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                                PRINCIPLES &
                         PRACTICAL DESIGN of
                         SCADA SYSTEM
                         Presented by ControlManuals.com



      Concept and Architecture of SCADA - Controlmanuals.com   1
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                                                                 Overview of
                                                               SCADA Systems



                       Presented by ControlManuals.com



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                                                 SCADA Terminology
           SCADA is an acronym for Supervisory Control and
           Data Acquisition
           Data Acquisition :
           Gathers information from widely distributed
           processes
           Supervisory Control :
           Calculate and give limited control instructions to
           distant process facilities




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                                               Terms & Terminology
           Field Instrumentation
           Data Acquisition
           Control Loop
           Supervisory Control
           Remote Terminal Unit (RTU)
           Master Terminal Unit (MTU)
           SCADA Server
           Communications Equipment




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                                    Historical Background (1)
                                                  1960s:
                                                   • Radio Telemetry : weather
                                                     monitoring using unmanned
                                                     balloon/rocket
                                                   • Hardwired Remote Monitoring :
                                                     oil & gas and processing
                                                     industries
                                                  1970s :
                                                   • Two-way radio telemetry
                                                   • Mini-computer
                                                   • Distributed Process Control
                                                     System (DCS)
                                                   • Programmable Logic Controller
                                                     (PLC)
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                                    Historical Background (2)
           1980s :
             • Low cost microcomputer (PC)
             • Satellite Communications
             • Cellular Telephone
           1990s :
             • Local Area Network (LAN)
             • High Speed Communication Devices
             • Internet




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                                                          Data Acquisition
                            Device Status




                                                                                  PROCESS
                           valve status (open/close)
                            switch position (on/off)
                              pump (start/stop)




                                                               FIELD- INTERFACE
                     Variables
                       pressures
                        flow rates
                     temperatures
                       tank levels



                                 Alarms
                            Low Tank Level Alarm
                            High Tank Level Alarm
                                 Fire Alarm




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                     Data Acquisition on an ESP System

                  Load
                Current (A)

                                                               ESP Compensator
                                                                Pressure (Mpa)
                 Line
             Frequency (A)
                                                                   Intake
                                                                  Pressure


                                                                     Intake
           Vibration (Hz)                                        Temperature (oC)


               Current
             Leakage (A)
                                                                Motor Winding
                                                               Temperature (oC)


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                                                 Types of Field Devices
           Conventional                                   Fieldbus based
             •   4-20 mA analog signal                     • Microprocessor and
             •   Discrete status (0/1)                       embedded system
             •   Point-to-point configuration                technology
             •   Dedicated wiring for each                 • Digital signal
                 devices                                   • Point-to-point or point-to-
                                                             multipoint
                                                           • Simplified wiring, drawings,
                                                             and control engineering
       Conventional 4-20 mA                    Fieldbus    • Embedded control algorithm
                       I/O
                     Modules
                                      Bridge               • example :
                                                                 Foundation Fieldbus
                                                                 Transmitter
                                                                 Profibus Transmitter
                                                                 HART transmitter


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                                                               Control Loop

                                                               P&ID
                                                               ON-OFF
                                                               Sequential
                                                               Fuzzy Logic
                                                               Neural Network
                                              Set Point
                                                                                  Process
       Manipulated                                                                Variable
                                                                                   Temperature
        Variable                                                                   Pressure
           Flow rate                     CONTROLLER                                Level
           Heat in                                                                 Flow rate


                      Actuator                                      Sensor

                     input                                                      output

                                 PROCESS
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                            Example : Flow Control Loop
           Objective :
             • maintain flow rate at a desired value (set point)
           Control elements :
             • Sensor : Flow Transmitter
             • Controller : PLC (PID)
             • Actuator : Control Valve




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                                                    Supervisory Control
           Set point management for several control loops
           Optimization to achieve “the best operating point”
           Use advanced control algorithm
            • cascade controller
            • ratio controller                    Supervisory Control

            • override control                Set Point 1    Set Point 2            Set Point 3

            • etc
                                                   CONTROLLER


                                                                 CONTROLLER
                                        Actuator                   Sensor

                                                                              CONTROLLER
                                                      Actuator                  Sensor
                                                  PROCESS
                                        LOOP #1                    Actuator                   Sensor
                                                                PROCESS
                                                      LOOP #2
                                                                              PROCESS
                                                                    LOOP #3
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                                                         Goals to Achieve
           Technical :
             •   Safety
             •   Increased productivity
             •   Equipment protection and maintenance
             •   Operational optimization
             •   Energy saving
             •   Immediate access to inventories, receipts, deliveries, etc.
           Economical :
             • Plant-wide optimization
             • Optimization of personnel utilization




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                                               Applicable Processes
           Widely distributed processes; spreading over large
           areas
           Require frequent, regular, or immediate intervention
           High cost of routine visits to monitor facility operation
           Examples :
             •   Oil and gas production facilities
             •   Pipelines for gas, oil, chemical, or water
             •   Electric power transmission system
             •   Railroad traffic
             •   Feed water purification plant
             •   Building automation



