PDF | Supervisory control and data Acquisition (SCADA) systems are controlling and monitoring critical plants of the nation's infrastructure such as power. Supervisory Control and Data Acquisition (SCADA) is a control system architecture that uses .. "Supervisory Control and Data Acquisition (SCADA) Systems" (PDF). NATIONAL COMMUNICATIONS SYSTEM. ^ "SCADA Systems april ". SCADA systems integrate data acquisition systems with data transmission systems and HMI software to provide a centralized monitoring and control system for.
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Power System Operation. - Centralised Control Applications - an example. • SCADA. - SCADA architecture & Components. - SCADA system functions. Tracy A. Adams SCADA System Fundamentals. INTRODUCTION. Just as different countries have their own languages so do different technologies. SCADA systems evolve rapidly and are now penetrating the market of plants with a SCADA systems are used to monitor or to control chemical or transport.
Tabish S. Fundamentals of Control 2. Conclusion August 24, tabish yahoo. Control Server 2. Data Historian 8. Fieldbus Network 2.
For example, a PLC may control the flow of cooling water through part of an industrial process to a set point level, but the SCADA system software will allow operators to change the set points for the flow. The SCADA also enables alarm conditions, such as loss of flow or high temperature, to be displayed and recorded. Levels 3 and 4 are not strictly process control in the traditional sense, but are where production control and scheduling takes place.
Data may also be fed to a historian , often built on a commodity database management system , to allow trending and other analytical auditing. SCADA systems typically use a tag database , which contains data elements called tags or points , which relate to specific instrumentation or actuators within the process system according to such as the Piping and instrumentation diagram. Data is accumulated against these unique process control equipment tag references.
These systems can range from just tens to thousands of control loops , depending on the application. Example processes include industrial, infrastructure, and facility-based processes, as described below:. However, SCADA systems may have security vulnerabilities, so the systems should be evaluated to identify risks and solutions implemented to mitigate those risks. This is the core of the SCADA system, gathering data on the process and sending control commands to the field connected devices.
It refers to the computer and software responsible for communicating with the field connection controllers, which are RTUs and PLCs, and includes the HMI software running on operator workstations. In larger SCADA systems, the master station may include several HMIs hosted on client computers, multiple servers for data acquisition, distributed software applications, and disaster recovery sites.
To increase the integrity of the system the multiple servers will often be configured in a dual-redundant or hot-standby formation providing continuous control and monitoring in the event of a server malfunction or breakdown.
Remote terminal units , also known as RTUs , connect to sensors and actuators in the process, and are networked to the supervisory computer system. Also known as PLCs, these are connected to sensors and actuators in the process, and are networked to the supervisory system in the same way as RTUs.
PLCs are often used in place of RTUs as field devices because they are more economical, versatile, flexible and configurable. This connects the supervisory computer system to the RTUs and PLCs, and may use industry standard or manufacturer proprietary protocols. Both RTU's and PLC's operate autonomously on the near-real time control of the process, using the last command given from the supervisory system.
Failure of the communications network does not necessarily stop the plant process controls, and on resumption of communications, the operator can continue with monitoring and control. Some critical systems will have dual redundant data highways, often cabled via diverse routes.
The human-machine interface HMI is the operator window of the supervisory system. It presents plant information to the operating personnel graphically in the form of mimic diagrams, which are a schematic representation of the plant being controlled, and alarm and event logging pages.
In many installations the HMI is the graphical user interface for the operator, collects all data from external devices, creates reports, performs alarming, sends notifications, etc.
Mimic diagrams consist of line graphics and schematic symbols to represent process elements, or may consist of digital photographs of the process equipment overlain with animated symbols. Supervisory operation of the plant is by means of the HMI, with operators issuing commands using mouse pointers, keyboards and touch screens.
For example, a symbol of a pump can show the operator that the pump is running, and a flow meter symbol can show how much fluid it is pumping through the pipe.
