17.4
SEL-400 Series Relays Instruction Manual Date Code 20171006
IEC 61850 Communication
IEC 61850 Operation
Logical nodes can be organized 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.
Simply run an MMS browser to query devices on an IEC 61850 network and dis-
cover what data are available. Self-description also permits extensions to both
standard and custom data models. Instead of having to look up data in a profile
stored in its database, an IEC 61850 client can simply query an IEC 61850 device
and receive a description of all logical devices, logical nodes, and available data.
Unlike other supervisory control and data acquisition protocols (SCADA) that
present data as a list of addresses or indices, IEC 61850 presents data with
descriptors in a composite notation made up of components. Table 17.2 shows
how the A-Phase current expressed as MMXU$A$phsA$cVal is broken down
into its component parts.
Data Mapping
Device data are mapped to IEC 61850 logical nodes (LN) according to rules
defined by SEL. Refer to IEC 61850-5:2013(E) and IEC 61850-7-4:2010(E) for
the mandatory content and usage of these LNs. The relay logical nodes are
grouped under Logical Devices for organization based on function. See
Table 17.3 for descriptions of the logical devices in a relay. See Logical Nodes on
page 17.29 for a description of the LNs that make up these logical devices.
Table 17.2 Example IEC 61850 Descriptor Components
Component Description
MMXU Logical Node Polyphase measurement unit
A Data Object Phase-to-ground amperes
PhsA Subdata Object A-Phase
cVal Data Attribute Complex value
Table 17.3 Relay Logical Devices
Logical Device Description
CFG Configuration elements—datasets and report control blocks
PRO Protection elements—protection functions and breaker control
MET Metering or Measurement elements—currents, voltages, power, etc.
CON Control elements—remote bits
ANN Annunciator elements—alarms, status values
MU
a
a
This only applies to merging units.
Merging unit elements—voltage and current channels
To Next Page
Loading...
