FACULTY OF ENGENNERING
COMPUTER & AUTOMATIC CONTROL DEPT.
CONTROL ON PETROLUM'S PIPE LINES
USING SCADA SYSTEM & DATA
Prof.Mostafa Safwat Elqayaty
WHAT SCADA MEAN:
SCADA stands for Supervisory Control and Data Acquisition as the name indicates, it is not a full control system, but rather focuses on the supervisory level. As such, It is a purely software package that is positioned on top of hardware to which it is interfaced in general via Programmable Logic Controllers (PLCs), Or other commercial hardware modules.
SCADA is the technology that enables a user to collect data from one or more distant facilities and / or send limited control instructions to those facilities. SCADA makes it unnecessary for an operator to be assigned to stay at or frequently visit remote locations when those remote facilities are operating normally. SCADA includes the operator interface and the manipulation of application – related data-but it is not limited to that.
Some manufactures are building software packages that they call SCADA, and while these are often well suited to act as parts of a SCADA system, because they lack communications links and other necessary equipment they are not complete SCADA systems.
Definition of SCADA:
A SCADA system allows an operator to make set point changes on distant process controllers, to open or close valves or switches, to monitor alarms, and to gather measurement information from a location central to a widely distributed process, such as an oil or gas field, pipeline system, or hydroelectric generating complex. When the dimensions of the process become very large – hundreds or even thousands of kilometers from one end to the others- one can appreciate the benefits SCADA offers in terms of reducing the cost of routine visits to monitor facility operation.
SCADA technology is best applied to processes that are spread over large areas, are relatively simple to control and monitor, and require frequent, regular,or immediate intervention. The following examples of such processes should help you visualize the range of application types SCADA is suitable for:
1. groups of small hydroelectric generating stations that are turned on and off in response to customer demand are usually located in remote locations, they can be controlled by opening and closing valves to the turbine, they must be monitored continuously, and they need to respond relatively quickly to demands on the electric power grid.
2. oil or gas production facilities – including wells, gathering systems ,fluid measurement equipment , and pumps are usually spread over large areas ,require relatively simple controls such as turning motors on and off , need to gather meter information regularly, and must respond quickly to conditions in the rest of the field .
3. Pipelines for gas, oil, chemicals, or water have elements that are located at varying distances from a central control point, can be controlled by opening or closing valves or starting and stopping pumps, and must be capable of responding quickly to market conditions and to leaks dangerous environmentally sensitive materials.
4. Electric transmission systems may cover thousands of square kilometers, can be controlled by opening and closing switches, and must respond almost immediately to load changes on the lines.
5. irrigation systems often cover hundreds of square miles, can be controlled by opening and closing simple valves, and require the gathering of meter values for the water supplied to consumers .
These examples are just that examples. SCADA has been successfully installed on each of these types of processes as well as many others.
Signals sent from the SCADA central location to the remote site are usually limited to discrete binary bit changes or to analog values addressed to advice at the process. An example of a binary bit change would be an instruction to change a valve controller set point to 70 percent.
· Hardware Architecture:
One distinguishes two basic layers in a SCADA system: the "client layer" which caters for the man machine interaction and the "data server layer" which handles most of the process data control activities. The data servers communicate with devices in the field through process controllers. Process controllers, e.g. PLCs, are connected to the data servers either directly or via networks.
Data servers are connected to each other and to client stations via an Ethernet LAN. The data servers and client stations are NT platforms but for many products the client stations may also be W95 machines.
· Software Architecture:
The products are multi-tasking and are based upon a real-time database (RTDB) located in one or more servers. Servers are responsible for data acquisition and handling (e.g. polling controllers, alarm checking, calculations, logging and archiving) on a set of parameters.
Communications is the movement of data or intelligence from one location to another. For communications to happen, several things must be in place. First, a communication path must exist; some medium must be selected over which the data will travel. Second, equipment must exist at the sending end of the communications path to condition the data and to put it into a form that can be sent over the communications medium. Third, equipment must exist at the receiving end of the path to extract the message from the medium and understand its meaning.
