CN104361216A - Insulator pollution flashover early warning method on basis of variable weight analytic hierarchy process - Google Patents

Abstract

The invention discloses an insulator pollution flashover early warning method on the basis of a variable weight analytic hierarchy process, which comprises the following steps of: (1) carrying out quantitative evaluation on intrinsic factors of an insulator, wherein the intrinsic factors of the insulator comprise a specific creepage distance, insulator hydrophobicity and an insulator aging degree; (2) calculating to obtain intrinsic factor indexs m of the insulator by adopting the variable weight analytic hierarchy process and according to atmospheric environment parameters and meteorological conditions, calculating a surface pollution degree index Pf of the insulator; and (3) according to the product of the intrinsic factor indexs m of the insulator and the surface pollution degree index Pf of the insulator, judging an insulator pollution flashover early warning index R and determining an early warning grade. The method can give out the comprehensive early warning index of the insulator in a region and release the early warning grade and implements scientific insulator pollution flashover early warning so as to effectively improve power supply reliability, reduce economic loss of a power grid and improve reliable operation ability of the power grid.

Description

A kind of insulator contamination method for early warning based on becoming power analytical hierarchy process

Technical field

The present invention relates to the insulator contamination early warning field of preventing and reducing natural disasters in a kind of electric system, particularly relating to a kind of insulator contamination method for early warning based on becoming power analytical hierarchy process.

Background technology

At present, in electric system, insulator is by electric conductors different for current potential mechanically interconnective vitals, and the safe operation of quality to whole transmission system of its performance plays a part very crucial.Especially the insulator run out of doors, except should having the mechanical property of certain electrical insulation properties and some strength, also should possess the invasion and attack of tolerance physical environment and pollution etc. to ensure the condition of safe power supply.Along with the fast development of national economy, various types of pollutant gets more and more, and the inclement weather such as haze, sandstorm is also more and more serious, and power circuit and equipment large area pollution flashover accident happen occasionally, and the harm caused is also increasing.According to statistics, that pollutes along with transmission line of electricity increases the weight of, and 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 studies and takes precautions against pollution flashover and also just become current key subjects.

Owing to being uneven along the Electric Field Distribution of insulator chain, therefore the degree in insulator chain, each insulator surface depositing dust is also different, continuous contamination can make the close continuous increase of the attached salt of the equivalence of equipment, once experience a thick fog or the weather such as drizzle after drouth, pollution layer is fully moistening and progressively expansion forms the conductive layer of insulator surface time, will leakage current be produced, cause external insulation to change along surface-potential gradient, form local brush electric discharge; And the electric field intensity between electric arc increases with flame current and weakens, Shi Shiwu district field intensity raises, and produces intermittence electric discharge, recurrence exhibition of laying equal stress on.When field intensity change exceedes critical value, electric arc runs through whole insulator chain surface and flashover over the ground occurs.

Current existing insulator on-line monitoring early warning system, although the state parameter of insulator can be gathered, as leakage current, working voltage grade and insulator model etc., but the analyses and prediction process of system background is obviously delayed, only has each value of consult volume of input, managerial personnel cannot be made to judge analysis to filthy state, therefore cannot implement the prevention of effective pollution flashover.And electric system has countless multiple insulator, install pick-up unit on a large scale unrealistic.

Because insulator pollution flashover generation needs two conditions are filthy and moistening, therefore how to consider that the impact of insulator contamination and weather conditions combines with insulator contamination, has just become this area technical issues that need to address.

Summary of the invention

The object of this invention is to provide a kind of insulator contamination method for early warning based on becoming power analytical hierarchy process, can for prior art above shortcomings, this method effectively can improve power supply reliability, reduces the economic loss of electrical network, improves the reliability service ability of electrical network.

