Industrial Automation Automation Industrielle Industrielle Automation Enterprise Manufacturing Execution
Supervision (SCADA) Group Control Individual Control Field Primary technology
1.4
Automation Hierarchy Hiérarchie de l'automation Leitsystem-Hierarchie Prof. Dr. H. Kirrmann
EPFL / ABB Research Center, Baden, Switzerland 2011 February, HK
1.4 Contents
1 Introduction 1.1
Automation and its importance
1.2
Examples of automated processes
1.3
Types of 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 plants
1.4
Automation hierarchy
1.5
Control system architecture
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Automation System Structure Although applications differ widely, there is little difference in the overall architecture of their control systems.
Why the control system of a power plant is not sold also for automating a brewery depends largely on small differences (e.g. explosion-proof devices), on regulations (e.g. Food and Drug Administration) and also tradition, customer relationship.
But the biggest difference is the amount of application know-how embedded in the control system.
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Large control system hierarchy (1) 5
Planning, Statistics, Finances
4
Production planning, orders, purchase
3
Workflow, order tracking, resources
2
Supervisory
administration enterprise (manufacturing) execution
SCADA = Supervisory Control And Data Acquisition
Group control Unit control 1 Field Sensors & actors 0
A V
T
Primary technology Industrial Automation
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Large control system hierarchy (2) Administration Enterprise Manufacturing Supervision Group (Area)
Unit (Cell)
Field
Finances, human resources, documentation, long-term planning Set production goals, plans enterprise and resources, coordinate different sites, manage orders Manages execution, resources, workflow, quality supervision, production scheduling, maintenance. Supervise the production and site, optimize, execute operations visualize plants, store process data, log operations, history (open loop) Controls a well-defined part of the plant (closed loop, except for intervention of an operator) • Coordinate individual subgroups • Adjust set-points and parameters • Command several units as a whole Control (regulation, monitoring and protection) part of a group (closed loop except for maintenance) • Measure: Sampling, scaling, processing, calibration. • Control: regulation, set-points and parameters • Command: sequencing, protection and interlocking . transmission data acquisition (Sensors & Actuators), data no processing except measurement correction and built-in protection.
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Field level
the field level is in direct interaction with the plant's hardware (Primary technology, Primärtechnik)
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Group level (Area) unit controllers
the group level coordinates the activities of several unit controls
the group control is often hierarchical, can be also be peer-to-peer (from group control to group control = distributed control system)
Note: "Distributed Control Systems" (DCS) commonly refers to a hardware and software infrastructure to perform Process Automation
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Local human interface at group level sometimes, the group level has its own man-machine interface for local operation control (here: cement packaging)
also for maintenance: console / emergency panel
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Supervisory level: Man-machine interface
control room (mimic wall) 1970s...
formerly, all instruments were directly wired to the control room
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Mosaic is still in use – with direct wiring
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Supervisory level: SCADA (SCADA = Supervisory Control and Data Acquisition)
Trend e rapporti Interfaccia operatore
Gestione ricette
Base dati di processo
Controllo di processo
Gestione allarmi Supporto manutenzione Sistema esperto
OPC
- displays the current state of the process (visualization) and can modify it (process control) - displays the alarms and events (alarm log, logbook “giornale di bordo”) - displays the trends (historians) and analyse them - displays handbooks, data sheets, inventory, expert system (documentation) - manages maintenance and working plans (recipes) - allows communication and data synchronization with other centres Industrial Automation
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Today’s control rooms
beamers replaces the mosaics, there is no more direct wiring to the plant.
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Plant management
- store the plant and product data for further processing in a secure way (historian), allowing to track processes and trace products -> Plant Information Management System (PIMS) sistema informativo
- make predictions on the future behaviour of the processes and in particular about the maintenance of the equipment, track KPI (key performance indicators) -> Asset Optimisation (AO) ottimizzazione delle attività
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Engineering workplace
The engineering workplace manages the control system, not the plant. The engineer can configure the networks and devices, load the software, assign authorizations, troubleshoot the control system,...
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ANSI/ISA 95 standard classification the ANS/ISA standard 95 defines terminology and good practices (procedures, benchmark) Level 4
Business Planning & Logistics
Enterprise Resource Planning
Plant Production Scheduling Operational Management, etc.
Level 3
Manufacturing Operations & Control Dispatching Production, Detailed Product Scheduling, Reliability Assurance,...
Levels 2,1,0 Batch Control
Continuous Control
Discrete Control
Manufacturing Execution System
Control & Command System
Source: ANSI/ISA–95.00.01–2000
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Example: Power plant
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Example of generic control siemens: Siemens WinCC (Generic)
Unternehmensleitebene Enterprise level
Betriebsleitebene Production level
Prozessleitebene Process level
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Response time and hierarchical level
ERP
Planning Level
(Enterprise Resource Planning)
MES Execution Level
(Manufacturing Execution System)
SCADA
(Supervisory Control and Data Acquisition)
Supervisory Level
DCS (Distributed Control System)
Control Level
Note: a complex and powerful PLC has the same HW than a DCS
PLC (Programmable Logic Controller)
ms
seconds
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weeks
month
years
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Data Quantity & Quality and Hierarchical Level Higher Levels When ascending the control hierarchy, data are reduced: higher level data are created (e.g. summary information) Processing and decisions becomes more complicated (requires using models). Timing requirements are slackened. Historical data are stored SCADA level Presentation of complex data to the human operator, aid to decisions (expert system) and maintenance. Requires a knowledge database in addition to the plant's database Lower Levels Lowest levels (closest to the plant) are most demanding in response time. Quantity of raw data is very large. Processing is trivial (was formerly realized in hardware). These levels are today under computer control, except in emergency situations, for maintenance or commissioning.
