SCADA Systems and their Integral Role in Todays Control Environment - Report Example

SCADA Systems and their Integral Role in Today’s Control Environment Institution Name Table of Contents Table of Contents 2 Introduction 3 Background of SCADA System 3 Technologies in SCADA systems and related technical details 5 Field technologies 6 a) Remote Terminal Unit (RTU) 6 b) Programmable Logic Controllers 7 Management systems 8 a) Master Station Computer system 8 b) Human machine interface (HMI) 9 c) SCADA Software 9 SCADA Communication system 10 a) Transmission network technology 10 c) Private media transmission 10 d) Public media transmission 11 SCADA Systems Application in control environments 11 Industrial SCADA Application 11 Operational application advantages 13 Conclusion 16 References 17 Introduction Process Control Systems (PCS) are complex set of systems design to perform various tasks as within an industrial production process (Alcaraz et al., 2013). They make up the central control framework for critical infrastructures such as nuclear energy systems, electrical energy systems, and transportation systems. According to Alcaraz et al. (2013), PCS perform the fundamental function of monitoring and controlling remote sensors at the critical infrastructure to perform automated operations of a production plant’s systems. Current literature has identified two types of PCSs based on geographical distribution: Distributed Control Systems (DCS) and Supervisory Control and Data Acquisition (SCADA) System (Alcaraz et al.,2013). The SCADA system consists of a distributed network covering an expansive geographical area in which industrial automation services are provided to oversee the performance and continuity of operation of the critical infrastructure (Kumar, 2010). DCS systems, on the other hand, share the same functionality as SCADA systems, except for the fact that they are geographically at close proximity to the industrial facilities. Of the two types of PCS, the scope of this paper is limited to SCADA systems, based on the assumption that they are the more fundamental components within the critical infrastructure (Sahin, 2013). Additionally, they have significant impact on the overall performance of other interconnected critical infrastructure. Background of SCADA System After the first digital computer was introduced in the early 1960s, it presented system designers with the means to centralise data for extensively large systems (Fisher, 2002). Later, after minicomputers (mid-size units) emerged in 1965, it presented the capacity for two-way communication between the central control facility and the remotely situated field units. As stated by Fisher (2002), this marked the birth of SCADA. According to Alcaraz (2013), SCADA systems play the central role of data acquisition from remotely connected devices such as transmitters, pumps and valves. They provide control remotely from the SCADA Host software platform, which in turn ensures localised process control, resulting to the switching “on” and “off” of the critical infrastructure at the appropriate time. Further, they support a system’s control strategy, in addition to a remote means of capturing data and events, with the view of monitoring these processes. Critically therefore, the system performs supervisory control and data acquisition functions simultaneously (Kumar, 2010). The SCADA system facilitates data transfer between the central host computer and the remote Terminal Unites (RTUs) at several remote sites, and the operator terminals and the central host. Figure 1 below illustrates the SCADA system that integrates data multiplexing (MUXs) between the RTUs and the central host. The MUXs undertake the critical function of routing data from multiple RTUs on a local network, through the Wide Area network (WAN) (Bentley Systems, 2004). Figure 1: SCADA system network (Bentley Systems, 2004). Technologies in SCADA systems and related technical details The basic structure of the SCADA system combines a range of components for varied communication protocols. In Goel and Mishra’s (2008) view, operating such an extensive and diverse infrastructure demands a broad network of electronic devices, monitoring, and communication and control systems. Technically, the SCADA system controls, monitors and alarms used by plants’ operating systems make up the communication protocol, and convey signal between the SCADA’s central host computer, in addition to other programmable logic controllers (Alcaraz et al., 2013). For instance, in a water filtration facility, the remote units are used in measuring the pressure inside the pipes before reporting the readings to the central computer situated within the control tower. In the event of an anomaly, the SCADA system notifies the operator’s station of the hitch. The SCADA system also furnishes the operators with information regarding the measurement values and anomalies. The system’s components are divided into four Master Terminal Unit (MTU), Remote Terminal Unit (RTU), Remote Standby, and communications systems (Lakhoua & Jbira, 2012). The four are further classifiable into three groups of technologies: the field devices, management systems and communication systems. Field technologies a) Remote Terminal Unit (RTU) The RTU is a technology designed for monitoring one or several parameters at a particular point in a wire network or piping system. While it has similar function to that of a meter or gauge, it also transmit signal through a modem. Essentially therefore, RTUs alter sensor signals into digital ones (Patil, 