The Iterative Learning Control Research For The Direct Blowing Pulverizing System

The power plant system powder system has the multivariable and strong coupling, largeinertia and changeable etc. Characteristics, for a long time hard to put into automatic control.Therefore, automatic control study become the hot issues in the of power industry. In the pastthermal power plants of our country adopt the low speed ball mill pulverizing system withintermediate storage bunker. However the pulverizing system with large area, theshortcomings of higher power consumption. Contrary, the direct blowing pulverizing systemhas the advantages of simple system, convenient operation, flexible, easy to realize automaticcontrol, compact layout, less steel consumption, small floor area, low power consumption ofunit milling. Therefore, in the domestic and foreign large and medium-sized units widespreadadoption of medium speed mill pulverizing system.This paper detailed studies and analyzes the direct blowing pulverizing system workingprinciple and characteristics, adopting the method that under the multiple working conditionsand multiple model object describe the dynamic characteristics. According to the analysisresults, the direct blowing pulverizing system into coal mill and mill exhauster two objects.Coal mill object has 3 inputs(coal Fc, recirculating air volume Fr, hot air volume Fh) and 3output( the differential pressure signalΔP, entrance pressure P, the wind outlet of powdermixture temperature T ). In this paper, using a ball mill before the bearing component ofvertical vibration of W instead of differential pressure signal of deltaΔP characterization ofcoal storage. The volume will not affect the coal quantity signal, and coal on the negativepressure signal effects can be ignored ,on the influence of temperature signal can be regardedas measurable disturbance. So mill object is decomposed into a coupled to the two input twooutput object and a single input, single output object. Row powder machine object adoptsone-order inertia model. Combined with PID control and iterative learning control, design thedirect blowing pulverizing system controller.The simulation results show that, the combination of PID control and iterative learningcontrol on the direct blowing pulverizing system change, coupling and delayed controlachieved good results.