CN110912126B - Circuit breaker defect positioning method based on failure mechanism analysis - Google Patents
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Abstract
A circuit breaker defect positioning method based on failure mechanism analysis comprises the following steps: collecting fault history data of the circuit breaker; classifying and sorting historical data, and constructing a fault tree model; performing FMMEA analysis on the fault tree, and determining the priority of the fault, namely the hazard degree of each fault mode; and sorting the hazard degrees of the faults according to the hazard degree calculation results of various fault modes to obtain weak links of the system in design, structure or operation, and determining the positioning distribution of the possible defects of the circuit breaker. The invention not only can analyze the failure reason, but also can obtain the failure generation and development mechanism, thereby strengthening targeted equipment defect troubleshooting.
Description
Technical Field
The invention belongs to the technical field of power systems, relates to a detection and diagnosis technology of power equipment, and particularly relates to a defect positioning technology of primary power equipment.
Background
The circuit breaker is important equipment in the power grid, and the safe operation of the circuit breaker has important significance for the stability of the power grid. At present, common fault analysis methods in the engineering fields at home and abroad comprise fishbone pictures, FTA, FMEA, FMECA and FMMEA.
(1) Fishbone map (aka causality map, Ishikawa map).
The fishbone map is a theory that is proposed by mr. shichuan dian, a major administrative specialist in japan in 1953, and can conveniently and effectively research the association between the result and the cause, and is one of the popular analysis methods for finding the root cause of the problem. Researchers have constructed a perspective view that is structurally similar to a "fishbone" by organizing all possible factors that lead to system failure.
The fishbone graph is simple in structure, clear in hierarchy and good in observability, problems or defects are marked at the tail end of the graph, a plurality of subbranches are pulled out from the head end to the tail end, the reasons which can cause the problems are listed according to the occurrence probability, and the correlation and constraint relation between input (reasons) and output (problems) is determined. The disadvantages are that: firstly, the application range is narrow; secondly, the pertinence is not strong, and the reason analysis is not fully developed; thirdly, the analysis result of the complex equipment is inaccurate, and the like.
(2) Fault tree analysis FTA.
The FTA is a tree-shaped analysis structure, is developed by H.A.Watson of Bell laboratories, adopts a top-down deductive reasoning method to process system faults, has wide application range, is popularized from the military missile field to the engineering field in main application occasions, and is used for analyzing the failure of a large-scale complex system, the influence of events and the like. The result of FTA is a tree diagram showing the combination of events that may cause a system failure, all of which are unwanted events from top to bottom, all of which are classified into three types, top, middle and bottom, where the bottom event is considered to be the root cause of the failure, which is further classified into a basic failure and a trigger event, and the events are connected by different symbols through mutual causal relationships. The most important step is to construct a fault tree which can accurately describe the operation state of the system under various fault conditions, and the method is directly related to whether the fault reason can be accurately determined. Meanwhile, the FTA has the advantages of clear level, intuition and easy reading, and can perform qualitative analysis and quantitative analysis. The purpose of the qualitative analysis is to find the cause event or the combination of cause events causing the top event, i.e. to find all the minimal cut sets of the fault tree. The quantitative analysis aims to realize the risk evaluation of the equipment or the system, and the realization mode is to utilize the occurrence probability of the bottom event to evaluate the occurrence probability of the top event, namely, the occurrence probability of each minimal cut set is determined, and the analyzed occurrence probability of the fault, the reliability degree of the whole system and other contents are further objectively evaluated. However, FTA is a top-down deductive reasoning method for identifying a part of a system related to a specific failure, if FTA is used alone to analyze how the system avoids a single (or multiple) initial failure, it is impossible to find all possible initial failures by using fault tree analysis, and for a circuit breaker, such a complex electrical device with multiple disciplines crossing, if FTA is used only and depends on expert experience, objectivity of an analysis result is difficult to guarantee.
(3) Failure mode, failure mechanism and impact analysis FMMEA.
FMMEA was proposed in 1995 by the experts of CALCE, Maryland university, USA, Michael Pecht and Abhijit Dasgupta, with FMEA as the theoretical basis. FMMEA is a fault analysis method that studies the failure mechanism and its failure mode that each component of the system may have and determines the impact of each failure mechanism on the other components and operational functions of the system. It differs from FTA in that it is a bottom-up, from cause-to-effect, inductive analysis, with the order of analysis starting from the bottom analysis level (e.g., a component or a part) and proceeding upward to the set top analysis level. FMMEA alone can exhaustively list all incipient faults and identify their local effects and failure mechanisms, but is not suitable for testing multiple failures or their effects on the system level.
The FTA-FMMEA analysis method is used, mutual defects are complemented, the defects of the FMMEA serving as a single-factor analysis method in multi-fault analysis are made up, and the problems that the FTA initial fault analysis is incomplete and the blank in local influence and fault mechanism analysis are solved. Meanwhile, the innovation point of the invention is not only that the FTA-FMMEA comprehensive analysis method is used, but also that the quantitative analysis part is correspondingly improved, namely, the CA quantitative analysis method replaces the traditional RPN analysis, and the uncertainty brought by the expert experience to the FTA is optimized. Meanwhile, the implementation difficulty of the invention is that the required data type is historical statistical data, the required data is various and large in data amount, the observation time of the equipment of the data source is required to be longer, if the data is analyzed by being placed on a certain part, the workload is smaller, but the calculation amount is larger in the application of complex equipment.
