Scada technology : Paper presentations
ABSTRACT:
SCADA is a computer system for gathering and analyzing “real time data”.SCADA system are used to monitor and control a plant or equipment in industries.
Introduction of SCADA –SCADA systems have made sustainable progress over the recent years in terms of functionality, performance.
Evolution –Created sensaphone SCADA 3000 a Y2K-complaint hardware and software system designed to accommodate in small to mid-sized companies.
The architecture of SCADA– hardware architecture and software architecture.
Functionality – alarm and event monitoring, data acquisition, operator interface, non real time control, Data bases and data logging, use of MMI, logging/archiving, report generation, automation.
Development with the help of SCADA –Rapid expansion in communication systems and increase processing power available at site.
Operation – operation of SCADA with remote telemetry unit.
Applications of SCADA –waste water control and monitoring petroleum and hydrocarbon rocessing, power generation, food processing, steel manufacturing, Remote tele-communication and plant machinery maintenance.
Case study –Updating SCADA system at power plant for increased capability and reliability.
Advantages and disadvantages – The advantages and disadvantages in using “SCADA” technology.
Developments in SCADA –Tecnomatix technology, Schneider electric’s new telemecanique brand.
Conclusion –purpose of using SCADA systems which reduce down time; increase throughput; limit the frequency of accidents; improve record etc;
SCADA –SUPERVISORY CONTROL AND DATA ACQUISITION:
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 purely software package that is positioned on top of hardware to which it is interfaced, in general via Programmable Logic Controllers (PLC’S), or other commercial hardware modules. Contemporary SCADA systems exhibit predominantly open-loop control characteristics and utilize predominantly long distance communications, although some elements or closed-loop control and/or short distance communications may also be present. It is process control software that remotely gathers “real time data” used in
manufacturing to acquire measurements of process variables and machine states, and for
performing regulatory or machine control. SCADA is used by the energy industry, telecommunication industry, transport industry, and water and waste control industry. SCADA –is also called supervisory control and data acquisition system or supervisory control and data acquisition software.
INTRODUCTION
Widely used in industry for Supervisory Control and Data Acquisition of industrial processes, SCADA systems are now also penetrating the experimental physics laboratories for the controls of ancillary systems such as cooling, ventilation, power distribution, etc. More recently they were also applied for the controls of smaller size particle detectors such as the L3 muon detector and the NA48.
SCADA systems have made substantial progress over the recent years in terms of functionality, scalability, performance and openness such that they are an alternative to in house development even for very demanding and complex control systems as those of physics experiments.
EVOLUTION:
Phonetics created the SENSAPHONE SCADA 3000, a Y2K-complaint hardware and software system design to accommodate small to mid-size companies seeking SCADA control. The system main unit uses two microprocessors to perform all control and communication functions. In terms of hard ware, the standard SENASAPHONE SCADA 3000 is equipped with 16 universal inputs, eight relay outputs, two RS-232 ports for local programming and radio communications, and a four line by 20-characters LCD.
WHAT DOES SCADA MEAN?
SCADA stands for Supervisory Control and Data Acquisition, it is a computer system for gathering and analyzing “real time data” SCADA systems are used to monitor and control a plant or equipment in industries.
SCADA systems are used not only in industrial processes: e.g. steel making, power generation (conventional and nuclear) and distribution, chemistry, but also in some experimental facilities such as nuclear fusion. The size of a plant ranges from few 1000 to several thousand to 10 thousand input/output (I/O) channels. SCADA systems used to run on DOS, VMS, and UNIX; in recent years all SCADA vendors have moved to NT and some also to Linux.
ARCHITECTURE:
1. Hardware Architecture:
One distinguishes two basic layers in a SCADA system: the “client layer” which caters for 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 which are connected to data servers.
Figure 1: TYPICAL HARDWARE ARCHITECTURE
2. 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, typically those they are connected to.
figure2: GENERIC SOFTWARE ARCHITECTURE
FUNCTIONALITY:
1. Alarms and Event Monitoring:
A SCADA system must be able to detect, display, and log alarms and events. When there are problems the SCADA system must notify the operators to take corrective action. Alarms and event must be recorded so that engineers and programmers can review the alarms to determine what caused the alarm and prevent them happening again. More complicated expressions can be developed by creating derived parameters on which status or limit checking is then performed. The alarms are logically handled centrally, i.e. the information only exists in one place and all users see the same status, and multiple alarm priority levels are supported.
2. Data Acquisition:
SCADA must be able to read data from PLCs and other hardware and then to analyze and graphically present that data to the user. SCADA systems must be able to read and write multiple sources of data.