The present invention adopts following technical proposals: a kind of insulator contamination method for early warning based on becoming power analytical hierarchy process, comprises the following steps:

(1), to the intrinsic factor of insulator carry out quantitatively evaluating, the intrinsic factor of described insulator includes retting-flax wastewater, insulator hydrophobicity, the Ageing of Insulators degree, calculates insulator retting-flax wastewater index k ₁, insulator hydrophobicity index k ₂, the Ageing of Insulators index k ₃, obtain insulator intrinsic factor index vector K=(k ₁, k ₂, k ₃):

Wherein insulator retting-flax wastewater index k ₁computing method 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 _maxfor the maximum retting-flax wastewater of insulator, λ _minfor the minimum retting-flax wastewater of insulator;

Wherein insulator hydrophobicity index k ₂be determined by the mode of scoring, and normalized taked to grading system D, the insulator hydrophobicity index k after normalized ₂for:

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

In formula, D is insulator hydrophobicity grading system; Wherein the Ageing of Insulators index k ₃be adopt Weibull distribution to describe, 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 working time, and β is form parameter, and α is scale parameter, and γ is location parameter;

The Ageing of Insulators index k ₃directly add up failure function with insulator to represent, that is:

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

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

(2) change power analytical hierarchy process, is adopted to calculate the intrinsic factor index m of insulator; Specifically comprise the following steps:

2.1), according to change power analytical hierarchy process comparing between two the intrinsic factor relative importance of insulator, obtain insulator intrinsic factor index comparator matrix A such as formula shown in (5), the element value of comparator matrix A is:

Element a on diagonal line _ii=1; The i-th row j column element a on off-diagonal _ijrepresent that i factor is to the significance level of j factor, of equal importancely get 1, importantly a little get 3, more importantly get 5, strongly importantly get 7, extremely important 9, the intermediate value desirable 2,4,6,8 of two adjacent judgements, now, a _ji=1/a _ij;

$\begin{array}{c}\begin{array}{ccc}{k}_1& k_2& k_3\end{array}\\ A=\begin{array}{c}{k}_1\\ k_2\\ k_3\end{array}\left[\begin{array}{ccc}{a}_{11}& a_{12}& a_{13}\\ a_{21}& a_{22}& a_{23}\\ a_{31}& a_{32}& a_{33}\end{array}\right]\end{array}---\left(5\right)$

2.2), initial weight vector is calculated by specification column average method that is:

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

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) change power analytic approach, is utilized to calculate variable weight vector any one Zhi Guo big city of the intrinsic factor index of insulator makes insulator be in danger level, and namely their weight should increase with desired value and increase, and stimulable type therefore should be selected to become power, become weight coefficient a > 1, its become power formula into:

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

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; k ₁for insulator retting-flax wastewater index; k ₂for insulator hydrophobicity index; k ₃for the Ageing of Insulators index;

(3), according to the SO that environmental administration provides ₂, NO ₂, the Weather Forecast Information issued of PM10 concentration measurement data and weather bureau, calculate pollution severity of insulators level index P _f, specifically comprise the following steps:

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

The SO that environmental administration is provided ₂, NO ₂, PM10 concentration measurement data substitutes into formula (10) and calculates air quality index P, then the P value substitution equivalent salt density value and air quality index empirical formula (11) that calculate gained calculated insulator equivalent salt density value ρ:

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

ρ＝-0.015+0.0806P (11)

In formula: U is the monthly measured concentration of pollutant, mg/m ³; B is pollutant evaluation criterion value, mg/m ³; SO ₂, NO ₂, PM10 evaluation criterion value get 0.06mg/m respectively ³, 0.05mg/m ³, 0.1mg/m ³;

U in formula _pM10/ B _pM10independent entry can convert, the factor that chosen area impact is the most outstanding;

Application air quality index P predicts the development trend of insulator contamination, controls insulator surface equivalent salt density value, reasonable arrangement cleaning plan; When the equivalent salt density value of insulator and permissible value have larger nargin, cleaning period can be extended; After cleaning works completes, system insulation sub-surface equivalent salt density value resets, if the time of clearing is in of that month t day, then after resetting, the equivalent salt density value at the end of month is

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

In formula, ρ _mfor pressing the moon accumulation equivalent salt density value that air quality index calculates;

