System specification is statement that clearly states what the device or product is to be and do as well as the design criteria. The systems monitor and control the process variable in the oil and Gas Process pl.ant
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4.2.1 Functionality of Industrial Automation System
According to Akpado (2011), modern industrial automation systems should be capable of conducting real-time online data acquisition and manipulation, recentralized system resources management, and networked data sharing. It must have a flexible configuration capability. It should be capable of flexible setting up of general local area network (LAN) capability and wide area network (WAN) capability in order to meet specific industrial measurement and control requirements. It should also be able to build comprehensive monitoring network, integrating various functions such as data collection, condition monitoring, fault diagnosis, resource management, and decision-making. Such an industrial automation system should be suitable for operation and management at different levels such as workshop, branch factory, and corporation.
The basic requirements for an industrial automation system are listed as follows:
It should be able to effectively conduct the desired measurement and control tasks in order to ensure the proper operation of the industrial process. By uninterrupted system monitoring and recording, the database stores gathered information on plant operation status. These data can be used latter on the further analysis and diagnosis of plant conditions.
It should be able to effectively utilize various signal processing techniques to analyze the gathered data from different measurement points (channels). Moreover, appropriate and effective data processing algorithms need to be incorporated into the industrial automation software so as to fully exploit the merits of computational resources provided by modern computers as well as satisfy time constraints on data manipulation. By doing so, real-time measurement and through data analysis can be effectively accomplished.
It should be able to increase the software versatility by allowing for flexible configuration of a variety of system parameters. The principles and main functions of industrial automation software may remain unchanged for different industrial applications.
However, the details for any specific application can be redefined by modifying the configuration database according to any specific user requirement. Finally, by combining configuration database with the fixed system modules, system configuration for the specific application is accomplished and thus the industrial automation software with desired functionality is built.
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Human-machine interfaces should be designed according to the current popular development trends. User-friendly graphical user interfaces (GUls) are always beneficial to improve software quality because they make user operations more convenient and pleasant. For instance, using the multimedia provided by the modern computer technology, all of the plant statuses can be displayed in an animated form as their corresponding industrial parameters are updated in real time.
It should have comprehensive alarming and reporting capability. The alarm module in the industrial automation software compares the gathered data with the user-set parameters.
Audiovisual alarms and exception reports are generated for immediate remedial action if the data levels detected exceed the preset parameters. The alarming function should be able to provide various alarming patterns in order to promptly inform the corresponding technical and management personnel of the presence of emergency situations. These flexible alarming modes include vivid screen indicator, speaker, automatic telephone dialing, beeper, e-mail, fax, and so on. E-mails can be sent to the cell phones of corresponding people in the form of SMS message, informing them of plant emergencies in a timely manner, which cuts machine downtime. All of these functions can be made available without needing extra prohibitive telemetry investments.
It should be able to directly perform various measurement and control tasks using commonly used web browsers. Previously, the special purpose industrial automation software package had to be installed on the industrial computer before hand in order to conduct the tasks. The networked system provides the network server, which allows the user to accomplish industrial measurement and control from anywhere through the network web browser (for example, Internet Explorer of Netscape). It avoids the installation of any special-purpose software. Thus, software maintenance becomes more convenient, and such systems should be more economically priced. Using the network technologies, an industrial automation system is no longer an ―island of automation‖ that only confines to stand-alone, local or dedicated network. The remote management activity allows operators anywhere to access the real-time data from the factory floor. Internet-enabled industrial automation system also allow for automatic software upgrades and remote maintenance. However, the challenges of handling security issues for such internet-enable systems should be well considered in adopting it.
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In line with the above recommendations and requirement for a process control system that would meet the challenges for optimum productivity, the software and hardware specifications of our system are shown in Table 4.1 and 4.2. Table 4.1 is the set point values of the nine units.
Table 4.1 Set point values
Temp Press Level Flow
Well Steam Heater 150 90 850 NA
Production and Test M 45 105 NA NA
Inlet separator 45 102.8 NA NA
Liquid Cooler 20 50 65 NA
Gas Compression 35 98 NA 65.9
Gas Cooler 25 50 NA NA
Condensation Stabilization 23 15 A NA
Dehydration Tag 45 102 NA NA
Pump 42 52 NA NA
[Source SPDC GP manual)
4.2.3 Brief Description of the Design Architecture.
This design is microcontroller-based interfaced with the ANN and Rule-based expert system. The ANN is for the classification of the different values of the process variables while the rule based expert systems contain rules in the knowledge base. The rules are used to generate questions for the user and to provide recommendation using the knowledge and interference engine. One of the reasons for the development of expert system is its potential to provide knowledge and advice to large number of users. The expert is implemented as knowledge servers. Expert systems running on a PC/server can support a large group of users and communicate with the system over the GSM network.
74 4.2.4 Database.
A database is provided for the management of information, such as calibration data setting, the parameter for calibration and calibration status. The parameters are read and compensation calculation for the measured values are made in order words necessary adjustments are made to control the system. It also stores maintenance records, diagnosis records, and steps taken to remedy the faults as well as related information. By monitoring the message history, the system can continuously manage and control operation and remedy future repairs. In addition a database for temperature, pressure, level and flow rate is created.
4.2.5 Further Specifications
Before designing the architecture for SMS Based Remote Monitoring and Control (SBRMC) the requirements should be specified. The major task in the requirement specification is to identify and resolve trade-offs between goals and constraints of the system that are conflicting or not completely achievable.
Important requirements concerning SBRMC are as follows:
Tasks, which require a deterministic timing regime, should be avoided because they may not be achievable due to GSM-related traffic delay.
It is necessary to minimize the communication load between the GSM network level and the existing control level.
Direct access to a controller (for example a PLC) is not a requirement and is probably not desirable because of security reasons. Information exchange between Process plants and GSM-based clients can be achieved through corporate systems – such as relational databases or real-time databases, instead of control units.
Reliability and the possible system failures should be considered in order to keep the system robustness from the system architecture point of view.
The different requirements will lead to different control structures having its own advantages and disadvantages
75 4.2.6: Hardware Subsystem Specification:
Table 4.2 is the hardware subsystem specification of the envisaged system. It comprises of the components shown in this table.
Table 4.2 Main Features of the Hardware System
ITEM CONTENT
Controller IC Microcontroller
Interface IC Bus Expander
Power Supply 5-10V D.C/220V Ac
Dedicated Input Lines 8
Dedicated Output Lines 16
Input/Output Lines 36
Control Lines 17
Input Mode Digital (3-5V)
Output Mode Digital (3-5v)
Display Type LCD
Text Format Alphanumeric
Operating Temperature 60-700 C
Power Extension Yes, 3