PID Adaptive Control Based On Control History And Its Application On The Objects In Thermal System

Classical PID control algorithm is simple, versatile, in Thermal Process control iswidely available. Thermal Control object widespread large delay, large inertia,nonlinear and uncertain characteristics, resulting in the traditional PID control method isdifficult to obtain the desired control effect. With modern electricity production towardshigh-parameter, high-capacity unit direction, the object on the thermal control system isalso put forward higher requirements. To further improve the PID control algorithm forthe adaptive capacity of thermal objects, this paper constructs a historical control basedadaptive PID control strategies. The main work includes:(1) Thermal Control object for the main features of the traditional PID controllerincremental improvements. Inverse dynamics of the delay system on the basis ofqualitative analysis, by introducing control history information to redefine a newbaseline correction to replace the original baseline, and was designed based on thecontrol of history (Based on Control’s History, BCH) from adaptation PID controller(abbreviated as BCH-PID controller).(2) For an order inertia plus time delay control object, the second order inertia anddelay control object,300MW boiler main steam temperature control object,600MWboiler main steam temperature control objects, were carried out BCH-PID controlsimulation tests. The results showed that the BCH-PID controller into account the delayin the control system, the control of the current history, the dynamic characteristic whenthe object is changed, without changing the controller parameters in the case ofBCH-PID control scheme using more traditional PID control scheme has good controlperformance and a certain adaptability.(3) By introducing a recursive least squares method, online identificationBCH-PID controller control history of the weight coefficients corresponding to thequantity of BCH-PID optimize the structure, to form a modified BCH-PID controlalgorithm. Will improve the BCH-PID control algorithm is applied to the boiler mainsteam temperature process control. Simulation results show that the improved BCH-PIDadaptive capacity has been significantly improved. It can also be based on the weightcoefficient distribution, estimated under different load on the boiler main steam temperature control object whose delay time.