SCADA


Supervisory
Control and  Data Acquisition







Problem statement 


There are many systems used for decades, these are collectively called Distributed Control Systems (DCS). Systems are effective only in a closed area like a factory complex. There is also example like nuclear fusion facilities where the operations are remote controlled due to safety considerations.    

Main concept




A large scale control system 

Centralized systems 

Open-loop control systems


Hardware Architecture

Supervisory System
 responsible for gathering data and sending commands to the process with the field equipment .
Remote Terminal Units
 responsible for converting electrical signals to digital data and send to the supervisory system.

Programmable Logic Controller (PLCs)

Programmable Logic Controller (PLCs) is connected to the data servers either directly or via networks or fieldbuses

Software Architecture


       The products are multi-tasking and are based upon a real- time database (RTDB) located in one or more servers. Servers are responsible for data acquisition and handling.
However, it is possible to have dedicated servers for particular tasks, e.g. data logger a SCADA architecture that is generic for the products that were evaluated.


Communication Architecture


Internal Communication

Server-client and server-server communication is in general on publish-subscribe and event-driven basis and uses a TCP/IP protocol.

Access to Devices

The data servers poll the controllers at a user define polling rate. The controllers pass the requested parameters to the data servers. 

Interface Architecture

The provision of OPC client functionality for SCADA to access devices in an open and standard manner is developing

Scalability Architecture

Scalability is understood as the possibility to extend the SCADA based control system by adding more process variables, more specialized servers or more clients

Redundancy Architecture

The products often have built in software redundancy at a server level, which is normally transparent to the user

Service Provided


A telemetry system
connect PLCs and RTUs with control centers, data warehouses, and the enterprise

A data acquisition server 

a software service whichuses industrial protocols to connect software services with field devices such as RTUs and PLCs

A human–machine interface or HMI 

it is the equipment or device which presents processed data to a human operator


A Historian 

a software service, which accumulates time-stamped data, Boolean events, and Boolean alarms in a database, which can be queried or used to populate graphic trends in the HMI


A supervisory (computer) system 

gathering (acquiring) data on the process and sending commands (control) to the process

Strength

Derived Control functions

SCADA will allow you to issue derived controls (automated responses) to specific combinations of sensor inputs, and it will also give you the freedom to design the exact response you need.

Reliability

the costs of system failure are extremely high. A failed part can be replaced without interrupting the process. A failing part can be quickly identified and its functionality automatically taken over by backup hardware.


Backup master support

Support several backup masters, located at different sites.

If main SCADA master fails, a backup master at a different site can resume.

 
 

Support for a variety of protocols and devices

Support a variety of open-source protocols 

to prevent  system becoming obsolete even if vendor goes out of business.


Automatic pager and email alarm notification 

-  SCADA master will automatically send a page or email directly to on-call technicians if there is a problem at your site.


Many data presentation options

-  Display alarms in a language you can understand.
-  It also give you a complete description of every alarm, and how you can correct the problem


    Weakness

    Open system

    - Open systems risk with real and cyberspace attacks by terrorists.
    - Unauthorized access to the control the software
    - The control protocol lacks any form of cryptographic security. Meaning that they are allowing an attacker to control a SCADA device by sending commands over a network.


    Application specific

     Most SCADA systems are very application specific and each component is made to its specific application.


    Wireless sensor networking

     The current SCADA systems are not enabled to be integrated with wireless networking systems.


    Extensible

    Current SCADA systems are found lacking is extensibility. There is limitation of RTUs ability to take proactive measures to prevent accidents.

    Predecessor Technology



    GENERATION I : “Monolithic”

    No network

    Use mainframe computers > independent systems

    Redundancy > since a back-up mainframe system was connected at the bus level


    GENERATION II : “Distributed”

    LAN > shared information in real time

    The network protocols used were still mostly proprietary







    GENERATION III : “Networked”

    WAN


    Open system (Open standards and protocols)


    Internet Protocol (IP) is used for communication between the master stationand communications equipment


    Main Customer and Market



    Power industry

    monitor the power flow, power line voltage, circuit breaker status, and electrical processes

    Manufacturing companies

    monitor  inventory & reduces inventory costs


    Food Production

    control temperature & movement of liquid and solid ingredients and mixtures

    Electric and Gas Utilities

    control the movement of electricity and gas

    Competing Technologies

    1. Distributed Control Systems (DCS)

    Data Distribution Service (DDS) is a data-centric publish/subscribe  for real-time communications. 

    Similarity

    System used to control and monitor

    Difference

    DCS is implemented in closed-loop control.
    Doesn't cover large area (no third party communication)








    2. Building Automation System (BAS)

    Building Automation System (BAS) is designed to monitor and control the mechanical, security, fire and flood safety, lighting (especially emergency lighting), HVAC and humidity control and ventilation systems in a building.


    Similarity
    system used to control and monitor(close relationship)
    Difference
    more specific in usage ex. control climate, humidity

    3. Direct Digital Control (DDC)

    Automatic control of a condition or process by a computer. Data bus is used for communication.


    Similarity
    system used to control and monitor
    Difference
    used in small area because of using LAN

    Member


    SECTION 1

    Sukritta Harnmetta 5488034

    Nattha Apiraknanchai 5488060

    Suttichai Kitoanon 5488063

    Krisanat Khlayprasit 5488257

    Yanin Rotprasitporn 5488262






    THANK YOU

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