industrial automation automation industrielle industrielle automation 1.3types of plants and control...
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Industrial AutomationAutomation IndustrielleIndustrielle Automation
1.3 Types of Plants and ControlTipos de plantas y de controlSystèmes contrôlés et contrôleStrecken und Steuerungen
Types of plants and control 1.3 - 2Industrial Automation
1.3 Contents
1 Introduction
1.1 Automation and its importance
1.2 Applications of automation
1.3 Plants and controls
1.3.1 Open loop and closed loop control
1.3.2 Continuous processes
1.3.3 Discrete processes
1.3.3 Mixed processes
1.4 Automation hierarchy
1.5 Control system architecture
Types of plants and control 1.3 - 3Industrial Automation
Plant types
Despite the large diversity of applications, the principles of automation are always the same.
There are a few basic types of plants and the same control system hardware and basic software is shared by most applications.
Distinction is often question of a point of view, profession-specific vocabulary and marketing.
Types of plants and control 1.3 - 4Industrial Automation
Control Tasks
Leiten - die Gesamtheit aller Massnahmen, die einen im Sinne festgelegter Ziele erwünschten Ablauf eines Prozesse bewirken (DIN 19222)
control: el conjunto de medidas que permiten influenciar el estado de un proceso para un propósito dado
Conduite: l'ensemble des mesures qui permettent d'influencer l'état d'un processus dans un but fixé.
messen - steuern - regeln - leiten
mesure - commande - régulation - conduite
measure - command - control
Types of plants and control 1.3 - 5Industrial Automation
Open loop and closed loop
1
23
4
5
temperature
temperature is imprecise,depends on ambient temperature andcooking quantity but time of heating can be modulated.
120
140180
200
220 temperature closely controlled, requires measurement of the output variable (temperature)
+
-higher/lower
temperature sensor
open loop:
closed loop:
on/off
Types of plants and control 1.3 - 6Industrial Automation
Open loop and closed loop
outputcontroller+
-
plant state
display
control variable(analog)
set-point (solicited)valeur de consigneSollwert,
plant
measurement
plant state
sequencer
on/off
plant
display
closed-loop control / regulation(régulation, Regelung)
keywords: feedback, analog variables, continuous processes, "process control"
open-loop control / command(commande / pilotage, Steuerung, )
keywords: sequential / combinatorial, binary variables, discrete processes,"batch control", "manufacturing"
output
error(deviation)
binary
%process value(valeur mesurée,Istwert)
measurement
clock
Types of plants and control 1.3 - 7Industrial Automation
Traditional allocation of function of computers in control systems
open-loop functions
Data acquisition and pre-processing
Sequential control
Data transfer between plant and operator
Display the plant state
Logging and history recording
Simulation and training
closed-loop functions
Protection and interlocking*
Regulation
Process-driven sequential control
Process optimization algorithms
Interlocking*: prevent dangerous actions,such as all lights on green at a crossing(interbloquage, Verriegelung, enclavamiento)
the control system acts directly and autonomously on the plant
Types of plants and control 1.3 - 8Industrial Automation
Discrete and continuous plants
discrete control(binary)
continuous control(analogue)
Types of plants and control 1.3 - 9Industrial Automation
Continuous plants
Examples: Drives, Ovens, Chemical Reactors
F(p)yx
Continuous plants (processes) have states that can be described by a continuous (analog) variable (temperature, voltage, speed,...)
Between plant input and plant output, there exists a fixed relation which can bedescribed by a continuous model (transfer function).
Continuous plants are mostly reversible and monotone: These are the conditions necessary to control them, i.e. impose the value of their output.
The transfer function may be described by a differential equation, simplified to a Laplace or a z-transform when the system is linear.
The principal control task in relation with a continuous process is its regulation (maintain the state on a determined level or trajectory)
Types of plants and control 1.3 - 10Industrial Automation
Discrete plants
ec + ¬d
1
2 3
6 5
4
7
a
bc + d
e
init
A discrete plant is modeled by well-defined, exhaustive and non-overlapping states, and by abrupt transitions from one state to the next caused by events.