2011). Additionally, they have telemetry hardware that can relay data in digital format to the administrator’s system. These devices also receive digital commands from the supervisory system. These technologies tend to have control capabilities, including ladder logic that assists in accomplishing Boolean logic operations (Alcaraz et al., 2013). Positioned at the remote site, the RTU acquires data from the field devices such as alarms, valves and pumps, until the Master Technical Unity (MTU) sets off a send command. Within the RTU, the central processing unit (CPU) obtains data stream (Kumar, 2010). Once the RTU sights its address entrenched in the protocol, it interprets the data before directing the required action to occur (Figure 2). The CPU uses protocol such as the Internet Protocol (TCP/IP), Transmission Control Protocol, Modbus, in addition to a proprietary closed protocol (Sahin, 2013). There are some RTUs, such as the Remote Access PLCs (RAPLC), that offer remote programmable applications while still managing to retain RTU’s communication capabilities. Such devices are intended to undertake control, re-program anywhere anytime, and to monitor the conditions of the site. Additionally, they have an alarm that alerts the operator’s personal computer without waiting for MTU directions (Alcaraz et al., 2013). Figure 2: Position of RTU, MTU and servers in the SCADA system b) Programmable Logic Controllers Programmable Logic Controllers (PLCs) are microprocessors integrated to the RTU. PLCs improve the functionality of RTUs, enabling them to be ‘smarter.’ The PLCs are designed based on the philosophy of automation. By being reprogrammable, they enable the RTUs to debug and to integrate themselves on the field automatically (Alcaraz et al., 2013). Additionally, they enable the RTU to have added functionalities such as the capability to perform exception reporting and manifold polling. This is what allows the RTUS to perform simple logical processes without waiting for instructions from the master station. Manufacturers who use a range of communication and coding on the PLC has led the way in standardizing the RTU languages and protocols, such as the IEC 61131-3 language, which call for limited training based on the instinctive approach different from the conventional languages such as FORTRAN (NBT, 2014; Bentley Systems, 2014). Management systems a) Master Station Computer system The Master Station Computer System refers to the stores of the reported data, acquired from the networked remote terminal units. Also known as the Master Terminal Unit (MTU), master computer system is essentially a standardized computer hardware device, also known as the supervisory station. Alcaraz (2013) considers MTU the heart and brain of the SCADA system. Fisher (2002) comments that MTUs are run using a Man/Machine interface (M/MI), which describes a means of allowing the system operator to issue and execute commands through the MTU facility to the field devices. The supervisory station describes the set of software and servers designed for communication with field devices and back to the HMI software that runs on the workstations, within the control room (Lakhoua & Jbira, 2012). Master station may comprise a single PC in small SCADA systems while for larger one, the master station is made up of several servers and disaster recovery sites and distributed software application. The multiple sites increase the integrity of the system once they are configured to a stand-by formation or dual-redundant formation, which offers continual monitoring and control, in case the server experiences failure (Kumar, 2010). b) Human machine interface (HMI) The human machine interface is a critical component of the master station or host station. Kumar (2010) illustrate that values stored in the host computer are transmitted to the human operator in simplified means through the HMIs. The HMI is a user interface within the SCADA system. In essence, the HMI provides location where processing of data takes place before being presented for viewing by the human operator. The interface often has controls that allow the human operator to interface SCADA system (NBT, 2014). This component provides a means for standardizing the facilitation of monitoring several PLCs or RTUs. Often, the HMI is connected to the software programs and the data systems of the SCADA system (Alcaraz et al., 2013). It provides trending, diagnostic data and management information to allow for trending, data diagnostics and information management in several ways such as detailed schematics, logistic information as well as troubleshooting guides. The HMI often provides information to the human operator graphically. This implies that the operator is able to view a schematic representation of the plant that is to be controlled (Kumar, 2010). c) SCADA Software The SCADA software links to the systems HMI and database in order to offer diagnostic data, trending and information management functionalities, including information on logistics, scheduled maintenance procedures and schematics for certain machine or sensor, as well as, troubleshooting guides on expert-system. They can either be proprietary of open type. Their key problem is their overdependence on the system’s supplier (Alcaraz et al., 2013). SCADA Communication system a) Transmission network technology In addition to the commands received by the RTU, the relay of data to the master station from the RTU is performed over SCADA system’s communication system. Since the SCADA system may not be localized strictly at one