Basler Electric BE1-11 IEC 61850 Protocol - Manual (Page 21)

9424200892 Rev F 15
also referred to as Data Tags. As specified in IEC 61850–7–2 clause 9, the DataSets are part of a Logical
Node. They are included in the LLN0.
Report Control Blocks (RCB)
The contents of an RCB are listed in IEC 61850– 7–2 in clause 14, table 23. The RCB contains a list of
attributes which handle and secure the communication between the client and the server.
•
Buffer Time - This parameter describes how long the report should wait for other expected events
before it sends the report to the client. When known, additional events are generated as a follow
up. It is useful to wait for approximately 500 ms for additional events stored in the report. This
feature reduces the number of telegrams transmitted in case of a burst of changes. But it
increases the overall transaction time for events from IED input to presentation on HMI which is
normally one second.
•
Trigger Options - Data attributes have three trigger options (dchg, qchg, dupd). Within the RCB,
two others can be defined integrity and general interrogation. The attribute Trigger Option is a
multiple choice and allows masking of the supported trigger options in this RCB.
•
Integrity Period - When period is selected in the trigger option attribute, it is needed to define an
integrity period to force the transmission of all data listed in the DataSet. This is done by the
attribute Integrity Period. This feature can be used as a background cycle to ensure that the
process image in all partners is the same.
•
General Interrogation - A general interrogation is only done on request from a client. Not all
DataSets contain information which is needed for a general update of the client. For example,
data with T(ransient) = TRUE are not part of a GI. When the RCB attribute general interrogation
is set to TRUE a GI request from the client will be handled. The report handler will transmit all
data defined in the DataSet with their actual values. The IEC 61850 standard defines that all
buffered events are transmitted first before the GI is started. A running GI is stopped and a new
GI is started, when a new GI request is received while a GI is running.
Trigger Options
IEC 61850 has defined five different TrgOp. Three of them belong to data attributes and they are marked
per data attribute in the column TrgOp of the CDC tables in part 7–3. The other two belong to the
configuration of control blocks. The five trigger options are:
•
dchg = data-change - The classical trigger. Whenever a process value has changed its value
either binary or a measurement a transmission is done.
•
qchg = quality change - Looking to the possibilities of the quality data attribute type (q) any
changes in the quality description are transmitted.
•
dupd = data value update - This trigger option gives the possibility to define that a transmission
should be done on a condition which can be controlled by the application.
•
Period - This trigger forces the transmission of all process values defined in the DataSet when a
timer value (the integrity period) expires. For example, it can be used to do a process signal
update in the background (e.g. every 15 minutes).
•
General Interrogation - This trigger is forced by the clients (= station level IED; NCC gateway,
station HMI, ...). Normally a GI is asked for when the client and the server start or restart a
session. When the client is able to receive the actual values and when the Logical Device has
scanned all process values at least once, an image of the actual process signal status can be
transmitted to the client.
Goose Control Blocks (GoCB)
The Generic Object Oriented Substation Event (GOOSE) class model is used to distribute input and
output data values between IEDs on bay level through the use of multicast services. GOOSE messages
bypass the server which results in a fast transmission from publisher to one or several subscribers
(receivers).
The GOOSE message concept is used for all application functions where two or more IEDs are involved.
BE1-11 IEC 61850 Engineering