Research on Building Automation Control Network Technology
In modern society where there are more and more high-rise buildings and super-large buildings, how to realize centralized management and control of large-scale equipment scattered in buildings is an important factor affecting the benign operation of buildings. This decentralized control demand also determines the birth of a new automatic control system, which needs to realize the monitoring, control and measurement of decentralized construction equipment. This paper compares the advantages and disadvantages of various systems in the development of building automation control system, expounds the significance of Ethernet to the construction of building automation control system, and on the basis of following relevant standards, principles and bases, probes into the composition and established objectives of building automation control network. Finally, based on Ethernet technology, the field bus control system is integrated, and the OPC server is established to realize the efficient data transmission of communication interface and the design of automatic control system.
Keywords architecture; Automatic control; Network; Ethernet; Procyanidins (same as OligomericProanthoCyanidins)
With the rapid development of China's economy and the continuous progress of science and technology, building automation control technology in China has been greatly improved in recent years. The so-called building automation control system is a systematic mechanism for highly automated management and control based on science and technology. Through such a network control platform, one-click management of various equipment in the building can be realized. The technology here includes computer network technology, automatic control and network communication technology, and the equipment that can be managed in a unified way includes air conditioning system, temperature system, elevator, fire fighting system and lighting equipment. Building automation control system can greatly reduce the management difficulty and labor cost, and has the characteristics of high efficiency, environmental protection and energy saving. It can be said that the development of automatic control network system determines the future development direction of intelligent building to some extent.
1 development of building automation control system
1. 1 the development of building automation system
Building automation control system, grasping the development trend of scientific information technology, has experienced four development stages in thirty or forty years. The first stage is the CCMS central monitoring system, which began in the 1970s. Its principle is to set up information collection stations all over the building, and then connect the bus with the central station to form the CCMS central monitoring system. The center of this system is the central computer. By receiving and processing the information from the information collection station, it makes corresponding decisions and issues commands to adjust the parameters of the equipment in the building. The second stage is the DCS distributed control system in1980s. In fact, the information collector in 1980s evolved into a scientific and technological product in 1980s: digital controller. By configuring a distributed control system computer for each digital controller, each independent digital controller can display and process the collected information, and the substation can realize the function of completely processing information independently only by setting a central computer on it. The third stage is the open distributed system in the1990s. Through the application on the field bus, the BAS control network system with three-layer structure is arranged, and the input and output structure of the central station, DDC substation and field network layer is formed, which makes the whole system more open and flexible in system configuration and management. The fourth stage is the network integration system after entering 2 1 century. There is a central master station in the network system to optimize the combination of subsystems such as fire protection, safety, lighting and temperature. , and then integrated management, more convenient and fast.
In the course of forty years' development, the biggest change of building automation system is that Fieldbus Control System (FCS) has replaced Distributed Control System (DCS). Although DCS has good simulation, operation and management performance, its high cost, poor reliability and poor system openness are the bottlenecks restricting its development. With the development of science and technology, the field bus control system appears like mushrooms after rain, which is branded with typical modern technology and has higher controllability and scientificity. Its biggest advantage is that it simplifies the wiring mode of the system, improves the operability and maintainability, optimizes the real-time performance and reduces the cost.
1.2 Ethernet began to enter the field of building automation.
Ethernet has always been the core technology network in LAN construction. With the further development of science and technology, the stations in Ethernet have completed the evolution of sending and receiving data information independently, reducing the collision, congestion and cache of physical layer data, which provides a unique idea for the development and design of building automation system. After the promulgation of IEEE802.3af standard, the number of industrial switch products based on Ethernet has greatly increased, and the open Ethernet standards based on fieldbus have emerged one after another. Such as ODVA, CI, HSE, Profinet, etc. The combination of Ethernet and fieldbus control system makes up for the shortcomings of all parties and makes the design of industrial automatic control system gradually take shape. Its successful application in industrial control field directly promotes its rapid development in building control system. From the initial information layer to the control layer, Ethernet has been used more and more.
The advantages of Ethernet are obvious, that is, it realizes the perfect transition from information network to control layer, realizes the unification of all layers, makes the development and management of such a system more convenient, and also realizes the rapid and perfect integration with other systems in intelligent buildings. But at the same time, we need to realize that the research on the integration of Ethernet technology and fieldbus control system is still in its infancy, because the research cost is high and the products are few, which will lead to fewer choices for users and hinder its popularization. The maintainability and real-time performance of Ethernet also need time to verify.
