Use of distributed topology detection for applications in Substation automation

Distributed functions in substation automation systems typically use distributed data (sensors) and act on more than one switch, i.e. on distributed actuators. The allocation of a distributed function to sensors and actuators is in many cases not fixed but dynamically depending on the actual switchgear topology i.e. of the actual switch states in the single line diagram. The detection of the actual topology is the key, which may be done in one central IED or in many distributed ones. A special problem is the extension of the substation e.g. with one new bay without reengineering the existing SA part and retesting of the existing part of the distributed functions. It is shown that this goal may be reached with a separate topology detection function which serves all distributed functions. The approach uses a topology detection distributed on several IEDs, since there are at least one or more IEDs of the existing system and typically one or two IEDs added by the extension. Application function examples like interlocking, zone protection like busbar protection, breaker failure protection, distributed synchrocheck, CT/VT plausibility control and topology based protections are described.