In view of the problems of the prior art such as dependence on expert experience, single analysis result, insufficient pertinence, low accuracy and the like in analyzing equipment defects.
The invention provides a circuit breaker defect research method based on failure mechanism analysis. The method is a comprehensive research method which takes Fault Tree Analysis (FTA) and Fault mode, Fault mechanism and influence Analysis (FMMEA) as Failure mechanism Analysis ideas and Criticality Analysis (CA) as judgment standards of Fault severity. And based on relevant historical statistical data, the effective positioning of the weak link of the circuit breaker can be realized by the fault generation and development mechanism of the circuit breaker. Compared with the prior art, the method can analyze the fault reason, can also obtain the fault generation and development mechanism, and further strengthen targeted equipment defect troubleshooting.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a breaker defect positioning method based on failure mechanism analysis.
In order to solve the above problems in the prior art, the present invention specifically adopts the following technical solutions.
A breaker defect positioning method based on failure mechanism analysis is characterized by comprising the following steps:
step 1: collecting fault history data of the circuit breaker, wherein the collected fault history data take the time as a unit, and the fault types comprise body faults and mechanism faults;
step 2: based on the historical data of the breaker faults acquired in the step 1, listing all the faults of the breaker in the running period corresponding to the historical data, and establishing a fault tree model which takes the breaker faults as a top event, a fault mode as an intermediate layer and a fault source of the fault mode as a bottom event according to a logical relation; and the connection symbol between the upper-layer event and the lower-layer event of the fault tree model is an OR gate.
In the fault tree model of the application, the fault tree model is divided into 5 layers, a breaker fault is taken as a top event, a fourth layer event containing an OR logic relation is taken under the top event, a fault expression form, namely a fault mode, of each fourth layer event is respectively taken as a third layer event and a second layer event, wherein the second layer event is used for further classifying the third layer event and is taken as a fault reason corresponding to the fault mode of the second layer event as a bottom event;
in the fault tree, if the second-layer event is not included under the third-layer event, the fault mode of the third-layer event directly corresponds to the fault reason of the bottom event.
In the present application, the fourth layer events are "body failure" and "mechanism failure", respectively;
the next layer of the 'body fault' comprises a 'conductor loop fault' and an 'insulation fault' which are used as third-layer events, and an 'OR' logical relation is formed between the conductor loop fault and the insulation fault;
the next layer of the mechanism fault comprises a rejection fault, a misoperation fault and an energy storage fault which are used as third-layer events, and an OR logic relationship is formed among the rejection fault, the misoperation fault and the energy storage fault;
each third-layer event comprises a second-layer event according to the concrete expression of the failure mode, and the second-layer events belonging to the same third-layer event have logical relations of OR and/or Inclusion.
And step 3: in the fault tree model, FMMEA analysis is carried out on all bottom events one by one, so that the priority of the fault is determined;
in the fault tree model, the FMMEA analysis specifically includes the following:
3.1 selecting analysis subject (breaker or part thereof), analyzing failure mode
The analysis main body is a breaker corresponding to the top event, and can also be a component corresponding to the next layer event to which the top event belongs; searching all fault modes contained in the analysis main body according to the node structure of the fault tree model;
failure modes are the second and third levels of the failure tree,
the third layer includes but is not limited to conductive loop faults, insulation faults, failure to operate, malfunction faults, energy storage faults;
the second layer under failure of the conductive loop includes but is not limited to poor contact, contact erosion;
the second layer under insulation failure includes but is not limited to outer insulation failure, inner insulation failure;
the second layer under the rejection fault includes but is not limited to a secondary circuit fault, a mechanical fault;
the second layer under the malfunction failure includes, but is not limited to, a secondary circuit failure, a mechanical failure.
3.2 analyzing the fault reason for each fault mode;
subdividing each fault mode in a fault tree one by one, analyzing the fault reason of a certain fault mode when the fault mode is not subdivided any more, wherein the fault reason generated by the fault mode which is not subdivided any more is the bottom event of the fault tree;
3.3 determining the priority of each failure mode;
wherein, determining the fault modulus priority comprises the following steps:
3.3.1 analyzing each fault mode to determine a corresponding fault mechanism, and dividing the fault modes into stress type faults and loss type faults based on different fault mechanisms;
3.3.2 for each fault mode, calculating the occurrence probability, namely the fault modulus-frequency ratio of the fault mode based on the fault historical data of the circuit breaker;
wherein alpha isijIs a failure mode frequency ratio calculated as
Wherein N isiIndicates the total number of failures, N, during which the failure history data of the component i as the subject of the analysis occursjRepresenting the total number of occurrences of the jth failure mode within the same time period;
3.3.3 calculating the degree of harmfulness C of each component of the circuit breaker corresponding to various fault modesij：
Analyzing the threat level of the failure mode j of the subject i as CijThe expression is as follows:
Cij＝αijβijλit
in the formula, alphaijIs a failure mode frequency ratio; beta is aijThe failure influence rate indicates the fatality caused by the failure mode j, and the fatality is from small to large [0, 1 ]]Taking values, wherein the value of the fault influence rate of each fault mode corresponds to the determined hazard level of the fault mode;
λiis an average failure rate, representing i the average failure rate during the failure history data; t is the duration in days.
