The Resach Of Modle-free Control In Circulating Fluidized Bed Boiler Combution Process

Industrial production is the lifeline of the country’s economic development, and the boiler play the important role in industrial production. Circulating Fluidized Bed Boiler(CFBB) apply the circulating fluidized bed combustion technology, that make it be equipped with the high combustion efficiency and controllable emissions of polluting gas. Today, the world are facing the shortage of resources, increasingly serious environmental pollution and other issues. In this situation, automation control of CFBB process has important significance. However, the combustion process of CFBB is a very complex process has characteristics that large time-delay,nonlinear, multivariable coupling and time-varying. All of these factors resulting in a huge difficulty to build an exact mathematical model for control system. That means tradition control methods can?t meet its control requirements nicely, which severely restricted the promotion of this kind of clean and efficient combustion technology.In this thesis, author make an analysis for dynamic characteristics of bed gentle and main steam pressure those are main controlled objects of circulating fluidized bed boiler combustion process. According to its control requirements and control difficulties, model-free adaptive control( MFAC) should be considered as the control method. With this method, controller can be directly designed without exact model to reach the control objectives. Given the large time-delay of CFBB, the control law in MFAC is analyzed on the basis of basic model free control method by changing the period of D-value,and control algorithm should be improved by increasing the period of D-value, in this way an improved model free adaptive control(IMFAC) is born. At the same times, consider the multivariable coupling characteristic of controlled object, algorithm that expanded to multi-input multi-output(MIMO) systems called MIMO-IMFAC make complex MIMO system like CFBB can be controlled without external decoupling link, direct control of whole two controlled objects include bed temperature and main steam pressure can be achieved.In Matlab, the model free controller module be desiged by using S-function, and then make a mass of simulation experiments for control effect of bed tempreture control system, main steam pressure control system and coordinate control system. The result of experiments show that MIMO-IMFAC method can meet control requerments and simultaneously has a satisfactory control effect and adaptability.Beside work summaries, there are some shortcomings and expectation in the edd of thesis.