Development Of Distributed Control System On Coal Powder Preparation

In order to realize the monitor and control during the raw coal hoisting, feeding, milling, powder separation, storage, weighting and feeding, a control system based on Profibus-DP was developed for a new coal powder preparation line in a Iron Ore Group, Shandong. After extensive research on recent situations about Distribute Control System (DCS) in native and abroad and real needs of the project, a IPC & PLC & field-bus structure is adopted to solve the control problems, such as the complexity of the manufacturing flow, multiplicity of equipments, excessiveness and disperse of I/O and high demand of avoiding blast. In the locale, AC transducers and soft starters form the DP slaves by field-bus communication card in the field to realize the driver and control. The data of actual temperature and pressure measured by devices is transfened by RS485(Modbus) bus. A S7-300 PLC, which acted as a DP master and MPI slave, form the middle control layer. Besides finishing the basic logical function, it can also harmonize the work among these DP slaves and realize some special control arithmetic via field-bus communication. A ADVANTECH IPC, which acted as a MPI master, is used to display parameters, deal with alarm information, print report forms and so on. The whole system is not only embodied the distributed control, centralized management of distributed control system, but also incarnate the characteristics such as total digital communication, highly openness and reciprocation of field-bus control system.As the model of pipeline pressure control system is time-variational, non-linear and coupling, the classical control theory could not work out it. So it is necessary to find a new control theory without the need of exact mathematic model for designing a new controller. A fuzzy PID parameter self-adaptive algorithm is adopted to tune the PID parameters on line according to the different demand for PID parameters at different response phases in the dissertation. According to the result of simulation, we can find the fuzzy PID algorithm has improved the control effectiveness and dynamic and static performance of system significantly.The coal powder preparation distributed control system has been put into practical use. This system, which can provide preferable references for the designs of other preparation control systems, proves to be steady and easy to operate. It can improve the productivity and the quality of production as well.