CN103969519A - Scheme guaranteeing reliability of electrical system - Google Patents

Scheme guaranteeing reliability of electrical system Download PDF

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Publication number
CN103969519A
CN103969519A CN201310029286.1A CN201310029286A CN103969519A CN 103969519 A CN103969519 A CN 103969519A CN 201310029286 A CN201310029286 A CN 201310029286A CN 103969519 A CN103969519 A CN 103969519A
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China
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system
reliability
element
probability
scheme
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CN201310029286.1A
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Chinese (zh)
Inventor
马玉芳
李飞龙
刘尹霞
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辽宁工程技术大学
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Priority to CN201310029286.1A priority Critical patent/CN103969519A/en
Publication of CN103969519A publication Critical patent/CN103969519A/en

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Abstract

The invention discloses a scheme guaranteeing the reliability of an electrical system. The scheme is characterized in that the reliability of a single element is analyzed according to two important factors including the work time (t) and the work temperature (c) and affecting the reliability of an electrical element, and especially when the work time and the appropriate work temperatures of all elements are different, the system reliability is analyzed difficultly with a traditional method. According to the scheme, the reliability degree of the electrical system is guaranteed by adjusting the replacing period of the elements (events). The scheme mainly comprises the reliability confirmation of the electrical elements, the reliability confirmation of the electrical system and the electrical system element replacement period scheme confirmation. The scheme can be widely applied to analyzing the characteristics of the electrical system fault probability under the effect condition of the binary or even the multi-element factors, and then the reliability of the system can be confirmed and guaranteed.

Description

A kind of scheme that guarantees electrical system fiduciary level

Technical field

the present invention relates to electrical system reliability, particularly relates to a kind of scheme that guarantees electrical system fiduciary level of using.

Background technology

Electrical system is modal system in present every field, and its reliability directly affects the overall performance of place system.From system perspective analysis, its reliability can be divided into two parts and study.The one, the primary element of composition system, the character of these elements is applied to the reliability of self, and then affects the reliability of this electrical system.The 2nd, the structure of system itself, is exactly the building form of primary element, and the difference of building form will directly determine that element affects the effect degree of system reliability.The reliability of whole system is both combinations.For the diode element in electric system, its probability of malfunction just with the length of working time, the size of working temperature, have direct relation by electric current and voltage etc. [5].Supposing the system fault is because component wear causes, and carries out fault eliminating by changing element.To become the key factor that affects component reliability the service time of element so, this factor affects the degree of probability of malfunction and obeys exponential expression.Another factor is exactly working temperature, significantly, for electrical equipment excess Temperature with too lowly all can cause the decline of its reliability and the rising of failure rate, substantially obeys cosine curve.First paper builds the probability of malfunction space based on service time (t) and working temperature (c) of electric elements, then using event tree to form structure to system is described, and then Simplification System structure, finally according to the probability of malfunction space of the probability of malfunction space drafting whole system of each original paper.Paper shows, classical event tree cannot represent under multifactor impact condition, the failure condition of discrete component.Can only use the even polynary event tree of binary could describe the element fault situation under multifactor impact, and then describe the distribution that a plurality of elements form the probability of malfunction of system, by adjusting element (event) replacement cycle, guarantee the fiduciary level of element system.

Summary of the invention

For better invention being described, the electric system of simplicity of design is discussed here, and this system is constituted by a diode, and the nominal operation state of diode is affected by several factors, and wherein that main is t and c.Herein for the electric system by these two factors impacts as research object.In system, there are five primary elements , , , , , and be made as the element that had a significant effect by t and c, shown in its classical event tree Fig. 1.The event tree abbreviation of this system obtains: .

1. the fail-safe analysis of electrical equipment

5 essential electronic element in system , , , , probability of malfunction, be all subject to twith cimpact, i.e. the probability of malfunction of element , wherein under same, be twith cfunction as independent variable.When twith cduring one of two aspects fault, element just breaks down, according to the concept of logical OR as the formula (1).

(1)

Determine , must first determine with .The discrete component in system of setting up departments can not be repaiied after breaking down, and system is fixed a breakdown and realized by changing element.? can think the not cell failure probability of repairable system [8], and establish fault and reach 0.9999 element and should change (these data can obtain by given system failure rate back analysis, conventionally much smaller than this value), as shown in Equation 2.

(2)

In formula: for cell failure rate.

For , the normal work of electric elements all will have certain operating temperature range, higher or lower than this temperature range element, just breaks down, and this rule is expressed as to cosine curve herein, as shown in Equation 3.

(3)

In formula: afor range of temperature.

In fact dissimilar element has different life-spans service time and the scope of suitable working temperature.

2. the fail-safe analysis of electrical system

By Fig. 1 systematic failures tree abbreviation, obtained, formula (4) is as follows:

(4)

By classical event tree theory, obtain the system failure (top event) probability of happening, as the formula (5):

(5)

From formula (5), the function of reflection electrical malfunction probability, this function by determine, by formula (1), known again be by with , be by twith cfunction, by , twith cthe three-dimensional probability space forming distributes and equivalent curve.

