1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationAnalysis techniques for dependability Petri net techniquesBS EN 62551:2012National forewordThis British Standard is the UK implementation of EN 62551:2012. It is identical to IEC
2、 62551:2012.The UK participation in its preparation was entrusted to Technical Committee DS/1, Dependability.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. User
3、s are responsible for its correct application. The British Standards Institution 2012.Published by BSI Standards Limited 2012 ISBN 978 0 580 61353 1 ICS 21.020 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of
4、the Standards Policy and Strategy Committee on 30 November 2012.Amendments issued since publicationDate Text affectedBRITISH STANDARDBS EN 62551:2012EUROPEAN STANDARD EN 62551 NORME EUROPENNE EUROPISCHE NORM November 2012 CENELEC European Committee for Electrotechnical Standardization Comit Europen
5、de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2012 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62551:2012 E ICS 21.020 English version
6、 Analysis techniques for dependability - Petri net techniques (IEC 62551:2012) Techniques danalyse de sret de fonctionnement - Techniques des rseaux de Petri (CEI 62551:2012) Analysemethoden fr Zuverlssigkeit - Petrinetze (IEC 62551:2012) This European Standard was approved by CENELEC on 2012-11-06.
7、 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained
8、 on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to th
9、e CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hu
10、ngary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 62551:2012EN 62551:2012 - 2 - Foreword The text of document 56/1476/FDIS, future edition 1 of
11、 IEC 62551, prepared by IEC/TC 56 “Dependability“ was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62551:2012. The following dates are fixed: latest date by which the document has to be implemented at national level by publication of an identical national standard or by e
12、ndorsement (dop) 2013-08-06 latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2015-11-06 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held respo
13、nsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 62551:2012 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards in
14、dicated: IEC 61508 Series NOTE Harmonised as EN 61508 Series (not modified). IEC 61508-4:2010 NOTE Harmonised as EN 61508-4:2010 (not modified). IEC 61508-1:2010 NOTE Harmonised as EN 61508-1:2010 (not modified). IEC 61165:2006 NOTE Harmonised as EN 61165:2006 (not modified). IEC 60812:2006 NOTE Har
15、monised as EN 60812:2006 (not modified). IEC 61025:2006 NOTE Harmonised as EN 61025:2007 (not modified). IEC 61078:2006 NOTE Harmonised as EN 61078:2006 (not modified). IEC 61511-3:2003 NOTE Harmonised as EN 61511-3:2004 (not modified). IEC 61703:2001 NOTE Harmonised as EN 61703:2002 (not modified).
16、 BS EN 62551:2012- 3 - EN 62551:2012 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated r
17、eferences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Titl
18、e EN/HD Year IEC 60050-191 1990 International Electrotechnical Vocabulary (IEV) - Chapter 191: Dependability and quality of service - - BS EN 62551:2012 2 62551 IEC:2012 CONTENTS INTRODUCTION . 7 1 Scope . 8 2 Normative references . 8 3 Terms, definitions, symbols and abbreviations 8 3.1 Terms and d
19、efinitions 8 3.2 Symbols and abbreviations 10 4 General description of Petri nets 12 4.1 Untimed low-level Petri nets 12 4.2 Timed low-level Petri nets . 12 4.3 High-level Petri nets 13 4.4 Extensions of Petri nets and modelling with Petri nets . 13 4.4.1 Further representations of Petri net element
20、s 13 4.4.2 Relationship to the concepts of dependability 14 5 Petri net dependability modelling and analysis 15 5.1 The steps to be performed in general 15 5.2 Steps to be performed in detail 16 5.2.1 General . 16 5.2.2 Description of main parts and functions of the system (Step 1) 16 5.2.3 Modellin
21、g the structure of the system on the basis of Petri net-submodels and their relations (Step 2). 16 5.2.4 Refining the models of Step 2 until the required level of detail is achieved (Step 3) 18 5.2.5 Analysing the model to achieve the results of interest (Step 4) 18 5.2.6 Representation and interpre
