Introduction toIntroduction to

S C A D AS C A D A

NIDHIN MANOHARNIDHIN MANOHARSenior Research Senior Research

EngineerEngineer

acronym foracronym for

Supervisory Control Supervisory Control And And

Data AcquisitionData Acquisition

S C A D AS C A D AS C A D AS C A D A

Supervisory Control And Supervisory Control And

Data AcquisitionData Acquisition

Computer based system that allows operators in Computer based system that allows operators in a central location to continuously monitor and a central location to continuously monitor and remotely control field equipmentremotely control field equipment

Supervisory Control RequirementsSupervisory Control Requirements at plants / networksat plants / networks

• Centralized supervision Centralized supervision • Leak Detection and loss preventionLeak Detection and loss prevention• Safe operationsSafe operations• Several levels of Operations hierarchySeveral levels of Operations hierarchy• Historical registers and real time Historical registers and real time

informationinformation• Ability to maintain operations even with Ability to maintain operations even with

loss of communicationloss of communication• Ease of future upgrade economicallyEase of future upgrade economically

OIL TERMINALOIL TERMINAL

PUMPING STATIONSPUMPING STATIONS

PRESSURE REDUCTION PRESSURE REDUCTION STATIONSSTATIONS

BLOCK VALVESBLOCK VALVES

MARINE TERMINALMARINE TERMINAL

MAIN PIPELINE MAIN PIPELINE CONTROL CENTRECONTROL CENTRE

EMERGENCY EMERGENCY CONTROL CENTRECONTROL CENTRE

• Unlike DCS, traditionally SCADA is Unlike DCS, traditionally SCADA is

not considered a full not considered a full Control Control

System,System, but often as system but often as system

focusing on focusing on Supervisory Control Supervisory Control

and Monitoringand Monitoring..

• However, many new SCADA However, many new SCADA

implementations include smaller implementations include smaller

DCS units.DCS units.

Supervisory Control + . . . .Supervisory Control + . . . .

We may look at SCADA as a software We may look at SCADA as a software

that is that is layeredlayered over the Data over the Data

Acquisition and Interface hardware incl. Acquisition and Interface hardware incl.

Programmable Logic Controllers (PLCs), Programmable Logic Controllers (PLCs),

variable-speed drives, or other variable-speed drives, or other

commercial hardware modules that commercial hardware modules that

may be present locally or distributed may be present locally or distributed

geographically apart.geographically apart.

. . . . + Data Acquisition. . . . + Data Acquisition

•reads data from PLCs and other reads data from PLCs and other hardwarehardware

•analyze and graphically present data analyze and graphically present data to the user.to the user.

• reads and writes multiple sources of reads and writes multiple sources of data, using multiple industrial data, using multiple industrial protocols. protocols. 

So lets see what a SCADA is like…So lets see what a SCADA is like…

. . . . + Data Acquisition. . . . + Data Acquisition

Benefits?Benefits?

• Increased informationIncreased information for better decision for better decision makingmaking

• Early detectionEarly detection of abnormal system of abnormal system conditions (take corrective action before conditions (take corrective action before massive failure)massive failure)

• Improve plant operation and reliabilityImprove plant operation and reliability

• Better equipment utilizationBetter equipment utilization (squeeze (squeeze more capacity out of existing equipment)more capacity out of existing equipment)

• Improve Improve productivityproductivity

• Reduce lossesReduce losses

Basic Features (Run Time)Basic Features (Run Time)

• SC Data Acquisition Including Standard SC Data Acquisition Including Standard DriversDrivers

• Alarm HandlingAlarm Handling• Data LoggingData Logging• Data Presentation (Synoptic/Trending)Data Presentation (Synoptic/Trending)• Access ControlAccess Control• RedundancyRedundancy• Network ConnectivityNetwork Connectivity• Reports Reports • Recipe HandlingRecipe Handling

• Master StationMaster Station– A centrally located computer that allows A centrally located computer that allows

personnel to view SCADA data and personnel to view SCADA data and initiate remote control actionsinitiate remote control actions

• Field EquipmentField Equipment– Equipment in substations and feeders Equipment in substations and feeders

for connecting the SCADA system to the for connecting the SCADA system to the power apparatuspower apparatus

• Communication EquipmentCommunication Equipment– Facilities (radios, landlines) that enable Facilities (radios, landlines) that enable

the Master station to connect to SCADA the Master station to connect to SCADA system field componentssystem field components

SCADA Master StationSCADA Master Station

• Control centre from which multiple Control centre from which multiple remote installations are controlled remote installations are controlled and monitoredand monitored

• Connected to other control centres Connected to other control centres as well.as well.

• Interfaces with human through HMI Interfaces with human through HMI (Human-Machine Interface), which (Human-Machine Interface), which may be local or remote.may be local or remote.

• Connected to RTUs and/or IEDsConnected to RTUs and/or IEDs

RTU StationsRTU Stations

• Remote Terminal UnitsRemote Terminal Units

• Appear as IED to SCADA master when Appear as IED to SCADA master when

DNP used for communicationsDNP used for communications

• Each RTU manages multiple actual Each RTU manages multiple actual

IEDsIEDs

• Attached IEDs referenced using Attached IEDs referenced using

absolute addresses by the SCADA absolute addresses by the SCADA

mastermaster

SCADA CommunicationsSCADA Communications• Client-server / “publish–subscribe” Client-server / “publish–subscribe”

methodsmethods

• Central servers collect, analyze and Central servers collect, analyze and present data to displays and to other present data to displays and to other servers.servers.

• Live inputs from Remote Data Live inputs from Remote Data Acquisition / Field Terminal UnitsAcquisition / Field Terminal Units

• Real-time communication is of utmost Real-time communication is of utmost importance.importance.

Communication ProtocolsCommunication Protocols

• DNP3: DNP3: Distributed Network Distributed Network ProtocolProtocol based on based on ISO/IEC 60870-5-ISO/IEC 60870-5-101101

• FieldbusFieldbus• IEEE 802.11IEEE 802.11• Wireless communications: CDMA, Wireless communications: CDMA,

GSM, etc.GSM, etc.

Use ofUse ofMicroSoft MethodologiesMicroSoft Methodologies

• APIAPI• DDE, NetDDE,DDE, NetDDE,• COM/DCOM, ActiveXCOM/DCOM, ActiveX• OLE for Process ControlOLE for Process Control• ODBC ODBC • ASCII/CSV (Configuration) ASCII/CSV (Configuration) • WebWeb