And 4, step 4: hazard level C in various failure modesijAnd sorting the damage degree of the faults according to the calculation result to obtain weak links of the system in design, structure or operation, and determining the positioning distribution of the possible defects of the circuit breaker.
The invention has the following beneficial technical effects:
compared with the traditional method, the superiority analysis of the invention is as follows:
the traditional fishbone picture has the following disadvantages: the method has the advantages that the application range is narrow, the method is generally only used for fault reason analysis, the research on fault generation and development mechanism is lacked, the early warning of the fault is difficult to realize, and the development for promoting the state evaluation of the electrical equipment is limited; secondly, the pertinence is not strong, and the reason analysis is not sufficiently developed; thirdly, for the circuit breaker and other multi-disciplinary crossing complex electrical equipment, the mapping relation between the fault cause and the fault itself is not one-to-one, if the fishbone diagram is used for fault analysis, the workload is large, the cause-effect relation cannot be clearly expressed, and omission is easily caused in the fault cause investigation stage, so that the analysis result is inaccurate.
Therefore, compared with a fishbone diagram, the FTA-FMMEA comprehensive analysis method has the advantages that the research on the failure mechanism of the system to be evaluated is added into the analysis thought, the root cause of the potential failure is promoted to be deduced, the early warning research on the failure can be realized, the defects of the system to be evaluated can be positioned, and the failure risk can be controlled from the source. Compared with the single-method application of FTA and FMMEA, the FTA-FMMEA makes up the blank of FTA in failure mechanism analysis and makes up the defect of FMMEA as a single-factor analysis method in multiple failure analysis.
Meanwhile, the conventional Risk Priority Number (RPN) quantitative analysis method is obtained by multiplying 3 Risk factors, namely, frequency, severity and undetected degree, but in the above quantitative evaluation, the analysis of the three Risk factors usually has a certain uncertainty, which is difficult to be represented by real numbers, i.e., the calculation model of the RPN lacks theoretical basis, and depends on the professional knowledge and the practical experience of the design engineer, so that the uncertainty of the evaluation is increased, and if the information fusion in the investigation stage is not good, the calculated RPN values are easy to be the same, so that the fault mode Risk sequence is disordered and the control measure arrangement is unreasonable. Therefore, quantitative evaluation of the FTA-FMMEA comprehensive analysis method is realized by a CA quantitative analysis method, and analysis errors caused by inaccurate representation of the RPN real number are avoided.
Drawings
FIG. 1 is a schematic diagram of the circuit breaker system of the present invention;
FIG. 2 is a schematic flow chart of a circuit breaker defect positioning method based on failure mechanism analysis according to the present invention;
FIG. 3 is a schematic diagram of a fault tree model structure with "breaker fault" as a top event according to the present invention;
fig. 4 is a fault tree for the present invention with "high voltage breaker operating mechanism fault" as the top event.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the drawings and the specific embodiments.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only relational terms determined for convenience in describing structural relationships of the parts or elements of the present disclosure, and do not refer to any parts or elements of the present disclosure, and are not to be construed as limiting the present disclosure.
In the present disclosure, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present disclosure can be determined on a case-by-case basis by persons skilled in the relevant art or technicians, and are not to be construed as limitations of the present disclosure.
For better understanding of the technical solution of the present invention, the technical terms used in the present invention are first described or defined as follows:
(1) the basic structure of the circuit breaker is as follows: the circuit breaker generally comprises an operating mechanism, a box body shell, a contact system, an arc extinguishing system, a release, a control unit and the like, and has the basic functions of switching on and switching off load and isolating faults through a switch, so that the aim of ensuring the safe and stable operation of a power system to the maximum extent is fulfilled. The circuit breaker is used as an electrical device integrating multiple disciplines and multiple professional fields, when the circuit breaker works in an opening state or a closing state, all sub-components in the circuit breaker must be matched in sequence and act in sequence through a control loop, and the action reliability of the circuit breaker can be guaranteed. The circuit breaker system is composed as shown in fig. 1.
(2) Other definitions.
a) The method has the following defects: some factor or factors that affect the maximum efficient operation of a device or system while it is still in operation.
b) Failure (also referred to as failure in this application): the device or system is forced to stop operating without the prescribed function.
c) The definition of the failure mode is: the failure mode refers to a certain expression that can be measured, observed and normatively described as the consequences and effects of a failure when the failure occurs, or can be understood as a certain expression that the subcomponents and systems at different levels cannot achieve or fulfill the intended functions.
Fig. 2 is a schematic flow chart of the failure mechanism analysis-based circuit breaker defect positioning method of the present invention, and the failure mechanism analysis-based circuit breaker defect positioning method disclosed by the present invention includes the following steps:
first, historical statistical data is collected.
The method comprises the steps of collecting fault history data of the circuit breaker, wherein the collected fault history data take the times as units, the fault types can be mainly divided into body faults and mechanism faults, the body faults include but are not limited to damage or burning of a switching-on/off coil, faults of an auxiliary switch, faults of a switching-on contactor, faults of secondary wiring, abnormal thermal imaging, external insulation pollution and the like, and the mechanism faults include but are not limited to mechanism jamming, sub-component deformation and displacement, shaft pin loosening or breakage, iron core clamping stagnation, locking failure, pull rod breakage and the like. Historical data of various faults above the circuit breaker are collected for analysis.