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

Pollution severity of insulators level index P _finsulator is used the probability of flashover to occur for P under certain equivalent salt density value ρ _frepresent, then single insulator string is at working voltage U _cunder, P _fcan be expressed as with the relation of equivalent salt density value ρ:

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

$\mathrm{\ϵ}=\frac{\mathrm{nc}}{(1-\mathrm{nc}){\left(\ln 2\right)}^{1/h}}---\left(14\right)$

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

In formula: n is disconnect parameter; C is the standard variance of insulator and the ratio of its withstand voltage of 50%; A is the coefficient relevant with pollution degree with insulator shape; L is insulator length, m; σ is the characteristic exponent that equivalent salt density value affects pollution flashover voltage; ε and h is intermediate computations amount;

(4), according to the intrinsic factor index m of insulator and pollution severity of insulators level index P _fproduct judge insulator contamination comprehensive pre-warning index R, determine advanced warning grade: specifically comprise the 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 pollution severity of insulators level index;

4.2), advanced warning grade is determined:

Determine advanced warning grade according to insulator contamination comprehensive pre-warning index R, advanced warning grade is divided into yellow, orange, red Three Estate, specifically as shown in table 1:

Table 1 advanced warning grade table

To dangerous insulator, according to the size of its advanced warning grade, issue corresponding early warning information: early warning information content comprises: early warning information numbering, early warning issuing time, advanced warning grade, line name, shaft tower ID.

The invention provides a kind of take atmosphere pollution as the insulator contamination method for early warning based on change power analytical hierarchy process inputted, the factor affecting insulator pollution flashover is carried out internal and external reasons classification process, by calculating insulator retting-flax wastewater index, insulator hydrophobicity index, the Ageing of Insulators index obtains the intrinsic factor index of insulator, the intrinsic factor index of COMPREHENSIVE CALCULATING insulator and pollution severity of insulators degree (running environment) index, provide the comprehensive pre-warning index of region insulator and issue advanced warning grade, realize the insulator pollution flashover early warning of science.

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

1) the present invention has considered the intrinsic factor of the insulator affecting insulator pollution flashover and pollution severity of insulators degree, more realistic;

2) significance level that contemplated by the invention between factor can change with the difference of each factor state value, adopts and becomes the intrinsic factor index of power analytical hierarchy process calculating insulator, reduce subjective uncertainty, improve accuracy and the confidence level of result;

3) the present invention adopts air quality index method to calculate pollution severity of insulators equivalent salt density value, have and be easy to obtain data from environmental administration, without the need to installing the advantages such as online monitoring equipment, effectively can instruct the work of operation of power networks personnel reasonable arrangement insulator cleaning;

4) the present invention is generally applicable to transmission line of electricity, generating plant, the early warning of Substation Insulator pollution flashover, for electrical network and power plant's staff's Flash Decontamination Measurements provide the aid decision making reference of science, reduce insulator pollution flashover failure rate, ensure that the safety and stability of passway for transmitting electricity is powered.

Accompanying drawing explanation

Fig. 1 is method flow diagram of the present invention.

Embodiment

Meteorological condition is the most important extraneous factor affecting insulator pollution flashover, even if pollution severity of insulators is quite serious, under the weather of drying, insulator pollution flashover probabilistic machine can be zero.But when wet weather comes interim, contaminated insulator, the oneself factors such as its retting-flax wastewater, hydrophobic nature, degree of aging also to a certain degree can affect insulator pollution flashover.Therefore, the present invention is to provide a kind of take atmosphere pollution as the insulator contamination method for early warning based on change power analytical hierarchy process inputted.The related data that this method is tested according to transmission line foundation data and insulator contamination, consider the intrinsic factor of insulator and running environment factor, establish insulator contamination Comprehensive State Evaluation index system, calculate intrinsic factor index value and pollution severity of insulators level index value, obtain insulator contamination comprehensive evaluation index value.Under the weather such as mist, dew, drizzle of forecast, quantize the safety problem of electric transmission line isolator pollution flashover, provide the comprehensive pre-warning index of region insulator and issue advanced warning grade, realizing the insulator pollution flashover early warning of science; For operation of power networks, personnel provide decision-making foundation, and raising system resists the ability of severe disaster.

