Research On Variable-flow Feedforward Control And Energy-saving Effect In VAV Air-conditioning Chilled Water System

In recent years, China’s energy shortage that people pay more and more attention tobuilding energy efficiency, greatly promoted the development of the central airconditioning control technology. The key lies in the central air conditioning energysaving operation control technology and equipment choice, it directly affect the airconditioning system during the period of life after the completion of the long-termoperation of the economy and stability. Therefore, in the water system for use in theoperation of the advanced control technology and equipment, improve water chillers,chilled water pump, cooling water pump, cooling tower fan and water systemequipment energy efficiency of the air conditioning system is the key. Because of the airconditioning load of the variety, and in part load, chilled water system often in the bigflow, small temperature difference state operation, causing the waste of energyconsumption of frozen water pump delivery. Using modern frequency control of motorspeed technology, can make the pump characteristic curve and chilled water system inany flow of to match demand, make the working point and adapt to changing flow, so asto save energy. Therefore, according to the load change dynamic regulation frozen waterflow variable flow system for air conditioning energy conservation has very importantmeaning.The central air conditioning chilled water system is a time delay, time varying,large time-delay, nonlinear, multivariable and strong coupling between the complexsystem, aiming at the chilled water system of air supply temperature control loop andsupply and return water temperature difference control loop of the existing interference and big delay, put forward respectively feedforward control and PID control, Smithcontrol and IMC control combination of control strategy, through the simulation it isconcluded that the feedforward control and Smith control combination of controlperformance is better than the former two, and analyzes its in the central airconditioning variable flow water system of feasibility. Finally, will write good controlprogram loading in the variable air volume air conditioning system, and to realize theoperation for water system variable flow control, and from the results of control andtraditional control energy consumption comparison shows that supply air temperatureand supply and return water temperature difference using feedforward control andSmith control has better control performance and energy saving effect, for intelligentcontrol in the application of the central air conditioning system provides an importantreference significance.