Study On Internal Model Control With Decoupling And Its Application In Thermal Processes

With the rapid development of industrial technology, large-capacity and high-parameter thermal power units are gradually becoming the mainstream. Besides, the expanding production scale and more complicated equipment structure and process raise strict demand on the thermal control system. The classic PID control method has been widely applied into the production process of thermal power plant and can function well in most cases. However, the classic PID often fails to operate excellently when the control system has complicated features such as nonlinear, time-delay and multi-parameter coupling. Thus, it is practically and academically meaningful to design efficiently automatic control system to deal with the complexity of the thermal system, which can guarantee the operation of unit more safe, economic and stable.In this paper, I firstly summarize the existing studies on advanced technology of thermal system control.Then I take the turbine-boiler coordinated control system as main research object. I mainly introduce the components of plant unit coordination system and the features of the control system, and then conduct performance analysis and simulation study on different load control methods of the coordination system. In the following section, I introduce two design programs of the unit coordinated control system targeting at its multi-parameter coupling feature. These two design programs combine the theories of multi-parameter coupling and internal model control together to incorporate the control method of multi-parameter coupling and internal model control.1. The design of internal model PID controller based on improved inverted decoupling: Decoupling the objects of coordinated system into several single-input and single-out objects with typical two-order inertial link, then design PID controller respectively and set PID controller parameters based on internal model control principles.2. The design of integration of decoupling and intermal model controller: Combine the decoupling and internal model control, and in turn, make decoupling and internal model control achievable in the controller. Specifically, Choose main control channel based on relative gain coefficient matrix and then design controller based on reverse decoupling principles. The whole process is simple but applicable in high-order object.Under MATLAB/SIMULINK, I conduct simulation study for these two programs. And the results prove that both two programs function well in eliminating the coupling effects of parameters and have excellent value-tracking and disturbance-retraining ability.