CN106371008A - Switchgear vacuum circuit breaker life evaluation method - Google Patents

Abstract

The invention discloses a switchgear vacuum circuit breaker life evaluation method, and relates to a vacuum circuit breaker life evaluation method based on counting of a discharge amount of a circuit breaker during failure. According to the method, through counting discharge amount data of a vacuum circuit breaker of a certain model during discharge failure, a vacuum circuit breaker life evaluation model based on Weibull distribution is established, unknown parameters in a Weibull function are solved by use of a maximum likelihood function, iteration solving is performed on the maximum likelihood function by means of MATLAB, finally, a solution is substituted to the Weibull distribution, a life evaluation curve of the vacuum circuit breaker is obtained, and according to discharge amount monitoring information, the life of the vacuum circuit breaker is timely evaluated. Through performing statistics on the Weibull distribution function under a discharge amount, insulation state information of the circuit breaker can be timely reflected. The method is simple and effective, and can also timely reflect the operation state of the switchgear vacuum circuit breaker.

Description

A kind of switch cubicle vacuum circuit breaker lifetime estimation method

Technical field

The present invention relates to a kind of chopper life appraisal computational methods, particularly a kind of based on switch cubicle vacuum circuit breaker Lifetime estimation method.

Background technology

Using vacuum as arc extinguishing and dielectric, it has pollution-free and environmental protection for environment to switch cubicle vacuum circuit breaker Characteristic, and because its compact conformation, drop-out current are big, easy to maintenance, the high feature of reliability, in low and medium voltage distribution network Arrive extensive application.Vacuum circuit breaker to be divided by structure and can be divided into: 1. Switch main body；2. conduction and arc-extinguishing unit；3. actuating Mechanism；4. control unit.Vacuum circuit breaker function is realised in that effective cooperation of each part, and therefore vacuum circuit breaker is overall Reliability depends on the combined reliability of each part.

Switch cubicle vacuum circuit breaker, in During Process of Long-term Operation, should be realized substantially cut-offfing function, guarantees that vacuum is broken again Road device whole machine safe and reliable operation.It is related to the content of two aspects: mechanical stability and electric stability.Mechanical stability It is heavily dependent on manufacturing process.Electric stability there has also been rapid progress.But in long-term running Due to cut-offfing high current, bear the impact such as overvoltage, the insulating properties of switch cubicle vacuum circuit breaker start decline, chopper Stability reduces, and when insulating properties reduce to a certain extent it is impossible to normally cut-off, causes switch cubicle damage accident, to power supply Company and user cause huge economic losses.Therefore need badly and carry out the lifetime estimation method research to vacuum circuit breaker, so that and When more exchange device, it is to avoid cause huge economic losses.

Content of the invention

For solving the problems, such as the life appraisal of switch cubicle vacuum circuit breaker, the present invention propose a kind of based on discharge capacity- Vacuum circuit breaker lifetime estimation method under weibull distribution.

Present invention employs a kind of following technical scheme: switch cubicle vacuum circuit breaker life appraisal to achieve these goals Method, comprises the following steps:

1) feature according to switch cubicle vacuum circuit breaker, chooses switch cubicle vacuum circuit breaker life appraisal function.

2) discharge capacity when switch cubicle vacuum circuit breaker of some same models of measurement lost efficacy, and counted, according to system Meter result simplifies life appraisal function.

3) utilizing maximum likelihood function to step 2) unknown parameter in the life appraisal function that simplifies carries out point estimation.

4) matlab software is utilized to combine discharge capacity statistical result when switch cubicle vacuum circuit breaker lost efficacy, to maximum likelihood Unknown parameter (parameter in step 3) under function is iterated calculating.Concrete matlab software is under maximum likelihood function Transcendental equation in unknown parameter be iterated calculate.

5) calculated location parameter value is substituted into step 2) the life appraisal function that simplifies, obtain based under discharge capacity Vacuum circuit breaker life appraisal function.

On the basis of above step, obtain the longevity with specific reference to based on the vacuum circuit breaker life appraisal function under discharge capacity Life assessment curve, is estimated to the switch cubicle vacuum circuit breaker life-span with this.

In the present invention:

Step 1) described switch cubicle vacuum circuit breaker life appraisal function be weibull distribution function.At present, weibull Distribution is one of distribution of being most widely used in Reliability Engineering.Vacuum circuit breaker lost efficacy and was mainly lost by vacuum tube, electronics The collective effects such as effect cause, and therefore its durability analysis adopts weibull distributed model the most suitable.And its function obeys chi Degree parameter t₀, the weibull distribution function of location parameter γ and form parameter m.

Step 2) due to location parameter γ, < when 0, expression chopper just has occurred and that lost efficacy this and installation before runtime Chopper does not meet；When γ=0, represent that chopper has worked from the beginning and just gradually lost efficacy；As γ > 0 when, represent disconnected Road device is before running γ all without inefficacy.Usual γ=0 in Practical Project, therefore by three parameter weibull distribution functions It is reduced to two parameter and carry out life of product assessment.

