The Research Of Advanced Control Strategy Of Coal Reservoir In Ball Mill Pulverizing System

The ball mill plays an important role among the production facilities of the power plant. A good control of ball mil could achieve high-productivity. In aspects of energy saving, environmental protection, the effect will also be significant. However, because of strong decoupling, great inertia, large time delay and time varying, it is hard to achieve desired performance. Simply applying Two-Input-Two-Out strategy could not satisfy the demand. Above all, it is necessary to develop an advanced control strategy that suit for ball mill control.This work includes the following four aspects:(1) Research on Two-Input-Two-Output system takes major part on the study of coupling systems. After a carefully analysis of the structure of feed-forward decoupling, the author proposes a modified feed-forward decoupling strategy. Simply dividing the desired transfer function and the original one, can we get each element of decoupling matrix. The computational progress is easy. With this method, one can get a completely decoupling.(2) By calculating amplitude and phase at the specific frequencies, can we simplify the complex transfer function into a simple one-a FOPDT model. The stability margin is also introduced in this paper so that the model reduction method could be comprehensive.(3) A controller includes the function of decoupling and Internal Model Control is designed in this article in order to advance the research on ball mill. It is proved that if the model matching is perfect, the controller turns out to have zero steady-state error. At the same time, one loop does not interact on others.(4) This paper also develops a Cascade-coal supply-Internal Model Control strategy aiming at ball mill load control. It will be faster and more accurate using that way.