index P, is determined_f：

Pollution severity of insulators level index P_fThe probability that flashover occurs using insulator under certain equivalent salt density value ρ is P_f Represent, then single insulator string is in working voltage U_cUnder, P_fRelation with equivalent salt density value ρ is represented by：

In formula：N is cut-out parameter；C is the standard variance of insulator and the ratio of its 50% withstanding voltage；A be with absolutely The edge shape coefficient relevant with pollution degree；L is insulator length, m；σ is that the feature of equivalent salt density value influence pollution flashover voltage refers to Number；ε and h is intermediate computations amount；

(4), according to insulator intrinsic factor index m and pollution severity of insulators level index P_fProduct judge insulator Pollution flashover comprehensive pre-warning index R, determines advanced warning grade：Specifically include following steps：

4.1) insulator contamination comprehensive pre-warning index R, is calculated：

R=m × P_f (16)

In formula：R is insulator contamination comprehensive pre-warning index；M is the intrinsic factor index of insulator；P_fFor insulator surface is dirty Dirty level index；

4.2) advanced warning grade, is determined：

Advanced warning grade is determined according to insulator contamination comprehensive pre-warning index R, advanced warning grade is divided into yellow, orange, red three Individual grade, it is specific as shown in table 1：

The advanced warning grade table of table 1

To dangerous insulator, according to the size of its advanced warning grade, corresponding early warning information is issued：In early warning information Appearance includes：Early warning information numbering, early warning issuing time, advanced warning grade, line name, shaft tower ID.

The invention provides it is a kind of with atmosphere pollution be input based on become power analytic hierarchy process (AHP) insulator contamination it is pre- Alarm method, will influence the factor of insulator pollution flashover to carry out internal and external reasonses classification treatment, be referred to by calculating insulator retting-flax wastewater Mark, insulator hydrophobicity index, the Ageing of Insulators index obtain the intrinsic factor index of insulator, COMPREHENSIVE CALCULATING insulator it is intrinsic because Plain index and pollution severity of insulators degree (running environment) index, the comprehensive pre-warning index for providing region insulator are concurrent Cloth advanced warning grade, realizes the insulator pollution flashover early warning of science.

The present invention has the following advantages that compared to existing technology：

1) present invention has considered the intrinsic factor of insulator and pollution severity of insulators of influence insulator pollution flashover Degree, more meets reality；

2) significance level that the present invention is considered between factor can change with the difference of each factor state value, use Become power analytic hierarchy process (AHP) calculate the intrinsic factor index of insulator, reduce subjective uncertainty, improve result accuracy and Confidence level；

3) present invention calculates pollution severity of insulators equivalent salt density value using air quality index method, with being easy to from environmental protection The advantages of department obtains data, need not install online monitoring device, can effectively instruct power grid operation personnel's reasonable arrangement to insulate Sub- cleaning works；

4) it is power network and electricity present invention is generally applicable to transmission line of electricity, power plant, Substation Insulator pollution flashover early warning Factory staff Flash Decontamination Measurements provide the aid decision reference of science, reduce insulator pollution flashover fault rate, ensure transmission of electricity The safety and stability of passage is powered.

Brief description of the drawings

Fig. 1 is flow chart of the method for the present invention.

Specific embodiment

Meteorological condition is the most important extraneous factor for influenceing insulator pollution flashover, even if pollution severity of insulators is quite tight Weight, insulator pollution flashover probabilistic machine can be zero under dry weather.But, it is contaminated exhausted when wet weather comes interim The oneself factors such as edge, its retting-flax wastewater, hydrophobicity, degree of aging also can to a certain degree influence insulator pollution flashover.Therefore, The present invention is to provide it is a kind of with atmosphere pollution be input based on become power analytic hierarchy process (AHP) insulator contamination method for early warning. The related data that this method is tested according to transmission line foundation data and insulator contamination, it is considered to the intrinsic factor of insulator and operation Environmental factor, establishes insulator contamination Comprehensive State Evaluation index system, calculates intrinsic factor index value and insulator surface Pollution level desired value, obtains insulator contamination comprehensive evaluation index value.Under the weather such as mist, dew, drizzle in forecast, quantify The safety problem of electric transmission line isolator pollution flashover, provides the comprehensive pre-warning index of region insulator and issues early warning etc. Level, realizes the insulator pollution flashover early warning of science；For power grid operation personnel provide decision-making foundation, raising system resist it is severe from The ability of right disaster.

