OVER VIEW, ARCHITECTURE
MAIN COMPONENTS
T Srinivas, Chief Manager, SRLDC
SCADA SYSTEM
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SCADA SYSTEM
OVER VIEW
ARCHITECTURE
MAIN COMPONENTS
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SCADA :Supervisory Control and Data Acquisition
It is the system responsible for gathering, processing, and displaying information about the state of a monitored system.
From a SCADA control center, operators and application programs can oversee and change the operating state of monitored devices.
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Southern Regional Load Despatching Facilities
CDP
Bangalore
10 Sec
2 Sec
2 Sec
RTU
INT SCADA
Chennai SCC UTPSLDC
Sub LDC
RLDC
RTU
WGL TVMVIJ
RTU RTU
GTR LGR
RTU RTU RTU
TVM
RTU
MDI
RTU
ERD
RTU RTU
Bangalore Hyderabad Kalamassery
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TYPICAL SCADA SYSTEM
SCADAH/W &S/W
MEDIA
C TXO RX M EM QN P T
C TXO RxM EM QN P T
R
T
U
T PR AA NN ES LDUCER
C & R
PANEL
CONTROLCENTRE SUBSTATION / GEN STATION
COMMNMEDIA
FIELD UNIT / RTU
Scada System - Overview
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Scada System - Architecture
• First Generation – Monolithic
• Second Generation – Distributed
• Third Generation – Networked
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Scada System - Architecture
MONOLITHIC SCADA SYSTEM8
Scada System - Architecture
MONOLITHIC SCADA SYSTEM
Computing Centered with Main Frame
Non existant of Networks
Centralised System
Standalone sytem
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Scada System - Architecture
DISTRIBUTED SCADA SYSTEM10
Scada System - Architecture
DISTRIBUTED SCADA SYSTEM
• Advantage of developments andimprovement in system miniaturization and Local Area Networking (LAN)
technology to distribute the processing across multiple systems.
• Multiple stations, each with a specificfunction, were connected to a LAN and shared information with each other in real-time
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Scada System - Architecture
DISTRIBUTED SCADA SYSTEM
• Communications processors, primarilycommunicating with field devices such
as RTUs.
• operator interfaces, providing the human-machine interface (HMI) for system operators.
• calculation processors or database servers.
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Scada System - Architecture
DISTRIBUTED SCADA SYSTEM
• Network-connected systems served not only to increase processing power, but also to improve the redundancy and reliability of the system as a whole.
• Distributed architecture often kept allstations on the LAN in an online state
all of the time.
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Scada System - Architecture
NETWORKED SCADA SYSTEM 14
Scada System - Architecture
NETWORKED SCADA SYSTEM
• The major improvement in the thirdgeneration is that of opening the system
architecture, utilizing open standards and protocols and making it possible to distribute SCADA functionality across a WAN and not just a LAN.
• There are still multiple networked systems, sharing master station functions. There are still RTUs utilizing protocols that are vendor-proprietary. 15
Scada System - Architecture
NETWORKED SCADA SYSTEM
• Utilization of off-the-shelf systems makes it easier for the user to connect third party peripheral devices (such as monitors, printers, disk drives, tape drives, etc.) to the system and/or the network.
• Because of “open” or “off-the-shelf” systems, SCADA vendors have gradually gotten out of the hardware development business.
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Scada System - Architecture
NETWORKED SCADA SYSTEM
• Advantage of the use of WAN protocols such as the Internet Protocol (IP) for communication between the master station and communications equipment.
• Advantage brought about by the distribution of SCADA functionality over aWAN is that of disaster survivability.
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Control Room Hardware
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IT application servers (DMZ)
CFE Servers 2 No.
Serial Cards (including 8 pair of modems) /Splitters
RTUs on 60870-5-101 Protocol
Router cum Firewall 2 Nos.
RTU on 104/ PMU 0n
C37.118/ other IP devices
DATA ACQUISITION VLAN
SCADA NAS Storage SCADA ServersLCD / Video Projection
GPS , Time and
Frequency DisplaysDatabase Servers
ICCP ServersRouter cum Firewall 2 Nos.Routers at RLDCs and SLDC Dual Monitor Training ConsolesDTS Server
UPS, CMC, RD, PDS, ISR, NMS / Management LAN
Developmental Workstation
Programmer Development Server (1 Nos.) NMS Servers Printers
(B/W & Color)
Replica ServersCMC
ISR Servers2 No.
