Based On The Double Track Method Of Large Time-delay System Stability Analysis And Simulation Study

Delay phenomenon is widespread in the actual long process of industrial production such as nonferrous metallurgy production. The long time-delay process is complex long, multi-procedures. Big dead-time in such systems can be caused by several elements, such as the transmission time of material and energy in a pipe or the tank, material reactions and energy exchange need certain of time, and the action time of detection equipment or device response time and enforcement agencies. The existence of the time-delay item is the main cause of instability to control system. General engineering application, more for through the configuration of the parameters of the PID controller makes the system stable, but in a specific conditions, the process conditions such as raw material properties, environmental conditions change, process object model parameters are also will change, which makes the prior set controller parameters can’t meet the changed requirements any more, even leading to the control effect becomes poor and instable.Therefore, this paper is mainly aimed at the condition when the controller parameters of large delay system are fixed, analysis the stable object parameters stable region which can make large delay system maintain stable. First of all, in allusion to the production process of large delay characteristics in the closed-loop control and adjusting working point caused unstable condition, in-depth analyze the characteristics of large time delay system, and viewed from unbalance energy dissipation and excessive accumulation to analyze the feedback information dislocation evolution mechanism in large delay closed-loop control system. In additional, it’s going to reveal the mechanism of oscillation in the closed-loop large time-delay system with the multiple time series and time scales theories. Second, when the system controller parameters are given, based on the double track method analytical form, gain the sufficient and necessary conditions which can keep the robust stability of the first order plus time-delay control object, and then deduce the time-delay stability field of system parameters; Furthermore, with extending the traditional D segmentation method to dead-time systems, and get closed loop system stable domain in k-T the planar and the relationship of the steady-state gain k, time constant T and the time lag and among the factors influencing the stability of the system. And put the two methods to meet the margin of the stability of the conditions and get the stability domain. Finally, build systems with time delay simulation platform by MATLAB graphical user interface (GUI) environment. The platform can transfer the parameters of Simulink GUI and output graphic at the current time. Through setting up different parameters of system structure, we can get the outputs curves in the simulation platform directly, and analyze system as stable or oscillation, divergent or convergence. According this, we can conclude the relationship of the margin of the PID controller parameters and stability which satisfied stability under the stability margins, and further analysis the influence of the time constant T, steady-state gain k and the time lag to the stability of the system through the simulation platform.