| Ocean rig is the production base to exploit oil and gas resource under the sea. It is significant for ocean rig to be equipped with reliable and safe control system.Up to now, Fieldbus Control System (FCS) has been still widely adopted in bottom floor in domestic ocean rig control system, which brought on some problems, such as low speed of data transmission, poor performance in mutual-operation and so on. Especially, there is no uniform communication protocol and standard in FCS, it can not meet the requirements of modern Networked Control System (NCS) because of its bad compatibility for different equipment. Most of models and functions of software used in traditional monitoring and control system are mainly implemented by programmer. When monitoring object is changed, designers have to amend the program greatly. Therefore traditional control system is of disadvantages such as heavy load, low reliability and flexibility.In order to improve these questions, the advantages and characters of Ethernet and FCS are studied in this thesis. Combining with the requirements of Safety and Automation System (SAS), the networked control system of SAS is constructed in which FCS technique is used in bottom equipment layer and Ethernet technique is used in control and information layers. The network interface is also supplied in the upper software of SAS in which WinSock is used for networked transmission of the real-time data. This kind of network structure fully embodies the advantages of Ethernet technique, such as high speed of data transmission, good compatibility and network performance. In additional, FCS is fit for the bottom equipment layer because of its strong ability of anti-disturbance and good performance in safety.Configuration software is selected as upper monitoring and control software which possess the advantages of simple operation, universal utilization and good flexibility. In the configuration software of SAS, Real-time database is designed in order to ensure the real time of data acquisition and data process. By using windows multi-thread technique, main models of data disposal can be simultaneously operated in the control software which can ensure to monitor the real state of ocean rig timely.Using Visual Basic 6.0, configuration software aimed at SAS has been finished in the article, which consists of system configuration, graphics configuration, alarm configuration, curve configuration, control strategy configuration, historic database configuration and so on. By using related database technique, historic database is created automatically in order to realize the historic data inquiry in the form of historic curve and data report. SAS configuration software is of some advantages, such as rich graphic interface, vivid animation show and simple and flexible configuration setting, etc.Finally, networked transmission of real-time data is achieved in laboratory LAN. Taking the ballast system of SAS for example, the main function models of SAS have been tested. The control task of the ballast system for ocean rig is completed. The reality and reliability of the whole design have been verified. |
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