How SCADA system transitions the Internet of Things
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First, system concept The development of information technology will certainly promote the revolution of the automation system. With the development of information technology, the application in various fields has also continued to mature, and the industrial automation system has undergone major changes in the overall architecture, management model, application technology, and comprehensive mining. It is further standardized, scalable, open, and low cost. The overall goal goes forward. In particular, the introduction of the concept of the Internet of Things has enabled more and more companies to design target monitoring, data applications, and open interconnection as a complete solution.
Internet of Things IOT (Internet of Things) is a kind of network that uses intelligent identification, positioning, tracking, monitoring and management through information sensing equipment such as radio frequency identification (RFID), and the use of the Internet for information exchange and communication according to the agreed protocol. . The functional characteristics of the Internet of Things are comprehensive perception of information, reliable transmission of information, and intelligent processing of information in order to implement intelligent control and management of objects.
SCADA (Supervisory Control And Data Acquisition) system is supported by computer and network technology to achieve on-site data acquisition, device control, data measurement, parameter adjustment and signal alarm. The application of SCADA system has been very mature, and its application has completely exceeded the scope of basic data monitoring and control. A complete set of SCADA system has not only realized simple data collection and remote control functions, but has been given more rich connotations.
Second, the system features 2.1 Internet of things system Internet of Things system is the use of computer Internet platforms, relying on radio frequency identification (RFID) technology to achieve the automatic identification of end nodes and information sharing and sharing. The Internet of Things can be divided into three layers: the first is the sensory layer, which is the skin and facial features of the Internet of Things to identify objects and collect information; the second is the network layer, which is the nerve center and brain information transfer and processing of the Internet of Things; the third is the application layer, ie The deep integration of the Internet of Things and industry expertise combined with industry requirements to achieve industry intelligence.
2.2 SCADA System The general SCADA system can be divided into three layers. The first layer is the data acquisition layer, which is composed of an RTU and a meter to complete the collection and preprocessing of on-site raw data. According to the design requirements, it can also realize the on-site data storage to ensure the continuity of data after communication interruption; the second layer is the data monitoring layer. In this layer, various software will be used to remotely simulate the site, real-time data monitoring and real-time alarm. This layer can be divided into sub-control centers, master control centers, etc. according to the corresponding management mode, and a large amount of historical data can also be stored according to design requirements. The third layer is the data application layer. Analyze and collate the collected data at the application layer and implement multiple forms of distribution as needed. Many companies in the industry have extremely stable products and rich system integration experience in the data acquisition layer, data monitoring layer, and data application layer.
2.3 Other layers For the industrial automation architecture, there is also a layered theory of three layers. The first layer is the basic automation layer represented by PCS (Process Control System). Mainly includes control software, measurement technology, database technology, data fusion and data processing technology, DCS, FCS, sensing technology, special implementing agencies, etc.; second layer, the production process represented by MES (production process manufacturing execution system) Run the optimization layer. The main contents include modeling and process simulation technology, advanced planning and scheduling technology, real-time optimization technology, dynamic cost and management technology, etc. The third layer, the enterprise production and management optimization layer represented by ERP (Enterprise Resource Management). The main contents include enterprise resource management, supply chain management, product quality data management, data warehouse technology, equipment resource management, enterprise e-commerce platform and so on.
2.4 Common Features SCADA systems, Internet of things systems, and other industrial automation systems are all products of computer network technology development. According to the rapid development trend of the Internet of Things, it will gradually replace some SCADA systems. By analyzing the architecture of the two types of systems, the two have the following common features:
(l) Layered architecture. Both types of systems have a clear and complete hierarchy that is easy for designers and users to understand. The three layers of the SCADA system and the three layers of the Internet of Things system all have clear definitions and boundaries between layers, but there are some overlaps in the functions between the three layers. Layers close to the site use fieldbus technology to make device files and diagnostic information more abundant; the middle layer shows more of the operational data monitoring and device management; and the most advanced application layer can involve deep data applications, equipment maintenance plans, Spare parts management, equipment asset management, etc.
(2) One-time instrument data acquisition. Both types of systems require the collection of on-site raw data, and their accuracy and data availability depend entirely on the data collection of the primary table. In the IOT, the control function is more prominent. In the SCADA system, the conventional control strategies are mainly single-loop control, cascade regulation, ratio regulation, uniform regulation, feedforward regulation, automatic selection regulation, split-range regulation, nonlinear regulation, etc. The implementation function is still based on PID regulation. , supplemented by certain functional blocks and control algorithms. The conventional control in the IOT can be extended to use. Multiple functional blocks can be connected in series, in parallel, selectively connected, automatically compensated, automatically tracked, and bumplessly switched. Multi-formulas automatically change the connection of parameters or function blocks, making automation possible. The application becomes transparent and simple.