Secondly, listing all faults of the breaker in the operation period corresponding to historical data based on the historical data of the breaker faults acquired in the step 1, and establishing a fault tree model with 'breaker faults' as a top event, a fault mode as an intermediate layer and fault reasons of the fault mode as bottom events according to a logical relation;
in the fault tree model of the application, the fault tree model is divided into 5 layers, a breaker fault is taken as a top event, a fourth layer event of logical relation including OR is arranged under the top event, and the fourth layer event represents two major types of breaker faults divided from components.
Respectively taking the fault expression form, namely the fault mode, of each fourth layer event as a third layer event and a second layer event, wherein the second layer event is used for further classifying the third layer event and is taken as a bottom event which is a fault reason corresponding to the fault mode of the second layer event;
in the fault tree, if the second-layer event is not included under the third-layer event, the fault mode of the third-layer event directly corresponds to the fault reason of the bottom event.
In the present application, the fourth layer events are preferably "body failure" and "mechanism failure", respectively; namely, the breaker failure covers two major types of "body failure" and "mechanism failure".
The next layer of the 'body fault' comprises a 'conductor loop fault' and an 'insulation fault' which are used as third-layer events, and an 'OR' logical relation is formed between the conductor loop fault and the insulation fault;
the next layer of the mechanism fault comprises a rejection fault, a misoperation fault and an energy storage fault which are used as third-layer events, and an OR logic relationship is formed among the rejection fault, the misoperation fault and the energy storage fault;
each third-layer event comprises a second-layer event according to the concrete expression of the failure mode, and the second-layer events belonging to the same third-layer event have logical relations of OR and/or Inclusion.
As shown in fig. 3, the fault tree model is established for the present invention, wherein the "breaker fault" is used as a top event, the fault mode is used as a middle layer, and the fault cause of the fault mode is used as a bottom event. Referring to table 1, in the fault tree, the "breaker fault" T1 is taken as a top event, the breaker fault includes two major categories of a body fault F1 and a mechanism fault F2, and in the fault tree, the body fault F1 and the mechanism fault F2 are taken as a fourth layer of the fault tree belonging to the top event.
Continuing to decompose the fourth level event, in the body fault F1, it can be further divided into the conductive loop fault F3 and the insulation fault F4, so in the fault tree, the conductive loop fault F3 and the insulation fault F4 are regarded as the third level event belonging to the body fault F1 with logical or relationship.
Continuing with the analysis of insulation fault F4, which includes outer insulation fault F10 and inner insulation fault F11, inner insulation fault F11 includes both inner insulation flashover F17 and air gap discharge F18. In the fault tree, the outer insulation fault F10 and the inner insulation fault F11, which are in an or logical relationship, and the fault subordinate to the inner insulation fault F11 including the inner insulation flashover F17 and the gap discharge F18 are taken as the second layer of the fault tree. Each failure mode in the second and third layers serves as a middle layer of the failure tree, and some third-layer events in the failure tree cannot or need to be subdivided, such as the energy storage failure F7, which is a third-layer event belonging to the second-layer event mechanism failure F7, and the failure mode types are not further subdivided for the third-layer event energy storage failure F7.
And analyzing the fault reasons of the fault modes in detail, and taking the fault reasons corresponding to the fault modes of the second-layer events and the third-layer events which are not further subdivided in the fault tree as bottom events of the fault tree.
TABLE 1 implications of layers in breaker failure tree model
Thirdly, in the fault tree model, performing FMMEA analysis on all bottom events one by one, thereby determining the priority of the fault modes and calculating the hazard degree of each fault mode;
in the fault tree model, FMMEA analysis is carried out on all bottom events one by one, and the method comprises the following specific steps:
3.1 selecting an analysis subject (breaker or component thereof), analyzing the failure mode;
the analysis main body is a breaker corresponding to the top event, and can also be a component corresponding to the next layer event to which the top event belongs;
searching all fault modes contained in the analysis main body according to the node structure of the fault tree model;
failure modes are the second and third levels of the failure tree,
the third layer includes but is not limited to conductive loop faults, insulation faults, failure to operate, malfunction faults, energy storage faults;
the second layer under failure of the conductive loop includes but is not limited to poor contact, contact erosion;
the second layer under insulation failure includes but is not limited to outer insulation failure, inner insulation failure;
the second layer under the rejection fault includes but is not limited to a secondary circuit fault, a mechanical fault;
the second layer under the malfunction failure includes, but is not limited to, a secondary circuit failure, a mechanical failure.
3.2 analyzing the fault reason for each fault mode;
subdividing each fault mode in a fault tree one by one, analyzing the fault reason of a certain fault mode when the fault mode is not subdivided any more, wherein the fault reason generated by the fault mode which is not subdivided any more is the bottom event of the fault tree;
the failure cause is the corresponding bottom event of each layer of the failure tree: including but not limited to, loop resistance, unqualified mechanical characteristics, abnormal thermal imaging, current value and times of open circuit and break circuit exceeding the specified values of manufacturers, manufacturing process and familial defects, external insulation dirt, unqualified micro-water, insufficient internal insulation distance, internal burr tip discharge, conductive loop formed by metal impurities, secondary element loss, poor loop contact, mechanism jamming, mechanical abrasion, penetrating oil gas blocking, secondary element damage, parasitic loop, direct current high resistance grounding, product quality problems, motor damage, oil gas leakage and the like.
Failure mechanisms include, but are not limited to, wear, fatigue, electromigration, and external forces.
(a) A failure mode is determined.