plant, the size of the network also needs to be taken into perspective, in addition to the accuracy, performance, speed, and security (Robles & Choi, 2009). Before the advent of the computer networking application, the community systems were strictly communication-based. Similarly, the SCADA communication systems were constructed around similar infrastructure. However, the need for corporate to integrate SCADA information network into the core networks over the security concerns have paved the way from WANS and LANS that enable seamless networking with the office communication systems (NBT, 2014). Essentially, the RTU/MTU transmission network may vary although they need to use bi-directional communication approach to facilitate effective functioning of the system. This can be enabled through the Private Medium (where the licenses, medium and operates are owned wholly by the end-user) or the Public Medium (where end-users pay for data volume used). c) Private media transmission Private media transmission can be enabled through wire line, modems and buried cables that are often limited to the low bandwidth. Wireless transmission can be enabled through VHF/UHF radios, Microwave and Spread Spectrum. The Spread Spectrum is accessible to the public within the range of 900 MHz to 5.8GHz bands (NBT, 2014). They are used in spanning distances and contain built-in encryption and error correction, which improves their reliability and security. On the other hand, the Microwave radio relays radio transmission at high frequencies using parabolic dishes that are installed on the towers. The use of point-to-point technology by the media leaves communication vulnerable to interruption, depending on the conditions on the atmosphere or misalignment. The VHF/UHF radios are effective within the range of 30 miles. They consist of electromagnetic transmission that has 175MHz-450MGz-900MHz frequencies (NBT, 2014). d) Public media transmission The public media transmission consists of communication technologies provided by services providers within some subsystems or systems to enable data transfer across the SCADA system. Examples include Cellular network and Public Switch Telephone Network (PSTN). For high-speed and minimized error rate, Integrated Service Digital Network (ISDN) and Digital Subscriber Lines (DSL) can be used (NBT, 2014). SCADA Systems Application in control environments Industrial SCADA Application The SCADA systems are essentially designed for the automation of industrial processes that are either too rapid or complex to be managed manually by humans (Robles & Choi, 2009). SCADA systems have found wide application in power distribution first for monitoring production and distribution of power. In particular, the SCADA systems can monitor power flow, and the status of circuit breakers. Additionally, they can be applied in controlling individual sections of the power grid (Alcaraz et al., 2013). Additionally, private water utility firms apply SCADA systems in managing and controlling sewage and water plants. Some of the critical functions at this stage include collection of water, information dissemination, scaling supply levels and examining the pressure readings (Robles & Choi, 2009). The SCADA systems are also applied in controlling environmental factors at a range of physical sites. They also support the functions of data collection at the facilities and buildings for monitoring lighting, temperate and entry systems. Examples of control functions in this regards includes maintenance of heat at required levels and refrigeration units online. Within the manufacturing plants, the SCADA system is used for monitoring inventory. At this stage, the SCADA system can be applied in regulating production machinery and implementing quality control tests. The application benefits just-in-time manufacturers as it automates productions to ensure that demand is met accurately, as well as by reducing in the cost of inventory. The SCADA systems is also used in mass transit/transport systems in regulating critical points of transportation, in addition to automation of related devices such as railroad crossing gates and transport. For instance, they can track the progress of individual vehicles in a transportation network, such as the buses on the streets or on certain subway line. Such a form of comprehensive tracking can notify the human operator of certain delays and problems that have the potential to lead to larger problems (Alcaraz et al., 2013). Energy utility companies apply the SCADA system in operating critical infrastructure components such as the electric grid, the energy production stations, compressor stations petroleum production lines, petroleum refineries, and strong facilities through automation. Figure 3: showing application of SCADA by Energy companies to Integrate control of remote facilities Operational application advantages SCADA systems are instrumental in system operation since they allow the operator to execute system control with improved efficiency and at minimal cost. Application of the SCADA system provides operation and economic advantages. - Allows for remote administration of large-sized distribution system: SCADA controls equipment is distributed over extensive geographical area, by dictating the major control points that have to be staffed interminably to allow for timely and frequent adjustment of the distribution system. The SCADA offers control of facilities remotely, or without the need to stay on-site except for cause of maintenance. Without the SCADA system, organizations would have to