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17.6
SEL-400 Series Relays
Instruction Manual
Date Code 20171006
IEC 61850 Communication
IEC 61850 Operation
Direct Control Models
The “Direct” control models provide the simplest means to initiate actions on the
server. In these models, the client issues a control request via MMS, the server
validates the request. Once validated, the server attempts to act upon the request.
Note that if multiple clients are trying to perform control actions, the server will
do nothing to prevent this.
SBO Control Model
The SBO control model supports the Select or SelectWithValue Service and can
be used to prevent multiple clients from performing simultaneous control actions.
In this mode, a client has to “reserve” the control object by sending a “select”
control command. Once an object is selected, only the client that made the selec-
tion is allowed to perform control actions on it. If that client does not send a valid
operate request for the object by the time the ten-second selection timer runs out,
the object becomes available for selection again. The relay will support as many
as ten pending control object selections at any time.
NOTE:
When an IED is configured
with the SBO with Enhanced Security
control model, the sboTimeout
attribute of the controllable CDCs in
the CID file is set to ten seconds. This
time-out is not configurable via
Architect.
The attribute stSeld (selected status) of the controllable CDC is set to TRUE
when a client successfully selects the control object. The attribute is reset to
FALSE when either the control (operate) command is successfully executed, an
error occurs, or no operate command is received within the select time-out
period. The stSeld attribute may trigger a report just like any data attribute with
trigger option.
Security in Control Models
“Security” in the control model context refers to additional supervision of the sta-
tus value by the control object. The “enhanced security” models report additional
error information on failed operations to the requesting client than the models
with “normal security”. Enhanced security control models also provide a com-
mand termination report indicating if the control actually reached the new state as
commanded within a configurable time-out period.
NOTE:
The maximum time required
for a control operation to be
completed should be less than the
configured time-out period in order to
avoid erroneous command
termination reports indicating failure.
The time-out period between the execution of a control and the generation of a
command termination report indicating failure has a default value of 1 s and is
configurable via the CID file. This time-out is not configurable via Architect.
Optional Control Configurations
SEL-400 series relays do not support (by default) the pulse configuration option
specified in Clause 6.7 of IEC 61850-7-3. However, control objects may be con-
figured to be pulsed by direct modification of the CID file of the device.
SEL-400 series relays do not support the concept of local/remote control author-
ity defined in Annex B of IEC 61850-7-4:2010. However, a similar behavior can
be achieved by associating some variable device data with the appropriate origi-
nator categories (orCats) by direct modification of the CID file of the device.
Contact the factory if any of these features is necessary for your application.
Control Requests
IEC 61850 control services are implemented by reading and writing to pseudo-
variables in the relay in response to MMS requests. Similar to how client requests
are generated and mapped to MMS read or write service requests, server actions
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