3. Operator Interface:
A SCADA system collects all of the information about a process. The SCADA systems then need to display this data to the operator so that they can comprehend what is going on with the process.
4. Non Real Time Control:
For simple control requirements, the SCADA system should be able to control instead of a PLC. For anything other than simplistic control we prefer a PLC to do the real time control with SCADA doing the non real time control. The SCADA system is the medium between the operator and the real time controller.
5. Data Bases And Data Logging:
Most applications require recipes, data logging, and other means of reading and writing databases. SCADA systems can log incredible amounts of data to disk for later review. This is helpful for solving problems as well as providing information to improve the process.
6. Use Of MMI:
SCADA uses MMI to present the data acquire from the process to allow the process operation to be supervised e.g. start/stop or changing set points. SCADA provides MMI functions such as: Mimics-a graphical representation of the process with dynamically up dated values; Trends-graphs of variables against selected time periods; Reports-allows process variables to be summarized on a period basis; Alarms-they also support the concept of a “generic” graphical object with links to process variable’s.
7. Logging/Archiving:
Logging is the medium term storage of data on the disk, where as archiving is the long term storage of data on disk or any other permanent storage medium. Logging of data can be performed at a set frequency, or only initiated if the value changes or when a specific predefined event occurs. The logged data is time stamped and can be filtered when viewed by the user.
8. Report Generation:
One can produce reports using SQL type queries to the archive, RTDB or logs. Although it is sometimes possible to embed EXCEL charts in the report. Facilities exist to be automatically generated, print and archive reports.
9. Automation:
The majority of the products allow actions to be automatically triggered by events. Scripting languages provided by the SCADA products allow these actions to be defined. The concepts of receipts is supported, whereby a particular system configuration can be saved to a file and then re-loaded at a latter date. Sequencing is also supported; it is possible to execute a more complex sequence of actions on one or more devices. Sequences may also react to external events.
DEVELOPMENT WITH THE HELP OF SCADA:
SCADA system were developed for gathering data from far and wide using poor quality comms and providing and providing high levels of reliability and operability. Given the rapid expansion of communication systems,(satellite, cellular, fiber, microwave etc)and the increasing processing power available at site.
When the data gathering, integrity and validations requirements of SCADA can be met by commonly used for IT systems, then there will be even further convergence. SCADA system can be justified cost, but the really big payoff is to reduce the capital investment. In many cases the applications that run at that level are becoming more important than the user stuff. However applications like batch tracking and leak detection are SCADA advantages.
OPERATION OF SCADA:
Supervisory control and data acquisition (SCADA) technology collects real-time data from virtually any environment where there is a need to monitor machinery or processes, make adjustments based on measurable conditions, measure down time, or regulate processes to avoid costly problems. The computer-based technology was designed to do all the things with little human involvement. From a central reading location, a SCADA system can monitor a number of remote sites equipped with RTUs. The RTUs measures various conditions and parameters, including tank levels, temperature, voltage, current, volume, and flow. The unit reports the data back to the CPU, carrying out the necessary analysis and cost functions.
Additionally, SCADA technology personal of current or potential alarm situations, allowing an operator to and fine tune a process. Control can be automatic or initiated by operator commands, based on the sophistication of the individual system. The technology is widely accepted as a reliable and efficient control system within numerous industrial markets.
APPLICATION OF SCADA:
A typical SCADA application requires several low cost distributed RTUs, controlled by a central station/master.
Common applications for SCADA systems typically include water and waste treatment, petroleum and hydro carbon processing, power generation, food processing, steel manufacturing, remote telecommunications and plant machinery maintenance. Unlike in plant process control systems, SCADA systems typically include a remote telecommunication link. Real-time measurements and controls at remote stations are transferred to a CPU through the communication link. Large systems can monitor and control 10-2000 remote sites, with each site containing as many as 2000 I/O points.
A SCADA system for small applications:
SCADA is not a new technology by any means, but innovations and significant improvements have been made since its introduction. Until recently, SCADA technology was often viewed as a luxury item by small industrial companies. The technology was deemed unobtainable because of high association with that systems could not be fully used because of their massive I/O capacities.
CASE STUDY:
UPDATING SCADA SYSTEMS AT POWER PLANTS FOR INCREASED CAPACITY, RELIABILITY.
Companies have long monitored and controlled electric power generating
operations using computer-based Supervisory Control and Data Acquisition systems.
Power pumped storage station:
Many power plants are brought on-line and continue to run uninterrupted until maintenance is required. It is a pumped storage hydroelectric plant, designed specifically to help the power plant meet peak demand. Pumped storage is the most economic method of doing so.
