摘要
本课题来源于广东省中山食品水产进出口集团的实际冷库项目。本文首先对制冷系统进行集中参数建模,然后根据建立的系统模型选择了ITAE二次优化控制对系统进行控制,从仿真结果可以看出,控制系统的各项动态性能指标比Smith预估控制要好。
冷库制冷系统是一个十分复杂的能量传递系统,建立一个准确的数学模型对于系统的控制以及节能的效果都有很大的影响。本文首先利用能量守恒对冷库建立了冷藏间的数学模型,然后采用广义最小二乘法建立了蒸发器的数学模型,最后依次建立了温度传感器、执行器和送风管道的数学模型,综合系统各部分建立的数学模型,本文建立了冷库从蒸发器到冷藏间这一系统的集中参数模型。从建立的数学模型看,我们所建立的冷库系统的数学模型是一个高阶、大惯量、大滞后的系统。
针对冷库系统高阶、大惯量、大滞后的特点,本文经过对比之后,选择采用ITAE最佳调节律建立的二次优化控制对系统进行控制。二次优化控制对大惯量大滞后系统具有很好的控制效果,但是二次优化控制主要针对一阶惯性加延迟的对象,所以在第三章采用最优降阶方法对冷库系统进行了降阶处理,接着设计了二次优化控制器,并对控制器的各个参数进行了推导计算;最后研究了二次优化控制器的鲁棒性。
对前面选择的控制策略,本文的最后一章用SIMULINK建立了用二次优化控制器进行控制的冷库系统的仿真模型并对系统进行仿真研究,从仿真结果可以看出,根据前面第三章的公式计算出来的参数的控制器对系统的控制效果并不太理想,经过微调控制器的参数后,系统有很好的控制效果。经过跟Smith预估控制的比较研究,特别是加入扰动之后,可以看出,ITAE二次优化控制的系统的各项动态性能指标,系统的鲁棒性都比Smith预估控制好。
The topic of the dissertation comes from the in actual cold storage project of Guangdong Food & Aquatic Products Import & Export Group of Zhongshan. This paper establish the concentrated parameter model of the refrigeration system first, then choose the ITAE twice optimum control to control the refrigeration system acoording to the model. We can see from the simulation result that diversified dynamic capability target of the system is better than that of the Smith estimate controlled.
The refrigeration system of the cold storage is a very complicated energy transmitting system. Established an accurate mathematics model has a very big inflence of the system control and the energy saving effect. This paper established a mathematics model of refrigeration room by the conservation of energy first, then modeling the evaporator by employing least-squares in a broad sense, at the end, modeling the temperature sensor, executant and the piping. Synthetize the model of each part, this paper establish the concentration parameter model of refrigeration system. At this time, we can see that the mathematics model is a high-level, big inertia, large time-delay system.
Aim at the high-level, big inertia, large time-delay system, I choose the ITAE twice optimum control to control the system after comparing. Twice optimum control has the good control result on the big inertia, large time-delay system, but the object of this method is one rank inertia add time-delay system. So in chapter 3 I adopt the optimum decline rank method to deduce the refrigeration system model first, and then designed the twice optimum controller with calculation the parameter. At the end, i study the robustness of twice optimum control.
For the control strategy that the front choose, the last chapter establishecd the emluate model of twice optimum control in SIMULINK and simulate the system. Since the simulation result can see that the control effect is not too good use the controller with the parameter calculated according to the formula in chapter 3. After adjusted the patameter of the controller tinily, the system has a good control effect. Through comparison with Smith estimate control, especially add disorder input, can see that the system with twcie optimum control has good performance to Smith estimate control. The system's strong robustness is represented when the mathematics model isn't accurate.
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