A hybrid load flow and event driven simulation approach to multi-state system reliability evaluation

Hindolo George-Williams, Edoardo Patelli

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)
2 Downloads (Pure)


Structural complexity of systems, coupled with their multi-state characteristics, renders their reliability and availability evaluation difficult. Notwithstanding the emergence of various techniques dedicated to complex multi-state system analysis, simulation remains the only approach applicable to realistic systems. However, most simulation algorithms are either system specific or limited to simple systems since they require enumerating all possible system states, defining the cut-sets associated with each state and monitoring their occurrence. In addition to being extremely tedious for large complex systems, state enumeration and cut-set definition require a detailed understanding of the system׳s failure mechanism. In this paper, a simple and generally applicable simulation approach, enhanced for multi-state systems of any topology is presented. Here, each component is defined as a Semi-Markov stochastic process and via discrete-event simulation, the operation of the system is mimicked. The principles of flow conservation are invoked to determine flow across the system for every performance level change of its components using the interior-point algorithm. This eliminates the need for cut-set definition and overcomes the limitations of existing techniques. The methodology can also be exploited to account for effects of transmission efficiency and loading restrictions of components on system reliability and performance. The principles and algorithms developed are applied to two numerical examples to demonstrate their applicability.
Original languageEnglish
Pages (from-to)351-367
Number of pages17
JournalReliability Engineering and System Safety
Early online date9 Apr 2016
Publication statusPublished - 31 Aug 2016


  • system reliability
  • event-driven simulation
  • multi-state system
  • complex system
  • availability
  • load-flow


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