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Complexity and Hierarchical level
Complexity
Reaction Speed months
ERP MES
Command level Führungsebene,
Sys. d'exécution Ausführungssystem
Supervision étage de conduite
Prozessleitung Conduite de processus
Group Control (area) Gruppenleitung Conduite de groupe
Individual Control (Cell) Einzelleitung,
days
minutes
seconds
0.1s
Conduite individuelle
Field Feld,
0.1s
terrain campo
Site Anlage,
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dispositivi
1.4 Automation hierarchy
Operation and Process Data base Consideration of human intervention breaches this hierarchy. Normally, the operator is only concerned by the supervisory level, but exceptionally, operators (and engineers) want to access data of the lowest levels. The operator sees the plant through a fast data base, refreshed in background. This database is the pivot for logging and simulation. knowledge base
man-machine communication operator
history
logging
process data base
simulation instructor
maintenance engineer
actualization process data plant
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The process database is at the centre (example: Wonderware)
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Process Data Base and Historical Data Base
The Process Data Base reflects the latest known state of the plant The Historical Data Base registers the events that happened in the plant (and is therefore a subset of the Process Data Base snapshot) “Compression” problem “Data find and data recovery” problem “The digital dark age” problem (obsolescence of supports or formats)
E.g. the “compression” problem applied to a trend - compression in data (less information, less resolution) - compression in time (undersampling) Solutions that compress data (source, ID, mean value, median value, standard deviation, min & max, date & time) for a variable time (small time during events, long time in steady-state) Industrial Automation
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SCADA Acronym for Supervisory Control and Data Acquisition a computer system for gathering and analyzing real time data, SCADA systems are used to monitor and control a plant or equipment in industries such as telecommunications, water and waste control, energy, oil and gas refining and transportation, building and home. A SCADA system gathers information, such as where a leak on a pipeline has occurred, transfers the information back to a central site, alerting the home station that the leak has occurred, carrying out necessary analysis and control, such as determining if the leak is critical, and displaying the information in a logical and organized fashion. SCADA systems can be relatively simple, such as one that monitors environmental conditions of a small office building, or incredibly complex, such as a system that monitors all the activity in a nuclear power plant or the activity of a municipal water system. In many industrial applications, SCADA are commonly used for HMI, alarms, trends and reports, process controls, maintenance actions, working plans and recipes, statistical analysis and expert systems, and other functions. Nowadays solutions benefit from a single, open and scalable software architecture that can connect to virtually any automation system, remote terminal unit (RTU), intelligent electronic device (IED), programmable logic controller (PLC), database, historian or business system in use today. www.plcscada.com
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SCADA
www.plcscada.com
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PLC The PLC (Programmable Logic Controller) was invented in response to the needs of the American automotive manufacturing industry. PLCs were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam-timers (timer multipli a motore), and drum sequences (sequenziatori a tamburo) and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire relays. In 1968 GM Hydramatic (the automatic transmission division of general motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedfors, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics,and later acquired by German Company AEG and then by French Schneider Electric, the current owner. One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance. The automotive industry is still one of the largest users of PLCs. www.plcscada.com Industrial Automation
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PLC
• Compact, robust and nice • modular architecture • well-connected and integrated • programmable
www.plcscada.com
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DCS Distributed Control Systems (DCSs) are dedicated systems used to control manufacturing processes that are continuous or batch-oriented, such as oil refining, petrochemicals, central station power generation, pharmaceuticals, food and beverages ,manufacturing production, steelmaking, and papermaking. Similarly to PLCs, DCSs are connected to sensors and actuators and use setpoint control to control the flow of material through the plant. The most common example is a setpoint control loop consisting of a pressure sensor, controller, and control valves. Pressure or flow measurements are transmitted to the controller, usually through the aid of a signal conditioning Input/Output (I/O) device. When the measured variable reaches a certain point, the controller instructs a valve or actuation device to open or close until the fluidic flow process reaches the desired setpoint. Large oil refineries have many thousands of I/O points and employ very large DCSs. Processes are not limited to fluidic flow through pipes, however, and can also include things like paper machines and their associated variable speed drives and motor control centers, cement kilns, mining operations, ore processing facilities, and many others. A typical DCS consists of functionally and/or geographically distributed digital controllers capable of executing from 1 to 256 or more regulatory control loops in one control box. The input/output devices (I/O) can be integral with the controller or located remotely via a field network. Today’s controllers have extensive computational capabilities and, in addition to proportional, integral, and derivative (PID) control, can generally perform logic and sequential control. DCSs may employ one or several workstations and can be configured at the workstation or by an off-line personal computer. www.plcscada.com Industrial Automation
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DCS
• Typically dedicated to a particular process • More attention to safety (e.g. ATEX) -large areas, less operators- and redundancy • A PLC can be integrated in a DCS • With peripherals and real-time Ethernet, the architectural differences between PLC and DCS decrease • PLC -> Logic Controller, factory automation • DCS -> Process Controller, expensive • A PLC stand-alone is also called DDC (Direct Digital Control) • A DCS could integrate a SCADA (warning with ambiguity for the more general meaning of term DCS)
www.plcscada.com
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