As shown in figure 1, carrying out detailed specific descriptions to the present invention below：

By taking certain common disc insulator of 220kV circuits as an example, the air SO of environmental administration's issue₂、NO₂, PM10 concentration difference It is 0.0285mg/m³、0.0512mg/m³、0.0832mg/m³, retting-flax wastewater is 45mm/kV, and insulator hydrophobicity marking is 4 points, Run 5 years.

Of the present invention a kind of based on the insulator contamination method for early warning for becoming power analytic hierarchy process (AHP), specific report includes following Step：

(1), the intrinsic factor to insulator carries out quantitatively evaluating, and the intrinsic factor of described insulator is included climbs electric ratio Away from, insulator hydrophobicity, the Ageing of Insulators degree；Calculate insulator retting-flax wastewater index k₁, insulator hydrophobicity index k₂、 The Ageing of Insulators index k₃, obtain the intrinsic factor index vector K=(k of insulator₁, k₂, k₃)：

11), insulator retting-flax wastewater index k₁

Circuit and the corresponding equivalent salt density value of power plant, transformer station's gradation for surface pollution are as shown in table 2.

The corresponding salt density value of the circuit of table 2 and power plant, transformer station's gradation for surface pollution

State Grid Corporation of China's issue《Power system is dirty to distinguish level and external insulation selection standard》Give unification and climb electric ratio Away from the correlation with site pollution degree, the retting-flax wastewater of common disc insulator (with reference to insulator) is selected, then according to not Effective specific creepage distance conversion relation between similar shape size insulator and common disc insulator determines climbing for insulator used Electric ratio is away from conversion relation can determine according to the longtime running experience of each department.The retting-flax wastewater of each gradation for surface pollution insulator is such as Shown in table 3.

The retting-flax wastewater of each gradation for surface pollution insulator of table 3

So, insulator retting-flax wastewater index k₁Computational methods are：

In formula, λ is insulator retting-flax wastewater, λ_maxIt is insulator maximum retting-flax wastewater, λ_minFor insulator minimum climbs electric ratio Away from；

Air quality index is calculated by formula (10)

The salt density value of pollution severity of insulators concentration is calculated by formula (11)

ρ=- 0.015+0.0806P=0.1785mg/cm²；

As shown in Table 1, salt density value ρ=0.1785mg/cm²Corresponding gradation for surface pollution is III grade；

The insulator retting-flax wastewater index for then being calculated according to table 2 and formula (1)：

12), insulator hydrophobicity index k₂, insulator hydrophobicity index k₂It is to be determined by way of scoring, and to scoring Grade D is normalized, the insulator hydrophobicity index k after normalized₂For

In formula, D is insulator hydrophobicity grading system.

Main condensation, the collision of hydrone and surface, the moisture absorption of pollution layer, the moisture by mist of moistening of insulator surface pollution layer Son is caused in the diffusion of pollution layer.The good holding of insulator surface hydrophobicity, can improve insulator anti-pollution characteristic.Insulator Hydrophobicity index k₂Standards of grading are as shown in table 4.

The insulator hydrophobicity index k of table 4₂Standards of grading

When hydrophobicity is tested, there is the separate globule and water band in insulator surface to common disc insulator, completely simultaneously The water band area of moistening is less than 2cm², less than the 90% of tested region area, insulator hydrophobicity scoring is 4 points to the gross area, by Formula (2) calculates insulator hydrophobicity index：

13), the Ageing of Insulators index k₃

With operation the time limit increase, due to being influenceed by electric field, mechanical stress, atmospheric environment, heat radiation etc. for a long time, absolutely Edge is gradually aging, in fact it could happen that the phenomenon such as hydrophobicity reduction, cracking, breakage, ablated surface, it is impossible to meets project of transmitting and converting electricity and prevents Pollution flashover requirement, it is therefore desirable to consider the Ageing of Insulators problem.The Ageing of Insulators degree, Weibull point are described using Weibull distribution The failure density function of cloth is defined as：

In formula, t is insulator run time, and β is form parameter, and α is scale parameter, and γ is location parameter；

The Ageing of Insulators index k₃Directly represented with the accumulative failure function of insulator, i.e.,：

In formula, t is insulator run time, and β is form parameter, and α is scale parameter, and γ is location parameter.