. Ease of modification
.Supported protocols (most popular: Ethernet, Data
Real Application of SCADA:
Remote access At the
Control's new Virtual Server helps
The National Museum of Science and
Industry, one of the
To enable senior staff gain dial up
access to this WAN, an Interchange Virtual Server is being used.The Interchange
VS1000 unit sits on the London LAN with its driver loaded on th
A mixture of modems (28.8 - 56Kbps) and ISDN terminal adapters are connected to the VS1000 to give staff working from home or on the move access to their e-mail and the resource on the network.
One of the key
resources, now accessible to mobile staff is a massive database of the complete
inventory at each of the NMSI's sites.The speed at which this can now be
accessed and updated has been greatly increased since the installation of
Control's Interchange VS1000 was selected from a wide range of remote access products because it gave excellent cost/performance and was simplicity itself to set up. The excellent management facilities and its ability to be easily expanded as the remote access demand increases were also keypointsinitsfavor.
The various LANs are connected using BT's Kilo Stream. Basic Rate ISDN, linked via the VS1000, will be used as the back up option should the Kilo Stream link fail. As the demand for remote access increases a VS1100 is to be added to the system to give a further 16 ports.
· Airport data -Acquisition &display
This application called (Flight information handling) or (Finding the correct flight)
BAA plc has equipped
During the late 1980s the system for displaying flight information at Heathrow and BAA's other airports were becoming overwhelmed by the amount of information they were required to handle. A new solution was needed and it was developed in-house by BAA (then British Airports Authority.
The system adopted relies on a series of
centralized PC based Flight Information Systems (FIS), which receive the
details of all aircraft movements. This information is then processed by a PC
based Graphical Display Controller (GDC). This, in turn, feeds a network of
Graphical Display Units (GDUs) and these are the monitors that display
information to the general public.
The communications between each component in the system is controlled by Hostess i boards, chosen because of their reliability and ease of use. Information fed into the Flight Information System is collated and sent to the Graphical Display Computer via a Hostess i eight port board. The processed data from the GDC is fed into the SDLC based network (about 5km long at Heathrow) via a Hostess i two port board. A further Hostess i two port board is used to extract the data from the network and display it on the Graphical Display Unit.
The present FIS/GDC/GDU systems are in place at Gatwick (40 GDUs),
Heathrow, Terminal 1 (70 GDUs),
Control system For
A sophisticated Station Information Management System (SIMS) is being installed as part of GPT's £60m contract for the Jubilee Line Extension communications systems. The interface between the central computers and the various display boards is being provided by Control Europe to Encore, who are providing the hardware and operating system to GPT. This system is designed to control.
· High legibility displays in the stations and 'next station' displays in the trains
· Public address systems which adjust its volume automatically to account for background noise
· Digitally recorded station announcements
· 100% coverage surveillance cameras
· Sliding glass doors on the platform which only open when the train is in the right position
· Decision support systems
An Encore Infinity Real Time high
availability system, comprising of two DEC alpha computers tightly coupled
using Encore's Reflective Memory running under Digital UNIX V.3.2 forms the
heart of the system. The interface between these computers and the various
display boards etc. is being supplied by Comtrol Europe.
This interface provides full duplex HDLC over a synchronous, modified RS-485 electrical interface. The link effectively operates point to point although it is to be multi dropped between the 2 DEC Alpha computers.
To provide a system to this exacting specification, Comtrol Europe is
supplying Encore with its Gazelle NR7. This provides 16 RS-485 ports, each
selectable for synchronous and asynchronous mode. Control
Each DEC Alpha will have a Gazelle
Controller which communicates with the rack mounted Interface Unit via a
dedicated high speed Ethernet link. The various display boards connect to the
Interface Unit and are then controlled by the SIMS.
To minimize the load on the central computers, much of the processing takes place on the Controller and the Interface boards. To gain the high performance needed for this contract, the Controller and Interface used the 18 MIPS, 32 bit Hitachi SH2 series processors.