2 composition and basic functions of building automation system
2. 1 composition of building automation system
Building automation control system usually includes air conditioning, fire protection, power supply, elevator, safety management, water supply and drainage subsystems. Through Ethernet technology, communication network can be established, field bus control system can be integrated, control layer, management layer and equipment layer can be established, and the connection between operation station and network control unit can be realized. The transmission control protocol/protocol is adopted, the user data protocol is established, and the OPC server is constructed, which not only centrally completes the management of all devices by the control terminal, but also realizes the free access of users to the client, avoiding the tedious process of personally checking the devices. By adding the network control unit, the monitoring, sharing and management of each subsystem in the building can be realized, and the portable emergency information processing and instruction control can be completed by replacing the function of the operation station with various corresponding statistical calculation functions under certain circumstances.
2.2 Functions of Building Automation System
The basic functions of the building automation control system are as follows:
(1) realizes the start-stop control of multiple subsystems and the monitoring of equipment operation status.
(2) Collect the historical data of equipment operation and complete the technical data analysis of equipment life-cycle operation;
(3) Automatically adjust the operation parameters of the equipment according to the change of the external environment;
(4) Monitor the possible faults and emergencies in the operation of various systems in the building, and configure a complete treatment scheme;
(5) Scientific management of water, electricity and gas. , energy saving, high efficiency and automation;
(6) For the equipment in each subsystem, keep a equipment management report, including operation documents, history and maintenance for reference.
3 building automation control network system design scheme
3. 1 general principles of automatic control system design. The main function of building automation system is to monitor the subsystems in the building, collect operation data, compare and analyze the operation situation, ensure the normal operation of equipment under any circumstances, and realize fast and simple remote monitoring. The most obvious advantage is that it greatly reduces the probability of accidents and correspondingly prolongs the service life of equipment. Through such centralized control and management, we can realize the unified and orderly management of each subsystem, make it run healthily, give full play to the functions of each system, and lay a solid foundation for the construction of intelligent buildings. Taking the most representative high-rise modern intelligent building as the design object, this paper briefly expounds the key technologies of creating an automatic control network system.
As mentioned above, the building automation control system must first ensure the efficient operation of subsystems and realize the orderly operation and flexible automatic operation of subsystems, thus reducing personnel management and saving human resources and capital costs. The system designed here is mainly based on the requirements of ordinary owners and high cost performance, and adopts the optimal scheme to design an automatic control system that can realize centralized management and decentralized management at the same time. For example, the famous BACTalk building management system is an automatic control system based on BMS, which can control fire control system, security system, lighting system, elevator, etc. on one platform, with advanced field controller and open interface with other system equipment. According to the characteristics of modern high-rise buildings, the main monitoring subsystems are designed: elevator system, central air conditioning system, lighting system, water supply and drainage system, etc.
3.2 Design principles and basis of building automation control network system
When designing a building automation system, the following principles must be followed. The first is reliability. Reliability is the first criterion to test whether an automatic control system is qualified. Decentralized control system takes priority, and the task of automatic control is given to multiple field processors, which can avoid the situation that the failure of a single processor affects the healthy operation of the whole system. Another performance of reliability is the accuracy of data collection and recording of the system, which can not be misreported or omitted, so the requirements for system hardware and software are extremely strict. Secondly, it is flexible and extensible. Like other network systems, building automation system will evolve and upgrade with the development of science and technology. After the initial system is established, it should be considered that with the development of scientific information technology, the original system must be optimized and upgraded, so this puts forward new requirements for the scalability of the system. Of course, flexibility is also very important, mainly because the increase or decrease of the field controller cannot affect the performance of the whole system, and the composition and functional application of the system must be flexible in order to change the system with the change of the external environment. The third is practicality. The designed system is always applied, which requires designers to extract common knowledge from advanced scientific information technology, and the system can meet different needs according to the versatility of the building. Convenience is another sign of practicality. Whether the management mode is reasonable and simple is an important sign to test whether a system is mature. A good building control system can realize the perfect synthesis of the data content of each subsystem of the building, present it uniformly at the central level, and reduce the difficulty of management. Finally, the economy. We require the system design to adopt the most accurate and cutting-edge technology, and also consider the actual demand height. The use of on-site processor can satisfy the long-term operation of the system, so it is necessary to plan rationally and never invest blindly.
The design of building automation control system should be based on the corresponding electrical drawings and standards, so as to meet the national and other international standards. For example, building design standards for fire protection system, lighting design standards, elevator design standards, air conditioning installation and ventilation design standards, and power supply system design standards for industrial and civil buildings. For each subsystem that needs to be designed, the system design guidance should be carried out according to the corresponding national specifications.
3.3 System Function Design
The designed system scheme is based on Ethernet technology, which realizes the integration of each bus. It consists of three layers: network layer, control layer and device layer. Among them, the network technology of equipment layer relies on CAN bus and Lonworks, and Ethernet technology is used to realize the communication between management layer and control layer.
