The Research And Application Of Fuzzy Control In HVAC And Room System

With the rapid development of social economy, HVAC (heating, ventilating, and air-conditioning) system has been applied to every aspects of buildings. However, HVAC system is a typical complex multivariable nonlinear time-varying system which is difficult to model. Meanwhile, most of the domestic HVAC systems used to work with power frequency which may cause serious energy wasting. Thus, the research of advanced control strategies of HVAC system which is helpful for energy saving is of great importance. According to the HVAC system characteristics, this paper designs a intelligent fuzzy control strategy to realize efficient and energy saving control.The main contents of the paper are as follows:Firstly, according to the requirement of experiment validation, a HVAC SCADA system is developed in this paper, which includes system design, equipment order, hardware and software implementation. All HVAC motors (fans, pumps and compressors) are equipped with variable speed drives (VSD) so that the designed HVAC system is quite advanced and can be used to verify the advanced control strategy. Meanwhile, MATLAB and configuration software based SCADA system is proposed in this paper, which takes the advantages of MATLAB in writing advanced control strategy.Secondly, an adaptive fuzzy control strategy is designed in HVAC control loops, including supply cooling water temperature, supply and return cooling water temperature, supply chilled water temperature, supply and return chilled water temperature, supply air static pressure of AHU (air handling unit), the simulation and practical results shows that the control strategy not only fulfills the variable frequency control of chilled water pump, cooled water pump, compressor, cooling tower fan, AHU fan, but also has a good energy saving effect.Thirdly, the room temperature model of HVAC system is developed and identified. With the identified model, a simulation study is conducted which shows that fuzzy PID control strategy is better than the PID control strategy and adaptive fuzzy control strategy in room temperature control loop. Then several real process tests are successfully developed by using PID control strategy, adaptive fuzzy control and fuzzy PID control strategy. The practical results show that fuzzy PID control strategy can achieve zero overshoot and shows shortest settling time.