INDUSTRIAL CONTROL SYSTEMS &

COMPUTER PROCESS CONTROL

PRESENTED BY:Kartik Ayyar (PRN 08020771001)Arpit Desai (PRN: 08020771002)

Abhishek Kumar (PRN 08020771003)Deepak Kumar (PRN: 08020771004)

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INDUSTRIAL CONTROL - DEFINED

The automatic regulation of unit operations and their associated equipment as well as the integration and coordination of the unit operations into the larger production system Usually refers to a manufacturing operation Can also apply to material handling or other

equipment

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INDUSTRIAL CONTROL SYSTEMS

Process Industries vs. Discrete Manufacturing Industries

Continuous vs. Discrete Control Computer Process Control

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CONTINUOUS AND DISCRETE

VARIABLES AND PARAMETERS

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DISCRETE VARIABLES AND PARAMETERS

Categories: Binary - they can take on either of two possible

values, ON or OFF, 1 or 0, etc. Discrete other than binary - they can take on

more than two possible values but less than an infinite number of possible values

Pulse data - a train of pulses that can be counted

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CONTINUOUS CONTROL

Usual objective is to maintain the value of an output variable at a desired level Parameters and variables are usually continuous Similar to operation of a feedback control

system Most continuous industrial processes have

multiple feedback loops Examples of continuous processes:

Control of the output of a chemical reaction that depends on temperature, pressure, etc.

Control of the position of a cutting tool relative to workpart in a CNC machine tool

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TYPES OF CONTINUOUS PROCESS CONTROL

Regulatory control Feed forward control Steady-State optimization Adaptive control

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REGULATORY CONTROL

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FEEDFORWARD CONTROL COMBINED WITH FEEDBACK CONTROL

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STEADY STATE (OPEN-LOOP) OPTIMAL CONTROL

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ADAPTIVE CONTROL OPERATES IN A TIME-VARYING ENVIRONMENT

The environment changes over time and the changes have a potential effect on system performance Example: Supersonic aircraft operates differently

in subsonic flight than in supersonic flight If the control algorithm is fixed, the system may

perform quite differently in one environment than in another

An adaptive control system is designed to compensate for its changing environment by altering some aspect of its control algorithm to achieve optimal performance

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ADAPTIVE CONTROL SYSTEM

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TWO BASIC REQUIREMENTS FOR REAL-TIME PROCESS CONTROL

1. Process-initiated interrupts Controller must respond to incoming signals

from the process (event-driven changes) Depending on relative priority, controller may

have to interrupt current program to respond2. Timer-initiated actions

Controller must be able to execute certain actions at specified points in time (time-driven changes)

Examples: (1) scanning sensor values, (2) turning switches on and off, (3) re-computing optimal parameter values 13

OTHER COMPUTER CONTROL REQUIREMENTS

3. Computer commands to process To drive process actuators System initiated events - communications

between computer and peripherals Program initiated events - non-process-

related actions, such as printing reports4. System- and program-initiated events5. Operator-initiated events – to accept input from

personnel Example: emergency stop

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FORMS OF COMPUTER PROCESS CONTROL

1. Computer process monitoring2. Direct digital control (DDC)3. Distributed control systems 4. Numerical control and robotics5. Programmable logic control 6. Supervisory control

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APPLICATION

Continuous or semi-continuous production operations involving materials such as chemicals, petroleum, foods, and certain basic metals.

In these operations the products are typically processed in gas, liquid, or powder form to facilitate flow of the material through the various steps of the production cycle.

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Measurement of important process variables such as temperature, flow rate, and pressure,

Execution of optimizing strategy. Actuation of devices as valves, switches, and

furnaces that enable the process to implement the optimal strategy

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COMPUTER PROCESS MONITORING

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Batch Furnace commissioned by Bickley Inc., USANominal temperature: up to 900’C

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(A) PROCESS MONITORING, (B) OPEN-LOOP CONTROL, AND (C) CLOSED-LOOP CONTROL

(a)

(b)

(c)

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COMPONENTS OF A DIRECT DIGITAL CONTROL SYSTEM

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DISTRIBUTED CONTROL SYSTEMS (DCS)

Multiple microcomputers connected together to share and distribute the process control workload

Features: Multiple process control stations to control

individual loops and devices Central control room where supervisory control

is accomplished Local operator stations for redundancy Communications network (data highway)

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DISTRIBUTED CONTROL SYSTEM

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DCS ADVANTAGES

Can be installed in a very basic configuration, then expanded and enhanced as needed in the future

Multiple computers facilitate parallel multitasking Redundancy due to multiple computers Control cabling is reduced compared to central

controller configuration Networking provides process information

throughout the enterprise for more efficient plant and process management

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Computerized Process Control improves Sugar Refinery Production

NUMERICAL CONTROL AND ROBOTICS

Computer numerical control (CNC) – computer directs a machine tool through a sequence of processing steps defined by a program of instructions Distinctive feature of NC – control of the position of

a tool relative to the object being processed Computations required to determine tool trajectory

Industrial robotics – manipulator joints are controlled to move and orient end-of-arm through a sequence of positions in the work cycle

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PLASTIC INJECTION MOLDING MACHINE BLD 280 CNC USE FOR…A) MULTIPLE HYDRAULIC CORE PULLING B) CYLINDER TRANSDUCER CONTROL C) MULTIPLE OPTIONS OF ...