Server Management Console
UPS Monitoring
SystemIdentity Server
PD
S, IS
R, N
MS
LA
N
RD
, CM
C, U
PS
& S
ER
VER
MA
NA
GEM
EN
T L
AN
CORPORATE LAN
Web Servers
S C A D A / E M S VL A N (DMZ)
NETWORK
Renewable
Control / mon
RTUs on Other Protocol
Fig 1
Control center Architecture
WorkStation LAN
Remote WorkStation for Boss
(Single monitor
No controls)
SO WorkStation
(Dual Monitor)
SO WorkStation
(Dual Monitor)
SO WorkStation
(Dual Monitor)
SO WorkStation
(Dual Monitor)
Historian
ABT Scheduling, Poc & Market Operation
Energy accounting FTP Server
Redundant Internet from different service provider
Secure VPN
Report Generation
EMS Servers
PCPCPCPCPCPC
Corporate NAS Storage
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Scada System – Main Components
• Field Data Interface Devices
• Communication Network
• Central Host Computer
• Operator Workstations and Software Components
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Scada System – Main Components
• "eyes, ears and hands" of a SCADA system
• Before any automation or remote monitoring can be achieved, the information that is passed to and from the field data interface devices must be converted to a form that
is compatible with the language of the SCADA system.
Field Data Interface Devices
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Scada System – Main Components
• To achieve this, some form of electronic field data interface is required – RTU
• RTU - primarily used to convert electronic signals received from field interface devices into the language (known as the Communication protocol) used to transmit the data over a communication channel.
Field Data Interface Devices
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Scada System – Main Components
• Sensors/transducers that convert physical parameters to electrical signals.
• Signal conditioning circuitry to convert sensor signals into a form that can be converted to digital values.
• Analog-to-digital converters• A Scada system to process this
digital data.
Field Data Interface Devices
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HARDWARE CONNECTIVITY DIAGRAM FOR SCADA AT SUBSTATION / GEN.STATION
MAINCPU
BOARDPSU
COMMNBOARD
ANALOG
I / P
DIGTAL
I / P
CONTROLO/P
TERMINALBLOCK
TERMINAL BLOCK
TERMINALBLOCK
REMOTE TERMINAL UNIT
TRANSDUCER O/P TERMINAL
MVAR VOLTMW
TRANSDUCER I/P TERMINAL P TSEC
110VAC
CT SEC1 AMPS
FROM
SWITCHYARD-FIELD
EVENT LOGGERPANEL
DRIVER
RELAY
TRANSDUCER PANEL
RS232 PORT
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Basic Data Acquisition
TRANSDUCER
RTU Ang In
CB
RTU Dig In
Field
DAS
CT
PTPotential Free Contact
NO Coil for Close
NC Coil for Trip
Close
Trip
RTU Dig out
Pannel control
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TRANSDUCERS
CLASSIFICATION SELF POWERED/AUXILARY POWERED
INPUT VOLTAGE/CURRENT
OUTPUT 0-10mA, 4-20mA, 0-5mA 0-5v,0-10v
OUTPUT IMPEDANCE 500Ω,1000Ω,2000Ω
ACCURACY 0.2 CLASS, 0.5 CLASS, CLASS 2 AND ABOVE
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A/D CONVERSION AT RTU LEVEL(16 BIT ADC).
FOR MW / MVAR TRANSDUCER:INPUT: PT SEC PHASE TO PHASE : 110VAC CT SEC TWO PHASE CURRENT (R & B): 1 A.
OUTPUT : 4 – 20mA(TRANSDUCER OUTPUT)
IN ADC:
AT 4mA = 6553 CountAT 20mA = 32767 Count12mA IS THE CENTRE POINT.
(+/- 0.1% IS THE ACCEPTABLE RANGE OF ERROR ON FULL SCALE) 28
TELEMETRY FOR SCADATELEMETRY FOR SCADA
P Q
V
O
SS
DS
DC
MW MVAR
VOLTAGE
TAP POSITION
SINGLE STATUSISOLATOR POSIITION, PROTECTION,
LOSS OF VOLTAGE
DOUBLE STATUS CIRCUIT BREAKER POSITION
DIGITALCONTROLCIRCUIT BREAKER CONTROL
F FREQUENCY
THE PARAMETERS ARE MONITORED FOR FOLLOWING STATIONS :
•Substations 220 KV and above
•132/110KV AC Interstate Tie lines and in loop of 220 KV transmissions system
•Generating Station above 50MW capacity.
•Significant stations identified by constituents
P Q
DS DC
SS
SS
V F
DS
SS
SS
O
P Q
SS
DS
P Q
P Q
DS
DS
SS
SS
SS
SS
Q
DS
V F
SS
SS
SS
SS
SSSS
SS
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Scada System – Main Components
• Intended to provide data transfer between the central host computer servers and the field-based RTUs
• The Communication Network refers to the equipment needed to transfer data to and from different sites. The medium used can either be cable, telephone or radio.
