Efficient Operation of Air-Side Economizer Using Extremum Seeking Control

摘要

As the heating, ventilating, and air conditioning (HVAC) systems accounts for a majornsector of energy consumption for commercial buildings, there has been a greater demandnfor improving the efficiency of such systems. The air-side economizers have been developednas a class of energy-saving HVAC devices that may increase the energy efficiency byntaking advantage of outdoor air during cool or cold weather. However, many economizersndo not operate in the expected manner and waste even more energy than beforeninstallation, mostly due to the unreliable sensors and actuators in practice. Better controlnstrategy is needed for optimal and robust operation. In this paper, an extremum-seekingncontrol (ESC) based self-optimizing strategy is proposed to minimize the energy consumption,nwith the feedback of chilled water supply command rather than the temperaturenand humidity measurements. The mechanical cooling load is minimized by seekingnthe optimal outdoor air damper opening in real time. Such scheme does not need temperaturenand humidity sensors, and depends much less on the knowledge of the economizernmodel. Simulation was performed on a MODELICA based transient model of a singleductnair-handling unit developed with DYMOLA and AIRCONDITIONING LIBRARY. Thensimulation results demonstrated the potential of using ESC to achieve the minimal mechanicalncooling load in a self-optimizing manner. In addition, an antiwindup ESCnscheme is proposed to handle the ESC windup issue due to actuator (damper) saturation.nThe simulation results validated the effectiveness of the proposed antiwindupnESC.