Hostess I from Control Europe is involved at the heart of a major
Control, Automation and Monitoring Systems for the
Transmitton Ltd, a leading international integrator of Supervisory
Control and Data Acquisition Systems (SCADA), has chosen the Hostess from
Control Europe as their preferred method of connecting serial devices to their
CROMOS control and management software. This has been used very successfully as
part of a £70 million revamp of Shell
Shore based control room operators are presented with process data, plant status and alarms so that they can monitor and control processes remotely. The plant communications is taken care of by a number of Hostess i controllers which interface to CROMOS through the PC's ISA bus via dual ported RAM. The on-board intelligence and versatility of the Hostess i have allowed Transmitton's proprietary MT700 protocol and a number of third party protocols to be programmed onto the controller, removing the communications overhead from the host PC.
This approach has provided an overall response time of less than three seconds from off-shore to on-shore on any one of 140,000 points, even though a modest data rate of 9600 baud is used.
For their next generation, CROMOS 2000, Transmitton will continue to use Control Europe's communication controllers as an integral part of the system, the vital link between the control room and the process.
SCADA provides the following benefits:
· A user-friendly interface for plant operators to monitor and control plant operation and performance.
· Immediate user-friendly notification of faults and out of specification operation.
· A history of plant performance and events which allow easy fault finding.
· Data upon which to base continual improvement djustments.
· A window into the plant for remote operators and supervisors via connection to the site through standard grade telephone line and remote computer systems.
This card for making an interface between the real world and the computer. And we use it instead of the PLC for many reasons:
1. You make a good technology by your self.
2. You are free for the specification of the card like the number of the digital input/output, but the PLC you are not free for this.
3. The cost of the card we design and make is lower from the PLC
4. With our card you free to use any programming language, but with PLC you must use its language.
2. SOFTWARE INSTALLATIONS:
The card has DLL driver software making by visual C++ that support the operation of the card with high performance with any programming language.
3. HARDWARE INSTALLATIONS:
The SW driver will discover the card that CIO-ADC16-DAC02 base address is from 300 hex (768 decimal) to 31F hex (799 decimal).
5. CONNECTOR PINOUTS:
DP: Digital input/output Pin
AOP: Analog Output Pin
AIP: Analog Input Pin
S: 50-pin connector pinout
5. ANALOG CONNECTIONS:
5.1 ANALOG INPUTS:
Analog signal connection is one of the most challenging aspects of applying a data acquisition board. The CIO-ADC16-DAC02 provides sexes teen separate analog input channels.
5.2 ANALOG OUTPUTS:
Analog outputs are simple voltage outputs which can be connected to any device which will record, display or be controlled by a voltage. The CIO-ADC16-DAC02 provides two separate analog output channels.
+5V, 1.4 A typical, 2.1 A max
Analog input section:
A/D converter type ADC
Resolution 8 bits
Voltage ranges 0 to 3.5V
Number of channels 16 separate channels
conversion time 100 µs
Clock Frequency 640 kHz
Differential Linearity error ± 1/2 LSB
Integral Linearity error ±1 LSB
Low Power 15 mW
Input leakage current (@25 Deg C) 200 nA
Resolution 8 bits
Number of channels 2 separate channels
D/A type DAC
Voltage ranges 0 to 3.5V
Differential Linearity error ± 1/2 LSB
Integral Linearity error ±1 LSB
Relative accuracy ±0.19% error maximum
Fast settling time 150 ns typ
High speed multiplying input slew rate 8 mA/µs
Power supply voltage range ±4.5V to ±18V
Low power consumption 33 mW @ ±5V
Digital Input / Output:
Digital Type 82C55
Number of channels 160 separate channels
Output High 3.0 volts min @ -2.5 mA
Output Low 0.4 volts max @ 2.5 mA
Input High 2.0 volts min, 5.5 volts
Input Low 0.8 volts max, -0.5 volts
7. Feasibility study:
Cost price: 750 $
Market price: 1000 $ www.MeasurementComputing.com)
8. Card Images:
ORCAD is a SW product that helps us in cards design and testing. By making layout using ORCAD then you can make a real printed card by any company.
10. Layout Image: