Collaborative optimization scheduling strategy for HVAC with a three-layer optimization architecture

Abstract

Heating, ventilation, and air conditioning (HVAC) systems with different terminal devices can achieve the synergistic effects of multiple heat exchange methods. However, ineffective scheduling strategies for terminal modes during operation hinder cooling (or heating) performance and energy efficiency improvements. Multi-terminal system optimization has the characteristics of multi-variable and multi-objective challenge, which involves a complex coupling problem consisting of condition selection among different decision variables and interference of the same variable to different targets. Single-layer models struggle with coupling interference, while two-layer models only partially address coupling issues. A three-layer optimization architecture is proposed to decouple terminal mode selection from continuous parameter optimization, enhancing scheduling strategies for multi-terminal cooperative operation. And convection-radiation combined cooling system for air-cooled chiller is used as an example to validate the impact of the three-layer optimization architecture on thermal comfort and energy efficiency. The architecture optimizes terminal modes, chilled water flow rates, supply water temperatures, and air supply flow rates for each time period, while minimizing the influence of variable coupling. Additionally, four scheduling strategies are selected for experimental comparison, analyzing the variations in indoor temperature and power consumption to calculate the energy cost and thermal comfort cost for each strategy. The results show that, compared to the other four strategies, the scheduling strategy based on the three-layer optimization architecture can reduce energy costs by 1 % to 45 % and thermal comfort costs by 70 % to 94 %. This architecture enhances the performance of different terminal devices in a coordinated operation process within the HVAC system.