Step 3) in be that two parameter is carried out with the point estimation method, the estimated accuracy of Maximum-likelihood estimation is higher, and for The requirement of data volume is less, adaptable, therefore selects Maximum Likelihood Estimation in numerous methods of estimation.

Step 4) it is to containing parameter m and parameter t using matlab programmed method₀Maximum-likelihood estimation equation enter line number Value solves, and method for solving is iterative.

Step 5) it is to be taken back based in two parameter weibull distribution function according to iterative result, obtain being based on Vacuum circuit breaker life appraisal function under discharge capacity.

Chopper state of insulation information can be reflected in time based on the weibull distribution function under statistics discharge capacity.The party Method is simply effective, can reflect switch cubicle vacuum circuit breaker running status in time.

Brief description

Fig. 1 is the system flow chart of the present invention；

Fig. 2 is vacuum circuit breaker life appraisal function curve.

Specific embodiment

The present invention will be further described below in conjunction with the accompanying drawings.Obviously, described embodiment is that a present invention part is real Apply example, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not making creation Property work under the premise of the every other embodiment that obtained, broadly fall into the scope of protection of the invention.As shown in figure 1, bag of the present invention Include following steps.

Step one, according to the inefficacy described function of conventional device, in conjunction with the vacuum circuit breaker of actual switch cabinet vacuum circuit breaker The feature that device lost efficacy mainly by vacuum tube, electronics inefficacy, from the weibull distribution letter of the inefficacy function with tub curve Number is as chopper life appraisal function.

Step 2, simplifies to weibull distribution function parameter, according to adjustment statistics moment position ginseng in actual motion Number γ, makes 3 parameter distribution functions can be reduced to 2 parameter weibull distribution functions.

Step 3, according to switch cubicle vacuum circuit breaker electric discharge failure parameter feature and with reference to unknown parameter reliability index Feature, carries out point estimation from Maximum Likelihood Estimation Method to weibull Unknown Distribution parameter.

Step 4, in conjunction with actual count parameter, and using matlab software to based under Maximum Likelihood Estimation Method Weibull Unknown Distribution parameter is iterated solving, until solving parametric results to meet required precision.

Step 5, brings the life appraisal weibull under step 2 vacuum circuit breaker into using calculated unknown parameter In distributed model, obtain this model life appraisal curve, with this, switch cubicle vacuum circuit breaker life-span is estimated.

Based on above step, following examples are explained in further detail to the present invention.

Choose the distribution function weibull distribution letter of the single components and parts lifetime change rule of description in engineer applied first Number.Assume that vacuum circuit breaker component failure probability obeys the weibull distribution of 3 parameters, then its probability density function f (t), lost efficacy Distribution function f (t) is respectively as follows:

$f\left(t\right)=\frac{m}{t_0}{(t-\mathrm{\&gamma;})}^{m-1}\exp (-\frac{{(t-\mathrm{\&gamma;})}^m}{t_0})---\left(1\right)$

F (t)=1-exp [- (t- γ)^m/t₀] (2)

T >=γ >=0, t₀, m > 0.t₀For scale parameter, relevant with the minimum crash rate of chopper；M is form parameter, with open circuit Device crash rate variation tendency is relevant；γ is location parameter；T is discharge capacity.

During reality, 3 parameters can be simplified, adjust γ=0, and make t₀=η^m, note η is scaling function The power truth of a matter, make 3 parameter distribution be reduced to 2 parameters weibull distribution:

$f\left(t\right)=\frac{m}{\mathrm{\&eta;}}{\left(\frac{t}{\mathrm{\&eta;}}\right)}^{(m-1)}\exp (-{\left(\frac{t}{\mathrm{\&eta;}}\right)}^m)---\left(3\right)$

F (t)=1-exp [- t^m/t₀] (4)

It is unknown parameter (m and η) in above-mentioned (3), (4) formula to be solved, obtain chopper reliability of service life to refer to Mark.The point estimation of unknown parameter is key one step in fail-safe analysis.It is little to there is statistic in chopper electric discharge failure parameter Problem, therefore, estimates feature, higher with estimated accuracy, adaptable Maximum Likelihood Estimation pair in conjunction with actual parameter It is estimated.For illustrating the calculating process of the method, put with monitoring the ultra-high frequency signal obtaining during certain model purpose of breaker failure Illustrate as shown in table 1 as a example electricity:

Discharge capacity during certain purpose of breaker failure of table 1

Chopper is numbered	Discharge capacity (pc)	Chopper is numbered	Discharge capacity (pc)
				1	50000	2	42000
3	10010	4	26010
				5	36483	6	18051

Make vacuum circuit breaker cut-off inefficacy when discharge capacity be t, altogether inefficacy components and parts number be r.Then set up two ginsengs Number weibull be distributed inefficacy discharge capacity Censored Tests in the case of maximum likelihood function l (η, m):