The step of estimating Weibull distribution parameters using correlation coefficient process is as follows：

Equivalence transformation first is carried out to formula (4), logarithm twice is then taken, following formula is obtained

OrderX=ln (t- γ), A=β, B=-ln α then has：

Y=AX+B (32)

From formula (32), when location parameter γ estimates correct, X is linear with Y, i.e. have maximum between X and Y Coefficient correlation；Relation between the estimate and coefficient R of γ is：When coefficient R takes maximum, location parameter γ is Best estimate.

Coefficient R is asked to take maximum, the first derivative values for as solving coefficient correlation are equal to 0, and the formula of coefficient correlation is

In formula, X_i=ln (t_i- γ),I=1,2 ..., n

Line translation is entered to formula (33), is made：

It is more than 0 because the coefficient R of Weibull distribution is permanent, so it is one that first derivative result is taken to R to the quadratic sum of R Sample, therefore first derivative is taken to formula (34) and abbreviation is obtained：

Can be in the hope of out position parameter γ, according to formula (32) by linear after location parameter γ is obtained according to formula (35) Regression analysis can be in the hope of form parameter β and scale parameter α.

Formula (35) is transcendental equation, using dichotomy on computers by being programmed into row numerical computations, can be obtained in place Put parameter γ.Wherein use approximate Median rank formula

In formula：N represents maintenance frequency；I represents that i ＆ lt is repaired.

After obtaining location parameter γ, by t_iThree-parameter Weibull distribution is become two parameters by=t-m, then by returning Analysis least square method can obtain form parameter β and scale parameter α.

Assuming that according to existing fault data, being asked for by the above method, it is 17280, form parameter β to obtain location parameter γ It is 1.718, scale parameter α is 49266^1.718.So, the Ageing of Insulators fault rate represents the Ageing of Insulators index k₃For：

(2) the intrinsic factor index m of insulator, is calculated using change power analytic hierarchy process (AHP)；

2.1), according to power analytic hierarchy process (AHP) comparing two-by-two to the intrinsic factor relative importance of insulator is become, insulated Shown in sub intrinsic factor index comparator matrix A such as formulas (5), the element value of comparator matrix A is：

Element a on diagonal_ii=1；The i-th row j column elements a on off-diagonal_ijRepresent i factors to the important of j factors Degree, it is of equal importance to take 1, it is somewhat important to take 3, it is relatively important by force to take 5, it is strongly important to take 7, extremely important 9, in two adjacent judgements Between value desirable 2,4,6,8, now, a_ji=1/a_ij；

I.e.

2.2) initial weight vector, is calculated by specification column average methodI.e.：

Obtain initial weight：

I.e.：

2.3) it is, vectorial using power analytic approach calculating variable weight is becomeThe intrinsic factor index of insulator is appointed What Ge Zhiguo big city makes insulator be in danger level, i.e. their weight should increase and increase with desired value, therefore should The selection stimulable type becomes power, becomes weight coefficient a ＞ 1, its become power formula into：

I.e.：

2.4) the intrinsic factor index m of insulator, is calculated：

I.e.：

(3), the SO provided according to environmental administration₂、NO₂, PM10 concentration measurement datas and weather bureau issue weather forecast letter Breath, calculates pollution severity of insulators level index P_f, specifically include following steps：

3.1) air quality index P and insulator equivalent salt density value ρ, is calculated：

The SO that environmental administration is provided₂、NO₂, PM10 concentration measurement datas substitute into formula (10) calculate air quality index P, so The P values obtained by calculating are substituted into equivalent salt density value afterwards and calculates insulator equivalent salt density value ρ with air quality index empirical formula (11)：

ρ=- 0.015+0.0806P (11)

In formula：U is the monthly measured concentration of pollutant, mg/m³；B is pollutant evaluation criterion value, mg/m³；SO₂、NO₂、 The evaluation criterion value of PM10 takes 0.06mg/m respectively³, 0.05mg/m³, 0.1mg/m³；

U in formula_PM10/B_PM10Independent entry can be converted, and chosen area influences most prominent factor；

I.e.：

ρ=- 0.015+0.0806 × 2.4008=0.1785.