Communications Network
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Scada System – Main Components
• Historically,SCADA networks have been dedicated networks
• With the increased deployment of office LANs and WANs as a solution for interoffice computer networking, there exists the possibility to integrate SCADA LANs into everyday office computer networks.
Communications Network
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Scada System – Main Components
The foremost advantage of this arrangement is that there is no need to invest in a separate computer network for SCADA operator terminals.
In addition, there is an easy path to integrating SCADA data with existing office applications, such as spreadsheets, work management systems, data history databases.
Communications Network
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Lingasugur
Communication System
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Scada System – Main Components
Network of computer servers that provide a man-machine operator interface to the SCADAsystem.
The computers process the information received from and sent to the RTU sites and present it to human operators in a form that the operators can work with.
Central Host Computer
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Scada System – Main Components
Operator terminals are connected to the central host computer by a LAN/WAN so that the viewing screens and associated data can be displayed for the operators.
SCADA systems are able to offer high resolution computer graphics to display a graphical user interface or mimic screen of the site.
Central Host Computer
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Scada System – Main Components
Operator workstations are most often computer terminals that are networked with the SCADA central host computer.
The central host computer acts as a server for the SCADA application, and the operator terminals are clients that request and send information to the central host computer based on the request and action of the operators.
Operator Workstations and Software Components
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Scada System – Main Components
An important aspect of every SCADA system is the computer software used within the system.
The most obvious software component is the operator interface or Man Machine Interface/Human Machine Interface (MMI/HMI) package
Many SCADA systems employ commercial proprietary software upon which theSCADA system is developed
Operator Workstations and Software Components
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Scada System – Main Components
Central host computer operating system
Operator terminal operating system
Central host computer application
Operator terminal application
Operator Workstations and Software Components
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Scada System – Main Components
Communications protocol drivers
Communications network management software
RTU automation software
Operator Workstations and Software Components
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Scada System – Main Components
Operator Workstations and Software Components
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HMI -DAC -UI -DMC -ALARM EVENTS -ICCP -TDS
DAC MODULE (FOR SR ULDC)
Scans the RTUs cyclically or on demand by the user
The periodicity of scan can be defined
Analog Data – 10 SECONDS Status Data – By Exception /
Integrity check every 10 min
SOE Data processing
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Data types
SCADA processes and stores three different types of data:
Analog Measurement, Status (CircuirtBreakers and
Isolators Positions), and Count data (Like energy, Rainfall
during the day etc).
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Data Type
Analog Data : Analogs are numeric values representing the
state of variable-state devices, such as power lines, transformers etc
In the monitored system a physical variable is usually measured by a transducer, and the output of the transducer is passed through an analog-to-digital (A/D) converter in the RTU .
Status Data : Status values represent the state of devices,
such as circuit breakers, tap changers
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Data polling method
Analogs are defined as periodic/Cyclic data .
The periodicity varies from 10 seconds to 15 seconds depending upon the quantity of data and available bandwidth .
Digital input state changes are to be reported spontaneously .
The Digital input data have higher priority than Analog values.
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Data Flow
NLDC 4545
Digital Data Potential free contacts are used to transfer switch
position to control centre.
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Sequence Of Events
Sequence of events provides milli secs accurate time of status changes for devices monitored by Remote Terminal Units .
The RTU clock is synchronized periodically by the control center clock .
Reading its internal clock when a SOE status point changes state .
Time stamped digital data stored in RTU buffer and transferred as file or Digital data with time stamped is transferred for SOE
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UI & DMC
The UI subsystem facilitates interface to the User
It is through this module, the display, the real time status of the power system are viewed by the user.
The status of the hardware & logical devices, the communication with the RTU etc .. are closely monitored and failures are reported.
