The current text is confusing and mixes time representations.
Currently, the only available timestamp is the attribute
RefrTm. However, in IEC 61850-9-2, EntryTime is defined as a “48-bit TimeStamp as defined
in IEC 61850-8-1”. In IEC 61850-8-1, EntryTime is defined to be:
“EntryTime shall be mapped to the MMS DataType of BINARY-TIME. The size of the BINARYTIME
value shall be six (6) octets.
The MMS TimeOfDay epoch began at 0 hours on 1 January 1984 (MJD 40 587). Times
measured are designated in this standard as MMS TimeOfDay milli-seconds GMT and
TimeOfDay days GMT, and represent offets from the epoch. It should be noted that
exceptions to this mapping do occur.”
This means that the “absolute timestamp”, of a resolution required for synchrophasors can be
calculated for SV:
RefrTm(EntryTime) + SmpCnt/(SmpRate)
This text refers to EntryTime and not to TimeStamp.
Even as RefrTm(timeStamp) + SmpCnt/(SmpRate), the last equation makes no sense.
Exceptions are not defined.
Proposal
Proposed change, rewrite the paragraph
11.3.1.1 T -TimeStamp
There is need for event ordering to convey an absolute timestamp that applies to the contents of the stream.
The parameter T represents the instant of message transmission,
while the parameter RefTm represents the measurement time of the individual values.
Both times are expressed by the TimeStamp in IEC 61850 7-2 (mapped to UtcTime in IEC61850-8-1).
Discussion
Created
Status
Approve
11 Oct 22
Not Applicable
90-5 has been deprecated and replaced by IEC 62351-6 , IEC 62351-9, and IEC 61850-8-1 Edition 2 Amd 1