When the equivalent salt density value of insulator has larger nargin with permissible value, cleaning period can be extended；Using big makings Volume index P predicts the development trend of insulator contamination, controls insulator surface equivalent salt density value, and reasonable arrangement cleans plan；Table 5 Retting-flax wastewater, the permission close table of comparisons of salt tried for certain electric company.

The insulator retting-flax wastewater of table 5, the permission close table of comparisons of salt

After the completion of cleaning works, system insulation sublist face equivalent salt density value resets, if the time of clearing was at of that month t days, The equivalent salt density value at the end of month is after then resetting

In formula, in formula, ρ_mIt is the moon accumulation equivalent salt density value calculated by air quality index.

3.2) pollution severity of insulators level index P, is determined_f：

Pollution severity of insulators level index P_fThe probability that flashover occurs using insulator under equivalent salt density value ρ is P_fTable Show, then single insulator string is in working voltage U_cUnder, P_fRelation with equivalent salt density value ρ is represented by：

In formula：N is cut-out parameter；C is the standard variance of insulator and the ratio of its 50% withstanding voltage；A be with absolutely The edge shape coefficient relevant with pollution degree；L is insulator length, m；ε is that the feature of equivalent salt density value influence pollution flashover voltage refers to Number；σ and h is intermediate computations amount.

Insulator is 0.1785mg/cm in equivalent salt density value²The lower probability P that flashover occurs_fIt is calculated as follows：

Cut-out parameter n takes 2.1, and the standard variance of insulator takes 0.088 with the ratio c of its 50% withstanding voltage, and exhausted The edge shape coefficient A relevant with pollution degree takes 64.4, and insulator length L takes 2.17m, the equivalent attached close influence pollution flashover voltage of salt figure Characteristic index σ take 0.25, intermediate computations amount ε and h are 0.2692,2.1342.

(4), according to insulator intrinsic factor index m and pollution severity of insulators level index P_fProduct judge insulator Pollution flashover comprehensive pre-warning index R, determines advanced warning grade.

4.1) insulator contamination comprehensive pre-warning index R, is calculated：

R=m × P_f (16)

In formula：R is insulator contamination comprehensive pre-warning index；M is the intrinsic factor index of insulator；P_fFor insulator surface is dirty Dirty level index；

I.e.：R=0.4419 × 0.59=0.2607.

4.2) advanced warning grade, is determined：

Advanced warning grade is determined according to insulator contamination comprehensive pre-warning index R, advanced warning grade is divided into yellow, orange, red three Individual grade, R=0.2607 belongs to orange early warning, specific as shown in table 1：

The advanced warning grade table of table 1

To dangerous insulator, according to the size of its advanced warning grade, corresponding early warning information is issued：In early warning information Appearance includes：Early warning information numbering, early warning issuing time, advanced warning grade, line name, shaft tower ID, parameter format are as shown in table 6.

The early warning information of table 6 issues form

Above-described embodiment is the present invention preferably implementation method, but embodiments of the present invention are not by the embodiment Limitation, it is other it is any without departing from Spirit Essence of the invention and the change, modification, replacement made under principle, combine, simplification, Equivalent substitute mode is should be, is included within protection scope of the present invention.