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                                         SCADA System Architecture

                                                                 RTU
                                                                  01                 transducers/
                                                                                     transm itters

                   Enterprise Network                            Modem


                                                                                  RTU
                                                                                   02                transducers/
                                                                                                     transm itters

                                                                                  Modem
                                                            Plant Level Network
           Engineer                                            (Supervisory)
            Station                         Modem
                                                                                                 RTU
                                                                                                  03
                                            Modem

                                                                                                Modem                transducers/
           Manager                                                                                                   transm itters
           Station
                                MASTER TERMINAL                                                  Radio
                                                    Radio
                                   UNIT (MTU)
                                                                                                     Field Device Network
                                                                                     RTU
        Database                                                                      04
         Server

                                                                                    Modem                transducers/
                                                                                                         transm itters

                                                                                     Radio



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                                              Data Communications
           One MTU can exchange                          Two-way communications
           data with one or more RTUs                    (half or full duplex)
           Data exchange within MTU                      serial transmission
           and RTUs follows a pre-                       (asynchronous/synchronous)
           defined set of rules called                   Leased or non-leased line
           communication protocol                        Guided or wireless medium :
           Data is encoded as binary                       • radio link (UHF, VHF,
           signal (series of ones and                        microwave, satellite)
           zeros)                                          • cable link (telephone,
           This binary signal is                             twisted pair, coaxial, power
           modulated before it                               line carrier)
           propagates through                              • fiber optic
           communication medium                            • etc



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                              Remote Terminal Unit (RTU)
                                      Placed at remote plant location
                                      Integrated with instrumentation and
                                      control systems (PLC or DCS)
                                      Functions :
                                       • Gathers information from the field
                                       • Send the information to MTU
                                       • Process the supervisory control
                                         instruction from MTU




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                                                                                       Communications
                                            W indows 3.1
                                            W indows-95
                                            W indows N T             B usiness M anagem ent
                                            Client Applications



                                                                                                                 W indows N T
                                                                                                                 O perator C onsole
                                                                                                                 RT /History D ata
                                                                                                                 Server


                            W indow s NT                                  W indow s N T                     P lant H ighw ay
                            O perator C onsole                            R T/H istory Data
                                                                          Server

                              P lant H ighw ay

                                                                     P rocess M anagem ent
                                                       C ontroller

                                                                         Fieldbus


                                  Fis her
                                                                    PD M eters   Analytical
               M easurem ent                                      C om m on Head -Sim ple -Analog I/O H andheld
                                                    C oriolis                                                   C onfiguration and
                 -Pressure                                                       -C om plex -D iscrete I/O PD A
                               Valves                                                         -TC /RT D            M aintenance
                   -Tem p
                             Positioners
                    -Flow
                   -Level                                               Field M anagem ent

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             Actuator/Sensor Level                             Device Network
           Analog signals of the                                 Field Level
           conventional sensors and                      Intelligent field devices are
           actuators are transmitted via                 configured in multidrop/bus
           two-wire cable                                topology
           One dedicated two-wire cable is               Single or multi-master mode is
           required for each                             supported
           sensor/actuator
                                                         The numbers of field devices in
           Analog-to-digital and digital-to-             a field level network is limited
           analog converters are required
           to enable interfacing                         Interoperability issue
           and communications
           with other
           intelligent devices
           (programmable
           controllers,
           smart transmitter,
           fieldbus devices)


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                                                               Plant Network
                                                         RTU to Sub-MTU to MTU
                                                         connection
                                                         Medium
                                                           • guided : cable, telephone,
                                                             ISDN, optical fiber, etc.
                                                           • wireless : broadcast radio,
                                                             microwave, satellite
                                                         Protocol
                                                           • DH, DH+, DH-485,
                                                             ControlNet
                                                           • Modbus, ModbusPlus,
                                                             ModbusTCP
                                                           • Hostlink
                                                           • DNP


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                         Corporate/Enterprise Network
           Ethernet
           TCP/IP
           Corporate Applications
             •   Real time asset management
             •   Business support
             •   Marketing & sales
             •   Procurement
             •   Manufacturing
             •   Distribution
             •   Data warehouse




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                                Master Terminal Unit (MTU)
           Customized configuration for each applications
           Connected to Local Area Network (LAN)
           Equipped with auxiliary devices (data storage,
           console, pointing devices, etc)
           Functions :
             • Collect process information from RTUs and share the
               information on the LAN
             • Online operator interface (MMI)
             • Send supervisory control instruction to RTUs
             • Alarm management
             • Report generation
             • System security
             • Central data processing
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                          Man Machine Interface (MMI)
           Provides human access to field automation system
             • Operational
             • Maintenance & troubleshooting
             • Development
           Function :
             • Communicates with field I/O from Programmable Logic
               Controllers (PLCs), Remote Terminal Units (RTUs), and
               other devices.
             • Gives up-to-date plant information to the operator using
               graphical user interface
             • Translates operator instruction into the machine
             • Engineering development station
             • Operator station

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                                           Man Machine Interface
           Plant information :                           Presentation Method :
             •   Process Variables                         •   Graphics Trending
             •   Device status                             •   Charts
             •   Alarms                                    •   Reports
             •   Control Loops                             •   Animation
             •   etc                                       •   etc
                                                         Equipment :
                                                           • Keyboard
                                                           • Mouse or other pointing
                                                             devices
                                                           • Touchscreen or CRT
                                                           • etc.




