Improved Active Disturbance Rejection Control And Its Application To Thermal System In Power Plant

The principle of Active Disturbance Rejection Control(ADRC)is to treat model uncertainty,external disturbances,parameters changes as a “total disturbance”,which is then estimated and compensated,so that accurate model is no longer required and control design can be greatly simplified to accomplish control process.But the thermal system in power plant has the characteristics of large time delay,big inertia and strong nonlinear,which increased the problems existed in ADRC such as stability and a lot of parameters to tune.In order to promote the performance of existing ADRC method to guarantee stable and economic operation of power system,this paper mainly made improvements on the following aspects.Firstly,in order to increase disturbance rejection,an improved ADRC is proposed based on the structure of Linear Active Disturbance Rejection Control(LADRC).By adding a same Linear Extended State Observer(LESO)into ADRC,a total disturbance estimation error value is introduced.Secondly,in view of the observer bandwidth limitation problem existing in parameter tuning of ADRC,some improvements on original parameter tuning method is made and its tuning steps are summarized in this paper.This method ensures tuning simplicity and at the same time greatly reduces the influence of observer bandwidth to the speed of Extended State Observer(ESO).Finally,the effectiveness of the method is verified in a 660 MW supercritical unit coordinated control system(CCS).Simulation results indicate that the improved ADRC technology can get good tracking effect.Compared with traditional control methods,improved ADRC has a better rapidity and disturbance rejection,it has great value in engineering application.