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RSCC, BANGALORE CONTROL CENTRE
APPLICATION PROCESSOR
WORK
STATIONS
FRONT END PROCESSORS
DUAL LAN
RAID
WS1 WS2 WS3 WS4 WS5
FE-1 FE-2
AP-1 AP-2 AP-4 AP-5 AP-6
SCADA AGC
DATA
SERVER
AP-3
BACKUP
SERVER
PNA/ICCP
SERVER
COPS
SERVERBACKUP
SERVER
Switch
AP-7
DTS
SERVER
AP-8
DTS
SERVER
WS6 WS7
DTS SYSTEM
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PNA:POWER NETWORK ANALYSIS
COPS: COMPREHENSIVE OPERATION PLANNING AND SCHEDULING
ICCP: INTER CONTROL CENTRE COMMUNICATION PROTOCOL
RAID:- REDUNDANT ARRAY OF INDEPENDENT DISKS49
Fig 2.41
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Alarm/Events & Log Subsystem
Responsible for processing alarm & event messages, updating the alarm/events, sending event messages to the log subsystem, acknowledging and deleting alarms and generating application trigger messages
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ICCP Responsible for data transfers between the control
centers The data includes real time data, interchange schedules,
application program results, operator messages, files and historical data
Data flows in a strict vertical direction. The data flows from a Sub-LDC to the SLDC The Sub LDCs attached to the SLDC do not communicate
directly with each other nor do they communicate with the RSCC, other SLDCs, the SCC or Sub-LDCs on another SLDC
Data flows from the SLDCs/SCC to the RSCC. However, data does not flow directly from SLDC to another SLDC or from a SLDC to SCC. The RSCC acts as an intermediary between the SLDCs and the SCC
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ICCP DATA FLOW
CLIENT SERVER
ANALOG/ STATUS POINT ANALOG/ STATUS POINT
ICCP POINT ICCP POINT
VAR LIST VAR LIST
DATA SET TRANSFER SET DATA SET TRANSFER SET
ASSOCIATION ASSOCIATION
DOMAIN DOMAIN54
PNA SYSTEM DATA FLOW
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TDS
Long term Storage of data in the system. The type of data include energy accounting data, telemetry from RTUs, schedules, operational planning data, random events such as system alarms, despatcher messages and activity logs.
Real time calculations
TDS ( Temporal database & archive database ) is built using the SYBASE relational database management
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TDS Archiving of the stored data – The archiving process copies data from the
Temporal database and stores it in a disk file. Archiving can be scheduled to occur or it can be done on demand. Once the disk file is created, it can be manually transferred to any type of off-line storage such as CD or cartridge tape.
Configurable Parameters Variable number Variable name Point Number Sample frequency ( 2 seconds – 1 year ) Storage frequency ( 2 seconds – 1 year ) Collection method ( maximum, minimum, summation,
average, integration, standard deviation ) Retention period ( 1 month to 1 year depending on the
storage frequency )
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60
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ALARMS
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ALARMS
ANALOG DIGITAL
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Alarms-Analogs
Normal limit-Range of limits which device is considers to be operating normally
Reasonability Limit-range of values that SCADA uses to determine whether the value retrieved for the analog is realistic.
Forbidden Limit-Range of values that SCADA considers violated when the analog point fall within that range
Dead band Limits-On a pair of low or high limits if it is violated the value must rise above the limit by at least the dead band amount before the SCADA consider s the analog to be back within normal limits .
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Normal Alarms-analogs
MW/MVAR/MVA/FREQ/VOLTAGE ALARM LIMIT-OPERATIONAL ALARM LIMIT-ALARMING ALARM LIMIT-EMERGENCY
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Alarm Limit -MW
ALARM LIMIT-OPERATIONAL+/- 1.05*(1.732*V*I*O.8) ALARM LIMIT-ALARMING+/- 1.10*(1.732*V*I*O.8) ALARM LIMIT-EMERGENCY+/- 1.15*(1.732*V*I*O.8)
V-NOMINALVOLTAGE I-NOMINAL CURRENT
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Priority Alarms Alarms are categorized in 8 category
Priority 1 -Emergency threshold overshoot and status point alarms of controllable switching devices, ICCP links and other ICCP data exchange related alarms)
• Priority 2 -Point alarms of non-controllable switching devices. • Priority 3 -Protection trips and substation alarms • Priority 4 -Alarms relevant to RTU’s, communication lines, and
alarms of “unreasonable” category • Priority 5 - “configuration management” alarms, i.e. hardware
failures (mimic board, printer, etc.) and software failures • Priority 6 –All Network alarms-state estimator , contingency
analysis) and the alarms detected by the generation applications (AGC and LF)
• Priority 7 -Scada topology alarms •Priority 8 -HDR, Tagging, Limit Replacement.