According to the national standard GJB451A-2005 reliability maintenance Provisioning terminology, the definition of failure mode is: the failure mode refers to a certain expression that can be measured, observed and normatively described as the consequences and effects of a failure when the failure occurs, or can be understood as a certain expression that the subcomponents and systems at different levels cannot achieve or fulfill the intended functions. For the determined portion, all possible failure modes are listed; for each sub-component to be included in the analysis, the corresponding function and potential failure mode needs to be identified. For example, for an auxiliary contact of a high-voltage circuit breaker, the potential failure mode is poor contact and the like.
(b) A potential cause of the fault is determined.
In the FTA-FMMEA analysis flow, the cause of failure is defined as the environmental conditions and operating conditions, i.e., stress conditions, that induce the failure mode. For example, aging and insufficient elasticity of the spring are one of the potential causes of jamming and non-starting of the iron core of the high-voltage circuit breaker. Analyzing the cause of the failure helps to determine the important failure mechanisms in the sub-component to be analyzed that lead to failure modes. The two common failure cause analysis methods are that the cause is searched from the design, manufacture, storage, transportation or use conditions causing potential failure modes; and secondly, the reason for inducing the fault of the system to be evaluated is confirmed according to historical data by referring to the maintenance and maintenance data of the same equipment or the same system.
(c) And determining a potential failure mechanism.
The failure mechanism is a concept distinguished from factors such as failure mode, cause, location, type, etc., and means a process of a specific combination of physical, electrical, chemical, and mechanical stress, etc., which causes a failure. There should be a corresponding failure mechanism for each failure mode. It can be classified into an overstress type failure and a wear type failure. The former refers to failure resulting from a single load (stress) condition, and the latter refers to failure resulting from an accumulated load (stress) condition. For example, if a high-voltage circuit breaker is in normal operation, if a sudden impact caused by some external force causes a crack in a porcelain bushing inside equipment to generate severe discharge, so that the circuit breaker is in a condition that the circuit breaker must be immediately withdrawn from operation, the failure mechanism can be considered to be an overstress type; if the failure is a failure of the iron core caused by jamming due to fatigue or abrasion, the failure mechanism is considered to be a wear type. The determination of the potential failure mechanism is similar to the determination method of the failure reason, and mainly depends on past experience, product tests, similar product methods and the like.
3.3 determining the priority of each failure mode;
wherein, determining the fault modulus priority comprises the following steps:
3.3.1 analyzing each fault mode to determine a corresponding fault mechanism, and dividing the fault modes into stress type faults and loss type faults based on different fault mechanisms;
3.3.2 for each fault mode, calculating the occurrence probability, namely the fault modulus-frequency ratio of the fault mode based on the fault historical data of the circuit breaker;
dividing various fault modes into n preset hazard levels from heavy to light according to the influence degrees of the various fault modes; when the technical scheme is used for positioning the defects of the circuit breaker, the technical staff in the field can classify the fault modes of the circuit breaker into different hazard grades according to the actual operation level of the circuit breaker, the safety requirements of the power grid where the circuit breaker is located and other actual conditions, and the classification of the different hazard grades does not influence the implementation of the technical scheme.
In the preferred embodiment of the present application, the failure modes are classified from heavy to light into 5 hazard classes (i.e., impact classes) (as shown in table 2).
TABLE 2
Calculating the occurrence probability of each fault mode, namely the fault modulus-frequency ratio according to the following formula,
wherein alpha isijIs a failure mode frequency ratio calculated as
Wherein N isiIndicates the total number of failures, N, during which the failure history data of the component i as the subject of the analysis occursjRepresenting the total number of occurrences of the jth failure mode within the same time period; table 3 below shows a reference table for estimation of failure probability levels (i.e., failure mode frequency ratios) in the present application.
TABLE 3
3.3.3 calculating the degree of harmfulness C of each component of the circuit breaker corresponding to various fault modesij：
Analyzing the threat level of the failure mode j of the subject i as CijThe expression is as follows:
Cij＝αijβijλit
in the formula, the meanings of the parameters are shown in Table 4, alphaijIs a failure mode frequency ratio; beta is aijThe failure influence rate indicates the fatality caused by the failure mode j, and the fatality is from small to large [0, 1 ]]The values of intervals are, in the preferred embodiment of the present application, as shown in table 5.
λiIs an average failure rate, representing i the average failure rate during the failure history data; t is the duration in days.
TABLE 4
TABLE 5
The fourth step: hazard level C in various failure modesijCalculating the damage degree of the fault according to the calculated resultAnd sequencing to obtain system weak links in design, structure or operation, and determining the positioning distribution of the possible defects of the circuit breaker.
In conclusion, based on the above steps, important information is summarized, the advanced research of an intelligent diagnosis technology aiming at a main fault mode and a fault mechanism thereof is emphasized, meanwhile, the protection and the monitoring of a system weak link are also enhanced, the service life and the service life of equipment can be effectively prolonged only by detecting the system weak link and stopping loss in time through effective maintenance when the system weak link is in a defective state, and a theoretical basis is provided for the daily maintenance management and the targeted planned maintenance of the system or the equipment.
The technical solution of the present invention is further described by a specific embodiment.
