Industrial AutomationAutomation IndustrielleIndustrielle Automation

1.5 Control System ArchitectureArquitectura de controlArchitecture de Contrôle - CommandeLeittechnik-Architektur

Control system hierarchy 1.5 - 2Industrial Automation

1.5 Control System Architecture

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 process

1.3.3 Discrete process

1.3.3 Dual plants

1.4 Automation hierarchy

1.5 Control System Architecture

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Principle

The control system is a communication system consisting of controllers and links.

The structure of the control system should reflect the structure of the plant

Ideally, each unit of the plant should have its own controller, interacting with the controllers of the other, related units, mirroring their physical interaction.

Example: Airbus: a wing is delivered with its own computers.

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System Architecture

Conceptual model presenting•Structure•Relationships •Behavior

Including•Description of most important elements of system•Mapping of functionality onto hardware and software components•Description of top-level human interaction with components

Goal:•support reasoning about elements, structure and behavior•guide for implementation

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Example: Power plant control - 1980 (!)

Control systems still look similar

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Buses and processors in industrial plants

PLC nodes(multi-processors)

fieldbus (30m..2 km)

Operator panelMimic board

plant (Werk, usine)

P

disk

processor pool

transducers

controlstations

plant network (500m .. 3 km) – includes control network

valve thermo-couple motor

Process pictures

Process Data Base

Logging

position

backplane bus

node bus

workstation bus

instrument bus(mimic board)

sensor bus

directly coupled input/output

open network, WAN

station

P P C

I/O MEM I/O

P P C P

MEM BC

station

M

sensor bus (0,5.. 30 m)

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Example: Production management system

transportationcell control

manufacturingcell control

scheduling maintenance quality control

plant network

floor network

productionplanning

robotcontroller

enterprise network

millingmachine

rail-guided vehicle

cell

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Plant with process (e.g. chemical) and electrical (substation) parts

horizontal communication

CN Connectivity Server (and router)

IEC 61850 connectivity server

plant networkEngineering

bay bus

substation networkprocess network

interface

SAN IEDs

CI871

Aspect Servers

controller

PIPB

PIPB

PIPB

PIPB

PIPB

PI = Process Interface MU = Merging Unit

PIPN

PIPN

PIPN

PIPN

PIPN

PIPI

PIPI

PIPI

PIMU

PIMUProfibus

Engineering

Engineering

Profinet RSTP

LANs are separate: there is no IP routing between

them

vertical communication

Workplaces

horizontal communication

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Example: Newspaper Printing Architecture

Each level has its own bus !

MPS = Managed Print Services

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Example: ABB Industrial IT (redundant system)

3rd partycontrollers,servers etc

Serial or fieldbus

engineeringworkplace

Field Bus

Firewall

Plant Network / Intranet

Field Bus

Plant Network (Ethernet)

3rd party application server

applicationserver

aspectserver

Workplaces(clients)

Enterprise Optimization

(clients)

MobileOperator

connectivityserver

Control Network (Ethernet)ProgrammableLogic ControllerAC 800C

RedundantAC 800M

touch-screen

sensor network

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Centralized (Hierarchical) Control Architecture

Sensors, Actors

PLCsGroup

Control

Group

Control

Group

Control

Central Computer

(Mainframe)

Classical, hierarchical, centralized architecture.

The central computer only monitors and forwards commands to the PLCs

plant

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plant

Decentralized Control System (DCS)

engineeringworkstation

operatorworkstation

data logger

controller controller controller controller

field bus

plant bus

all controllers can communicate as peers (without going through a central master), restricted only by throughput and modularity considerations.

hierarchical(vertical communication)

peer-to-peer (horizontal communication)

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Hierarchies are simple and traditional

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but Distributed Control Systems reflect a more complex world....

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Assessment

1. What is a bus and why do we have more than one kind of them in a plant?

2. Name the parts of a typical hierarchical control system its busses and controllers

3. How does the network hierarchy relate to the plant control hierarchy?

4. What is the difference between a centralized and a decentralized control system ?What are the (dis)advantages of the two approaches?