Simulation Of Coupling Control Of Wastesteam And Condensate Feedwater System In Marine Second Loop

Mobility is one of the important performances in the operation of a ship.The waste-steam and condensation feed-water system is an important part of the secondary loop system.While the thermal characteristics of the deaerator and the waste-steam main pipe interact and restrict each other,the waste-steam main pipe also serves as the working back pressure of each auxiliary machine,besides,the stability of the main pipe pressure determines the stability of the entire system.Therefore,it is of great significance to study the dynamic characteristics of the coupled control of the waste-steam and condensation feed-water system.This paper takes the secondary loop waste-steam and condensation feed-water system as the main research object,establishes the mathematical model,simulation model and control model of the secondary loop system by using GSE simulation software,and completes the model verification based on the design data.Aiming at the coupling relationship between the waste-steam main-pipe and the deaerator in the system,on the basis of the traditional PID control(Scheme I),a self-made fuzzy PID controller is applied to the pressure control of the waste-steam main-pipe,and thus formulated as Scheme II;On the basis of the Scheme II,the fuzzy controller is applied to the pressure control of the deaerator,and the control strategy of the Scheme Ⅲ is formulated;Finally,on the basis of the Scheme Ⅲ,the coordinated control idea is introduced,and the feedforward-feedback control method is designed,which is formulated as Scheme Ⅳ.Analyze the performance of system parameters under different control schemes.The simulation results are as follows:Whether it is the process of increasing the load or reducing the load,after replacing the traditional PID controller with the fuzzy PID controller,the overshoot of the wastes-team main-pipe pressure and the pressure of the deaerator is significantly reduced,and the stabilization time is greatly shortened,and the fluctuation amplitude of other system parameters is reduced,which proves that the fuzzy PID controller has better control performance.In the process of deaerator liquid level disturbance,whether it is a high working condition or a low working condition,the control of Scheme Ⅳ is compared with the control of Scheme Ⅲ,show that the overshoot of each parameter of Scheme Ⅳ is smaller,and the anti-disturbance convergence time is shorter.It is proved that the feed-forward control can effectively weaken the interaction between parameters.In the process of load change,comparing the control effects of the four schemes,the Scheme Ⅳ has the best adjustment effect on the parameters,which verifies that the fuzzy PID controller has better control performance.During the load reduction process,the pressure overshoots of the waste-steam main-pipe of Scheme I to Scheme Ⅳ were 3.8%,2.38%,1.23%,and 0.38%,respectively,and the stabilization times were 1200 s,900s,750 s,and 570s;Scheme I to SchemeⅣ,the pressure overshoot of the deaerator is 11%,10%,4.5%,3%,and the stabilization time is 1200 s,1000s,750 s,600s;In the process of increasing load,the pressure overshoot of the waste-steam main-pipe of Scheme I to Scheme Ⅳ is 6.8%,2.7%,1.57%,0.42% respectively,and the stabilization time is 1250 s,750s,510 s,360s respectively;Scheme I to Scheme Ⅳ,the pressure overshoots of the deaerators are 11%,9.5%,6%,and 4%,respectively,and the stabilization times are 1250 s,750s,600 s,and 450 s,respectively.