Research And Development Of Industrial Control System Based On OPC Technology

With the development of control technology, computer technology and network communication technology, the demands of automatic control system for sharing information within large scale become more and more urgent, thus the requirements for the openness of industrial control system become higher and higher. Presently, traditional control systems are comprehensively implemented in industry. But, it is difficult to interconnect and interoperate with other control systems or instruments produced by other companies, due to the reason that the traditional control system adopted custom-defined special communication networks and particular communication protocols that lack standard interface to other control systems. Thus, Each control system is unique in its style, which forms "information isolated island". As a result, they can not exchange data among each other easily. OPC technology is a series of industry interface standards developed in collaboration of a number of leading worldwide automation software and hardware suppliers working in cooperation with Microsoft. OPC technology can provide the possibility of system integration and data exchange among various software and hardware used in the control systems from different vendors. OPC technology also can provide the higher interoperability among field devices, automatic control applications and entrepreneurial management applications. Aiming at the Butadiene plant of certain petrochemical company, a set of software is developed based on OPC technology, which includes OPC client program, data acquisition program, data preprocessing program, advanced control program based on soft-sensing technology, real-time fault diagnosis expert system. The software has laid the good foundation for making full use of the greatly integrated control function of DCS. The main contents of the dissertation are as follows: In chapter 1, OPC technology is introduced totally firstly. Then a brief summary about the advanced control, data preprocessing and fault diagnosis in next chapters is given. Finally, the main works of this dissertation are presentation. In chapter 2, the interface object model and Data Access Specification of OPC are researched. The main methods and the steps of designing OPC client program based on OPC Data Access Automation Interface Specification are given. And the OPC client program is implemented with Visual Basic. In chapter 3, in view of the control problems of the distillation columns in the butadiene plant, the advanced control strategy based on soft-sensing technology is designed, and the implementing method based on OPC technology is proposed. Firstly, the control system is reconstructed. Then, the program of data acquisition, data preprocessing and soft-sensor are designed. Finally the control loops are reconstructed in Control Studio. The advanced control software has been used in the plant. In chapter 4, the monitoring technology and the real-time fault diagnosis expert system based on OPC are researched. Depending on the need of the plant and the advice of the field experts, the knowledge base is built, and the inference machine is designed. The real-time fault diagnosis expert system is developed with Visual Basic and Access. In chapter 5, the entire context and the work that author studied and fulfilled are summarized. The innovations in the dissertation are pointed out, and the next tasks are planed.