SWN Nets as a Framework for the Specification and the Analysis of FT Techniques Adopted in Electric Plant Automation

The use of formal methods for specification and analysis of dependable systems is considered a promising opportunity to support the evaluation of critical issues since the early design phases. Stochastic Petri nets can play an important role not only for the specification of functional issues of a system, but also for the predictive evaluation of performance and dependability properties. In this paper we investigate the possibility of using Stochastic Well-formed Nets (SWN) as a framework for specifying, validating and evaluating fault tolerance mechanisms used in plant automation. A temporal redundancy technique currently adopted in several electric plants to deal with transient faults is taken as a case-study. The peculiar feature of SWNs is the capability of directly generating an aggregated state space thus allowing for efficient model analysis.