| With the rapid development of our automation and industrial modernization,there is an increasing demand for energy.Supercritical thermal power technology has the advantages of high generating efficiency,low coal consumption,and strong load adaptability,enabling supercritical unit concurrent boilers to become the main units used in thermal power plants.However,the controlled objects under the combustion control system of thermal power plants have the characteristics of nonlinearity,strong interference,hysteresis,and large inertia,which makes the conventional PID control effect is not ideal,and the system adjustment requires a long time and is prone to overshoot.Therefore,it's necessary to further improve the control quality of combustion systems.The paper mainly analyzed the operating principle of supercritical units and the process flow of combustion control systems.It's concluded that a combustion control system is mainly composed of a fuel control system,an air supply control system,and an induced air control system.Besides,a step disturbance analysis was conducted on the dynamic characteristics of the controlled objects under each subsystem.Furthermore,a control scheme of each subsystem was established.Finally,a whole-process control scheme of the combustion control system was designed,in order to ensure a good control effect when the load of the unit changes.Based on the characteristics of combustion control systems and PID control,the deficiencies of the conventional PID control was improved by combining fuzzy control and PID control.Besides,a fuzzy self-tuning PID controller was designed to perform MATLAB simulation for the various subsystems of the combustion control system.The simulation results showed that such a control system performed a better control quality than conventional PID.In addition,a dynamic matrix optimization control scheme of the subsystems was designed according to the general industrial sites.Here,the first-order pure delay model of the generalized controlled objects of the subsystems was achieved through identification.Subsequently,DMC controller parameter setting was performed for the subsystems under different working conditions.What's more,DMC-PID cascade control simulation was conducted on subsystems,and a comparative analysis conducted between fuzzy self-tuning PID control and conventional PID control.The simulation results showed that the PID control combined with dynamic matrix performed a better control quality,with high practical significance,which improves,to a large extent,the stability,rapidity,and robustness of the system,has a good adaptability to the changes of working conditions,and can meet the control requirements of the complicated systems in power plants. |
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