The operator can switch the pump off from the mimic by a mouse click or screen touch. The HMI will show the flow rate of the fluid in the pipe decrease in real time. The HMI package for a SCADA system typically includes a drawing program that the operators or system maintenance personnel use to change the way these points are represented in the interface. These representations can be as simple as an on-screen traffic light, which represents the state of an actual traffic light in the field, or as complex as a multi-projector display representing the position of all of the elevators in a skyscraper or all of the trains on a railway.
A "historian", is a software service within the HMI which accumulates time-stamped data, events, and alarms in a database which can be queried or used to populate graphic trends in the HMI. The historian is a client that requests data from a data acquisition server.
The system monitors whether certain alarm conditions are satisfied, to determine when an alarm event has occurred. Once an alarm event has been detected, one or more actions are taken such as the activation of one or more alarm indicators, and perhaps the generation of email or text messages so that management or remote SCADA operators are informed. In many cases, a SCADA operator may have to acknowledge the alarm event; this may deactivate some alarm indicators, whereas other indicators remain active until the alarm conditions are cleared.
Alarm conditions can be explicit—for example, an alarm point is a digital status point that has either the value NORMAL or ALARM that is calculated by a formula based on the values in other analogue and digital points—or implicit: Examples of alarm indicators include a siren, a pop-up box on a screen, or a coloured or flashing area on a screen that might act in a similar way to the "fuel tank empty" light in a car ; in each case, the role of the alarm indicator is to draw the operator's attention to the part of the system 'in alarm' so that appropriate action can be taken.
They employ standardized control programming languages such as under, IEC a suite of 5 programming languages including function block, ladder, structured text, sequence function charts and instruction list , is frequently used to create programs which run on these RTUs and PLCs.
A programmable automation controller PAC is a compact controller that combines the features and capabilities of a PC-based control system with that of a typical PLC. By converting and sending these electrical signals out to equipment the RTU can control equipment, such as opening or closing a switch or a valve, or setting the speed of a pump. Some users want SCADA data to travel over their pre-established corporate networks or to share the network with other applications. The legacy of the early low-bandwidth protocols remains, though.
SCADA protocols are designed to be very compact. Many are designed to send information only when the master station polls the RTU. These communication protocols, with the exception of Modbus Modbus has been made open by Schneider Electric , are all SCADA-vendor specific but are widely adopted and used. This has the key advantages that the infrastructure can be self-contained not using circuits from the public telephone system , can have built-in encryption, and can be engineered to the availability and reliability required by the SCADA system operator.
Earlier experiences using consumer-grade VSAT were poor. RTUs and other automatic controller devices were developed before the advent of industry wide standards for interoperability. The result is that developers and their management created a multitude of control protocols. Among the larger vendors, there was also the incentive to create their own protocol to "lock in" their customer base.
A list of automation protocols is compiled here. OLE for process control OPC can connect different hardware and software, allowing communication even between devices originally not intended to be part of an industrial network.
SCADA systems have evolved through four generations as follows: The communication protocols used were strictly proprietary at that time. The first-generation SCADA system redundancy was achieved using a back-up mainframe system connected to all the Remote Terminal Unit sites and was used in the event of failure of the primary mainframe system. Information was shared in near real time.
The network protocols used were still not standardized. Since these protocols were proprietary, very few people beyond the developers knew enough to determine how secure a SCADA installation was. Similar to a distributed architecture, any complex SCADA can be reduced to the simplest components and connected through communication protocols. In the case of a networked design, the system may be spread across more than one LAN network called a process control network PCN and separated geographically.
Several distributed architecture SCADAs running in parallel, with a single supervisor and historian, could be considered a network architecture. This allows for a more cost-effective solution in very large scale systems. The growth of the internet has lead SCADA systems to implement web technologies allow users view data, exchange information and control processes from anywhere in the world.
