Co-Simulation of a load-shifting system with cold thermal storage in a campus environment
The increasing trend of climate change and its global effects has prompted a call for sustainable energy solutions and decarbonization efforts to protect our planet. Heat source systems, such as compression chillers, significantly contribute to the energy consumption of buildings. In this context, digital twin-based energy management has potential for enhancing efficiency through real-time monitoring and operational optimization. This paper presents part of an ongoing project at Waseda University "Development and Standardization of Fundamental Technologies for Thermal Energy Management Systems" (FUTTEMS), which aims to digitize heat management from various heat utilization systems to improve energy utilization, enhance system performance, and reduce carbon emissions. To accurately represent the physical system, reliable models of system components and appropriate simulation tools are required. In this study, we introduce a co-simulation framework for a cooling system that includes a turbo chiller, and a cold thermal energy storage unit. The chiller and thermal storage components are modeled in Dymola using the Modelica language, while the building cooling load is simulated using EnergyPlus. Data exchange and synchronization between the two platforms was facilitated by the Building Controls Virtual Test Bed (BCVTB). The integrated system functions as a loadshifting mechanism within the central air conditioning system in the Waseda campus. Additionally, this loadshifting model represents an initial step toward developing a comprehensive energy management system (EMS) for the entire central air conditioning plant using digital twin technology. It is expected to enable a realistic evaluation of system performance under dynamic building demand and subsequently open up to optimal operation as an integrated part of the building. The models for the chiller and storage for load-shifting have been developed and tested using performance data from the installed chiller plant.