Development and Evaluation of a Rule-Based Control Strategy for Ice Storage Systems

• Published in: ASHRAE transactions Vol. 103; p. 344
• Main Authors: Drees, Kirk H, Braun, James E
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Atlanta American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc 1997; American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA (United States)
• Subjects: BUILDINGS; COLD STORAGE; COMPUTERIZED CONTROL SYSTEMS; Control systems; Cooling systems; Cost function; Costs; Dynamic programming; ENERGY ACCOUNTING; ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Microprocessors; OPTIMAL CONTROL; Performance evaluation; Storage systems; Storage tanks; THERMAL ENERGY STORAGE EQUIPMENT; Trajectory control; Trajectory optimization
• ISSN: 0001-2505

This paper describes the development and evaluation of a near-optimal control strategy for ice storage systems. The strategy is based upon simple heuristics that were developed from daily and monthly simulations of cooling systems with internal melt, areaconstrained ice storage tanks. Dynamic programming was used to obtain the optimal control trajectories which minimized an integrated energy and demand cost function for both the daily and monthly simulations. In addition to leading to simple heuristics, the monthly optimal control results were used as benchmarks to evaluate the performance of both conventional and the new control strategy. For a range of partial-storage systems, load profiles, and utility rate structures, the monthly electrical costs for the rulebased control strategy were, on average, within about 3% of the optimal costs. In contrast, the monthly electrical costs associated with the most common conventional control strategy, chiller-priority control, were as much as 20% greater than optimal, whereas a simple storage-priority strategy yielded costs that were within about 6% of optimal The rule-based strategy can be easily implemented within a small micro-processor controller and only requires measurements of the system cooling requirement, building electrical usage, and state-of-charge of storage.