2016 ASHRAE Annual Conference

The management of electricity grids requires the supply and demand of electricity to be in balance at any point in time. Electricity suppliers tend to minimize their procurement costs by offering consumers time-of-use variable electricity tariffs as an incentive to shift their demand from peak to off-peak hours. Typical new residential buildings are considered, equipped with air-to-water heat pumps that supply either radiators or floor heating system. The energy market is represented through time-varying electricity price profile. Different heating control strategies are compared in terms of thermal comfort, energy use, cost and flexibility, ranging from rule-based to predictive optimized control.

Stable operation of electric power systems requires power supply and demand to be matched on multiple time scales. For short time intervals of seconds to minutes, balance is generally achieved by actively controlling grid resources based on frequency deviations – hence the term frequency regulation. This presentation explores the practicality of using HVAC chillers as a demand side resource to provide frequency regulation ancillary service. Experiments were conducted on two commercial buildings in Boston. Results are discussed in the context of PJM Interconnection’s performance requirements and market structure.

In the context of day-ahead electricity prices, the method of Economic Model Predictive Control (EMPC) has been shown to provide expenditure reduction in building HVAC systems with thermal energy storage. However, these reductions can only be achieved if the EMPC prediction horizon is sufficiently large. This work develops an alternate controller, constrained economic linear optimal control (CELOC), and shows that CELOC will yield performance similar to large-horizon EMPC but with a virtual insensitivity to horizon size. Thus, application of CELOC will require a fraction of the computational effort while yielding nearly identical economic performance.