Study And Realization Of Intelligent Power Distribution Control System Based On Modbus Fieldbus

With the development of computer technology, communication technology and control technology, the traditional industry control is experiencing an unprecedented revolution which is directed towards network. As a result, the industry control network with fieldbus as the representative has achieved a great development.In the traditional power distribution facilities, the functions of power distribution, control, protection and surveillance are realized through such electric components as circuit breaker, contactor, relay, control appliance and electric meter. The presence of so many traditional components makes it very inconvenient to produce and repair these facilities. Moreover, the facilities are operated mainly by hand, not by computer, which results in the failure of realizing complicated control logic. Consequently, we design and realize a new intelligent distribution control system based on the fieldbus technology. The system is free from the management concept and mode of traditional distribution facilities, and employs a large number of advanced intelligent components, such as intelligent network meter, network I/O and intelligent circuit breaker. In addition, the system makes use of a very small number of ordinary control facilities. Thus, it is a brand new network integrated facility with true distribution control. With fieldbus as the focus, the paper mainly does research into the application of Modbus protocol to low-voltage network intelligent distribution system, which has a friendly human-computer interface and is simple and quick to operate.On the basis of further research on fieldbus technology, the thesis designs the intelligent distribution control system based on fieldbus. The design can act as a foundation for the ultimate realization of remote control, remote adjustment, remote communication and remote measure. The work of the thesis consists of the following parts:Firstly, the thesis presents the current application situation of fieldbus, introduces the technology of fieldbus and analyzes the development trend of intelligent distribution control system. Through the comparison with the traditional power distribution system, the thesis puts forwards the advantages of fieldbus. According to the design, the thesis works out an application plan of fieldbus in intelligent distribution control system, and studies the principle and means of software and hardware design.Secondly, in light of the characteristics of power distribution system, the thesis researches the realization of software and hardware of Modbus fieldbus technology in the present system, and puts forward CRC checking principle and means of realization of Modbus fieldbus. What is more, it solves the problem as to communication in distribution network control.Thirdly, based on the need of distribution control system, the thesis comes up with the structure of the hardware system, and respectively introduces the principles, functions and design thought in terms of hardware circuit design for communication interface module of the system, the network switch card of upper computer RS232/RS485 and distribution terminal controller. Meantime, the author also proposes the hardware circuit diagram of each part.Fourthly, the thesis analyzes the process of data collection for the control system and develops driver programs of lower computer. It also develops human-computer interaction interface and configuration software, and achieves the work of data collection, analysis and display, and the design of software as well.The control system is an advanced case in intelligent power distribution control and is characteristic of low cost, convenient and effective operation. It is rated as the trend of distribution automation with great theoretical significance and value of popularization in production.