451 LD name scope

Created: 07 Dec 2006

Status: In Force (green)

Part: Part 7-2 (2003)

Links:

Page: 36

Clause: 8.1.2.1

Paragraph:

Category: Issue for edition 2 of this part

Issue

LD names must be unambiguous in a system. The proxy concept in IEC 61850-7-1 defines that that the LD0 of a proxy mirrors the "original" LDs and uses the very same LD names in the proxy. We have the same LD name twice: in the original IED and in the proxy device.

This is in contradiction of the requirement to have unambiguous names in a system!

Proposal

1. Define the term system in clause 3 with regard to a scope. The term "system" in 2.137 in part IEC 61850-2 would comprise the proxies as part of the system. Or define the term "scope" and explain the relation between "scope" and "system.

2. Revise the definition 8.1.2.1 in IEC 61850-7-2:

old:
The attribute LDName shall unambiguously identify a LOGICAL-DEVICE within the scope of a system.

new:
The attribute LDName shall unambiguously identify an instance of LOGICAL-DEVICE within the scope of a system. Exception: Logical devices of a proxy device (see IEC 61850-7-1 clause 8) may have the same LD name than a mirrored logical device.

Discussion	Created	Status
The LDName has to be unique within a subnetwork. The restriction comes from the GOOSE telegrams that including GCBRef, and DatSetRef. With that restriction - uniqueness within the subnetwork - it is granted that 2 Logical Devices within a subnetwork are named differently and therefore send different GOOSE telegrams.	18 Apr 07	Ballot Period
This is another example, where a 'verbal' interpretation of 7-1 contradicts other parts of the standard, in this case not only 7-2. Part 6 defines that the LD name is the IED name, concatenated with an LD inst part, which is a relative LD name on an IED. This makes LD names unique, because IED names are unique, and contradicts the reuse of an LD name on a proxy in the same SCL file. Instead, the Proxy uses the LD name as its own relative LD name, and sets its own IED name in front to get the full LD name at Proxy level. Thus the 'spirit' of 7-1 is fulfilled, however not the 'strict' words. I suggest to reformulate 7-1 instead of 7-2 in this sense.	08 Dec 06	Discussion (red)

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