An Investigation Into Marine Boiler Drum Water Level Control Based On The Generalized Predictive Control

The current marine boiler control system mostly used feedback control system composed of PID controller.Because marine boiler system was a complex time-varying dynamic process,with many control loops,highly nonlinear coupling,delay and strong interference,it was difficult to achieve the ideal control effect with the traditional PID controller.To further improve control quality of marine boiler,guaranteed its security economy movement,this paper used the generalized predictive control theory to control the marine saturated steam auxiliary boiler steam drum water level system. Generalized predictive control theory was developing in the practical application as an advanced process control theory,it had shown attractive prospect in the control of complex industrial processes.Currently,in China,there were large power station boiler systems in the examples of successful application.This paper first according to the marine saturated steam auxiliary boiler's principle of work,through the mechanism model's method,obtained the boiler steam drum water level control object model,after certain supposition and the simplification,attained mathematical model of the steam drum water level under the different disturbance condition,and analyzed its dynamic characteristic with the model characteristic curve.Then the paper elaborated the generalized predictive control theory,given the algorithm flow, analyzed the algorithm characteristic and given the controller parameter selection principle.The generalized predictive controller had realized the marine boiler water system's control, further carried on the simulation analysis to the controller parameter.Through the simulation analysis and comparing with the conventional PID control the generalized predictive controller had confirmed its good robustness and compatibility.Generalized predictive control had its disadvantage of more calculation,long online-time because of repeated matrix inversion,and matrix may break down during the operation of matrix inversion if the matrix was not reversible or pathological.In this paper,a new algorithm of step generalized predictive formed from the multi-step control policy,based on the generalized predictive control algorithm,was introduced in a creative way for the control of marine boiler drum water level.Then the paper elaborated the step generalized predictive control theory,given the algorithm flow,had analyzed the algorithm characteristic and given the controller parameter selection principle.Further it studied the step generalized predictive controller's robustness,compatibility and its performance influence caused by the change of main parameter of the controller.Simulation results showed that the controller can be used to achieve a better level of marine boiler control system to overcome the generalized predictive control of a large calculation,matrix irreversible and pathological matrix,and it had characters of a little calculation,easy on-line control,more suitable for engineering applications required.This paper attempted to use the step generalized predictive control method in the marine boiler steam drum water control system by which to enhance the marine boiler's control quality,so it had high scholarly research value.And the marine boiler control quality's enhancement had very vital significance to the boiler's security and efficiency.The character suitable for project application of the step generalized predictive control enabled this paper's research to have the big practical application value.