PRISM PlayBack is an optional application that can be utilized by the operator to replay system events and disturbances on the system display as if they were happening in real-time. Analogous to a Video Recorder, the operator has PlayBack controls available for “Play”, “Pause”, “Stop”, “Fast Forward”, etc. to control the rate of replay. Coupled with system data and world coordinate graphic displays, PRISM PlayBack provides the system engineer or dispatcher a “birds-eye” view of the grid, displaying past events in a time lapse sequence as they actually happened.
PRISM PlayBack has multiple functional uses within the utility:
- Operators use PRISM PlayBack to rerun the events of a disturbance for post fault analysis, especially those leading up to the initiating event. This capability is very valuable in determining or confirming the initial cause of an outage before attempting system restoration.
- Dispatchers use PRISM PlayBack to direct field crews to the point of system failure.
- System Planning Engineers use PRISM PlayBack to determine the behavior of the system to past recorded major system disturbances, in order to understand and prevent system weaknesses.
- Operations Managers can use PRISM PlayBack to graphically show officials an easily understandable time-lapse replay of events leading to system disturbances or outages.
- Instructors use PRISM PlayBack to understand system dynamics while advancing their handling of major disturbances. PlayBack enables them to develop realistic training scenarios for the system dispatchers, enabling them to more effectively handle similar scenarios in the future.
PlayBack records actual event/data changes to the real-time database (RTDB) and recreates the events in correct chronological sequence for replay and viewing. The system creates a time stamped snapshot of the SCADA system RTDB. Following the RTDB snapshot, subsequent changes to the database are recorded in a file until the next snapshot. The changes are time tagged.
The real-time database is copied again at a user configured periodic interval (period is to be decided based on resources and performance). Time-tagged changes to each snapshot image are again recorded in a file.
Each paired snapshot/change file set is saved on disk for in a PlayBack repository. Storage of the attribute changes is also recorded to correctly reflect the true state of the data. Playback file sets may be stored for long term archiving. A naming convention allows for quickly determining what the data represents.
PlayBack initiates data retrieval when the operator enters the desired time/date. The PlayBack Player will load the nearest snapshot prior to the time specified into a playback database, which is similar to the real-time database. The change file will be applied to the PlayBack database up to the specified time of playback. At this time the PlayBack database is ready to begin playback.
PlayBack Player Control Panel
The viewing of the playback data is performed via the SCADA operator interface (OI) when placed in the PlayBack mode. When in normal viewing mode the OI communicates with the real-time database and with the PRISM alarm processor to receive notification of alarms in the system.
When the operator places the OI in PlayBack mode, OI will not allow any real-time point updates, control actions, or alarm manipulation. The mute function remains available during playback to eliminate confusion. If more than one playback player is available or another play back database is in progress, a dialog box will be presented to allow selection of the player of choice. Once selected, the OI will provide information on the message line to indicate that it is in playback mode and will indicate which player is being utilized.
Once placed in playback mode, the OI is a viewer of the Playback database, which is being modified by the PlayBack Server program. The online diagram can be viewed at any zoom level and the display panned while showing status and analog data, as well as show alarm information in the alarm zone.
The Player will be in control of the time and will simulate the clock for SCADA time. Alarms are disseminated to the registered OI programs during playback. Actions taken by operators during the actual event (alarm acknowledgements, silence and/or mute actions, etc.) are recorded in the snapshot and played back as well. During playback, the user is not able to modify the data or acknowledge the alarms, as this will change the Playback scenario. The speed of the data replay is controlled from the player control panel.