Research And Application Of Parameter Stability Region Of Adrc Based On Dual-locus Diagram Method

In most industrial processes,e.g.petrochemical,robot,liquid conveying,constant temperature boiler and wastewater recovery,control targets such as liquid level,flow rate,temperature,pressure,etc.are limited by devices,surroundings and human factors.The asynchronous response of the controlled object caused by the time-delay has an impact on the response time,response overshoot and even the stability of the system,leading to the whole system cannot be fast stable or even divergent.Active disturbance rejection control(ADRC)observes the difference between the set value and the actual value by using the extended state observer(ESO)and estimates the disturbance and achieve the effect of automatic compensation.Applying it mainly to process control can not only achieve the original PID control effect,but also shorten the control time.However,for active disturbance rejection controller,since the proposed time is not long,the stability region theory of the controller parameters is not perfect enough to compare the development of PID.As its application becomes more and more extensive,how to select the stability region of active disturbance rejection controller parameters facing the time-delay systems can ensure that the system can overcome the interference in time in its stable region.Even for high order systems with time-delay systems,the controller can also track the set point in a timely and stable manner.In this paper,the following research is made for the above summary:On the one hand,on the theoretical analysis side,the linear active disturbance rejection controller is selected as the control algorithm for the time-delay system and the control loop is built.For the control systems of different orders,the dual-locus diagram method in frequency domain is adopted,and the intersection point is used as the critical condition of system stability to obtain the stability region of controller parameters,which can ensure the stability of the system.The stability region is provided for parameter selection and tuning of ADRC.On the other hand,as far as the application process,the 1.2 million tons hydrotreating back-flushing process in the process of petrochemical industry is selected.Firstly,according to the reaction process,the liquid level control is the process core,that is,the first order time-delay system.The parameter stability region of the first-order linear active disturbance rejection controller is obtained by the above theory.The effectiveness of the control algorithm and the accuracy of the obtained stability region are verified by numerical simulation.The parameters can ensure that the system is stable,and the optimal parameters are selected in the stability domain.The feasibility and validity of the obtained theory are further verified.