Applications Of DCS In Fuel GAS/Steam-combined Cicular Power Stations

In this thesis applications of novel-type DCS in fuel gas/steam-combined circular power plants are studied and discussed.First the development and the trend of DCS are overviewed to analyze the existing defects of DCS and to emphatically discuss its applications in monitoring control systems of thermal power stations as well. In the thesis a method to implement DCS control is formulated based on PCS in field bus technique and applied into DCS control systems of Yang Ling Power Station. Meanwhile, aiming at the practical situations a detailed project design is presented.The thermal power unit plant, which is a complex multivariable controlled system with uncertainty, is composed of boilers, steam turbines, dynamos, power networks, loads and such other equipment. Therefore, it is very difficult to accurately construct its mathematical model. For coordinated control system designed using general control methods, the parameters are made up artificially in certain operating situations. When the situation changes, control performance will change for worse or even lead to abnormal operation of the unit. A decouplingcontrol method based on neural networks is formulated for the problem and aiming the problem of load control over the unit plant, system design and simulations are made to verify the feasibility of the method.Moreover, in DCS of Yang Ling Power Station, various communication equipment as well as the different communication protocols / agreements for varied equipment (mainly including RS232, RS485, MODBUS, PROF1BUS-DP and OPC technique) lead to considerable difficulty in communicating among diverse control system, incomplete overall monitoring data of the unit plant and incoordination. Therefore, communication among control systems is the key problem of the whole design while ensuring good control performance. Therefore communication hardware / software designs in the systems are discussed in detail and reasonable communication design scheme is presented in the project so as to reduce system cost and help increase system automation level.