The evolution of control architectures

Contents ƒ Review of industrial control systems ƒ Evolution of control system architectures ƒ Advantages of true distributed control ƒ Challenges and research topics ƒ Summary and conclu

INH S

The Evolution of

Control Architectures

Hoang Minh Son Dr.-Ing.

Contents

ƒ Review of industrial control systems

ƒ Evolution of control system architectures

ƒ Advantages of true distributed control

ƒ Challenges and research topics

ƒ Summary and conclusion

Mechanical Devices

(James Watt’s Flying-Ball Governer, 1870)

Direct Digital Control

(1965-1975)

Programmable Logic

Controllers

(Bedford, Allen-Bradley, 1969)

Electronic PIDs

(1940-1950)

Compact Digital

Controllers

(80s)

Mechanical Devices

Electromagnetical Relays

(1920)

Distributed Control Systems

(TDC2000, Honeywell, 1975)

Pneumatic PIDs

(1920-1930)

Hybrid Control System

(90s)

Fieldbus Control Systems - Networked Control Systems

A brief history of industrial control systems

Levels of distribution

Centralized

Control

Distributed I/O

Distributed Control

Distributed Intelligence

Higher performance

Increased reliability

PLC, DCS

PLC, DCS

NCS, FCS

NCS/FCS Architecture

True distributed control using fieldbus technology

Direct communication between field devices

Integrated Control and Fieldbus Engineering

Coordinating Controller High-level Controller

Most of basic control functions implemented in field devices

Wiring and installation

Distribution of control function

AO AI

PID AI

PID

AO

PID AO AI

AO

Engineering: traditional way

Controller

control programming field device configuring

Fieldbus

Engineering: FCS/NCS

Controller

Fieldbus

Integrated Engineering

Information integration

TAG = LIC-012 VALUE = 70.34 UNIT = m 3

STATUS= GOOD ALARM = Y/N

NCS/FCS

TRANSMITTER

15.3 mA

DCS/PLC

TRANSMITTER

ƒ Reduced material and installation cost (cables, I/O modules, I/O terminations, transmitters,

control box, )

ƒ Higher performance and increased reliability

ƒ Integrated engineering, simplified configuration and parameterization of field devices

ƒ Control configuring instead of programming

ƒ Powerfull diagnosis and maintenance ability

Process A/D D/A

Digital Controller Clock

ƒ Existing Digital Control Theory based on:

– Centralized architecture, centralized (multivariable) controllers

– Synchronized I/Os

– In general: monorate sampling, deterministic delays

ƒ Also known as “Plant-wide control”, one of the the most actual topics in process control

ƒ Problem: Given an interconnected, large-scale system, how to:

– Select appropriate input and output variables for

control purpose – Automatic pairing of manipulated input to controlled output for single-loop, decentralized control design – Design appropriate control strategy

– Assign single-loop control algorithms to specific field devices and controllers

Sensor I/O

Controller

Actuator Sensor

Actuator I/O

Bus trường

Tsd

Tad

Tc1

Ts

Tbus

Tio

Tc2

ƒ Time periods (sampling time, scan time, bus

cycles, control cycles) not synchronized between interconnected devices

ƒ Different characteristics among bus systems

ƒ Uncertain time delays

ƒ Event-based sampling, multi-rate sampling

ƒ NCS/FCSs are complex hybrid systems:

continuous-time, time and

discrete-event characteristics

ƒ Issues:

– Modeling and simulation approach

– Analysis and design

– Implementation and commissioning

– Fault detection and diagnosis

– Performance monitoring and optimisation

– Predictive Maintenance

Control Engineering Computer Science

Communication Technology

Real-time systems

Industrial

communication

Distributed computing

Distributed control Networked control

Summary and conclusion

ƒ The evolution of control architecture is very

similar to the history of human society forms

ƒ The trend of industrial control system is toward distributed intelligence (true distributed control)

ƒ Advatages of distributed control: cost savings,

more functionality, higher performance and

increased reliability

ƒ Research topics needed: distributed control

structure design, real-time issues, hybrid systems

ƒ Future direction: 3C interdisciplinary research

INH S