Claims (1)

1. a kind of based on the insulator contamination method for early warning for becoming power analytic hierarchy process (AHP), it is characterised in that：Comprise the following steps：

(1), carry out quantitatively evaluating to the intrinsic factor of insulator, the intrinsic factor of described insulator include retting-flax wastewater, Insulator hydrophobicity, the Ageing of Insulators degree, calculate insulator retting-flax wastewater index k₁, insulator hydrophobicity index k₂, insulator Ageing Index k₃, obtain the intrinsic factor index vector K=(k of insulator₁, k₂, k₃)：

Wherein insulator retting-flax wastewater index k₁Computational methods are：

$k_1=\frac{{\mathrm{\λ}}_{max}-\mathrm{\λ}}{{\mathrm{\λ}}_{max}-{\mathrm{\λ}}_{min}}---\left(1\right)$

In formula, λ is insulator retting-flax wastewater, λ_maxIt is insulator maximum retting-flax wastewater, λ_minIt is insulator minimum retting-flax wastewater；

Wherein insulator hydrophobicity index k₂It is to be determined by way of scoring, and normalized is taken to grading system D, returns Insulator hydrophobicity index k after one change treatment₂For：

$k_2=\frac{D-1}{7-1}---\left(2\right)$

In formula, D is insulator hydrophobicity grading system；

Wherein the Ageing of Insulators index k₃It is to be described using Weibull distribution, the failure density function of Weibull distribution is defined as：

$f\left(t\right)={\frac{\mathrm{\β}(t-\mathrm{\γ})}{\mathrm{\α}}}^{\mathrm{\β}-1}\exp (-\frac{{(t-\mathrm{\γ})}^{\mathrm{\β}}}{\mathrm{\α}})---\left(3\right)$

In formula, t is insulator run time, and β is form parameter, and α is scale parameter, and γ is location parameter；

The Ageing of Insulators index k₃Directly represented with the accumulative failure function of insulator, i.e.,：

$k_3=F\left(t\right)=1-\exp (-\frac{{(t-\mathrm{\γ})}^{\mathrm{\β}}}{\mathrm{\α}})---\left(4\right)$

In formula, t is insulator run time, and β is form parameter, and α is scale parameter；

(2) the intrinsic factor index m of insulator, is calculated using change power analytic hierarchy process (AHP)；Specifically include following steps：

2.1), according to power analytic hierarchy process (AHP) comparing two-by-two to the intrinsic factor relative importance of insulator is become, obtain insulator and consolidate Have shown in factor index comparator matrix A such as formulas (5), the element value of comparator matrix A is：

Element a on diagonal_ii=1；The i-th row j column elements a on off-diagonal_ijSignificance level of the i factors to j factors is represented, It is of equal importance to take 1, it is somewhat important to take 3, it is relatively important by force to take 5, it is strongly important to take 7, extremely important 9, the median of two adjacent judgements Take 2,4,6 and 8, now, a_ji=1/a_ij；

2.2) initial weight vector, is calculated by specification column average methodI.e.：

${\mathrm{\ω}}_i^0=\frac{\underset{j=1}{\overset{3}{\Σ}}{a}_{ij}}{\underset{i=1}{\overset{3}{\Σ}}\underset{j=1}{\overset{3}{\Σ}}{a}_{ij}}---\left(6\right)$

Obtain initial weight：

${\mathrm{\ω}}_{k_i}^0={({\mathrm{\ω}}_{k_1}^0,{\mathrm{\ω}}_{k_2}^0,{\mathrm{\ω}}_{k_3}^0)}^T---\left(7\right)$

2.3) it is, vectorial using power analytic approach calculating variable weight is becomeThe intrinsic factor index of insulator is any One Ge Zhiguo big city makes insulator be in danger level, i.e. their weight should increase and increase with desired value, therefore should Selection stimulable type becomes power, becomes weight coefficient a ＞ 1, its become power formula into：

$\begin{array}{cc}{\mathrm{\ω}}_{k_i}(k_1,k_2,k_3)=\frac{{\mathrm{\ω}}_{k_i}^0{k}_i^{a-1}}{\underset{i=1}{\overset{3}{\Σ}}{\mathrm{\ω}}_{k_i}^0{k}_i^{a-1}}& i=1,2,3\end{array}---\left(8\right)$

2.4) the intrinsic factor index m of insulator, is calculated：

$m=K\×\mathrm{\ω}={\mathrm{\ω}}_{k_1}{k}_1+{\mathrm{\ω}}_{k_2}{k}_2+{\mathrm{\ω}}_{k_3}{k}_3---\left(9\right)$

