Application of the hottest Fieldbus Technology in

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Thinking about the application of Fieldbus Technology in power plants

1. Preface

in the process of power plant information construction, more and more experts, scholars and power engineering designers realize the importance and urgency of promoting the application of Fieldbus Technology in power plants, and many papers have put forward the application ideas and suggestions of control system based on Fieldbus Technology in power plants. But so far, in domestic power plants that have been built and are under construction, the real examples of comprehensive and systematic application of fieldbus control system have not been reported, and only partial pilot applications can be seen in the literature. Everyone holds a positive attitude that fieldbus technology represents the development direction of power plant automation in the future, but why is it difficult to enter substantive application in engineering design

in order to facilitate the following discussion on this issue, although the meaning of fieldbus and fieldbus control system has been repeatedly described in relevant literature, the author still feels that it is necessary to quote the definitions of fieldbus and fieldbus control system made by IEC and experts of the International Electrotechnical Commission first

according to the definition of IEC61158 standard of International Electrotechnical Commission: the data bus of digital, serial, bidirectional and multipoint communication between the field device installed in the manufacturing or production process area and the automatic control device in the control room is called fieldbus. The control system composed of fieldbus and field intelligent devices is called Fieldbus Control System FCS (Fieldbus Control System). There are three key points to measure whether a control system is a real Fieldbus Control System FCS, namely: core, foundation and essence. The core of FCS is the bus protocol. Only the control system that follows the fieldbus protocol can be called a fieldbus control system; The foundation of FCS is digital intelligent field instrument, which is the hardware support of FCS; The essence of FCS is the fieldization of information processing, which is the embodiment of FCS system effectiveness

from the above definition, it can be seen that the fieldbus control system is a new type of control system with full computer, full digital and two-way communication. The essential difference between it and DCS lies in the digitization and networking of field level equipment, which realizes the two-way communication between control devices and field devices, and eliminates the information "blind spot" of production process monitoring. It can be said that the digitalization and networking of field equipment level is the basis of power plant information management

2. The characteristics and current situation of Fieldbus Technology

the development of CPU technology has led to the digital revolution of field instruments and devices, and also made the digital communication between field instruments and devices possible. Digital and intelligent field instruments and devices (such as sensors, actuators, etc.) not only replace the 4~20 mA analog system, but also realize the control function and equipment management function in the field equipment. With digital communication, many information of field equipment can be obtained in the control room, such as diagnosis, measuring range, configuration and identification. With the emergence of fieldbus technology, many field device signals that originally required a large number of cables for point-to-point connection can be transmitted through a network cable, which can significantly reduce the use of cables and reduce the related materials and installation costs

the starting point of fieldbus technology development is to provide users with open, interoperable, exchangeable and unified standard measurement and control products, overcome the closure problems caused by traditional DCS, PLC and other patented control systems, select the products of different companies, integrate the best production process control system, reduce the construction and operation costs of engineering projects, and improve the competitiveness of enterprises

based on the discussion of relevant data, compared with traditional DCS and PLC control systems, October was the first import increase in the second half of the year, The advantages of FCS, a control system based on fieldbus technology, can be summarized in the following aspects:

(1) interoperability

(2) decentralization

(3) reliability

(4) accuracy

(5) openness

(6) economy

(Bazhong will use natural gas and graphite resources 7) maintainability

these characteristics and advantages are described in detail in relevant literature, and will not be repeated here. Since there are so many benefits, why don't we actively use it? This leads to the standard dispute of fieldbus and the limitations of Fieldbus itself

first of all, the result of the debate over fieldbus standards is that IEC TC65 (the 65th Standardization Committee responsible for industrial measurement and control) adopted eight types of Fieldbus as the IEC61158 international standard at the end of 1999. In August 2001, 10 types of fieldbus standards (the Third Edition) were revised and formulated, They are:

type 1 ts61158 fieldbus

type 2 control net and ethernet/ip fieldbus

type 3 PROFIBUS Fieldbus

type 4 P-NET fieldbus

type 5 FF HSE fieldbus

type 6 swift net fieldbus

type 7 WorldFIP fieldbus

type 8 INTERBUS fieldbus

type 9 FF H1 fieldbus

type 1astm-d6420 PROFINET Fieldbus (it became a formal international standard in April 2003)

in addition to the above 10 standards, this steel bar bending tester is developed according to the provisions of the national standard metal bending test method (gb232 (8)), there are also the fieldbus standards SDS (smart distributed system), ASI (actuator sensor interface) and DeviceNet passed by IEC tc17b, as well as the CAN protocol of iso11898, as well as some European standards. So many standards have brought great confusion to user applications, which leads to the lack of a unified standard in fact, because different fieldbus standard protocols cannot be directly interconnected and communicated

secondly, the above-mentioned fieldbuses are developed for different application fields, and Fieldbus itself has limitations in application fields

in the field of factory automation, discrete logic control is dominant, because factory automation contains fast-moving machinery, which has faster response than slower process automation. The fieldbus types suitable for this kind of occasion are DeviceNet, ControlNet, PROFIBUS (DP and FMS application rules), as well as INTERBUS and ASI (as interface)

in the field of process automation, continuous regulatory control is dominant, but it also includes discrete or on-off control. The fieldbus types suitable for such occasions include foundation fieldbus, PROFIBUS PA, WorldFIP, etc

3. Control characteristics of power plant production process

the production of power plant includes the following main process: fuel system (transportation and storage of coal and fuel/gas

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