As shown in Figure 1, below detailed specific descriptions are carried out to the present invention:

For the common disc insulator of certain 220kV circuit, the air SO that environmental administration issues ₂, NO ₂, PM10 concentration is respectively 0.0285mg/m ³, 0.0512mg/m ³, 0.0832mg/m ³, retting-flax wastewater is 45mm/kV, and insulator hydrophobicity marking is 4 points, has run 5 years.

A kind of insulator contamination method for early warning based on becoming power analytical hierarchy process of the present invention, concrete report comprises the following steps:

(1), to the intrinsic factor of insulator carry out quantitatively evaluating, the intrinsic factor of described insulator includes retting-flax wastewater, insulator hydrophobicity, the Ageing of Insulators degree; Namely insulator retting-flax wastewater index k is calculated ₁, insulator hydrophobicity index k ₂, the Ageing of Insulators index k ₃, obtain insulator intrinsic factor index vector K=(k ₁, k ₂, k ₃):

11), insulator retting-flax wastewater index k ₁

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

Table 2 circuit and generating plant, the close value of the corresponding salt of transformer station's gradation for surface pollution

" level and external insulation choice criteria are distinguished in electric system dirt " that State Grid Corporation of China issues gives the mutual relationship of unified retting-flax wastewater and site pollution degree, select the retting-flax wastewater of common disc insulator (with reference to insulator), then determine the retting-flax wastewater of insulator used according to the effective specific creepage distance conversion relation between difformity size insulator and common disc insulator, conversion relation can be determined according to the long-time running experience of each department.The retting-flax wastewater of each gradation for surface pollution insulator is as shown in table 3.

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

Like this, insulator retting-flax wastewater index k ₁computing method 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 _maxfor the maximum retting-flax wastewater of insulator, λ _minfor the minimum retting-flax wastewater of insulator;

Air quality index is calculated by formula (10) $P=\sqrt{\frac{0.1832}{0.1}\×\frac{1}{3}|\frac{0.0585}{0.06}+\frac{0.0512}{0.05}+\frac{0.1832}{0.1}|}=2.4008;$

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

ρ＝-0.015+0.0806P＝0.1785mg/cm ²；

As shown in Table 1, salt close value ρ=0.1785mg/cm ²corresponding gradation for surface pollution is III grade;

Then according to the insulator retting-flax wastewater index that table 2 and formula (1) calculate:

12), insulator hydrophobicity index k ₂, insulator hydrophobicity index k ₂be determined by the mode of scoring, and grading system D be normalized, the insulator hydrophobicity index k after normalized ₂for

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

In formula, D is insulator hydrophobicity grading system.

The collision on the moistening condensation primarily of mist of insulator surface pollution layer, hydrone and surface, the moisture absorption of pollution layer, hydrone cause in the diffusion of pollution layer.The good maintenance of insulator surface hydrophobic nature, can improve insulator anti-pollution characteristic.Insulator hydrophobicity index k ₂standards of grading are as shown in table 4.

Table 4 insulator hydrophobicity index k ₂standards of grading

Common disc insulator is when hydrophobic nature is tested, and insulator surface exists the globule and the water-band of separation simultaneously, and completely moistening water-band area is less than 2cm ², the total area is less than 90% of tested region area, and insulator hydrophobicity scoring is 4 points, calculates insulator hydrophobicity index by formula (2):

13), the Ageing of Insulators index k ₃

Along with the increase running the time limit, due to the impact for a long time by electric field, mechanical stress, atmospheric environment, heat radiation etc., insulator is aging gradually, the phenomenons such as hydrophobic nature reduction, cracking, breakage, ablated surface may be there is, the requirement of project of transmitting and converting electricity antifouling work can not be met, therefore need to consider the Ageing of Insulators problem.Adopt Weibull distribution to describe the Ageing of Insulators degree, 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 working time, and β is form parameter, and α is scale parameter, and γ is location parameter;