In formula, m is the intrinsic factor index of insulator；k₁It is insulator retting-flax wastewater index；k₂It is insulator hydrophobicity index；k₃ It is the Ageing of Insulators index；

(3), the SO provided according to environmental administration₂、NO₂, PM10 concentration measurement datas and weather bureau issue Weather Forecast Information, Calculate pollution severity of insulators level index P_f, specifically include following steps：

3.1) air quality index P and insulator equivalent salt density value ρ, is calculated：

The SO that environmental administration is provided₂、NO₂, PM10 concentration measurement datas substitute into formula (10) calculate air quality index P, then will P values obtained by calculating substitute into equivalent salt density value and calculate insulator equivalent salt density value ρ with air quality index empirical formula (11)：

$P=\sqrt{\frac{U_{PM10}}{B_{PM10}}\×\frac{1}{3}|\frac{U_{{\mathrm{SO}}_2}}{B_{{\mathrm{SO}}_2}}+\frac{U_{{\mathrm{NO}}_2}}{B_{{\mathrm{NO}}_2}}+\frac{U_{PM10}}{B_{PM10}}|}---\left(10\right)$

ρ=- 0.015+0.0806P (11)

In formula：U is the monthly measured concentration of pollutant, mg/m³；B is pollutant evaluation criterion value, mg/m³；SO₂、NO₂, PM10 comments Valency standard value takes 0.06mg/m respectively³, 0.05mg/m³, 0.1mg/m³；

U in formula_PM10/B_PM10Independent entry can be converted, and chosen area influences most prominent factor；

The development trend of insulator contamination is predicted using air quality index P, insulator surface equivalent salt density value is controlled, rationally peace Clear the plan of sweeping；When the equivalent salt density value of insulator has larger nargin with permissible value, extend cleaning period；When sweeper is finished Cheng Hou, system insulation sublist face equivalent salt density value resets, if the time of clearing was at of that month t days, the equivalent salt at the end of month after resetting Close value is

${\mathrm{\ρ}}_m^{\′}=\frac{{\mathrm{\ρ}}_m}{30}\×(30-t)---\left(12\right)$

In formula, ρ_mIt is the moon accumulation equivalent salt density value calculated by air quality index；

3.2) pollution severity of insulators level index P, is determined_f：

Pollution severity of insulators level index P_fThe probability that flashover occurs using insulator under certain equivalent salt density value ρ is P_fRepresent, Then single insulator string is in working voltage U_cUnder, P_fRelation with equivalent salt density value ρ is represented by：

$P_f=1-\exp (-{\left(\frac{1}{\mathrm{\ϵ}}\left(\frac{{\mathrm{\ρ}}^{\mathrm{\σ}}}{(1-nc)AL/U_c}-1\right)\right)}^h)---\left(13\right)$

$\mathrm{\ϵ}=\frac{nc}{(1-nc){\left(ln2\right)}^{1/h}}---\left(14\right)$

$h=\frac{1.38}{\ln n-ln(n-1)}---\left(15\right)$

In formula：N is cut-out parameter；C is the standard variance of insulator and the ratio of its 50% withstanding voltage；A is and insulator The shape coefficient relevant with pollution degree；L is insulator length, m；σ is the characteristic index that equivalent salt density value influences pollution flashover voltage；ε It is intermediate computations amount with h；

(4), according to insulator intrinsic factor index m and pollution severity of insulators level index P_fProduct judge insulator contamination Comprehensive pre-warning index R, determines advanced warning grade：Specifically include following steps：

4.1) insulator contamination comprehensive pre-warning index R, is calculated：

R=m × P_f (16)

In formula：R is insulator contamination comprehensive pre-warning index；M is the intrinsic factor index of insulator；P_fIt is pollution severity of insulators journey Degree index；

4.2) advanced warning grade, is determined：

Advanced warning grade is determined according to insulator contamination comprehensive pre-warning index R, advanced warning grade be divided into yellow, orange, red three etc. Level, it is specific as shown in table 1：

The advanced warning grade table of table 1

To dangerous insulator, according to the size of its advanced warning grade, corresponding early warning information is issued：Early warning information content bag Include：Early warning information numbering, early warning issuing time, advanced warning grade, line name and shaft tower ID.