Robust scheduling of multi-chiller system with chilled-water storage under hourly electricity pricing

Multi-chiller systems with thermal storage units are widely used to supply the cooling load of residential and commercial buildings. Due to the significant energy consumption, economic dispatch has been a crucial issue in multi-chiller systems. This paper presents a robust optimization approach for the day-ahead scheduling of a multi-chiller system with a chilled-water storage unit. The objective function aims to minimize the overall electricity cost of the system under hourly electricity prices, considering the uncertainty associated with the cooling load. Two case studies with different cooling load profiles are considered in evaluating the effect of the storage unit in increasing the robustness of total cost against the changes in the uncertain parameter. The multi-chiller system with the storage unit is modeled as non-linear programming solved with the General Algebraic Modeling System (GAMS), and the optimal partial load ratio of chillers and charge/discharge status of the storage unit are determined. In both case studies, the performance of the system with/without the storage unit is analyzed. The results demonstrate that the integration of the chilled-water storage unit increases the robustness of total cost against the variation of cooling load, as well as reducing the overall electricity cost.