3. guarantee the element replacement scheme of system reliability

The system conversion cycle: top event probability of happening during for the operation of system requirements.The system conversion cycle is a set of replacing scheme, and this scheme guarantees that certain system is within the scope of appointment influence factor, and its top event probability of happening is less than continuously certain probability of happening value in all factors , and according to the scheme of some cycles replacing elementary event.With represent.When during value " maximum " be Optimal Replacement scheme .Deterministic process is shown in embodiment in detail.

Accompanying drawing explanation

The event tree of Fig. 1 electrical system

Fig. 2 X1 element fault probability space distributes and equivalent curve

Fig. 3 X1 probability of malfunction space distribution and equivalent curve thereof

Fig. 4 X2 probability of malfunction space distribution and equivalent curve thereof

Fig. 5 X2 probability of malfunction space distribution and equivalent curve thereof

Fig. 6 X3 probability of malfunction space distribution and equivalent curve thereof

Fig. 7 X3 probability of malfunction space distribution and equivalent curve thereof

Fig. 8 X4 probability of malfunction space distribution and equivalent curve thereof

Fig. 9 X4 probability of malfunction space distribution and equivalent curve thereof

Figure 10 X5 probability of malfunction space distribution and equivalent curve thereof

The three-dimensional probability space of Figure 11 X5 system failure distributes and equivalent curve

The three-dimensional probability space of Figure 12 system failure distributes and equivalent curve

The three-dimensional probability space of Figure 13 system failure distributes and equivalent curve

The computation process of Figure 14 maximum desired replacement cycle

The computation process of Figure 15 maximum desired replacement cycle

The computation process of Figure 16 maximum desired replacement cycle

The computation process of Figure 17 maximum desired replacement cycle

Embodiment

Embodiment is the electrical system shown in Fig. 1.

1. the fail-safe analysis of electrical equipment

5 essential electronic element in system , , , , probability of malfunction, be all subject to twith cimpact, i.e. the probability of malfunction of element , wherein under same, be twith cfunction as independent variable.When twith cduring one of two aspects fault, element just breaks down, according to the concept of logical OR as shown in the formula:

(1)

Determine , must first determine with .The discrete component in system of setting up departments can not be repaiied after breaking down, and system is fixed a breakdown and realized by changing element.? can think the not cell failure probability of repairable system [8], and establish fault and reach 0.9999 element and should change (these data can obtain by given system failure rate back analysis, conventionally much smaller than this value), as shown in Equation 2.For , the normal work of electric elements all will have certain operating temperature range, higher or lower than this temperature range element, just breaks down, and this rule is expressed as to cosine curve herein, as shown in Equation 3.

(2)

(3)

In formula: for cell failure rate, afor range of temperature.

In fact dissimilar element has different life-spans service time and the scope of suitable working temperature, This document assumes that their usable range, the working time scope of research my god, working temperature is interval ° C.And calculate according to formula (2) and formula (3) with expression funtcional relationship within the scope of each. with in research range separately, not continuous, but piecewise function.The segmentation of each function represents as shown in table 1.

By table 2 and formula (1), can construct system element probability of malfunction space distribution and equivalent curve thereof, as shown in Fig. 2-Figure 11.

Table 1 with expression formula in survey region

In Fig. 2-Figure 11, probability of malfunction space distribution and equivalent curve thereof be all different, this is due to it twith cimpact cause.With regard to working time t, in the search time region of each element, in probability of malfunction spatial distribution map, there is the probability of malfunction in two or three regions obviously to reduce, while reaching probability of malfunction 0.9999 due to element, change new element and cause.Probability of malfunction when in fact this is changed can be by setting the probability of malfunction of whole system, use the inverting of polynary event tree Space Theory to obtain, the probability of malfunction that actual computation obtains is much smaller, in view of not using the method herein, and this example, only for explanation, is not introduced here in detail.With regard to working temperature c, owing to using cosine curve as representative function, the position of probability of malfunction minimum is in the middle of adaptive temperature scope.From image, the position that element fault probability is less concentrates on the zone line of temperature range.But element accident probability acceptable scope is less on figure, this is owing to using binary event tree to represent the inevitable outcome of element probability of malfunction.The stack of two probability has increased element total breakdown probability, and this phenomenon is used classical event tree to analyze.Certainly, the reason that also has element replacement excessive cycle.

The fail-safe analysis of 2 electrical systems

By Fig. 1 systematic failures tree abbreviation, obtained, formula (4) is as follows:

(4)

By classical event tree theory, obtain the system failure (top event) probability of happening, as the formula (5):

(5)

From formula (5), the function of reflection electrical malfunction probability, this function by determine, by formula (1), known again be by with , be by twith cfunction, by , twith cthe three-dimensional probability space distribution forming and equivalent curve thereof are as shown in Figure 3.

