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Reliability analysis of substation automation system functions
KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.ORCID iD: 0000-0003-3014-5609
2012 (English)In: 2012 Proceedings - Annual Reliability and Maintainability Symposium (RAMS), IEEE , 2012Conference paper (Refereed)
Abstract [en]

This paper presents a case study applying a framework developed for the analysis of substation automation system function reliability. The analysis framework is based on Probabilistic Relational Models (PRMs) and includes the analysis of both primary equipment and the supporting information and communication (ICT) systems. Furthermore, the reliability analysis also considers the logical structure and its relation to the physical infrastructure. The system components that are composing the physical infrastructure are set with failure probabilities and depending of the logical structure the reliability of the studied functionality is evaluated. Software failures are also accounted for in the analysis. As part of the case study failure rates of modern digital control and protection relays were identified by studying failure logs from a Nordic power utility. According to the failure logs software counts for approximately 35% of causes of failures related to modern control and protection relays. The framework including failure probabilities is applied to a system for voltage control that consists of a voltage transformer with an on-load tap changer and a control system for controlling the tap. The result shows a 96% probability of successful operation over period of one year for the automatic voltage control. A concluding remark is that when analyzing substation automation system business functions it is important to reduce the modeling effort. The expressiveness of the presented modeling framework has shown somewhat cumbersome when modeling a single business function with a small number of components. Instead the analysis framework's full usefulness may expect to arise when a larger number of business functions are evaluated for a system with a high degree of dependency between the components in the physical infrastructure. The identification of accurate failure rates is also a limiting factor for the analysis and is something that is interesting for further work.

Place, publisher, year, edition, pages
IEEE , 2012.
, Reliability and Maintainability Symposium. Proceedings, ISSN 0149-144X
Keyword [en]
Power Systems, Probabilistic Relational Models, Reliability Analysis, Substation Automation Systems
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-98158DOI: 10.1109/RAMS.2012.6175459ISI: 000309184100040ScopusID: 2-s2.0-84860640110ISBN: 978-145771849-6OAI: diva2:535630
2012 Annual Reliability and Maintainability Symposium, RAMS 2012; Reno, NV;23 January 2012 through 26 January 2012

QC 20120620

Available from: 2012-06-20 Created: 2012-06-20 Last updated: 2016-04-21Bibliographically approved
In thesis
1. Analyzing Substation Automation System Reliability using Probabilistic Relational Models and Enterprise Architecture
Open this publication in new window or tab >>Analyzing Substation Automation System Reliability using Probabilistic Relational Models and Enterprise Architecture
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Modern society is unquestionably heavily reliant on supply of electricity. Hence, the power system is one of the important infrastructures for future growth. However, the power system of today was designed for a stable radial flow of electricity from large power plants to the customers and not for the type of changes it is presently being exposed to, like large scale integration of electric vehicles, wind power plants, residential photovoltaic systems etc. One aspect of power system control particular exposed to these changes is the design of power system control and protection functionality. Problems occur when the flow of electricity changes from a unidirectional radial flow to a bidirectional. Such an implication requires redesign of control and protection functionality as well as introduction of new information and communication technology (ICT). To make matters worse, the closer the interaction between the power system and the ICT systems the more complex the matter becomes from a reliability perspective. This problem is inherently cyber-physical, including everything from system software to power cables and transformers, rather than the traditional reliability concern of only focusing on power system components.

The contribution of this thesis is a framework for reliability analysis, utilizing system modeling concepts that supports the industrial engineering issues that follow with the imple-mentation of modern substation automation systems. The framework is based on a Bayesian probabilistic analysis engine represented by Probabilistic Relational Models (PRMs) in com-bination with an Enterprise Architecture (EA) modeling formalism. The gradual development of the framework is demonstrated through a number of application scenarios based on substation automation system configurations.

This thesis is a composite thesis consisting of seven papers. Paper 1 presents the framework combining EA, PRMs and Fault Tree Analysis (FTA). Paper 2 adds primary substation equipment as part of the framework. Paper 3 presents a mapping between modeling entities from the EA framework ArchiMate and substation automation system configuration objects from the IEC 61850 standard. Paper 4 introduces object definitions and relations in coherence with EA modeling formalism suitable for the purpose of the analysis framework.

Paper 5 describes an extension of the analysis framework by adding logical operators to the probabilistic analysis engine. Paper 6 presents enhanced failure rates for software components by studying failure logs and an application of the framework to a utility substation automation system. Finally, Paper 7 describes the ability to utilize domain standards for coherent modeling of functions and their interrelations and an application of the framework utilizing software-tool support.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xiii, 44 p.
TRITA-EE, ISSN 1653-5146 ; 2014:021
Reliability analysis, substation automation, Enterprise Architecture, probabilistic analysis, Probabilistic Relational Models, Bayesian networks, software reliability, failure rates, fault tree analysis
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-145006 (URN)978-91-7595-131-7 (ISBN)
Public defence
2014-05-19, Q2, Osquldas väg 10, KTH, Stockholm, 10:00 (English)

QC 20140505

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2014-05-05Bibliographically approved

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