increase the number of employees needed to run the plants. - Improving regularity and appropriateness of operational data: The SCADA system facilitates near real-time of real-time monitoring of the remote sites, as well as instantaneous logging of associated data. Consequently, each point can be investigated for data severally at a particular hour in comparison to the pre-automation method of hourly or twice each hour by phone (Patil, 2011). Integrated wireless SCADA system are used for monitoring and accessing the performance of device parameters positioned remotely, including humidity and pressure in real-time basis (Goel and Mishra 2008). - Integrated analysis of operations: SCADA system offers physical data or graphic schematics of the whole system in real time. This allows the operator to monitor the impacts of regional disruptions while operating the entire system. It also helps in making the appropriate counter measures instantly (Robles & Choi, 2009). - Ensure improved accuracy and decision-making using operational data: System operators use the SCADA system to acquire precise measurements from the remote sites. The application allows the system operators with the capacity to maintain precise and throughput data, and to make effective decisions and well-timed adjustments, which reduces the possibility of undertake or overtake penalties (Alcaraz et al., 2013). Figure 4: Impact of SCADA systems applications on operational management - Documenting accuracy of measurement equipment: SCADA systems are essential for provision of incessant record of variables applied in calculating delivered energy units. They also provide constants the system is configured to identify as relevant for meeting a regulator’s requirements, such as environmental compliance requirements enforced by the Environmental Protection Agency (EPA). - Responding rapidly to disruptions and emergencies: The SCADA systems are designed to supply audible alarms in the event of a failure of an operating parameter, which may have shifted above a preset range (Robles & Choi, 2009). The application makes it easy for the operator to act promptly in responding to the disruption. As a result, the system operator is provided with the capacity to handle problem from the control center rather than having to dispatch personnel to the site. Conclusion Integrated wireless SCADA system are essential for monitoring and accessing the performance of device parameters positioned remotely, including humidity and pressure in real-time basis. Essentially, SCADA systems components include controllers, computers, actuators, sensors, interfaces and networks that administer the control of automated industry processes. They also facilitate analysis of those systems through data collection. The specific technologies that make up its main components include MTU, RTU, communication technologies, programmable Logic Controllers and Human machine interface. Technically, the SCADA system integrates data multiplexing (MUXs) between the RTUs and the central host. The MUXs undertake the critical function of routing data from multiple RTUs on a local network through the Wide Area network (WAN). The SCADA systems automate industrial processes that may be either too rapid or complex to be managed manually by humans. They also furnish the human operators with information regarding the measurement values and anomalies. Additionally, they allow for remote administration of large-sized distribution system. They are used in mass transit systems in regulating critical points of transportation, in addition to automation of related devices such as railroad crossing gates and transport. Additionally, they can improve regularity and appropriateness of operational data, integrate analysis of operations as well as ensure improved accuracy and decision-making using operational data. Other roles include responding rapidly to disruptions and emergencies and documenting accuracy of measurement equipment. Effectively designed SCADA can save time and money through elimination of the need for the service personnel travel to each site for purposes of inspection. References Alcaraz, C., Fernandez, G. & carvajal, F. (2013). Security Aspects of SCADA and DCS Environments: In Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense, Advances in Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense. New York: Springer-Verlag, pp. 120-149, 2012 Bentley Systems (2004). The Fundamentals of SCADA. Retrieved: Fisher, R. (2002). Supervisory Control and Data Acquisition (Scada) Systems White Paper. Retrieved: Goel, A. & Mishra, R. (2008). Remote Data Acquisition Using Wireless - Scada System. International Journal of Engineering 3(1), 58-65 Kumar, R. (2010). Recent Advances in SCADA alarm System. International Journal of International Journal of Smart Home Smart Home 4(4), 1-10 Lakhoua, M. & Jbira, K. (2012). Project Management Phases of a SCADA System for Automation of Electrical Distribution Networks. IJCSI International Journal of Computer Science Issues 8(2), 157-162 NBT. (2014). A SCADA System Assessment. Retrieved: Patil, U. (2011). Study of Wireless Sensor Network in SCADA System for Power Plant. International Journal of Smart Sensors and Ad Hoc Network 1(2), 41-44 Robles, R. & Choi, M. (2009). Assessment of the Vulnerabilities of SCADA, Control Systems and Critical Infrastructure Systems. International Journal of of Grid and Distributed Computing 2(2), 24-34 Sahin, S. (2013). Modbus‐Based SCADA/HMI Applications. Journal of Information Technology and Application in Education 2(2), 61-66 Read More