The Improved Research Of Multi Stage Intelligent Control System In Boiler Main Steam Temperature

The boiler main steam temperature is an important parameter in the thermal control system of power plant,and its control quality directly affects the safety and economic operation of the whole unit.Being too high or too low,it will have a negative impact on the operation of the unit.Large inertia and large delay characteristics of the main steam temperature controlled object,and various disturbances in the actual control process,all will make it more complex and difficult to control the main steam temperature.Therefore,how to improve the control quality of the main steam temperature is an important part of this paper.Firstly,it describes the composition and working principle of the boiler steam water system in detail,and analyses the static and dynamic characteristics of the main steam temperature.Meanwhile,it introduces the existing control methods and their control ideas,and discusses the deficiencies in the control process.To solve the problem existing in main steam temperature control system that the original independent conventional control method cannot stabilize the main steam temperature well and the control section can not cooperate well with each other,this paper improves the conventional control method,and proposes a control scheme of double single inner loop intelligent cascade.This core is to design the two control section to be the inner loop of the whole control system,which respectively and quickly eliminate the disturbance of each section.The set value of the second control section steam temperature follows the output value of the first control section.When the system is disturbed,the desuperheating water regulating valves in two control section moves quickly,later the desuperheating water regulating valve in second level will work continuously to support that of in first level,making the two control section work in suitable condition,which balances the load of valve caused by the disturbance.The main steam temperature is stabilized by the introduction of the outer loop.The main circuit uses internal control model,and the controller parameters are dynamically modified by fuzzy intelligent online correction unit,which enables it to adapt to the changes of the working conditions.Secondly,it analyses the internal control system and steam flow feed-forward compensation controller scheme and designs the fuzzy intelligent online correction unit which corrects controller parameters,improving the defect that the fixed controller cannot control the main steam temperature well existing in conventional control method when the working condition changes.Then the paper analyzes the stability of the control system from two aspects of steady state performance and robust stability.Finally,through the MATLAB experimental simulation,the dynamic and steady-state performance parameters of the proposed control scheme are obtained in the aspects of tracking,anti-interference and robustness,and the simulation results are compared with that of the conventional PID control scheme.The results show that the performance of the improved double single inner loop intelligent cascade control system is better than that of the conventional PID control system,and the effectiveness of the proposed scheme is proved in theory.