Example FTA-FMMEA-based Circuit breaker operating mechanism failure mechanism analysis
The operating mechanism is not only a key mechanical part for the high-voltage circuit breaker to perform opening and closing operations, but also an action executing mechanism of the circuit breaker, which has the highest failure frequency and the annual rising failure rate in recent years according to the data display of the international large power grid organization in the last two times (1988 to 1991 and 2004 to 2007) of the global investigation in the world. In the section, a spring operating mechanism of the circuit breaker is taken as an example, FTA-FMMEA analysis is carried out based on a failure mechanism of the circuit breaker, and weak links are located.
First, the spring operation mechanism is divided into different positions. The operating mechanism can be divided into a breaking element (such as a switch and the like), a transmission mechanism (such as a mechanism output connecting rod and the like), a base and an operating mechanism (such as a closing spring, an opening spring and the like). Then, using "spring operating mechanism failure" as a top event, based on the historical data and the information obtained by similar product method combing, establishing a failure tree model as shown in fig. 4, wherein the top event, the middle event and the bottom event replaced by letters in the diagram are shown in table 6, and the relationship between the upper layer event and the lower layer event is "or".
Table 6 example top event, middle event and bottom event correspondence table
According to the data provided by the high-voltage switch of the institute of electrical power science in China, as shown in table 7 (1999) 2003, the distribution system of accidents and obstacles of the high-voltage circuit breakers of the national power system according to voltage grades and types), the feasibility of the FTA-FMMEA is verified. In terms of the occurrence frequency and trend of accidents, the circuit breakers with the voltage class of 110kV and 220kV have more accidents, wherein the accident rate of the circuit breakers with the voltage class of 220kV reaches 0.069-0.126 per hundred machines per year.
TABLE 7
As can be seen from the statistical data in table 7, during the period from 1999 to 2003, the total of 5 high-voltage circuit breakers of voltage classes from 66kV to 500kV have faults 1133 times, wherein the maximum fault rate of the circuit breakers of voltage classes of 110kV and 220kV is 437 times and 599 times, which together account for 91.4% of the total fault rate, especially the circuit breakers of voltage classes of 220kV have the greatest refusal, misoperation and insulation accidents, and the factors causing the most faults by the voltage classes are external force and other 392 times, which account for 71.7%, and the factors causing the most faults by the voltage classes are 82 times, which account for 15.0%, and are 48 times of misoperation, which account for 8.8%. Among mechanical faults capable of carrying out failure analysis, the action-refusing faults occur 177 times in total, account for 15.6% of the total number of faults, and the action-mising faults occur 95 times in total, account for 8.4% of total fault statistics data of the circuit breaker in 5 years.
The reason of the failure of the refusal action is analyzed by combining the statistical data and the fault tree model, and two main reasons of the failure of the refusal action are provided, namely, the failure caused by the secondary circuit and the auxiliary contact and the mechanical failure. The faults caused by the secondary circuit and the auxiliary contact include two types of secondary element loss and poor circuit or contact of the contact, and the mechanical faults are mainly reflected in three aspects of mechanism clamping stagnation, mechanical abrasion, seepage oil gas locking and the like. In practical conditions, the total number of failures caused by failures of the operating mechanism and the transmission mechanism thereof is 113, which is 63.8 percent of the total failure times, the number of failures caused by the electrical reasons of the control and auxiliary secondary circuit is 55, which is 31.1 percent of the total failure times, and the number of failures caused by other reasons such as external force is 9, which is 5.1 percent of the total failure times. Then the failure mode summary analysis statistical analysis for the failure to reject failure is as follows:
the electrical reasons causing the failure of the control and auxiliary secondary circuit mainly include the damage or burning of the switching-on and switching-off coil, the failure of an auxiliary switch, the failure of a switching-on contactor and the like. The damage or burning of the opening and closing coil is caused by the fact that the electrified time of the coil is prolonged to some extent due to the occurrence of mechanical faults; although the fault of the auxiliary switch and the fault of the closing contactor are distributed to the failure caused by the control and auxiliary secondary circuits due to the position of the component and the fault expression form, the fault is caused by mechanical factors such as the failure of the contact to normally perform the switching operation in many cases.
The main causes of faults of the operating mechanism and the transmission mechanism thereof are mechanism clamping stagnation, component deformation and displacement, shaft pin loosening or breaking, opening and closing iron core clamping stagnation and the like. The frequency of mechanism jamming is the highest, and the generation reason is mainly 4 points: firstly, because the working cooperativity of the coil and the iron core is poor, the resistance suffered by the iron core in the movement process is strong; secondly, the aging degree of the coil is deepened while the service life of the equipment is prolonged, and the voltage value is gradually insufficient to drive the iron core to generate enough displacement; thirdly, the transmission part (such as a connecting rod) deforms and breaks under the corresponding stress condition; fourthly, the inside of the valve body of the mechanism is rusted and the like.
The cause of the malfunction fault is analyzed by combining the statistical data and the fault tree model, and two causes of the malfunction are mainly used, namely, the malfunction of the secondary circuit caused by the electrical fault and the malfunction caused by the fault of the mechanical mechanism. The number of secondary circuit malfunctions due to an electrical failure is 48 times, which is 50.5 times the total number of malfunctions, the number of mechanical failure malfunctions is 21 times, which is 22.1 times the total number of malfunctions, and the number of external force malfunctions is 3 times.
In the malfunction fault, the main potential cause of the malfunction of the secondary circuit is that the humidity is unreasonable, so that the terminal strip is affected by moisture, the insulation strength is affected, and then the malfunction caused by the short circuit of the secondary circuit wiring terminal is easily induced. Other reasons are defects in the manufacture of the secondary parts, error signals from the relay protection device, etc. The malfunction caused by the mechanical failure is mainly due to quality problems at the manufacturing level and unreasonable equipment design.