22、tation of results of analyses (Step 5) 19 5.2.7 Summary of documentation (Step 6) 20 6 Relationship to other dependability models . 20 Annex A (informative) Structure and dynamics of Petri nets . 22 Annex B (informative) Availability with redundancy m-out-of-n . 33 Annex C (informative) Abstract exa
23、mple 39 Annex D (informative) Modelling typical dependability concepts . 43 Annex E (informative) Level-crossing example . 45 Bibliography 62 Figure 1 Weighted inhibitor arc 13 Figure 2 Place p is a multiple place 14 Figure 3 Marking on p after firing of transition t 14 Figure 4 The activation of t
24、depends on the value of V . 14 Figure 5 Methodology consisting mainly of modelling, analysing and representing steps. 15 Figure 6 Process for dependability modelling and analysing with Petri nets . 15 Figure 7 Modelling structure concerning the two main parts plant and control with models for their
25、functions and dependability . 17 Figure 8 Indication of the analysis method as a function of the PN model 19 BS EN 62551:201262551 IEC:2012 3 Figure A.1 Availability state-transition circle of a component 22 Figure A.2 Transition failure is enabled 23 Figure A.3 Faulty place marked due to firing of
26、failure . 23 Figure A.4 Transition comp1repair is enabled 24 Figure A.5 The token at the maintenance crew available location is not used . 24 Figure A.6 Transition is not enabled . 25 Figure A.7 Marking before firing . 25 Figure A.8 Marking after firing 25 Figure A.9 PN with initial marking 25 Figur
27、e A.10 Corresponding RG 25 Figure A.11 Transitions complprepair and comphpfailure are enabled 26 Figure A.12 Marking after firing of transition complprepair . 27 Figure A.13 A timed PN with two exponentially distributed timed transitions . 28 Figure A.14 The corresponding stochastic reachability gra
28、ph . 28 Figure A.15 Petri net with timed transitions 29 Figure B.1 Two individual item availability nets with specific failure- and repair-rates . 33 Figure B.2 Stochastic reachability graph corresponding to Figure B.1 with global states (as an abbreviation 1c is used for “comp1faulty”) . 33 Figure
29、B.3 Three individual item availability nets with specific failure rates and repair rates . 33 Figure B.4 Stochastic reachability graph corresponding to Figure B.3 with global states (as an abbreviation 1cis used for comp1faulty) . 34 Figure B.5 Specifically connected 1-out-of-3 availability net . 35
30、 Figure B.6 Specifically connected 2-out-of-3 availability net . 35 Figure B.7 Specifically connected 3-out-of-3 availability net . 36 Figure B.8 Stochastic reachability graph with system specific operating states 36 Figure B.9 Specifically connected 1-out-of-3 reliability net 37 Figure B.10 Reachab
31、ility graph for the net in Figure B.9 . 37 Figure B.11 Specifically connected 2-out-of-3 reliability net 37 Figure B.12 Reachability graph for the net in Figure B.11 . 37 Figure B.13 Specifically connected 3-out-of-3 reliability net 38 Figure B.14 Reachability graph for the net in Figure B.13 . 38 F
32、igure C.1 Individual availability net . 39 Figure C.2 Stochastic availability graph of the net in Figure C.1 with its global states and aggregated global states according to availability and safety 39 Figure C.3 Basic reliability and function modelling concept 40 Figure C.4 General hierarchical net
33、with supertransitions to model reliability . 41 Figure C.5 General hierarchical net with supertransitions and superplaces 41 Figure C.6 General hierarchical net with supertransitions to model availability . 41 Figure C.7 General hierarchical net with supertransitions and superplaces 42 Figure E.1 Ap
34、plied example of a level crossing and its protection system 45 Figure E.2 Main parts of the level crossing example model 46 Figure E.3 Submodels of the level crossing example model . 47 Figure E.4 PN model of car and train traffic processes . 48 BS EN 62551:2012 4 62551 IEC:2012 Figure E.5 PN model
35、of the traffic processes and traffic dependability . 49 Figure E.6 PN model of the traffic process with an ideal control function 50 Figure E.7 PN model of the level crossing example model . 51 Figure E.8 Collected measures of the road traffic flow of a particular level crossing: Time intervals betw
