Research And Development Of Station Control System For Natural Gas Gathering And Transportation Stations

Gas gathering station is an important part of the natural gas gathering andtransportation system. At present, there exist some problems such as confusion inmanagement of production data, difficulty in information exchange with other systemsand low efficiency of production management in process of natural gas in the gasgathering station. To this end, aiming at harsh environment and complex field devicesof the gas gathering station, around the practical needs of the station control system,this thesis makes a deep study of the station control system of natural gas gatheringstations and its core technologies. And a professional station control system special fornatural gas gathering station is developed based on siemens S7-300PLC.Firstly, the situation and the tendency of similar software system available in andoutside was studied. Aiming at the gas gathering station control system functionalrequirements and technological characteristics, a three-tier architecture scheme forPLC-based station control system for natural gas gathering stations was proposed,including scene equipment layer, process control layer and application layer. On thebasis of the overall system architecture, the station control system hardware structurewas planned, and the PLC control system software and PC monitoring software wasdesigned.Secondly，the key technologies involved in the system were studied which includemethod of natural gas flow measurement based on siemens S7-300PLC and solutionto data integration between gas gathering station and gas production plant based onOPC technology. According to the characteristic of natural gas flow measurement withhigh accuracy requirements at the exit of the gas gathering station, real-timemeasurement of natural gas flow was realized based on siemens S7-300PLC. With themeasurement method, a natural gas flow calculation model was built based on theorifice flowmeter and the PLC flow measurement procedures and PC man-machineinterface was designed. Through running the algorithm about natural gas flowcalculation in the PLC, real-time calculation of instantaneous flow of natural gas wasachieved and cumulative flow of the corresponding period of time was added up.According to the characteristic of gas field distribution in a wide range of fields, theproduction information of most of the gas gathering stations in a discrete state and theproduction with large amount of data, solution to data integration between gas gathering station and gas production plant was presented based on OPC technology.With the solution, data integration architecture was built through OPC specification.Then PC monitoring system was set to OPC server and gas production plantmonitoring software was set to OPC client. OPC client access to data from the OPCserver via the OPC interface and real-time data exchange among the differentmonitoring systems was achieved.Finally, based on the above studies, PLC-based station control system for naturalgas gathering station was developed and applied in the enterprises. The applicationresults show that the system realize centralized monitoring to gas gathering station,meet the need for on-site production and management, and effectively increase thecapability of monitoring and management to operating status of the work zone. Thesystem is characterized by strong practical applicability, good adaptability, goodexpansibility.