Quadratic Optimization In Delay Systems In The Air Conditioning Temperature And Humidity

As the widespread use of central air-conditioning (CAC), the issue of high energy consumption in CAC is increasingly outstanding. How to realize effective control and reduce energy consumption has become an important research subject. From the aspect of control, the control quality of CAC system directly impacts efficient, stabilization and energy saving in operating and it could have the influences on products quality or enterprise benefit. At the same time, in order to approach the demanding of control accuracy, the phenomenon that surface air cooler, heater and humidifier run simultaneously often appears in the real system, which cause tremendous waste of energy. In order to save the energy and ensure the control quality of CAC, optimal control is adapted. However, due to the couple of temperature and humidity, the existence of large time delay and inertia, optimal control is hard to realize. Because of large time delay of CAC system, PID control that is widely used in industrial production becomes powerlessness. In order to solve this problem, combining decoupling with optimal control theory, a feed forward compensator and ITAE twice optimal control which has good performance in time delay control are used.Under the specific constant air volume CAC for pharmaceutical factory background, the system transfer function matrix model was established by the theoretical analysis and the parameters of it were determined by analysis of experiment. Because the system runs normally in single-loop, while the system shows bad control quality in multi-loop. Using decouple design in multi-variable system is an effective way to maintain long, safe and effective operation and to adapt mature technique and experience of single-variable system. By introducing absolute humidity as an intermediate variable to control relative humidity, the coupling channel between heater and room relative humidity was decoupled; and a feed forward compensator was designed to decouple the channel coupling between cooler and room temperature. Twice optimum approach is presented after decoupling and parameters are calculated by Matlab simulating to realize the system optimal control. The simulating result of Matlab shows that this approach has a better performance than traditional PID control. At last, an electric circuit and software programming were designed for pharmaceutical factory. Electric circuit includes choosing sensing units, slave computers (PLCs), communication cables and host computer (PC) and designing the connection for them. And control programming of slave and HMI design of host is main tasks of software programming.