To sum up, Fieldbus Control System (FCS) is more open, distributed, easy to maintain and low in cost, so it is more suitable for the design of building automation control system, supplemented by Ethernet technology to realize building automation control. See figure 1 for detailed design drawings.
Figure 1 Ethernet Building Automation Control System Diagram
3.3. 1 Network structure of automatic control system
The designed system mainly includes management layer, control layer and equipment layer. The intelligent monitoring area layer composed of point-to-point communication between field controllers is the control layer, and the monitoring nodes are arranged on CAN bus and Lonworks bus. The management layer includes a central main computer and a subsystem computer system. The management layer is constructed by Ethernet technology, and the operating station in the management layer can control the central computer, carry out integrated and unified instruction management for each subsystem, and analyze and process all the data in the system. The equipment layer is the mechanical and electrical equipment in the building, which runs according to the preset program under the management of the control layer.
3.3.2 Automatic control system integration technology
OPC technology can standardize the exchange of equipment data information between control layer and management layer, speed up the speed and reliability of data transmission, and reduce the cost. When selecting OPC in building automation system, it is necessary to develop corresponding OPC servers according to different subsystems and functions to complete independent data acquisition at the equipment level.
A complete OPC server includes two parts: standard interface and communication interface. Use ASP. NET2005, and developed OPC server. The development of standard interface becomes simple because of database, and the development of communication-oriented interface requires specific communication protocols and data acquisition methods to write specific dynamic link libraries. The OPC server structure constructed by this method is shown in Figure 2.
Fig. 2 Overall structure diagram of OPC server
Call API function through this structure, record and cancel server data information, read and write exchange data according to specific interface module, and then package the read and write information to meet the needs of clients. The key of this design is to establish a dynamic link library by calling functions, and to establish an API function prototype by calling the DLL of ASP.NET2005. The commonly used communication protocol is generally TCP/IP protocol. Reading and writing the encapsulated information through the communication interface can realize the simultaneous access of computer and client data. In data management and control, the operator does not need to collect data from every hardware device, but only needs to check the OPC server corresponding to the subsystem, so as to realize independent data collection. With these data, we can get the basic data of automatic control of each subsystem. Through certain analysis and processing, the unified presentation of subsystem operation data and operation state can be realized, which greatly facilitates the subsequent automatic control and management. This is a complete building automatic control process.
4 conclusion
Intelligent building is becoming the development direction of future buildings, and the centralized and orderly management of building equipment system is the key link to realize the concept of social energy saving and labor saving. The development of scientific information technology makes it possible to design a reliable real-time building automatic control system at low cost. The system design can be realized by using fieldbus control system and Ethernet technology. Aiming at reliable and flexible use, CAN and Lonworks bus technologies are integrated based on Ethernet technology, and servers are created by OPC technology, which can quickly and accurately realize information and data integration of fire protection, lighting, elevators, air conditioning, temperature and power supply systems. At the same time, it can also distribute and control the subsystems in the building, monitor the running state of the equipment in real time, adjust the faults in time, reduce the personnel management cost and ensure the building. In the modern society where the building area is getting larger and higher, the automatic control network system will greatly improve the internal functions of the building and provide a safe and comfortable living and working environment.
refer to
[1] Yangmei. Research on the application of LonWorks technology in building automation system [D]. Southwest Jiaotong University, 2008.
[2] Lin Huanglong. Design and implementation of air conditioning system monitoring software in BAS [D]. East China Jiaotong University, 2009.
[3] Ji Shunping. Research and design of network control system controller and communication protocol [D]. Nanjing University of Aeronautics and Astronautics, 2009.
Zhang Hanyu. Application of Lonworks in Building Control System [J]. Electronic Manufacturing, 2014,04: 48.
Li Dan. Comparative Analysis and Development of Fieldbus Control Networks [J]. Equipment Manufacturing Technology, 2014,04: 240-242.
Wisdom Shu Ya. On the application of LonWorks technology in building automation system [J]. Journal of Jinling Institute of Technology, 2013,01:34-37.
Terry S. Davis, H. Nuri and Fred W. Britten. On the control of contact bounce [J].IEEE Trans. On components, packaging and manufacturing technology-Part A, 1996, 19(3).
[8] Jane Cyrocki, Flock Aldewater, Giry Siegle, et al. Experimental analysis on model predictive control of heating system in an energy-saving building [J]. Applied energy, 20 1 1, 88(9):3079-3087.
[9] Peter Feintech, Peter Vilander, Cedric Wanaz, etc. Dynamics of pesticide absorption by plants: from system function to simplified model [J]. Environmental modeling and design; ; Software, 2013,40 (February): 3 16-324.
Click the next page for details >>& gt Technical Paper on Building Automation