Development On The Control System Of MPS-HP-Ⅱ Medium Speed Coal Mill Based On PLC

In the power plant, the coal dust production is a primary section. The milling quality ofthe coal mill will directly affect the performing of the generator set. According to the millingspeed, the coal mills can be classified into three kinds, which are the low velocitymill(15~25rpm/min), the medium velocity mill(25~300rpm/min), and the high velocitymill(500~1500rpm/min). By far, the medium speed coal mill has been widely used due to itscompact structure, low power consumption, low noise and convenient control. Currently theMPS-HP-Ⅱ type coal mill developed by the Babcock Company in Germany is the mostpopular one, which has been brought in by many enterprises.Taking the MPS-HP-Ⅱ type coal mill made by Changchun Generating EquipmentGroup as the study object, this thesis develops a control system based on Schneider QuantumPLC, the primary work includes:(1) Firstly, the loading and the milling structure, the coal separating structure and theoverhaul structure are analyzed with the kinematics and dynamics theory. Meanwhile, thePID control of the milling system based on the practical parameter adjustment is alsodiscussed.(2) Secondly, the PLC hardware system is designed. The detailed type, quantity andcomposition scheme for the modules of the the CPU unit, the digital input, the digital output,the analog input, the analog output, the communication unit and power supply aredetermined. Moreover, the I/O point configuration and the connection diagram of the mainhardware are also designed.(3) Thirdly, the software system for the PLC control on the MPS-HP-Ⅱ type coal mill isdeveloped. The logical control flow for the mill’s start and stop is designed, and also theladder diagrams of the primary control model are designed. Then the human-machineinterface is designed by InTouch. The developed system is applied to the practical coal mill,and the experimental verification data shows that the control system has a good stability, asatisfied accuracy, and a qualified responsivity.This thesis aims at developing a functional control system for the MPS coal millbrought in from abroad. The study work and the achievements presented in the thesis canoffer a reference for the PLC-based control system design and therefore has positivemeaning and application worth.