GE B30 Communications Manual page 249

CHAPTER 3: IEC 61850 COMMUNICATION OVERVIEW
undergoing a change of state or value. Event messages contain only the values that have suffered events, reducing the
bandwidth requirements of report services. Report services are intended for supervisory control and data acquisition
(SCADA)-type applications, wherein transfer time is not as critical as in protection applications.
IEC 61850 specifies two types of report: buffered reports and unbuffered reports. The difference between these two is that
when the connection between server and client is lost, unbuffered reports flush events not yet reported to the client, while
buffered reports retain (buffer) any events not yet reported and any subsequent events so that the interruption does not
result in the loss of events. Unbuffered reports are thus more suitable where client is just displaying the reported values or
using them to make real-time decisions, such as tap-changer voltage control. In these applications, events during the
interruptions are not of interest, and preservation unnecessarily consumes server resources. Buffered reports are more
suitable where the client is using the data for historical purposes, such as for instance creating a load profile. In these
applications, the events during an interruption are necessary to prevent gaps in the history.
Each report service is controlled by a report control block in the information model of the publishing device, which since UR
7.30 is represented by either a buffered report element or an unbuffered report element. See the applicable UR instruction
3
manual for the number of report elements available. Typically, report control blocks are configured by the client using MMS
messages defined in the standard immediately on opening the client/server connection. However, EnerVista UR Setup also
allows manual entry of this information via Buffered report and Unbuffered report configuration pages. The figure shows
an example of a Buffered report configuration page.
Figure 3-7: IEC 61850 buffered report panel
The RptID setting allows each report service to be given a user-specified functional name, though if left blank a system
unique name in the format "<LDName>/LLN0$BR$"BRCB01" is used, where the last two digits are the report element
number. DatSet specifies the dataset that defines what values are to be included in report messages. TrgOps is a
bitmapped value, wherein each bit specifies a kind of event that is to be reported on: data-change, quality-change, data-
update, integrity (for example, periodic), and/or general-interrogation (for example, on request). BufTm specifies how long
after an initial event to collect and append possible additional events before sending a report message. IntgPd specifies
UR FAMILY – COMMUNICATIONS GUIDE 3-11