AN ADAPTIVE HIERARCHICAL FUZZY PID PARAMETERS CONTROL FOR SUPERHEATED STEAM TEMPERATURE SYSTEM

In this paper, during the course of controlling the boiler's superheated temperature in the power plant, in order to overcome the effects of the object's parameters varying on control qualities of the system, a new adaptive layer hierarchical fuzzy control method is proposed in accordance with the operation parameters which have greater influence on the boiler's dynamic characteristics. The analysis for this method is given and its advantages compared with other general fuzzy control are pointed out.The adaptive hierarchical fuzzy PID controller given in this paper is based on the following:In the closest analogy to the general two dimensional fuzzy controller,according to the variation of e and Δ e ,the PID parameters are real\|timely adjusted in the dynamic process in order that the system achievees the expected performance index(process level).In the case of variation in the object's parameters and operating parameters,this method can establish the plan level strategy to obtain the fuzzy adjust of the PID parameters based on human analysis to the real operation and using the nonlinear mapping of control rules formed by fuzzy sets(plant level and supervisory level).The process level and the plan level construct the dynamic correcting strategy on the basis of the hierarchical structure.The simulated example,the 19000t/honce\|through boiler's superheated temperature control system,shows that,the adaptive layer hierarchical fuzzy control system is very effective in the course of superheated temperature system.It can overcome the influence of the changed caused by the system parameters.Moreover,it is fast in response,minimal in overshoot,and robust.