The Ageing of Insulators index k ₃directly add up failure function with insulator to represent, that is:

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

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

Application correlation coefficient process estimates that the step of Weibull distribution parameters is as follows:

First equivalence transformation is carried out to formula (4), then get twice logarithm, obtain following formula

$\ln \left(\ln \frac{1}{1-F\left(t\right)}\right)=\mathrm{\β}\ln (t-\mathrm{\γ})-\ln \mathrm{\α}---\left(31\right)$

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

Y＝AX+B (32)

From formula (32), when location parameter γ estimates correct, X and Y is linear, namely has maximum related coefficient between X and Y; Pass between the estimated value of γ and coefficient R is: when coefficient R gets maximal value, and location parameter γ is best estimate.

Ask coefficient R to get maximal value, be the first derivative values solving related coefficient and equal 0, the formula of related coefficient is

$R^2=\frac{{(n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i{Y}_i-\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i\right)\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y}_i\right))}^2}{(n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y_i}^2-{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y}_i\right)}^2)(n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i^2-{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i\right)}^2)}---\left(33\right)$

In formula, X _i=ln (t _i-γ), i=1,2 ..., n

Formula (33) is converted, order $S_x=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i,S_y=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y}_i,S_1=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{X}_i^2,S_2=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y_i}^2,Y_0=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Y_i}^2-S_i^2,$ :

$R^2=\frac{{(n{S}_2-S_x{S}_y)}^2}{Y_0(n{S}_1-S_x^2)}---\left(34\right)$

Because the coefficient R perseverance of Weibull distribution is greater than 0, so it is the same for getting first order derivative result to the quadratic sum of R to R, therefore first order derivative is got to formula (34) and abbreviation obtains:

$(n{S}_1-S_x^2)\underset{i=0}{\overset{n}{\mathrm{\Σ}}}\frac{S_y-n{Y}_i}{t_i-\mathrm{\γ}}-(n{S}_2-S_x{S}_y)\underset{i=0}{\overset{n}{\mathrm{\Σ}}}\frac{S_x-n{X}_i}{t_i-\mathrm{\γ}}=0---\left(35\right)$

Just location parameter γ can be obtained according to formula (35), just can in the hope of form parameter β and scale parameter α by linear regression analysis according to formula (32) after obtaining location parameter γ.

Formula (35) is transcendental equation, adopting dichotomy on computers by being programmed into row numerical evaluation, can obtain location parameter γ.Wherein use approximate Median rank formula

$F_n\left(t_i\right)=\frac{i-0.3}{n+0.4}---\left(36\right)$

In formula: n represents maintenance frequency; I represents i-th maintenance.

After obtaining location parameter γ, pass through t _i=t-m becomes three-parameter Weibull distribution into two parameters, then can obtain form parameter β and scale parameter α by regretional analysis least square method.

Suppose, according to existing fault data, to be asked for by said method, to obtain location parameter γ be 17280, form parameter β is 1.718, and scale parameter α is 49266 ^1.718.Like this, the Ageing of Insulators failure rate represents the Ageing of Insulators index k ₃for:

$k_3=\mathrm{\λ}=1-\exp (-{\left(\frac{t-17280}{49266}\right)}^{1.718})=0.2823.$

(2) change power analytical hierarchy process, is adopted to calculate the intrinsic factor index m of insulator;

2.1), according to change power analytical hierarchy process comparing between two the intrinsic factor relative importance of insulator, obtain insulator intrinsic factor index comparator matrix A such as formula shown in (5), the element value of comparator matrix A is:

Element a on diagonal line _ii=1; The i-th row j column element a on off-diagonal _ijrepresent that i factor is to the significance level of j factor, of equal importancely get 1, importantly a little get 3, more importantly get 5, strongly importantly get 7, extremely important 9, the intermediate value desirable 2,4,6,8 of two adjacent judgements, now, a _ji=1/a _ij;

