Auto Disturbance Rejection Control Technology And Its Application In The Denitrification Control System Of Thermal Power Unit

SCR denitrification system is a typical nonlinear, large time delay and time varying system, the system is difficult to be controlled. If the system can not be controlled very well, the environment and the equipment of the unit are affected. In recent years, The government pays more and more attention to environmental pollution, SCR denitrification control of thermal power units becomes more and more important. To find a satisfactory performance control algorithm has become an urgent problem. Since auto disturbance rejection control technology has been presented by Han Jingqing, it has been used extensively and expanded. Because of its outstanding characteristics in the estimation and compensation of system disturbance, it has become a hot research topic in recent years.This thesis is built on the combination of theory and application. The SCR denitrification control system in a thermal power plant is the application background.The aim is to increase the control effect of SCR denitrification control system. Some problems about the application of auto disturbance rejection control in the SCR denitrification system are studied. For the nonlinear function and the parameter setting of the auto disturbance rejection controller, the thesis has carried on the theoretical research and algorithm improvement. The research results are applied to the SCR denitrification system, And it provides an effective control strategy for SCR denitrification system. The following two aspects of research work are carried out on the basis of comprehensive analysis of the auto disturbance rejection control technology:The auto disturbance rejection controller with non-smooth function is difficult to obtain an ideal control effect. The inverse hyperbolic sine function is a smooth function,which is approximated as a linear function near the equilibrium point, and is approximated as a saturation function far from the equilibrium point. According to the characteristics of the inverse hyperbolic sine function, it is applied to the algorithm of auto disturbance rejection controller. After the simulation analysis, it is verified that the auto disturbance rejection controller based on inverse hyperbolic sine function has good control effect.The SCR denitrification system of thermal power unit which has the nonlinear, large time delay and time varying characteristics is difficult to be controlled. Since the auto disturbance rejection control technique has the ability to estimate and compensate the disturbance, the Smith predictor can compensate the delay of the system. A method of combining the auto disturbance rejection control and the Smith predictor is proposed, and the auto disturbance rejection controller based on Smith predictor is designed. Throughsimulation analysis, it is proved that the controller can control the SCR denitrification system better, and the controller has strong anti-interference ability and adaptability.