(3) Dependence on communication networks. Both types of systems rely on the Internet, and IoT systems rely more on wireless communication networks. This shows that ensuring wireless communication is a necessary condition for realizing the Internet of Things. The main features of wireless communication are easy installation, flexible application, low cost, and easy expansion. The main application is for a variety of protocol standards, including 802.11a, 802.11b, and the latest hybrid standard, 802.11g.
(4) Data processing applications. After the original data was collected, both types of systems were comprehensively applied to the resulting data. It can be seen from the structure that the Internet of Things system is more in-depth in data processing. The massive production data of enterprises is an important basis for business decision-making, and has important reference value for procurement management, cost control, and improving the economic efficiency of operations. It can also provide important reference data for controlling production costs and expanding profits, so as to ensure corporate profit targets. The realization. It can be seen that the in-depth processing of data has a very important significance in guiding the production and operation of the whole company.
Third, the transition program Internet of things is an inevitable trend of industrial automation, will make industrial automation, distribution, openness, information, large-scale and many other features to be reflected. The distributed architecture of the Internet of Things ensures that each intelligent terminal can operate independently and interoperate with information while also spreading the danger of the system. The openness feature is that the network itself has multiple standard interfaces to facilitate the seamless access of new terminal nodes; The system information can be comprehensively processed in a timely manner on the collected data, and a large closed loop can be achieved through the use of network technology. On the other hand, the scale is to reduce the access cost, acquisition cost, and use cost of the terminal node, and complete the scale application under the premise of the optimal comprehensive cost.
Since the Internet of Things is entirely an open network, SCADA systems that involve industry secrets or national security will remain in their current state. Therefore, replacing some SCADA systems with the Internet of Things is an inevitable trend. According to the comparison of the two types of systems, whether it is a new IoT system or a reconstruction based on the SCADA system, the following solutions can be referenced:
(1) The SCADA system construction model is very mature, and existing cases and solutions all have very high reference values. When architecture is designed for the Internet of Things, reference can be made to the SCADA system architecture. After meeting the company's production management requirements, it further integrates information technology such as advanced control, online optimization, online performance monitoring, and on-line equipment accounting management.
(2) When the network system is selected, the sensing layer (or acquisition layer) adopts wireless design, and the data application layer adopts fast network such as optical fiber communication. The design of the entire network structure should fully consider the characteristics of flexibility, high speed, multiple redundancy, high performance, and high security. The network topology structure such as linear structure, ring structure, star structure, inverted tree structure, and various combinations can be flexibly used. Because multiple communication paths are provided between any two devices in the network, the communication will not be affected by the single-node failure, and the redundancy performance and reliability of the communication will be greatly improved.
(3) Add terminal status monitoring points. In the SCADA system, there are few concerns about the features and status of the instrument and other devices. However, according to the requirements of the Internet of Things, all terminal monitoring is necessary. Therefore, additional monitoring points are added to terminals that are not designed for monitoring. Field instruments commonly used in industrial automation include temperature meters, pressure meters, level meters, flow meters, on-line process analyzers, and actuators. The stable operation of the field instrument is the guarantee of real data, so in addition to the normal operation function, it is very necessary to monitor the working status of the instrument.
(4) Increase the depth of data mining to provide a rich and stable data interface. The Internet of Things system is an open system. In order to ensure the interoperability of the terminal information involved, there will be a large amount of data exchange with other peripheral networks. The SCADA system is a relatively independent system with relatively few interfaces to other systems. A successful automation system should be a system with multiple standard interfaces. The choice of operating system and the selection of on-site products will determine the possibility of standard interface implementation. At the same time, the standardized program interface also guarantees the exchange of data between hardware and software products of different manufacturers without worrying about the communication between them. This is also the premise of application scale.
(5) Strengthen the stability of counter-control functions. The SCADA system pays more attention to the monitoring function and the relative control is weaker. The Internet of Things system requires interoperability across the entire network. However, in order to ensure the balance of monitoring data across the entire network, some countermeasures need to be made based on real-time data. Under the current control theory, various intelligent algorithms have emerged. In addition to PID control, which is well known in the industry, multivariable prediction has been completed in the production practice stage. The Internet of Things is a collection of powerful data, and the data is dynamically updated. Therefore, the appropriate combination of multi-variable pre-side control and PID cascade control can be very effective in achieving the stability of the anti-control function.
The popularity of Internet of Things technology is irresistible. The change is not only the optimization of the production process, but also a major change in the management model. The Internet of Things fully integrates advanced process equipment technology, modern management technology, and information technology represented by advanced control and optimization technologies to provide an overall solution for industrial automation to achieve optimal operation, optimized control, and optimized management of the enterprise, thereby improving The core high technology of enterprise competitiveness.