1977   SwgTmms description confusing

Created: 06 May 2025

Status: Discussion (red)

Part: Part 7-4 (2020; Edition 2.1)

Links:

Page: 263

Clause: 6

Paragraph: 6.1310

Issue

The description of the DO SwgTmms (ING) is "Power swing detection time" which could be understand as "the instant of time the power swing is detected".
Protection relays implementing a dual-binder scheme as a power swing detection method measures the time interval that it takes for the impedance to cross the distance between the outer and inner blinders. If this time interval is higher than a set delay time (SwgTmms here), then a power swing is declared.

Proposal

Propose to update the description to "power swing detection time window".

Discussion Created Status
The setting defines the required time interval for the impedance trajectory to move from the outer to the inner blinder in a dual-blinder power swing detection scheme. If this interval exceeds the configured delay, the relay declares a power swing.
This setting is used to distinguish slow impedance changes caused by power swings from fast changes caused by faults.

My current conclusion considering the so far held discussions here and within WG10: The setting is a threshold delay, not a “window” or an instant of detection. Therefor I could imagine to change the description to something like the following:

Minimum time delay for power swing detection specifies the required time interval for the impedance trajectory to move from the outer to the inner blinder in a dual-blinder power swing detection scheme. If this interval exceeds the configured delay, a power swing is declared.

This replaces the (maybe) ambiguous “Power swing detection time” with a precise definition that reflects the actual function of the setting in my opinion.

Further I will have a look into an improvement of the data model regarding different implementations/algorithm types being properly reflected by the LN/data model and would raise the topic with WG10.
26 Feb 26 Discussion (red)
I agree with the former comment that the DO SwgTmms (ING) is already a setting and needs therefor no change in that regard. I however believe that we could improve the description (slightly) to avoid possible confusion in the future. 14 May 25 Discussion (red)
Open for discussion. 14 May 25 Accepted
Two thoughts:
1. CDC ING already indicates this is a setting and not a measurement, therefore no change needed (a measurement would be CDC=INS)
2. New description is marginally better than old description 		06 May 25 Triage

 

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