An Electric Power Plant Data Acquisition System Based On PROFIBUS

Nowadays, digital automation has been one of the focuses in computer control system field. In past decades, informational automation control system has developed so fast and a lot of new technology has be invented. In the past, Distributed Control System (DCS) has so many advantages and characteristics that it has developed a lot and applied in a large number of electric power plant automation systems.Fieldbus is a comprehensive technology with its contents based on intelligence sensor, controlling, computer, digital communication. Fieldbus is a communication and control system which is completely distributed, digital, intelligent, bidirectional, connected and multivariable. Because Fieldbus Control System (FCS) solved the problem that information isolated islands still exist in the DCS automation system, it has been a new generation of automation system to replace DCS and gotten great attention in digital automation field.In all of fieldbus protocols, PROFIBUS develops fast and has been applied in numerous places. Many famous corporations manufacturing automation devices in the world design and produce automation products based on PROFIBUS. Domestic electric power plant automation systems usually use devices and products of external corporations such as Siemens, and there are few products based on PROFIBUS. So this paper explains a design and realization of an electric power plant acquisition system based on PROFIBUS protocol, by doing theoretical analysis and research of PROFIBUS technology.First of all, the thesis introduces the composition of PROFIBUS and basic characteristics, including protocol structure, transmission technology, protocol of visiting PROFIBUS, etc. It has explained the function and communication mechanism of PROFIBUS in detail.Secondly, on the basis of the construct of electric power distributed control systems, the thesis gives a design idea of an electric power plant data acquisition system. In order to satisfy electric power digital automation control system's need for high reliability, the design constructs a PROFIBUS redundant buses network. The thesis gives this design and evaluates reliability of whole system.At last, the thesis explains design of slave station's hardware and software in detail. The hardware part realizes the communication and I/O module, including two modules'design idea, block diagrams, chips chosen, detailed design of every part. The software part explains design idea of the main program and PROFIBUS communication program, frame, and software flow pattern. By tested in the experiments, all slave stations in the data acquisition system can complete high speed and stable data communication. In the meantime, this system designed in the paper meet the need for high reliability.