船舶中央冷却系统串级控制的建模与仿真研究

Modeling and Simulation of Marine Central Cooling System Based on Cascade Control Principle

为了改善船舶中央冷却系统控制性能,针对目前使用传统PID反馈控制的冷却水出口温度控制系统惯性大、经常超调的特点,论文通过对某57 000t散货船中央冷却系统工作原理及其相关控制技术的分析,利用流体力学与传热学理论,建立中央冷却系统水力模型、稳态换热模型和动态换热模型。在此基础上引入串级控制方案,并使用经典控制理论建立控制模型。最后使用MATLAB软件对PID控制方案与串级控制方案进行对比仿真。仿真结果显示串级控制方案拥有良好的控制性能并在船舶中央冷却系统的控制设计中具有广阔的应用前景。

The objective of the work is to improve the control performance of central cooling system ana reuuce u^c dynamic deviation of the outlet temperature of fresh cooling water, which is caused by inertia of cooling water system when using traditional PID control model. Hydraulic model, steady heat transfer model and thermodynamic model of the central cooling system are presented in this paper based on fluid mechanics and heat transfer theory. Operating principle and corresponding control method is introduced to a 57 000 ton bulk carrier＇s central cooling system, and a cascade control model is established by using classical control theory. The performance of PID control scheme and that of the cascade control scheme is compared with the help of software Matlab. Simulation results show that the cascade control scheme possesses better control performance and has a good application prospect in the control design of central cooling system.