On the basis, the failure mode and the cause thereof are analyzed by taking the malfunction failure and the malfunction failure with the highest occurrence frequency as analysis objects. The reason sorting table based on the failure characteristics of the breaker spring operation mechanism is shown in table 8 (failure characteristics, reason sorting table based on the breaker spring operation mechanism).
TABLE 8
As can be seen from table 8, wear, fatigue, electromigration, and external force action are the main failure mechanisms causing the failure of the operation rejection and the malfunction, wherein the wear mechanisms can be subdivided into adhesive wear caused by insufficient lubrication, and abrasive wear caused by particles generated by dust and friction; the fatigue mechanism is a failure mechanism caused by alternating load and transition from defects such as dislocation, slippage, cavities and the like to crack generation and fracture generation, and can be subdivided into the operation mechanism and transmission mechanism component fractures caused by asymmetric pulse cyclic stress and pulse cyclic stress, such as contact finger fracture, latch component deformation, collision rod of a transmission mechanism, four-bar linkage and other component deformations; the electromigration mechanism is mainly current fluctuation or current leakage caused by wire mixing. The type of primary failure mechanism described above is wear-type.
According to the analysis result of the fault tree in this embodiment, that is, if the probability of occurrence of the operation rejection fault is 15.6% of the total fault rate and the probability of occurrence of the malfunction fault is 8.8% of the total fault rate, the reference table for estimating the level of the system failure probability is combined), it can be known that the level of the probability of occurrence of the operation rejection fault is level B and the level of the probability of occurrence of the malfunction fault is level C. When the fault of the refusal action and the fault of the misoperation occur, the breaker can not normally operate, the function of the equipment can be considered to be lost, meanwhile, the influence caused by the refusal action fault is not only reflected in the fault breaker and a connected line, meanwhile, the override trip can occur, the fault domain is further expanded, the influence level of the fault consequence generally divided into 5 and the like according to the general fault influence classification standard can be obtained, and the influence of the fault of the refusal action and the fault of the misoperation is II type. In conjunction with the failure priority evaluation criteria shown in table 9 (failure priority evaluation criteria), the risk levels of the malfunction-denied and malfunction failures are high risk level and medium risk level, respectively.
TABLE 9
On the basis, the damage degree of several fault modes of the circuit breaker failure and misoperation faults is evaluated by CA quantitative analysis, and each evaluation parameter value is shown in a table 10 (each evaluation parameter value of multiple fault modes of the circuit breaker failure and misoperation types).
Watch 10
Quantitative analysis of index C from CA calculated in Table 10ijThe severity of the obtained fault modes can be known, and the fault modes with the highest harm degree are damage or burning of the switching-on/off coil, secondary circuit misoperation, mechanism clamping stagnation, sub-component deformation and displacement, mechanical mechanism misoperation, shaft pin loosening or breakage and the like. Considering that the risk of a malfunction failure is higher than that of a malfunction failure, the failure modes in the two types of malfunction with high severity can be considered to be weaker in the monitoring level than the failure modes in the remaining 4 types of malfunction. The problems reflected by the above-mentioned high severity of weak links are as follows:
(1) manufacturing problems. Not only are domestic circuit breakers, but also imported equipment has quality problems at the manufacturing level from manufacturing and installation to operation. The domestic circuit breaker has the problems that the quality of raw materials for manufacturing mechanical mechanisms is worried, the manufacturing process of workmanship and imported equipment is rough, the control and inspection coverage in the production and manufacturing process is insufficient, the quality problem causes failure and damage of various sub-components when the sub-components are not in the expected service life, and the reliability of the daily operation of the circuit breaker cannot be guaranteed.
(2) And (5) overhauling. In the survey from 1999 to 2003, the failure due to improper service was 20.1%. Therefore, when strengthening the comprehensive training to the maintainer, in order to avoid the blindness maintenance, and accelerate the transition from the preventive maintenance to the state maintenance, the strength for popularizing the intelligent diagnosis technology should be enhanced, the establishment of the fault characteristic database is accelerated, and the health degree of the equipment is supervised by using the online monitoring system, so that the maintenance quality is ensured, the early warning of the high-voltage circuit breaker is researched and judged to the real position, and the brick and tile can be added to the long-term stable operation of the system.
