Research On Solid State Electric Heat Storage And Heating Control System Based On Improved Smith Predictive Controller

With the development of science and technology,the power generation methods gradually converge to those using renewable energy(such as nuclear power,wind power and hydropower,etc.),and the decrease of the total reserves of fossil energy leads to the constant rise of its price,and electric heating boilers begin to enter the public eye.The solid storage thermoelectric boiler uses electricity instead of coal,heating and storing heat through the trough electricity at night and releasing heat during the day,so as to absorb and discard wind and "cut peaks and fill valleys".At the same time,electric energy,as a secondary energy source,is more efficient,convenient and cleaner.By converting electric energy into heat energy through heat storage device,it is stored in solid boilers,which is cleaner and environmentally friendly compared with traditional coal-fired boilers,and there is no need to worry about large amounts of pollution during operation.However,compared with other forms of electric boiler,solid storage thermoelectric boiler starts late,there are still many technical problems to be solved.In particular,there are still many problems in the control strategy,and the temperature control is characterized by large inertia,hysteresis and nonlinearity.Conventional PID control is difficult to achieve satisfactory results.Even if a set of relatively ideal parameters are set,the working condition of solid heat storage boiler will constantly change in the process of use,and its mathematical model is also constantly changing.Quality of control is difficult to guarantee.In view of the above characteristics of solid storage thermoelectric boilers,based on the solid energy storage heating demonstration project platform of Hebei Institute of Civil Engineering and Architecture,an improved Smith predictive control is proposed to optimize the temperature control system of solid storage thermoelectric boilers.Based on the conventional PID controller,the dynamic model of the controlled object is estimated,and an improved Smith predictive controller is designed to compensate it,so that the controlled quantity delayed by time is fed back to the input end of the PID controller in advance,so that the PID controller can act in advance,so as to reduce the overcontrol and acceleration adjustment process.So that the heating system water temperature more quickly,more stable,more accurate to meet the control requirements,improve the control efficiency,reduce energy consumption.Firstly,the overall scheme of the control system should be determined on the basis of the solid energy storage heating demonstration project platform,and the control points should be planned.Secondly,a mathematical model is established for the controlled object,and an improved Smith predictive controller is designed according to this mathematical model.The improved Smith predictive controller was transformed into an inertial link and a differential link by Pade approximation algorithm,and then programmed into PLC controller by STEP 7-Micro/Win programming debugging software to realize the improved Smith predictive control.Finally,according to the designed controller,the PLC program is programmed and applied to the actual temperature control system.Step response experiment and step disturbance experiment were carried out on the original control system and the control system with the improved Smith predictive controller,and the experimental data were collected and compared.It is proved that the improved Smith predictive control can improve the temperature control system of solid storage thermoelectric boiler water supply.It is concluded that compared with conventional PID control,the improved Smith predictive control can perform better dynamic performance and steady-state performance.At the same time,the improved Smith predictive control has strong adaptability and strong anti-interference ability for the control system of solid storage thermoelectric boiler whose working conditions change from time to time,so as to ensure the stability of water supply temperature of solid storage thermoelectric boiler.