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ROBOTS

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PROGRAMMABLE LOGIC CONTROLLER (PLC)

Microprocessor-based controller that executes a program of instructions to implement logic, sequencing, counting, and arithmetic functions to control industrial machines and processes

Introduced around 1970 to replace electromechanical relay controllers in discrete product manufacturing

Today’s PLCs perform both discrete and continuous control in both process industries and discrete product industries

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PLC

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BLOW MOLDING MACHINE

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PONGRASS MODEL 32H 32MM CAPACITY MANDREL TUBE BENDING MACHINEPLC CONTROL USE FOR RISING CLAMP & LENGTH STOP BAR

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SUPERVISORY CONTROL

In the process industries, supervisory control denotes a control system that manages the activities of a number of integrated unit operations to achieve certain economic objectives

In discrete manufacturing, supervisory control is the control system that directs and coordinates the activities of several interacting pieces of equipment in a manufacturing system Functions: efficient scheduling of production,

tracking tool lives, optimize operating parameters Most closely associated with the process

industries35

SUPERVISORY CONTROL SUPERIMPOSED ON PROCESS LEVEL CONTROL SYSTEM

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Introduction to SCADA A subset of PCS systems that manage systems

over very large geographic areas are typically referred to as Supervisory Control and Data Acquisition systems or SCADA systems. SCADA systems make up the critical infrastructure associated with electric utilities, water and sewage treatment plants, and large-scale transportation systems like interstate rail.

Supervisory Control and Data Acquisition systems are basically Process Control Systems (PCS), specifically designed to automate systems such as traffic control, power grid management, waste processing etc.

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Aspects of SCADA Most often, a SCADA system will

monitor and make slight changes to function optimally

SCADA systems are considered closed loop systems and run with relatively little human intervention

One of key processes of SCADA is the ability to monitor an entire system in real time

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SCADA systems in INDIA SCADA systems are still to come into

widespread infrastructural use in India Now, they are being used primarily for

automation in industrial production, and to some extent for specialized process control

Ranbaxy Labs and Voltas are two of the companies in India using SCADA systems for controlling a variety of processes

Other examples of pseudo-SCADA usage also observed

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Components of SCADA The basic structure of PCS systems is made

up of a wide range of components and several different communication protocols. The operation of such a large and diverse infrastructure requires an extensive network of electronic devices, communications, and control and monitoring systems, such as:

Field Devices– Remote Terminal Units (RTU)– Programmable Logic Controllers (PLC)– Intelligent Electronic Devices (IED)– Programmable Automation Controller (PAC)

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Components of SCADA Management systems to monitor and control

field equipment– Human Machine Interface (HMI)– SCADA Controller or Real Time Processor– Historian

Communications– Ethernet, Wireless, Serial– Modbus, DNP3– ICCP, OCP

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Construction of SCADA SCADA systems are primarily control

systems. A typical control system consists of one or more remote terminal units (RTU) connected to a variety of sensors and actuators, and relaying information to a master station.

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A typical 3-tiered approach to SCADA systems

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Sensors perform measurement, and actuators perform control.

Sensors get the data (supervision and data acquisition)

Actuators perform actions dependent on this data (control).

The processing and determination of what action to take, is done by the master control system (i.e. SCADA).

Sensors & Actuators

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RTU/ PLC Remote Terminal Units (RTUs) connect

to sensors Convert sensor signals to digital data

and sending digital data to the supervisory system

Operate actuators as per control signals received/ generated

Provide local processing capability Applications that had previously been

programmed at the central master station can now be programmed at the RTU.

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Master StationMaster stations have two main

functions:• Periodically obtain data from RTUs/PLCs (and other master or sub-master stations)• Control remote devices through the operator station

Other duties include trending, alarm handling, logging and archiving, report generation, and facilitation of automation. These duties may be distributed across multiple PCs, either standalone or networked.

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Segregation of functions of a SCADA system into a functional representation

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Data Flow Data acquisition begins at the RTU or PLC

level and includes meter readings and equipment status reports that are communicated to SCADA as required

Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal RTU (PLC) controls

Data may also be fed to a Historian, often built on a commodity Database Management System, to allow trending and other analytical auditing.

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SCADA of Cooling System

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Applications of SCADA Electric power generation, transmission &

distribution (USA) Water supply, sewage & drainage (UK &

Netherlands) Buildings, facilities & environment Manufacturing (Robots-Toyota, Porsche, VW) Traffic Signals (USA) Mass transit (Rail crossing gates, USA) Suburban Railway system (Mumbai, Western

Railway)

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Bibliography

SCADA-IBM whitepaper Whitepaper on SCADA systems security-Arjun

Venkatraman SACAD-A. Daneels-CERN, Geneva www.wikipedia.org

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Thank You