(3) And (5) making related measures. According to various accident analysis experiences and from the perspective of anti-accidents, effective preventive measures are purposefully drawn up for various circuit breakers respectively, and the occurrence probability of similar accidents is effectively reduced.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (9)
1. A breaker defect positioning method based on failure mechanism analysis is characterized by comprising the following steps:
step 1: collecting fault history data of the circuit breaker, wherein the collected fault history data take the time as a unit, and the fault types comprise body faults and mechanism faults;
step 2: listing all faults of the circuit breaker in the running period corresponding to the fault history data based on the circuit breaker fault history data acquired in the step 1, and establishing a fault tree model with 'circuit breaker fault' as a top event, a fault mode as an intermediate layer and a fault source of the fault mode as a bottom event according to a logical relation; wherein, the connection symbol between the upper and lower events of the fault tree model is OR gate;
and step 3: in the fault tree model, performing FMMEA analysis on all bottom events one by one, thereby determining the priority of the fault and determining the hazard degree of each fault mode;
Cij＝αijβijλit
in the formula, CijThe severity of failure mode j for component i; alpha is alphaijIs a failure mode frequency ratio; beta is aijThe failure influence rate represents the fatality caused by the failure mode j; lambda [ alpha ]iThe average failure rate represents the average failure rate of the component i in the operation period corresponding to the failure history data; t is the time length in days; if the component i is broken and burnt out, the component i needs to be replaced; then beta isij1 is ═ 1; if the component i is deformed, bent and worn, the maximum operation efficiency of the equipment is influenced; then beta isij0.5; if the component i fails due to accidental external force factors with the occurrence probability less than or equal to 0.1 percent, beta isij0.1; if the component i does not fail, it is not damaged; then beta isij＝0；
And 4, step 4: hazard level C in various failure modesijAnd sorting the hazard degree of the fault modes according to the calculation results to obtain system weak links in design, structure or operation, so as to determine the positioning distribution of the possible defects of the circuit breaker.
2. The failure mechanism analysis-based circuit breaker defect positioning method according to claim 1, characterized in that:
in the step 1, the fault types are divided into a body fault and a mechanism fault, the body fault comprises damage or burnout of a switching-on/off coil, fault of an auxiliary switch, fault of a switching-on contactor, fault of secondary wiring, abnormal thermal imaging and external insulation pollution, and the mechanism fault comprises mechanism jamming, sub-component deformation and displacement, shaft pin loosening or breakage, iron core clamping stagnation, latch failure and pull rod breakage.
3. The failure mechanism analysis-based circuit breaker defect positioning method according to claim 1, characterized in that:
in the fault tree model described in step 2, the fault tree model is divided into 5 layers, a "breaker fault" is used as a top event, a fourth layer event containing an or logical relationship under the top event, and a fault expression form, i.e., a fault mode, of each fourth layer event is respectively used as a third layer event and a second layer event, wherein the second layer event is used for further classifying the third layer event, and is used as a bottom event for a fault reason corresponding to the fault mode of the second layer event.
4. The failure mechanism analysis-based circuit breaker defect positioning method of claim 3, wherein:
in the fault tree model, if the second-layer event is not included under the third-layer event, the fault reason corresponding to the fault mode of the third-layer event is directly used as the bottom event.
5. The method for locating the defect of the circuit breaker based on the failure mechanism analysis as claimed in claim 3 or 4, wherein:
the fourth layer events are 'body fault' and 'mechanism fault' respectively;
the next layer of the 'body fault' comprises a 'conductive loop fault' and an 'insulation fault' which are used as third-layer events, and an 'OR' logical relation is formed between the 'conductive loop fault' and the 'insulation fault';
the next layer of the mechanism fault comprises a rejection fault, a misoperation fault and an energy storage fault which are used as third-layer events, and an OR logic relationship is formed among the rejection fault, the misoperation fault and the energy storage fault;
each third-layer event comprises a second-layer event according to the concrete expression of the failure mode, and the logical relation of the second-layer events belonging to the same third-layer event is OR.
6. The failure mechanism analysis-based circuit breaker defect positioning method according to claim 1, characterized in that:
in step 3, the FMMEA analysis specifically includes the following:
3.1 selecting an analysis main body and analyzing a fault mode;
3.2 analyzing the fault reason for each fault mode;
in the fault tree model, each fault mode is subdivided one by one, when a certain fault mode is not subdivided, the fault reason of the fault mode is analyzed, and the fault reason generated by the fault mode which is not subdivided is the bottom event of the fault tree model;
3.3 determining the priority of each failure mode.
7. The failure mechanism analysis-based circuit breaker defect positioning method of claim 6, wherein:
in step 3.1, the analysis agent is a breaker corresponding to the top event or a component corresponding to the next layer event to which the top event belongs.
8. The failure mechanism analysis-based circuit breaker defect location method of claim 7, wherein:
in step 3.1, all fault modes contained in the analysis main body are searched according to the node structure of the fault tree model;
failure modes are the second and third levels of the failure tree model,
the third layer comprises a conductive loop fault, an insulation fault, a failure to operate, a malfunction fault and an energy storage fault;
the second layer under the failure of the conductive loop comprises poor contact and ablation of a contact;
the second layer under the insulation fault comprises an outer insulation fault and an inner insulation fault;
the second layer under the action rejection fault comprises a secondary circuit fault and a mechanical fault;
the second layer under the malfunction fault includes a secondary loop fault, a mechanical fault.
9. The method for locating the defect of the circuit breaker based on the failure mechanism analysis as claimed in claim 6 or 7, wherein:
in step 3.3, determining the priority of each failure mode specifically includes the following:
3.3.1 analyzing each fault mode to determine a corresponding fault mechanism, and dividing the fault modes into stress type faults and loss type faults based on different fault mechanisms;
3.3.2 for each fault mode, calculating the occurrence probability, namely the frequency ratio of the fault modes, of the fault mode based on the fault historical data of the circuit breaker;
wherein alpha isijIs a failure mode frequency ratio calculated as
Wherein N isiIndicates the total number of failures, N, of the component i as the analysis subject during the operation period corresponding to the failure history datajRepresenting the total number of occurrences of the jth failure mode within the same time period;
3.3.3 calculating the degree of harmfulness C of each component of the circuit breaker corresponding to various fault modesij。
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