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                                                        User Applications
           Development tools is provided by SCADA system supplier
           (scripting tools)
           Examples :
             •   Meter gross/net computation
             •   Pipeline terminal display
             •   Pipeline inventory
             •   Transient modeling systems
             •   Dynamic leak detection
             •   Pipeline simulator
             •   Compressor optimization
             •   Automatic well testing
             •   Well revenue calculation
             •   etc.



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                                                          System Database
                                                          Store historical process information
                                                          for engineering, production,
              Business                                    maintenance, and business
             Applications
                            Statistical                   purposes
                            Process
                             Control                      Features :
                                                           •   Engineering units conversion
                                            Process        •   Analog value filtering
                                          Visualization
                                                           •   Value limit checking
           Realtime
                                                          Standardized Data Structure
           Database
                                                           •   Analog point structure
                                                           •   Status point structure
                                          Engineering      •   Accumulator point structure
                                          Workstation
                                                           •   Container points
                                                           •   User defined structure
                                                          Each point in the database has a
                                Batch                     number of associated parameters,
                               Process
               Asset
             Management
                              Management                  all of which can be referenced
                                                          relative to a single tag name


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                             Industrial Automation Server

                                            OPC




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                        OLE for Process Control (OPC)
           Object Linking and Embedding (OLE) for Process Control
           A standard for process automation (SCADA) communications
           A standard software mechanism for sharing data between
           process automation (SCADA) of different manufacturers
           OPC is based on Microsoft OLE (Object Linking and
           Embedding) and DCOM (Distributed Component Object Model)
           OPC advantage :
             •   Simple to implement
             •   Flexible to accommodate multiple vendor needs
             •   Provide a high level of functionality
             •   Allow for efficient operation




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                            Plant-Office Data Integration
           Networking has been successfully
           implemented from field device
           level up to management level.




                                                          Office
                                                                     Business
           Data can easily be interchanged                          Applications
                                                                                    Statistical
                                                                                    Process
           between applications in the same                                          Control

           computer or different computers                                                          Asset
                                                                                                  Management
           over a network.
                                                                   Realtime          Dynamic Data Exchange
           SCADA system can give an                                                  OLE for Process Control
                                                                   Database
           immediate response needed from
           field device to management




                                                          Plant
           system.                                                                                Engineering
                                                                                                  Workstation
           Real-time plant information can be
           transferred to office application.
                                                                                        Batch
           Corporate information system                               Process
                                                                    Visualization
                                                                                       Process
                                                                                      Management

           must be designed to meet its
           business process.

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                          Dynamic Data Exchange (DDE)
           An application protocol that allows data exchange on real-time
           basis on Windows/WindowsNT platforms
           NetDDE = Dynamic Data Exchange over network


                                                               I/O Devices

                                    Driver



                                 Tag Database
                                                                     DDE Link

                     Windows DDE           Windows DDE                   Other
                      Application           Application                Applications
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                     Sample of System linked to Excel


                                                           DDE
                                                        Conversation    Excel Based
                                                                       Operating Panel




      MMI Software




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                        Web-based Process Monitoring
           Internet browser as an acceptable MMI standard will minimizes
           operator/user training by providing a familiar operating
           environment
           Many visualization techniques are available (JavaScript, Java,
           Shockwave/Flash, etc)
           Extra development effort is not needed since SCADA supplier
           software usually provide integrated web-based and application
           specific MMI development
           Allows the users (e.g. : supervisor/manager) to monitors process
           operation, documents and reports either in the Intranet or
           Internet
           Secured network design is a must to avoid cyber risk such as
           hacking attempts and virus



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                     Web Based Monitoring Example




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                                                               Summary
           SCADA is a two-way system : remote monitoring &
           controlling
           Applicable to widely distributed processes
           Two way communication system is required
           Basic Elements of SCADA :
             • Master Terminal Unit (MTU)
             • Remote Terminal Unit (RTU)
             • Communications Equipment




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Description: PRINCIPLES & PRACTICAL DESIGN of SCADA SYSTEM, SCADA Terminology, SCADA is an acronym for Supervisory Control and Data Acquisition, Data Acquisition : Gathers information from widely distributed processes Supervisory Control : Calculate and give limited control instructions to distant process facilities