Aplication Study On Boiler Control Sysrem Based On Decoupling Internal Model Controler

With the rapid development of thermal technology, the demand ofthermal efficiency and the running smoothness of boilers is much higher.Most of the power and chemical industry in our country still adopts thetraditional control model, and even artificially operation, which cannotcompletely meet efficient and stable operation requirements.In this paper, boiler combustion control system is studied as the thesis,considering the feature of coupling and great phase lag, according to therequirement of boiler industry; multivariable decoupling controlledvariables (steam pressure, composition of oxygen in the gas and negativepressure in the combustion chamber) and manipulated variables (fuel, fed air, drawn air). Fed air is made into proportion with fed fuel in order toensure the economic demands and safety of boiling process. Fed air isproportional to drawn air so that negative pressure in the combustionchamber is constant at the desired value. This paper takes QingdaoKaiYuan thermal power plant35h/t boiler combustion system as theexample and the simulink result shows that the method is practicable.The main contents of the research in this paper are as follows:(1)The boiler process of flow and control request is expound, boilercombustion process and controlled variables are demonstrated in detail.The complexity of control is shown. In theory, multivariable decouplingIMC based on SISO IMC is presented; the designed controller has thefunction of decoupling model during the controller design to calculateeasily and to be more practical.(2)The boiler in Qingdao KaiYuan thermal power plant is taken as anexample and is designed the drun water control system and the boilercombustion control system respectively. We simulate with Matlab. The result shows that the designed controller is simple in structure, convenientto adjust parameters. It makes the system not only with good performanceof set point tracking, disturbance rejection and robustness, but alsoreduces bad influence while satisfying technical demand.(3)In the final boiler control system, SIMATIC S7-300is used as thecontrol element, and the system is programmed with Force Control.