$\begin{array}{c}\begin{array}{ccc}{k}_1& k_2& k_3\end{array}\\ A=\begin{array}{c}{k}_1\\ k_2\\ k_3\end{array}\left[\begin{array}{ccc}{a}_{11}& a_{12}& a_{13}\\ a_{21}& a_{22}& a_{23}\\ a_{31}& a_{32}& a_{33}\end{array}\right]\end{array}---\left(5\right)$

Namely $\begin{array}{c}\begin{array}{ccc}{k}_1& k_2& k_3\end{array}\\ A=\begin{array}{c}{k}_1\\ k_2\\ k_3\end{array}\left[\begin{array}{ccc}1& 2& 1/3\\ 1/2& 1& 1\\ 3& 1& 1\end{array}\right].\end{array}$

2.2), initial weight vector is calculated by specification column average method that is:

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

Obtain initial weight:

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

That is: ${\mathrm{\ω}}_{k_i}^0={(0.3077,0.2308,0.4615)}^T.$

2.3) change power analytic approach, is utilized to calculate variable weight vector any one Zhi Guo big city of the intrinsic factor index of insulator makes insulator be in danger level, and namely their weight should increase with desired value and increase, and stimulable type therefore should be selected to become power, become weight coefficient a > 1, its become power formula into:

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

That is: ${\mathrm{\ω}}_{k_1}=\frac{0.3077\×{0.5}^{2.5-1}}{0.3077\×{0.5}^{2.5-1}+0.2308\×{0.5}^{2.5-1}+0.4615\×{0.2823}^{2.5-1}}=0.4190$

${\mathrm{\ω}}_{k_2}=\frac{0.2308\×{0.5}^{2.5-1}}{0.3077\×{0.5}^{2.5-1}+0.2308\×{0.5}^{2.5-1}+0.4615\×{0.2823}^{2.5-1}}=0.3143$

${\mathrm{\ω}}_{k_3}=\frac{0.4615\×{0.2823}^{2.5-1}}{0.3077\×{0.5}^{2.5-1}+0.2308\×{0.5}^{2.5-1}+0.4615\×{0.2823}^{2.5-1}}=0.2667.$

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

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

That is: $m=K\×\mathrm{\ω}={\mathrm{\ω}}_{k_1}{k}_1+{\mathrm{\ω}}_{k_2}{k}_2+{\mathrm{\ω}}_{k_3}{k}_3=0.4419.$

(3), according to the SO that environmental administration provides ₂, NO ₂, the Weather Forecast Information issued of PM10 concentration measurement data and weather bureau, calculate pollution severity of insulators level index P _f, specifically comprise the following steps:

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

The SO that environmental administration is provided ₂, NO ₂, PM10 concentration measurement data substitutes into formula (10) and calculates air quality index P, then the P value substitution equivalent salt density value and air quality index empirical formula (11) that calculate gained calculated insulator equivalent salt density value ρ:

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

ρ＝-0.015+0.0806P (11)

In formula: U is the monthly measured concentration of pollutant, mg/m ³; B is pollutant evaluation criterion value, mg/m ³; SO ₂, NO ₂, PM10 evaluation criterion value get 0.06mg/m respectively ³, 0.05mg/m ³, 0.1mg/m ³;

U in formula _pM10/ B _pM10independent entry can convert, the factor that chosen area impact is the most outstanding;

That is: $P=\sqrt{\frac{0.1832}{0.1}\×\frac{1}{3}|\frac{0.0585}{0.06}+\frac{0.0512}{0.05}+\frac{0.1832}{0.1}|}=2.4008$

ρ＝-0.015+0.0806×2.4008＝0.1785。

When the equivalent salt density value of insulator and permissible value have larger nargin, cleaning period can be extended; Application air quality index P predicts the development trend of insulator contamination, controls insulator surface equivalent salt density value, reasonable arrangement cleaning plan; The retting-flax wastewater that table 5 tries for certain electric company, the close table of comparisons of permission salt.