$\begin{array}{c}l(\mathrm{\&eta;},m)=\frac{n!}{(n-r)!}\underset{i=1}{\overset{r}{\&pi;}}f\left(t_i\right){\&lsqb;p(x>t)\&rsqb;}^{n-r}\\ =\frac{n!}{(n-r)!}{\left(\frac{m}{\mathrm{\&eta;}}\right)}^r\underset{i=1}{\overset{r}{\&pi;}}{t_i}^{m-1}\&centerdot;\exp \&lsqb;-\frac{1}{{\mathrm{\&eta;}}^m}\{\underset{i=1}{\overset{r}{\&pi;}}{t}_i+(n-r)t^m\}\&rsqb;\end{array}---\left(5\right)$

In formula, n is chopper total number, and r is by being counted chopper quantity, 0≤r≤n, f (t_i) under i ＆ lt discharge capacity Probability density function f (t), t_iFor the chopper discharge capacity of i ＆ lt statistics, p (x > t) is remaining (n-r) individual discharge capacity more than t Chopper quantity, t represents discharge capacity size.

Are taken the logarithm in likelihood function both sides, then respectively partial derivative is asked to m, n, and make each partial derivative be 0.Can after abbreviation To obtain equation below group:

${\mathrm{\&eta;}}^m=\frac{1}{r}\&lsqb;\underset{i=1}{\overset{r}{\&sigma;}}{t_i}^m+(n-r)t^m\&rsqb;---\left(6\right)$

$\frac{1}{m}+\frac{1}{r}\underset{i=1}{\overset{r}{\&sigma;}}{\mathrm{lnt}}_i-\frac{\underset{i=1}{\overset{r}{\&sigma;}}{t}_i^m{\mathrm{lnt}}_i+(n-r)t^m\ln t}{\underset{i=1}{\overset{r}{\&sigma;}}{t}_i^m+(n-r)t^m}=0---\left(7\right)$

Above-mentioned (6), (7) formula are transcendental equation it is impossible to pass through equation direct solution, in real process, in terms of numerical value Calculation method is iterated solving, and carries out solving equation by matlab software programming.Bring routine parameters in table 1 into, through iteration Being calculated estimates of parameters is:

$\begin{array}{c}\hat{m}=1.982\\ \widehat{\mathrm{\&eta;}}=36573\end{array}---\left(8\right)$

The parameter value m=1.982 that estimation is obtained, η=36573 substitute into formula (3), can obtain vacuum circuit breaker The probability density function of weibull distributed model is:

$f\left(t\right)=1.79\&times;{10}^{-9}{t}^{0.982}\exp (-{\left(\frac{t}{36573}\right)}^{1.982})---\left(9\right)$

Bringing this formula into (4), obtain the cumulative failure distribution function of vacuum circuit breaker weibull distributed model:

$f\left(t\right)=1-\exp (-{\left(\frac{t}{36573}\right)}^{1.982})---\left(10\right)$

The life appraisal function of the weibull distributed model under vacuum circuit breaker discharge capacity is:

$r\left(t\right)=1-f\left(t\right)=\exp ({\left(-\frac{t}{36572}\right)}^{1.982}---\left(11\right)$

From Fig. 2, curve understands, when discharge capacity is more than 3000pc, the life-span of vacuum circuit breaker is less than 50 percent, And the life-span drastically declines.Therefore chopper index of aging in 30000pc, when chopper is that discharge capacity exceedes in drop-out current During 30000pc, its operational reliability degradation, need to be changed in time.

Claims (5)

1. a kind of switch cubicle vacuum circuit breaker lifetime estimation method, comprises the following steps:

1) feature according to switch cubicle vacuum circuit breaker, chooses switch cubicle vacuum circuit breaker life appraisal function；

2) discharge capacity when switch cubicle vacuum circuit breaker of some same models of measurement lost efficacy, and counted, according to statistics knot Fruit simplifies life appraisal function；

3) utilizing maximum likelihood function to step 2) unknown parameter in the life appraisal function that simplifies carries out point estimation；

4) matlab software is utilized to combine discharge capacity statistical result when switch cubicle vacuum circuit breaker lost efficacy, to maximum likelihood function Under unknown parameter be iterated calculate；

5) calculated location parameter value is substituted into step 2) the life appraisal function that simplifies, obtain based on true under discharge capacity Empty chopper life appraisal function.

2. according to claim 1 a kind of switch cubicle vacuum circuit breaker lifetime estimation method it is characterised in that: according to described base Vacuum circuit breaker life appraisal function under discharge capacity obtains life appraisal curve, with this to the switch cubicle vacuum circuit breaker life-span It is estimated.

3. according to claim 1 a kind of switch cubicle vacuum circuit breaker lifetime estimation method it is characterised in that: step 1) described Switch cubicle vacuum circuit breaker life appraisal function is the weibull distribution function of 3 parameters.

4. according to claim 3 a kind of switch cubicle vacuum circuit breaker lifetime estimation method it is characterised in that: described step 2) Middle simplification life appraisal function, the weibull distribution function of 3 parameters is reduced to the weibull distribution function of 2 parameters.

5. according to right wants 1 or 2 or 3 or 4 a kind of switch cubicle vacuum circuit breaker lifetime estimation method it is characterised in that: institute Stating matlab software is the unknown parameter in the transcendental equation under maximum likelihood function to be iterated calculate.