VRV空调系统过热度及房间温度控制

发布时间：2018-01-20 00:24

本文关键词： VRV空调房间温度过热度离散最优控制离散鲁棒控制　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,VRV空调系统因设备数量少、安装布置灵活、运行节能高效、维护简单方便、冷量分配灵活等优点,被广泛应用于办公楼、宾馆、商场和别墅等中小型建筑中。VRV空调系统是由一台变频压缩机、一个冷凝器、多个室内蒸发器和多个电子膨胀阀构成的一个多变量、强耦合、非线性的系统,对变频压缩机转速和电子膨胀阀开度的协调控制是保证系统安全高效运行的关键。针对VRV空调系统中房间温度和过热度的调节问题,本文进行了相应的研究工作。在阅读了大量中外文献的基础上,总结了VRV空调系统现阶段的研究进展,分析了变频压缩机、冷凝器、蒸发器、电子膨胀阀的工作机理和模型。通过分析可知,在VRV空调系统中,由于蒸发器和冷凝器中的制冷剂状态与其中的压力、温度有着紧密的联系,通过机理建模得到的模型必然是高阶的、非线性的。在实际控制器的设计过程中,需要将模型进行简化处理,这会带来一定的建模误差。前人通过辨识实际VRV空调系统的运行参数,得到了低阶、线性增量式的状态模型,本文以该模型为基础,建立了适用于控制器设计的离散化的状态空间模型。该离散化模型是原有模型的推导与变换,既保留了原有模型的精度,也使控制器的选择更为广泛。在VRV空调系统离散化状态空间方程的基础上,将房间的温度偏差、蒸发器最佳过热度及控制器的输出增量作为系统的综合优化目标,基于最优控制策略,研究了房间温度和蒸发器过热度的最佳控制方法,实现VRV空调系统的整体节能优化运行。MATLAB的仿真结果表明,针对VRV空调系统的多种运行工况,该控制方法能够满足控制精度和过热度的安全性的要求。针对最优控制器无法克服由建模误差带来的系统参数不确定性的问题,本文设计了鲁棒控制器,以克服模型参数的不确定性,达到理想的控制精度,并使用MATLAB软件进行仿真实验。仿真结果表明,在VRV空调系统多种运行工况下,所设计的鲁棒控制器能够克服模型参数不确定性对运行性能的影响,仿真曲线变化平稳,没有波动,空调运行安全可靠。
[Abstract]:In recent years, VRV air conditioning system has been widely used in office buildings and hotels because of its small number of equipment, flexible installation and layout, energy saving and high efficiency, simple and convenient maintenance, flexible distribution of cold quantity and so on. VRV air conditioning system in small and medium-sized buildings such as shopping malls and villas is a multivariable and strongly coupled system composed of a frequency conversion compressor, a condenser, a plurality of indoor evaporators and a plurality of electronic expansion valves. In a nonlinear system, the coordinated control of the speed of frequency conversion compressor and the opening of electronic expansion valve is the key to ensure the safe and efficient operation of the system, aiming at the adjustment of room temperature and superheat in VRV air conditioning system. On the basis of reading a large number of Chinese and foreign literature, this paper summarizes the current research progress of VRV air conditioning system, analyzes the frequency conversion compressor, condenser, evaporator. The working mechanism and model of the electronic expansion valve. Through the analysis, it can be seen that in the VRV air conditioning system, the refrigerant state in the evaporator and condenser is closely related to the pressure therein, and the temperature is closely related. The model obtained by mechanism modeling must be high order and nonlinear. In the design process of actual controller, it is necessary to simplify the model. This will lead to certain modeling errors. By identifying the operating parameters of the actual VRV air conditioning system, a low order, linear incremental state model is obtained, which is based on this model. A discrete state space model suitable for controller design is established. The discrete model is the derivation and transformation of the original model, which preserves the accuracy of the original model. On the basis of the discrete state space equation of VRV air conditioning system, the temperature deviation of the room is put forward. The optimal superheat degree of evaporator and the output increment of the controller are taken as the comprehensive optimization objectives. Based on the optimal control strategy, the optimal control methods of room temperature and superheat degree of evaporator are studied. The simulation results of realizing the whole energy-saving optimization operation of VRV air conditioning system. MATLAB show that, aiming at various operating conditions of VRV air conditioning system. The control method can meet the requirements of the control precision and the safety of superheat. Aiming at the problem that the optimal controller can not overcome the uncertainty of the system parameters caused by the modeling error, a robust controller is designed in this paper. In order to overcome the uncertainty of the model parameters and achieve the ideal control accuracy, and use MATLAB software to carry out the simulation experiment. The simulation results show that under various operating conditions of VRV air conditioning system. The designed robust controller can overcome the influence of the uncertainty of the model parameters on the operation performance. The simulation curve is stable and there is no fluctuation, and the air conditioning operation is safe and reliable.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB657.2;TP273

【参考文献】