F.3
Date Code 20170927 Instruction Manual SEL-751 Relay
IEC 61850 Communications
IEC 61850 Operation
The IEC 61850 document set, available directly from the IEC at
www.iec.ch, contains information necessary for successful implementation of
this protocol. SEL strongly recommends that anyone involved with the design,
installation, configuration, or maintenance of IEC 61850 systems be familiar
with the appropriate sections of these documents.
IEC 61850 Operation
Ethernet Networking
IEC 61850 and Ethernet networking are available as options in the SEL-751.
In addition to IEC 61850, the Ethernet port provides support protocols and
data exchange, including FTP and Telnet. Access the SEL-751 Port 1 settings
to configure all of the Ethernet settings, including IEC 61850 enable settings.
The SEL Ethernet port supports IEC 61850 services, including transport of
logical node objects, over TCP/IP. The Ethernet port can coordinate a
maximum of seven concurrent IEC 61850 sessions.
Object Models
The IEC 61850 standard relies heavily on the Abstract Communication
Service Interface (ACSI) model to define a set of service and the responses to
those services. In terms of network behavior, abstract modeling enables all
IEDs to act identically. You can use these abstract models to create objects
(data items) and services that exist independently of any underlying protocols.
These objects are in conformance with the common data class (CDC)
specification IEC 61850-7-3, which describes the type and structure of each
element within a logical node. CDCs for status, measurements, controllable
analogs and statuses, and settings all have unique CDC attributes. Each CDC
attribute belongs to a set of functional constraints that groups the attributes
into specific categories such as status (ST), description (DC), and substituted
value (SV). Functional constraints, CDCs and CDC attributes are used as
building blocks for defining Local Nodes.
UCA2 uses GOMSFE (Generic Object Models for Substation and Feeder
Equipment) to present data from station IEDs as a series of objects called
models or bricks. The IEC working group has incorporated GOMSFE
concepts into the standard, with some modifications to terminology; one
change was the renaming of bricks to logical nodes. Each logical node
represents a group of data (controls, status, measurements, etc.) associated
with a particular function. For example, the MMXU logical node (polyphase
measurement unit) contains measurement data and other points associated
with three-phase metering including voltages and currents. Each IED can
contain many functions such as protection, metering, and control. Multiple
logical nodes represent the functions in multifunction devices.
You can organize logical nodes into logical devices that are similar to
directories on a computer disk. As represented in the IEC 61850 network,
each physical device can contain many logical devices, and each logical
device can contain many logical nodes. Many relays, meters, and other IEC
61850 devices contain one primary logical device where all models are
organized.
IEC 61850 devices are capable of self-description. You do not need to refer to
the specifications for the logical nodes, measurements, and other components
to request data from another IEC 61850 device. IEC 61850 clients can request
and display a list and description of the data available in an IEC 61850 server
device. This process is similar to the autoconfiguration process used within
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