36、een two cars coming to the level crossing . 52 Figure E.9 Approximated probability distribution function based on the measures depicted in Figure E.5 . 53 Figure E.10 Collected measurements of time spent by road vehicle in the danger zone of the level crossing . 53 Figure E.11 Approximated probabili
37、ty distribution function based on measurements depicted in Figure E.10 . 54 Figure E.12 Aggregated RG and information about the corresponding states . 59 Figure E.13 Results of the quantitative analysis showing the level crossing average availability for road traffic users as a function of the prote
38、ction equipment hazard rate for different used activation and approaching times TAC60 Figure E.14 Results of the quantitative analysis showing the individual risk of the level crossing users as a function of the protection equipment hazard rate for different used activation and approaching times TAC
39、. 60 Figure E.15 Availability safety diagram based on the quantitative results of the model analysis shown in Figure E.13 and Figure E.14 . 61 Table 1 Symbols in untimed Petri nets . 10 Table 2 Additional symbols in timed Petri nets . 11 Table 3 Symbols for hierarchical modelling 11 Table 4 Correspo
40、nding concepts in systems, Petri nets and dependability . 15 Table 5 Mandatory and recommended parts of documentation . 20 Table A.1 Corresponding concepts in systems, Petri nets, reachability graphs and dependability 26 Table A.2 Place and transition with rewards . 32 Table D.1 Dependability concep
41、ts modelled with PN structures . 43 Table D.2 Modelling costs of states and events 44 Table E.1 Car-related places in the submodel Traffic process (see Figure E.4) 52 Table E.2 Car-traffic related transitions in the submodel Traffic process and Traffic dependability (see Figure E.7) 55 Table E.3 Tra
42、in-traffic related places in the submodel Traffic process (see Figure E.7) 55 Table E.4 Train-traffic related transitions in the submodel Traffic process (see Figure E.7) 56 Table E.5 Places in the submodel Traffic dependability (see Figure E.7) 56 Table E.6 Transitions in the submodel Traffic depen
43、dability (see Figure E.7) . 56 Table E.7 Places in the submodel Control function (see Figure E.7) . 57 Table E.8 Transitions in the submodel Control function (see Figure E.7) 57 Table E.9 Places in the submodel Control equipment dependability (see Figure E.7) . 57 Table E.10 Transitions in the submo
44、del Control equipment dependability (see Figure E.7) 58 Table E.11 Specification of boolean conditions for states to be subsumed in an aggregated state . 59 BS EN 62551:201262551 IEC:2012 7 INTRODUCTION This International Standard provides a basic methodology for the representation of the basic elem
45、ents of Petri nets (PNs) 11and provides guidance for application of the techniques in the dependability field. The inherent power of Petri net modelling is its ability to describe the behaviour of a system by modelling the relationship between local states and local events. Against this background,
46、Petri nets have gained widespread acceptance in many industrial fields of application (e.g. information, communication, transportation, production, processing and manufacturing and power engineering). The conventional methods are very limited when dealing with actual industrial systems because they
47、are neither able to handle multi-state systems, nor able to model dynamic system behaviour (e.g. fault tree or reliability Block diagrams), and can be subject to the combinatory explosion of the states to be handled (e.g. Markov process). Therefore, alternative modelling and calculating methods are
48、needed. Dependability calculations of an industrial system intend to model the various states of the system and how it evolves from one state to another when events (failures, repairs, periodic tests, night, day, etc.) occur. Reliability engineers need a user-friendly graphical support to achieve th
49、eir models. Due to their graphical presentation, Petri nets are a very promising modelling technique for dependability modelling and calculations. Analytical calculations are limited to small systems and/or by strong hypothesis (e.g. exponential laws, low probabilities) to be fulfilled. A qualitative increase is needed to deal with i
