One of my biggest objections is against anyone referring to "IEC 61850 protocol"
IEC 61850 Protocol Does Not Exist!!!
The title is "Communication networks and systems .."
It does not say "protocol"!
IEC 61850 is not a mere protocol.
But it is fair to ask : "what is IEC 61850?"
The Standard is a vendor-agnostic system-engineering process (from specification to implementation to operation and into maintenance) to configure IEDs to be able to communicate between them to monitor, protect, control and manage infrastructure associated with electrical networks.
Please note the sequencing of the Parts of the Standard as an indication of the way in which the Standard should be applied ... - many fall into the trap of going straight to Part 8 or 9 where the different real time messages (MMS / GOOSE / Sampled Values) are defined, but our objective should not be simply to boast "we have a GOOSE in the substation".
Part 3: Physical requirements of the IED for environmental withstand including temperature etc., EMC, auxiliary supply ranges etc. (N.B.: a device can comply to just IEC 61850-3 without having any IEC 61850 functionality)
Part 4: a project management methodology
Part 5: the definition of the system communication requirements in the substation
Part 6: the prescription of the engineering environment for configuring of functions (which is ultimately supplied in IEDs) to communicate with other functions interoperably
Part 7: a set of defined object structures with semantics of what could need to be communicated
Part 8 and Part 9 There are two principal types of communication processes for the real time communication between the functions (supplied in IEDs)
Client-Server communications mechanisms Part 8-1:
SCADA master-slave command/polling
server event triggered reporting to the client
Publisher-Subscriber communication mechanism
Part 8-1 repetitive retransmission of the status of a function with fast repetition of that changed status when an event occurs (GOOSE)
Part 9-2 (and independent IEEE Guideline 9-2LE) for continuous transmission of instantaneous Sampled Values
Across all of these above (IEC 61850 Part 8-1 and 9-2) is the mapping onto TCP/IP Ethernet networks to actually get the message from device A to device B, C, D.... This is where the confusion of a protocol stems from.
Just "limiting" the definition of IEC 61850 to some small part of Part 8-1 and 9-2 as being a "protocol" clearly misses the whole point of IEC 61850 with the inevitable poor experiences.
Ignoring Parts 3, 4, 5, 6 and 7 in projects and specifications is quite possibly (probably) going to lead you into the same sorts of problems that have been reported by ENTSO-E as 41 transmission utilities in Europe following their first 8 years of using IEC 61850.