Self-tuning Pid Control Technology In The Heating System

An economical and practical control system of central heating in city has been given in this paper. In the control system, we reviewed some typical PID control methods in industry process control, and a PID parameters auto-turning method based on relay-feedback with hysteresis which is a popular method in industry process control in these few years has been introduced .We apply the method in the control system of central heating in city. By doing some simulations ,the paper analyzes the stabilization and the robustness of the method. The results of the simulation experiments show that the relay-feedback control with hysteresis has better controlling quality and stronger robustness than general PID methods in long time-delay systems. Following is the main content of the paper:In the first chapter , the development of central heating in city is discussed and the problems about the central heating in city is pointed out, at the same time we give referenced ideas to resolve the problems.The development of PID controller is also discussed at last.In the second chapter, the control system of central heating in city is introduced. A really feasible controlling scheme is proposed .The successful application in the power plant in Zhangqiu show that the scheme is credible and economical. It alsoshow that the scheme not only can save energy source but also can protect environment.In the third chapter, the basic principle of PID control and turning methods of PID parameters are discussed in detail.In the fourth chapter ,the auto-turning method of PID parameters based on relay-feedback with hysteresis is applied in the controlling system of central heating in city. At first, the least-squares method and relay-feedback control are summarized. Second, the second-order plus dead time model is used to simulate practical system of central heating in city. Then we have some simulation using the proposed method. Simulation results show the effectiveness of auto-tuning method based on relay-feedback with hysteresis. At last, we analyse the stability of the system.