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

After cleaning works completes, system insulation sub-surface equivalent salt density value resets, if the time of clearing is in of that month t day, then after resetting, the equivalent salt density value at the end of month is

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

In formula, in formula, ρ _mfor pressing the moon accumulation equivalent salt density value that air quality index calculates.

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

Pollution severity of insulators level index P _finsulator is used the probability of flashover to occur under equivalent salt density value ρ for P _frepresent, then single insulator string is at working voltage U _cunder, P _fcan be expressed as with the relation of equivalent salt density value ρ:

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

$\mathrm{\ϵ}=\frac{\mathrm{nc}}{(1-\mathrm{nc}){\left(\ln 2\right)}^{1/h}}---\left(14\right)$

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

In formula: n is disconnect parameter; C is the standard variance of insulator and the ratio of its withstand voltage of 50%; A is the coefficient relevant with pollution degree with insulator shape; L is insulator length, m; ε is the characteristic exponent that equivalent salt density value affects pollution flashover voltage; σ and h is intermediate computations amount.

Insulator is 0.1785mg/cm in equivalent salt density value ²the probability P of lower generation flashover _fbe calculated as follows:

Disconnect parameter n gets 2.1, the ratio c of the standard variance of insulator and its withstand voltage of 50% gets 0.088, the coefficient A relevant with pollution degree with insulator shape gets 64.4, insulator length L gets 2.17m, the close characteristic exponent σ affecting pollution flashover voltage of equivalent attached salt figure gets 0.25, and intermediate computations amount ε and h is 0.2692,2.1342.

$P_f=1-\exp (-{(\frac{1}{0.2692}\×(\frac{{0.1785}^{0.25}}{(1-2.1\×0.088)\×64.4\×2.17/220}-1))}^{2.1342})=0.59$

$\mathrm{\β}=\frac{2.1\×0.088}{(1-2.1\×0.088){\left(\ln 2\right)}^{0.4686}}=0.2692$

$h=\frac{1.38}{\ln 2.1-\ln (2.1-1)}=2.1342.$

(4), according to the intrinsic factor index m of insulator and pollution severity of insulators level index P _fproduct judge insulator contamination comprehensive pre-warning index R, determine 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 pollution severity of insulators level index;

That is: R=0.4419 × 0.59=0.2607.

4.2), advanced warning grade is determined:

Determine advanced warning grade according to insulator contamination comprehensive pre-warning index R, advanced warning grade is divided into yellow, orange, red Three Estate, and R=0.2607 belongs to orange early warning, specifically as shown in table 1:

Table 1 advanced warning grade table

To dangerous insulator, according to the size of its advanced warning grade, issue corresponding early warning information: early warning information content comprises: early warning information numbering, early warning issuing time, advanced warning grade, line name, shaft tower ID, parameter format is as shown in table 6.

Table 6 early warning information issues form

Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not limited by the examples; change, the modification done under other any does not deviate from Spirit Essence of the present invention and principle, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (1)

1., based on the insulator contamination method for early warning becoming power analytical hierarchy process, it is characterized in that: comprise the following steps:

(1), to the intrinsic factor of insulator carry out quantitatively evaluating, the intrinsic factor of described insulator includes retting-flax wastewater, insulator hydrophobicity, the Ageing of Insulators degree, calculates insulator retting-flax wastewater index k ₁, insulator hydrophobicity index k ₂, the Ageing of Insulators index k ₃, obtain insulator intrinsic factor index vector K=(k ₁, k ₂, k ₃):

Wherein insulator retting-flax wastewater index k ₁computing method 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 _maxfor the maximum retting-flax wastewater of insulator, λ _minfor the minimum retting-flax wastewater of insulator;

Wherein insulator hydrophobicity index k ₂be determined by the mode of scoring, and normalized taked to grading system D, the insulator hydrophobicity index k after normalized ₂for:

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

In formula, D is insulator hydrophobicity grading system;

Wherein the Ageing of Insulators index k ₃be adopt Weibull distribution to describe, the failure density function of Weibull distribution is defined as:

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

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

The Ageing of Insulators index k ₃directly add up failure function with insulator to represent, that is:

