How to improve reliability on IEC 61850 substations

Reliability concerns demotivated companies to implement substations using IEC 61850-9-2-based protection. There is a common fear that the new technology could introduce message delays and fail to deliver of trip messages amongst other issues. However, one of the main advantages of devices with this technology is an improved diagnostic capability and the possibility to create contingency operation strategies. Considering a traditional substation, there are conditions that could result in outage and are not expected to be identified by the system (e.g. closing permission short-circuited by a dead rat, or during maintenance the cable responsible for blocking a signal was not reconnected). Those conditions could cause circuit-breakers to be successfully commanded closed when it should be blocked, or prevent trips and commands from being executed. However, the digital communication between protection IEDs have advanced diagnostic capabilities that can be used to increase the availability of the protection and control system. This paper focus on two aspects of LAN-integrated protection systems: describing similarities between traditional and process-bus-based protection and ensuring the detection of communication loss to maximize dependability.