The older computer system at the plant was sufficient for monitoring the plant-just barely. It was operating at near capacity. It did not allow the collection and graphic display of data. Therefore the company upgraded the computer system with MODCOMP’s REAL/IX PX operating system a real time implementation of UNIX that runs on Intel-based platforms. The power plant has more computing power and greater flexibility to upgrade in the future because the SCADA system now uses industry standard hardware and software systems.
Defining Goals, System Design:
Power plant began the process of upgrading its SCADA systems with a number of broad goals. Those include:
1. Migrating to standard, open systems with a long useful life.
2. Maintaining existing user interfaces whenever possible.
3. Permitting future expansion without performance degradation.
4. Utilize the existing I/O infrastructure to contain costs.
The new system runs on two Intel-based host servers, one that is the primary system and other is the secondary backup and the information source. In case of hardware failure, plant operators can fail over to the secondary servers. Eight RTUs are connected to the servers. Each of the six generators is monitored by the independent RTUs. The RTUs communicate with the host servers over a dual-redundant fiber optic TPC/IP network. The new system is far more responsive.
Migrating to Open Systems:
The power plant first goal for the new system was to migrate to standard open systems. The new systems use Intel-based computers running the REAL/IX PX operating system. The UNIX operating system platform is compactable with a number of third party programs that power plant can integrate into its SCADA or reporting systems at the later date.
Maintaining User Interfaces, functionality:
The important requirement was to minimize the impact of the changeover on daily operations and the need for re-training. Existing applications software functionality was also migrated into the new SCADA package. The original 10000-point database, with 6500 digital inputs and 3500 analog inputs, was imported into the new software
.
Utilizing Existing I/O, Leaving Room to Grow:
The major challenges for SCADA systems are to keep the majority of the I/O infrastructure and to reduce the cost of the system by interfacing the existing MODACS interface over the new system. The important feature of the SCADA system is its scalability. Secondly, the REAL/IX PX operating system ensures that the systems will continue to run in real time.
New Capabilities:
As the part of the upgrade the power plant wanted to interface its real-time control and data with a data acquisition system with a data historian, creating a historical database for later analysis. Another new capability is remote access for maintenance. System engineers from MODCOMP can dial in to the system, diagnose many problems remotely and fix them. One can expect to see wide scale integration of SCADA and Geographic Information systems (GIS). With GIS, SCADA base users can integrate with real time data to pin point a disruption of service. It will make power companies more productive in determining where faults are located.
ADVANTAGES AND DISADVANTAGES OF SCADA TECHNOLOGY:
Advantages of SCADA system include Wide area connective and pervasive; routable; parallel polling; redundancy and hot stand by ; large addressing ranges; integration of I.T to automation and monitoring net works; standardization; reduce down time; limit the frequency of accidents; improve record; increase through put.
Disadvantages of SCADA Technology include IP performance over head; web enabled SCADA hosts users to remotely monitor, control remote sites via a web browser; security concerns.
DEVELOPMENTS IN SCADA:
SCADA 3000 was released to five beta sites for testing and evaluation. As a result of testing Phonetics has added several features such a additional ladder and C program functions.
Tenomatix technologies new product is eM-Insight, a data source neutral tolerance management and statistical process control product that helps manufacturing companies share and distribute parts inspection data throughout the organization. Schneider Electric’s new Telemecanique brand Unity plat form of PLC processors and automation software provide new tools designed to enhance productivity.
As far as new technology is concerned the SCADA products are now adopting:
1. Web technology, ActiveX, Java etc.,
2. OPC as a means for communicating internally between the client and server
modules. It should be possible to connect OPC complaint third party modules to the SCADA products.
ENGINEERING:
The need for proper Engineering cannot be sufficiently emphasized to reduced development effort and to reach a system that complies with the requirements, that is economical in development and maintenance and i.e., reliable and robust. The Engineering activities specific to the use of a SCADA system includes templates for different types of panels; Instructions on how to control; a mechanism to prevent conflicting controls; alarm levels, behavior to be adopted in case of specific alarms.
CONCLUSION:
SCADA systems are used to monitor and control a plant and equipment in industries. The benefits one can expect from adopting a SCADA system a rich functionality and extensive development facilities. The systems are used to mission critical industrial processes where reliability and performance are paramount. These systems are used to gather and analyze “real time data”.
REFERENCES:
www.marineeng.com/scada.
www.modcomp.com/scada/virgina_power.html.
www.electronics_x.com/electronic/waste water.html
www.modular-scada.co.uk/what -is-scada.html
www.electronics.com/power generation/scada.html
Under the Guidance of Chinna Subbanna.
A.Daneels, W.Salter, “technology survey summary of survey report.