Discrete plants are mainly reversible, but not monotone:the removal of the stimulus which caused a state transition will not necessarilybring the plant back to the previous state.
Example: a lift will not go back to the previous floor when releasing the button that called it.
Discrete plants are described by Finite State Machines, Petri Net, State transition tables Grafcet, or Sequential Function Chart diagrams.
The main task of a control system in relation with discrete plants is their command.
Going back to a previous state may require transit through several other states.
Types of plants and control 1.3 - 11Industrial Automation
Continuous and batch processes
Continuous process(processus continus, kontinuierliche Prozesse)
continuous flow of material or energye.g. motor control, cement, glass, paper production,rolling mill for wires, plate or profiles,
newspaper printing: 23 m/s, steel wire 90 m/s
Main task: regulation
Batch process(processus de charge (par lots), Stückgutprozesse)
discrete processes with handling of individual elementse.g. Numerical Controlled machine, packing machines,Bottle-filling, manufacturing, pharmaceutical and chemical processes.
Main task: command
Types of plants and control 1.3 - 12Industrial Automation
Mixed plants
All processes have some continuous and some discrete behavior - a question of point of view.
In reality, all plants consist of discrete and of continuous processes.
Example 1: Motor control of a cable-car with speed control and stop at stations
All parts must de described individually.
Processes can be described as continuous within a discrete state or as non-linear, continuous process.
Example: Time-triggered set-point of an oven temperature.
Mixed plants are the normal case.
Example 2: A bottle-filling line is in principle a continuous process, but each step consists of a sequence of operations
Types of plants and control 1.3 - 13Industrial Automation
Depends on industrial process
Automotive Manufacturing
Electronics
Machinery
Textiles
Pharmaceuticals
Fine Chemical
Food & Beverage
Metals & Mining
Water & Waste
Pulp & Paper
Vehicles
Petrochemicals
Oil & Gas
Electrical Power
discrete
continuous
source: ARC
Types of plants and control 1.3 - 14Industrial Automation
The main categories in industry
industry distinguishes the following categories of applications:
"process control": continuous processes, associated with fluxes, e.g. sewage water treatment, petrochemical process, cement…
"batch control": semi-continuous processes, associated with individual products, e.g. fine chemicals, pharmaceutical, brewery…
"manufacturing": also called “factory automation”discrete processes, associated with transformation of parts,e.g. automobile industry, bottle-filling, packaging
Types of plants and control 1.3 - 15Industrial Automation
Assessment: which answers are correct ?
1. open loop control is only usedwhen the plant can produce indefinitelywhen the plant is operated in on/off modewhen the operator can supervise the plant
2. closed loop control is needed whenthe plant is insufficiently knownthe plant is subject to perturbationsthe plant cannot be described by differential equations
3. the main task of a controller in a continuous process is:to keep the output always at the same valueto keep the output within a certain rangeto bring the output to a specific value in function of time
4. the main task of a controller in a discrete process is:to issue commands depending on the stateto maintain constant speed of productionto measure the state and present it to the operator
5. which of the following is a consistent plant categorization:open loop – continuous – closed loopdiscrete - continuous - hybridprocess - manufacturing- batch
Types of plants and control 1.3 - 16Industrial Automation
Assessment: which answers are correct ?
1. open loop control is only usedwhen the plant can produce indefinitelywhen the plant is operated in on/off modewhen the operator can supervise the plant
2. closed loop control is needed whenthe plant is insufficiently knownthe plant is subject to perturbationsthe plant cannot be described by differential equations
3. the main task of a controller in a continuous process is:to keep the output always at the same valueto keep the output within a certain rangeto bring the output to a specific value in function of time
4. the main task of a controller in a discrete process is:to issue commands depending on the stateto maintain constant speed of productionto measure the state and present it to the operator
5. which of the following is a consistent plant categorization:open loop – continuous – closed loopdiscrete - continuous - hybridprocess - manufacturing- batch
Types of plants and control 1.3 - 17Industrial Automation
Fill in the grid
hydro power plantcar factorypaper millcontainer harborluggage transportelectrical substationprinting machinelocomotivewater treatmentbuilding automationpetrochemical plantpharmaceutical
(continuous) process
batch manufacturing