62   RMS and avg Values

Created: 15 Mar 2005

Status: In Force (green)

Part: Part 7-3 (2003)

Links:

Page:

Clause: General

Paragraph:

Category: No impact on this part

Issue

RMS and avg Values
---------------------
The current CDCs MV and CMV in IEC 61850-7-3 do not provide explicit rms values. The CDCs for harmonic Data provide rms values.
In some cases the data of LNs are explicitly defined as rms data (CDC=MV), e.g., the Vol and Amp in the LN MMXN (non phase related measurements). In other cases like the LN MHAI we have data, e.g., HRmsA (CDC=WYE) that have the rms semantic tagged in the name.

In the wind power plant standard IEC 61400-25 we need rms, average, and standard deviation of analogue values.

Klaus-Peter proposed for CMV: We may define for the CMV (mainly used for electrical three-phase values) that the mag-value of the vector shall be a rms value if the "ang" value is not present. In this case we also need to
define that the attribute rmsCyc is implicitly 1 period.

What do you think?

This cannot be applied for MV because the attribute has no "ang".

I suppose a new CDC as we have defined one IEC 61400-25. The name could be AMV (advanced MV) - this would be a specialization of MV. The additional DataAttributes could be:
- Sel ENUM [mag, rms, avg] CF M
- rms AnalogueValue MX dchg Conditional
- avg AnalogueValue MX dchg Conditional
- rmsTmms INT32U CF Conditional
- avgTmms INT32U CF Conditional
We may define such a new CDC as part of the first amendment of 61850-7-3.

Proposal

Clarify and discuss.