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

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

(2) change power analytical hierarchy process, is adopted to calculate the intrinsic factor index m of insulator; Specifically comprise the following steps:

2.1), according to change power analytical hierarchy process comparing between two the intrinsic factor relative importance of insulator, obtain insulator intrinsic factor index comparator matrix A such as formula shown in (5), the element value of comparator matrix A is:

Element a on diagonal line _ii=1; The i-th row j column element a on off-diagonal _ijrepresent that i factor is to the significance level of j factor, of equal importancely get 1, importantly a little get 3, more importantly get 5, strongly importantly get 7, extremely important 9, the intermediate value desirable 2,4,6,8 of two adjacent judgements, now, a _ji=1/a _ij;

2.2), initial weight vector is calculated by specification column average method that is:

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

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) change power analytic approach, is utilized to calculate variable weight vector any one Zhi Guo big city of the intrinsic factor index of insulator makes insulator be in danger level, and namely their weight should increase with desired value and increase, and stimulable type therefore should be selected to become power, become weight coefficient a > 1, its become power formula into:

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

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; k ₁for insulator retting-flax wastewater index; k ₂for insulator hydrophobicity index; k ₃for the Ageing of Insulators index;

(3), according to the SO that environmental administration provides ₂, NO ₂, the Weather Forecast Information issued of PM10 concentration measurement data and weather bureau, calculate pollution severity of insulators level index P _f, specifically comprise the following steps:

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

The SO that environmental administration is provided ₂, NO ₂, PM10 concentration measurement data substitutes into formula (10) and calculates air quality index P, then the P value substitution equivalent salt density value and air quality index empirical formula (11) that calculate gained calculated insulator equivalent salt density value ρ:

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

ρ＝-0.015+0.0806P (11)

In formula: U is the monthly measured concentration of pollutant, mg/m ³; B is pollutant evaluation criterion value, mg/m ³; SO ₂, NO ₂, PM10 evaluation criterion value get 0.06mg/m respectively ³, 0.05mg/m ³, 0.1mg/m ³;

U in formula _pM10/ B _pM10independent entry can convert, the factor that chosen area impact is the most outstanding;

Application air quality index P predicts the development trend of insulator contamination, controls insulator surface equivalent salt density value, reasonable arrangement cleaning plan; When the equivalent salt density value of insulator and permissible value have larger nargin, cleaning period can be extended; After cleaning works completes, system insulation sub-surface equivalent salt density value resets, if the time of clearing is in of that month t day, then after resetting, the equivalent salt density value at the end of month is

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

In formula, ρ _mfor pressing the moon accumulation equivalent salt density value that air quality index calculates;

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

Pollution severity of insulators level index P _finsulator is used the probability of flashover to occur for P under certain equivalent salt density value ρ _frepresent, then single insulator string is at working voltage U _cunder, P _fcan be expressed as with the relation of equivalent salt density value ρ:

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

$\mathrm{\ϵ}=\frac{\mathrm{nc}}{(1-\mathrm{nc}){\left(\ln 2\right)}^{1/h}}---\left(14\right)$

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

In formula: n is disconnect parameter; C is the standard variance of insulator and the ratio of its withstand voltage of 50%; A is the coefficient relevant with pollution degree with insulator shape; L is insulator length, m; σ is the characteristic exponent that equivalent salt density value affects pollution flashover voltage; ε and h is intermediate computations amount;

(4), according to the intrinsic factor index m of insulator and pollution severity of insulators level index P _fproduct judge insulator contamination comprehensive pre-warning index R, determine advanced warning grade: specifically comprise the 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 pollution severity of insulators level index;

4.2), advanced warning grade is determined:

Determine advanced warning grade according to insulator contamination comprehensive pre-warning index R, advanced warning grade is divided into yellow, orange, red Three Estate, specifically as shown in table 1:

Table 1 advanced warning grade table

To dangerous insulator, according to the size of its advanced warning grade, issue corresponding early warning information: early warning information content comprises: early warning information numbering, early warning issuing time, advanced warning grade, line name, shaft tower ID.