Dual-Rate Adaptive Control Driven By Virtual Unmodeled Dynamics Compensation In Industrial Heat Exchange Process

The industrial heat exchanging process is a complex industrial process,in which is the process of heat exchange between steam and circulating water.Due to the existing of uncertainty of steam pressure,uncertainty of water released by heat user,and fouling in heat exchanger,parameters of plant model,such as steam pressure vary frequently,returned water flow,and heat exchanging efficiency,which could cause fluctuations on the steam flow-rate and the supplied water temperature,or even lead to serve system resonance.To solve the above problems,this thesis designed dual-rate control of industrial heat exchanging process,supported by SAPI in Northeastern University.The main work of this thesis is as follow:1.By using the feature of dual-rate sample,this thesis uses steam flow as the internal loop feedback variable,and uses the supplied water temperature as the external loop feedback variable.This thesis design cascade controller as PI controller with virtual unmodeled dynamic compensation to overcome the problem caused by the fluctuation of model parameters.In this thesis,the stability and convergence of the control method are analyzed theoretically,and a sufficient condition for keeping the controlled variable in the target interval is given.2.The semi-physical simulation system of industrial heat exchange process was designed and developed by using Siemens S7-300 PLC platform.The semi-physical simulation system uses computer programis based on the mechanism model of industrial heat exchange process as the virtual controlled object,and uses S7-300 PLC as the controller.In this thesis,development monitoring interface is developed by using WinCC software.3.Simulation experiments were carried out on the semi-physical simulation platform for industrial heat exchange process.By analyzing the simulation results,we can conclude that the dual-rate adaptive control method designed in this thesis can effectively control the water supplied temperature within the target range of the heat user's demand.