Research on control algorithms of systems with long time delay

In chemical industry, metallurgy, petroleum and other industrial production processes, due to the existence of time delay, it is easy to cause the control quality of the control system to deteriorate or even become unstable. In this paper, the common equipment in the industrial process control system - heat exchanger as the controlled object, to study the control algorithm of systems with long time delay. We discuss the conventional PID control algorithm and the control algorithm based on Smith predictive control. The Matlab software is used to simulate the controlled object. The results show that compared with the conventional PID control, Smith predictive control effectively reduces the overshoot and adjustment time of the system and improves the response speed of the system, but it is only suitable for occasions with high control precision. Gain-adaptive smith predictive control still has a good control effect in the case of changed gain. The system of modified Smith predictive with regulator responds quickly and maintains good control performance in the case of changed time delay.