As can be seen from Figure 12, system fault probability is minimum constantly at t=0, and main cause is that in system, all elements constantly enter use state at t=0 simultaneously, and the probability of malfunction of each element is all very low during this period of time, and the probability of malfunction of whole system is reduced.Aspect serviceability temperature, the serviceability temperature of majority element is all at 20 ° of C to 30 ° of C, so system is lower at the probability of malfunction of this temperature range work.But along with the development of time, the probability of malfunction of element constantly increases, start to have element to be replaced, simultaneously other elements also maintain original probability of malfunction curvilinear trend and continue development, and the effect that the new element that makes to change reduces system fault probability is cancelled.The ability that each replacement of element cycle difference causes new element to improve system reliability is cancelled out each other, make near t=0 the system failure rate in other regions very high.Figure 13 can find out, each probability of malfunction forms isolated island, except the feature of upper surface analysis, each isolated island at temperature Shang center and inconsistent, this has also reflected that the adaptive temperature scope of constantly having changed element and these elements at this is all different.

3. the replacement cycle determines

Not considering cost, press order determine.First according to Fig. 2 analysis, determine the element replacement cycle in the time of 20 ° to 30 ° is as shown in table 2.

The element replacement cycle of table 2 in the time of 20 ° to 30 °

As shown in table 2 is the maximum desired replacement cycle of each element, if by above-mentioned bring calculating into , its change procedure is as Figure 14-Figure 17.Its final replacing element number of times 124 times.In table 2 just a solution scheme.

If this electric elements system 's , use enumeration methodology to calculate in above-mentioned variation range, meet .10 5in have 50929 to meet the demands.The minimum replacing of system element number of times is 85, , with 127 replacing much less of table 3 scheme, but meet in specialized range .

Claims (7)

1. guarantee a scheme for electrical system fiduciary level, it is characterized in that just affect two key factors of electrical equipment reliability: working time (t) and working temperature (c) are analyzed the reliability of discrete component, when particularly the working time of each element and suitable working temperature are different, it is difficult using traditional methods analyst system reliability, the present invention guarantees the fiduciary level of electrical system by adjusting element (event) replacement cycle, the reliability that mainly comprises electrical equipment is determined, the reliability of electrical system is determined, determining of electrical system element replacement cycle regimen can be widely used in analyze even under multiple factors influence condition, analyze the feature of electrical malfunction probability, and then determine the system element replacement cycle scheme that guarantees system reliability.
2. electrical system method for evaluating reliability based on event tree according to claim 1, is characterized in that, just affect two key factors of electrical equipment reliability: working time (t) and working temperature (c) are analyzed the reliability of discrete component; Use on this basis accident tree representation system architecture, by event tree, system architecture is carried out to abbreviation, obtain considering that the system fault probability under t and the impact of c factor distributes.
3. the reliability of electrical equipment according to claim 1 is determined, it is characterized in that, the probability of malfunction of element be twith cas the function of independent variable, when twith cduring one of two aspects fault, element just breaks down, according to the concept of logical OR for: determine , must first determine with , in the system of setting up departments, discrete component can not be repaiied after breaking down, and system is fixed a breakdown and is realized by changing element.
4. in system according to claim 3, discrete component can not be repaiied after breaking down, it is characterized in that, can think the not cell failure probability of repairable system, and establish fault and reach 0.9999 element and should change (these data can obtain by given system failure rate back analysis, conventionally much smaller than this value), be shown below:
; in formula: for cell failure rate.
5. in system according to claim 3, discrete component can not be repaiied after breaking down, it is characterized in that, for , the normal work of electric elements all will have certain operating temperature range, higher or lower than this temperature range element, just breaks down, and this rule is expressed as to cosine curve herein, is shown below:
in formula: afor range of temperature.
6. the reliability of electrical system according to claim 1 is determined, it is characterized in that, the system failure (top event) probability of happening, is shown below:
From formula, the function of reflection electrical malfunction probability, this function by determine; be by with , be by twith cfunction, by , twith cthe three-dimensional probability space forming distributes and equivalent curve.
7. determining of electrical system element replacement cycle regimen according to claim 1, is characterized in that, cycle method is determined in system conversion: top event probability of happening during for the operation of system requirements, the system conversion cycle is a set of replacing scheme, and this scheme guarantees that certain system specifying within the scope of influence factor, and its top event probability of happening is less than continuously certain probability of happening value in all factors , and according to the scheme of some cycles replacing elementary event, use represent 11.when during value " maximum " be Optimal Replacement scheme , establish this electric elements system 's , use enumeration methodology to calculate in above-mentioned variation range, meet , 10 5in have 50929 to meet the demands, embodiment system is minimum, and to change element number of times be 85, , meet .
CN201310029286.1A 2013-01-27 2013-01-27 Scheme guaranteeing reliability of electrical system CN103969519A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104361202A (en) * 2014-10-19 2015-02-18 辽宁工程技术大学 Scheme for guaranteeing reliability of electrical element

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Publication number Priority date Publication date Assignee Title
US20050160324A1 (en) * 2003-12-24 2005-07-21 The Boeing Company, A Delaware Corporation Automatic generation of baysian diagnostics from fault trees
CN102436519A (en) * 2011-08-23 2012-05-02 戴志辉 Method for synthetically evaluating dynamic reliability of power system automatic device
CN103258110A (en) * 2013-01-23 2013-08-21 辽宁工程技术大学 Method for determining accident trend of electrical system on basis of states

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Application publication date: 20140806