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Flags
Gives Source and Quality of data Source of data
RTU -----------Telemetered ENTERED-----Manually Entered EXTERNAL----Always to be entered manually INTERSITE-----Data from other site CALCULATED—Calculation tag
Quality of data GARBAGE-The data is unreliable. The flag appears when
data is uninitialized. SUSPECT-Data is labelled suspect when there is one or
more of this flag (OLD, BAD, OVER and RESUSP) REPLACED-Data is labelled replaced when MANREP,
ESTREPor REMPL) GOOD-Data is labelled GOOD when it is not GARBAGE,
SUSPECT and REPLACED. 71
Flags Unit: - uninitialized. Old:-Could not be retrieved in the last scan Telemetry failure:- communication with RTU failed BAD: - when RTU returns one or more standard test values in
the RTU outside the allowed limits. Either Transducer is faulty or there is an RTU malfunctioning.
Over Range: - Raw Value Received from RTU is outside the expected Range.
Unreasonable:-The converted value has crossed the reasonability limit.
Anomalous:-Basically not a data quality Flag .State Estimator considers the above measurement not fit for the solution.
Manually replaced:-Replaced by operator
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Flags
State Estimator replaced:-Value for an analog is overridden, or replaced, by state Estimator on operator request.
Generalized Calculation: - Value replaced through generalised calculation.
Maintenance mode: - The Device has been placed in maintenance mode.
NIS:-device not in service. It will not allow scanning or calculation to update the record which is marked NIS
Alarm Inhibit: - Alarms for this device inhibited. Remote Suspect:-The value is suspect at source
control centre. Remote Replaced:-The value has been replaced by
source control centre 73
Historical DATA Recording
Historical Data Recording (HDR) function allows you to preserve a time series of any set of analog, status, and accumulator measurements . HDR functions
Saves the SCADA measurements in disk files called Historical files.
Keeps track of the Historical files that have been created and allows you to delete them.
The Database Reconstruction functions allow you to reconstruct or create a Data History listing from the data in the Historical files.
The reconstructed database can be moved to the network database for use by other applications.
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Trend Displays
Real Time Trend Display Digital, analog or counter value can be
viewed simultaneously in different displays. The information is usually sampled
cyclically, stored in memory on a circular buffer and plotted on a window against time.
Historical Trend Displays To trend the value (digital, analog counter)
with archived data
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Tagging Tags are free formatted text, which provide
critical information to next shift operator . Tags can be provided over digital, analog and
counters data-points. Operators can insert, edit or delete any number
of tags, if they have privileges to do so. Some operators may only be allowed to view
tags. These operations can be done from graphic
displays by selecting a dynamic object or from a system list of entities.
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EVOLUTION OF SCADA AT SRLDC
EARLY 90s : - Remote Console system i.e Getting Static Picture from Each SEB ,
displaying Limited values on cyclic telemetry.
- DOT dedicated Leased Circuit @1200 baud.
- No storage facility. - Operation Message transfer throu’ FAX
mile. - Remote Console Terminals used as MMI.
REMOTE CONSOLE78
Later 90’s : - Mini-SCADA system installed - One server & 3 MMI system ,Later Dual server system. - Data acquired from 17Nos of 400kV stations
by 8-bit Microprocessor based RTU. - Off Line studies. - Local Area Network - Storage on HDD & Backup done through DAT tapes.
EVOLUTION OF SCADA AT SRLDC
MINI SCADA79
EVOLUTION OF SCADA AT SRLDC
EARLY 2000 : - INSTALLATION & COMMISSION OF ULDC SCADA
SYSTEM. - MEASURANDS ACQUISION INCREASED FROM
FEW HUNDREDS TO FEW THOUSANDS. - STORAGE OF VOLUMINOUS DATA. - HIGH SPEED COMMUNICATION LINKS. - Used RISC based Servers & Workstations. - Time stamping at RTU as well as Control Centre
is possible with GPS. - Weather station used for EMS studies.
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SCADA SYSTEM EARLY 90’s AT SRLDC
REMOTECONSOLE
REMOTECONSOLE
REMOTECONSOLE
REMOTECONSOLE
MODEM
MODEM MODEM MODEM MODEM
MODEM MODEM MODEM
ND110TNEB
ND110APSEB
ND110KEB
ND110KSEB
DOT LEASEDLINE
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SCADA SYSTEM EARLY 90’s AT SRLDC (Contd …)
SRLDC CONTROL ROOM
APSEB KSEB TNEB KEB IOCC NLY TS 2 BANGL’RS/S
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HARDWARE CONFIGURATION OF MINISCADA AT SRLDC
MPCC
10
PORT
CARD
FRONT ENDPC
MPCC
MPCC
PENTIUMSERVER
PENTIUMSERVER
MMI MMI MMI
MODEM
MODEM
MODEM
MODEM
MODEM
MODEM
MONITOR
MPCC – MULTI PORT COMMUNICATION CARD
AP LD
TNEB LD
KEB LD
KSEB LD
IOCC
S’HALLI
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