Scada functions
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The document discusses the technical functions of a SCADA system. It describes data acquisition as the basic function that collects telemetry measurements and status indications from devices like CTs and PTs through RTUs and IEDs. Data is stored in a real-time database and acquired in less than 2 seconds. Other key functions include supervisory control that allows remote control of devices, tagging for authorization of device operations, alarms to notify of events, logging to record operations and alarms, load shedding for automatic or manual load control during emergencies, and trending to plot measurements over time. The SCADA system provides the operator complete visibility of the power system from a central control room.
Scada functions
- 2. TECHNICAL FUNCTIONS OF SCADA Some basics function of SCADA are discussed below • Data acquisition • Supervisory control • Tagging • Alarms • Logging (Recording): • Load shading • Trending
- 3. DATA ACQUISITION • The basic information of the power system collected is called the Data Acquisition. The data is collected by means of CTs, PTs and transducers. It provides the telemetry measurement and status indication to the operator • Scanning rate: 1 sample/2 seconds • As new Values come in from the RTUs/IEDs old values are overwritten. Measurements and Status Indications Collected are stored in a Real Time Database.
- 4. • Data acquisition is the function of the SCADA which is required to perform the following functions: •It is used to read the power system data from 100-250 RTU into the control center. •It detects and handle the error conditions of RTU and communication link as well as. •It can be used to check the limits such as high/low operating limit, thermal limits, and safe handling limits. •It can be used to convert the analog data into the binary data. •It stores only the error free data in the data b/c erroneous data causes the failure of program. •It can interface with the data base manager, which generated the data address where data can be stored in data base. •It completes all above tasks in less than 2 seconds
- 5. SUPERVISORY CONTROL: • It enables the operator to remotely control the devices. For example open and close of the circuit breaker. Tagging: • It prevents the device from unauthorized operation. Means it authorizes the device to perform the specific operation Alarms: • It informs the operator about the unnecessary events and undesired conditions.
- 6. Logging (Recording): • It logs all the operating entry, all alarms and other information. In other words it keeps the record of all the events. Load shading: • It provides both the automatic and manual control tripping of load during the emergency. Trending: • It plots the measurement on the selected time scale.
- 7. • It plots the measurement on the selected time scale. • The SCADA system enables the operator to attain the complete knowledge of the system in a single room by means of display. • Almost all the SCADA systems are computer based (Digital computer). This computer is located in the master unit. The master unit is the heart of the SCADA system, it comprises many of the i/p and o/p equipments to receive and send the control message from and to the RTU.