1944   Attribute type of SmpRate is not sufficient for TW application

Created: 21 Oct 2024

Status: Approval (Future Improvement)

Part: Part 7-2 (2020; Edition 2.1)

Links:

Page: 141

Clause: 19.2.2

Paragraph: MSVCB class definition

Issue

In accordance with TC38 :

The SmpRate has an attribute type of INT16U which means that the SmpCnt values can fall into the range [0; 65535].

However, for Traveling Waves and some Voltage Source Converter applications, it is necessary to sample with frequencies of 1 MHz or higher which means that the SmpCnt values should take values beyond 999999.

Ascendant compatibility issue to be discussed.

Proposal

Change the attribute type from UINT16 to UINT32.

Discussion Created Status
Currently, IEC 61869-9 is indicating a rollover of sample count for DC application. The rollover is also mentioned in IEC 61850-9-2 Ed2.1.
In 61869-9 special definitions were added to deal with a application sample rate of 96kHz. This work-around is allowing to have the current smv frame format usable for a sample rate of 96kHz.
Traveling Waves TF should discuss about the use case and the special definition to accommodate higher sample rate than 65535 in case there are needed by the Traveling Waves domain.
Propose to move to not applicable and have the TF Traveling Waves discussed the use-cases. 		17 Dec 24 Approval (Future Improvement)
I am uncertain that 61869-9 is suitable for TW.
61869-9 requires 16-bit sampling while typically TW needs far fewer bits. This would be a large waste of bandwidth.
Also, packet loss, while tolerable in 61869-9 is not tolerable for TW because signals span only a few samples at 1 MHz
Also, specialized CT/VT's are required for TW which are typically not used in 61869-9. 		21 Oct 24 Triage

 

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