Research On Fuzzy Dynamic Matrix Control In Main Steam Temperature Control System Of Thermal Power Plant

Today the world is involved in the fourth scientific and technological revolution.The variety of technological products is increasing.People’s daily life needs electricity,and the development of national industry,science and technology and economy cannot be separated from the support of electricity.Electric power industry as the basic industry of all industrial production,its importance is self-evident.With the increase of the demand for electricity,China’s power generation has also been rising year after year.At present,China’s power energy structure is still dominated by thermal power,supplemented by wind power,nuclear power,solar power and other power generation.As one of the important parameters that need to be monitored in real time in the thermal process,the main steam temperature is directly related to the boiler power generation efficiency and operation safety.It is one of the most difficult parameters to control because of its characteristics such as large inertia and large lag,and at the same time it is disturbed by a variety of factors.With the increase of demand and the progress of science and technology,the installed scale of thermal power generating units is also expanding day by day,the units are more complex,and the main steam temperature is also more difficult to control with the lengthening of the superheated pipe.Conventional PID cascade control and the introduction of differential signal to control the main steam temperature are far from reaching the control requirements.Therefore,it is necessary to seek better control methods to meet the higher control requirements.Firstly,the dynamic and static characteristics of main steam temperature in thermal power plant are analyzed.A mathematical model of the main steam temperature was selected to observe the dynamic characteristics.The principle and parameter selection method of PID cascade control are introduced briefly and verified by simulation.Then,the basic principle of Dynamic Matrix Control(DMC)Control algorithm is introduced in detail.DMC control parameter selection method and precautions are introduced.The main steam temperature control system based on DMC algorithm is designed.The problem of poor control effect of DMC controller in the case of serious model mismatch was put forward after the simulation experiment.Aiming at the shortcomings of DMC controller,the temperature compensation of Fuzzy Control is introduced and the principle of Fuzzy Control algorithm is described in detail,and a fuzzy dynamic matrix controller(Fuzzy-DMC)is designed,in order to further improve the control accuracy of the controller,solve the problems of fuzzy rules can not be adjusted after the design of the fuzzy controller,and the control accuracy of zero position is poor,the idea of variable domain is introduced and the scaling factor adjustment is used to make the scaling or expanding of the domain decrease or increase with the error,which improves the adaptive ability and control precision of the fuzzy controller.The controller designed in this thesis is verified by simulation,and simulation results show that compared with PID control,DMC control and Fuzzy-DMC control,Fuzzy-DMC control has better control effect in the case of model matching and model mismatch.Temperature overshoot and adjustment time are reduced and the system performs strongly.Flue gas disturbance is added to the main steam temperature control system after stabilization.The simulation results show that Fuzzy-DMC controller in variable theory domain can quickly recover to the set value after being disturbed.The system shows superior anti-disturbance performance.