Sigre 2015. — 14 с.
Alstom Grid, United Kingdom – [email protected], Alstom Grid, FranceThe introduction of the process bus and station bus to modern digital substations has raised many
questions and concerns. Protection Engineers are responsible for ensuring that protection and
automation systems have an adequate level of redundancy to be considered suitable for critical power
system applications.
Many new methods and technologies are now available that offer the means of providing this
redundancy; however the temptation to introduce many of these at once could lead to a design that is
unnecessarily complex, difficult to test and unreliable in practice as a result.
For example it is now possible to design a process bus architecture whereby protection relays
subscribe to multiple sampled value streams from redundant merging units. However the question of
whether this is actually necessary is a valid one. In a conventional substation such a design
philosophy would equate to protection relays being wired to multiple redundant instrument
transformers, which is not common practice nor indeed desirable.
This paper will review the contemporary protection engineering principles that have been used for
many decades to engineer redundant systems and then seek to establish how these same techniques
can be applied to new digital substation architectures.