SCADA systems that tie together decentralized facilities such as power, oil, gas pipelines, water distribution and wastewater collection systems were designed to be open, robust, and easily operated and repaired, but not necessarily secure. For example, United States Computer Emergency Readiness Team US-CERT released a vulnerability advisory  warning that unauthenticated users could download sensitive configuration information including password hashes from an Inductive Automation Ignition system utilizing a standard attack type leveraging access to the Tomcat Embedded Web server.
Security researcher Jerry Brown submitted a similar advisory regarding a buffer overflow vulnerability  in a Wonderware InBatchClient ActiveX control. Both vendors made updates available prior to public vulnerability release. Mitigation recommendations were standard patching practices and requiring VPN access for secure connectivity.
Consequently, the security of some SCADA-based systems has come into question as they are seen as potentially vulnerable to cyber attacks. SCADA systems are used to control and monitor physical processes, examples of which are transmission of electricity, transportation of gas and oil in pipelines, water distribution, traffic lights, and other systems used as the basis of modern society.
The security of these SCADA systems is important because compromise or destruction of these systems would impact multiple areas of society far removed from the original compromise.
For example, a blackout caused by a compromised electrical SCADA system would cause financial losses to all the customers that received electricity from that source. One is the threat of unauthorized access to the control software, whether it is human access or changes induced intentionally or accidentally by virus infections and other software threats residing on the control host machine.
In many cases, the control protocol lacks any form of cryptographic security , allowing an attacker to control a SCADA device by sending commands over a network. The reliable function of SCADA systems in our modern infrastructure may be crucial to public health and safety. As such, attacks on these systems may directly or indirectly threaten public health and safety.
Such an attack has already occurred, carried out on Maroochy Shire Council's sewage control system in Queensland, Australia. Pumps did not run when needed and alarms were not reported. More critically, sewage flooded a nearby park and contaminated an open surface-water drainage ditch and flowed meters to a tidal canal.
Poor performances in any of these project phases switches. Indicator is used to show that the respective unit is will very easily cause a SCADA project to fail.
These Switches are used to operate plant manually. Here we use two software, one is PLC software RSlogix This model also includes three relay and six power transistor. Its versatility shows with seamless integration to Every unit consists of a motor-generator pair. Three power other Rockwell Software and Microsoft products as well as transistors used as input switch on the motor side and three third-party applications.
RSView32 have distinctive features: used as output switch on the generator side. Three field relays are working as trip switches which works according to the i. Powerful graphics editor. Means if any damage occurs tripping have been occurred.
Customize the look of graphic displays. Comprehensive alarms editor. Full-featured data log editor. Sophisticated logic and control editor. RSLogix  was the first PLC programming software to offer unbeatable productivity with an industry-leading user interface. RSLogix comes in two editions: a Standard edition that provides basic ladder logic editing functions, and a Professional edition that provides additional functions to expand your automation solutions and make editing ladder Fig.
Hardware for power generation logic simple. Software i. Microsoft Visual Basic for Applications support. Custom Graphical Monitor. The most obvious software component is the operator interface or Man Machine iii. Editing project databases using Microsoft Excel.
Logic Trace. We deign a window for above hardware for controlling and monitoring system. As shown in fig. Programmable logic controller collects the data from the hardware and all this information send to the SCADA server.
For this task there is a different programming of PLC. The basic diagram for this operation is shown in fig 3. Because of this there is no input for the related transistor so it sends no signal. RTU The model for performing the operation is the combination detect that and activate the relay for that particular unit so that of hardware and the software programming which we have it replaces it with the spare unit.
There is another operation when there is requirement of When due to fault or any other reason any one of the three more generation. If such type of condition occurs than the units is damaged and interrupt the generation, SCADA will spare unit works with all other two main units. Two main units starts the spare unit. So that uninterrupted generation will be working as it is but with the combination of an extra unit just achieved. It means that plant output is In which three means that the plant output is As here shown that if there is no load than no If there is a requirement of heavy production then SCADA unit contributes for generation.
As far as requirement is use the logic that the spare unit is also working with the both increases or load is increases than no.