Permanent data loss in highly available substation automation systems

A substation automation system (SAS) is a computer network to which all events, indications and analog measured values collected from entire network are transmitted and logged in a server for future reference. Any SAS disconnection or failure may cause malfunctioning and data loss due to the interruption of data transfer. Highly available networks are the best solution for implementing fault-tolerance techniques for the improvement of SAS reliability. Such networks provide redundancy in appliances and/or data paths to decrease the impacts of failures in the network and increase network reliability. This paper studies permanent data loss in an SAS when a fault or failure occurs in the network. Knowledge of the physical characteristics of SAS elements is necessary for measuring this index. The elements that record data should be identified, and then the data lost due to failures in those elements must be determined. Also, as a case study, a typical SAS is examined in four states of failure, and the permanent data loss occurring under each state is calculated.