Software

TD: Temps Différé

TD is a PC-based application that connects to a SCADA system of a small-to-medium sized Generation and Distribution power system. The purpose of TD in such a configuration is twofold:

1. Obtain from SCADA real-time measurements and event information, and format and organise these data in a Data Base, with appropriate consulting interface for the TD-operator as well as for users on a LAN network to which the TD platform is connected.
2. Provide semi-online Distribution and Generation management functions which are not available in the SCADA system.

SCADA communication

TD communicates with SCADA via a LAN connection. Every 15 minutes, 24 hours, or on user request (depending on the type of data) TD requests particular measurement and event data from the SCADA system.

Historical database

All measurement and event data obtained from SCADA are stored in a uniform format in an historical database where they can be accessed from all applications. Appropriate maintenance functions are foreseen to purge older data accordingly user-defined criteria.

Data preparation for LAN users

All data received from SCADA is formatted appropriately and sent to the server of a LAN from where it can be consulted by any interested LAN-user.

Measurement analysis

Measurements from the historical database can be displayed for analysis with various resolutions and formats. The curves can be printed or exported for further analysis with specialized software if required.

In addition to the historical DB of measurements, the user maintains a library of 'typical' curves. Any daily historical curve may be modified by the user (ex. add 15% between 1900 and 2100 Hrs) and stored in the library.

In this library of special curves, 8 of them may be characterized as "reference" curves. This is one curve for each day of the week and a special day curve.

Unsupplied energy calculation

When a feeder supply is interrupted, TD is informed from SCADA of the start- and stop times of the interruption, as well as the current (Amps) at the moment of interruption. These data allow to estimate the energy which was not supplied due to this interruption.

The calculation distinguishes between:

1. Short interruptions (< 15 min). One assumes that the interrupted current would have remained constant during the interruption period.
2. Long interruptions (> 15 min). The program assumes that the feeder load would have followed the pattern of the last available same weekday for that feeder.

Load monitoring and alarming

The user may define several measurement points to be monitored automatically by TD. For each measurement, the user selects curves from the library, between which or around which, the measurement is expected to evolve.

Event analysis

All events are received from SCADA with their date/time stamp. This allows TD to generate various statistical reports for events related to particular equipment or a particular time period.

Unit commitment

A Unit Commitment module schedules the generation level of each generation unit in order to cover a total load curve from the library, and respecting unit availability and operating constraints as defined in the unit's data base.

Database maintenance

A set of utility functions is foreseen to create and maintain the database with the identification and description of substations, feeders, measurement points, switches, generating units etc.As far as the network elements are concerned, these objects are already defined in SCADA. Therefore, a procedure is foreseen to create and update the database automatically using a configuration diskette prepared by SCADA.