Ancillary Services Through Demand Scheduling and Control of Commercial Buildings

Prior work showed building Heating, Ventilation, Air Conditioning (HVAC) systems can provide ancillary services to the power grid without sacrificing occupant comfort if the reference power variation is of high frequency (seconds to a few minutes). This paper addresses the question of how to do that when the reference power variation is of lower frequency, e.g., periods of a few minutes to an hour. The proposed control system to do so uses a two-layer architecture. An optimizer schedules the baseline cooling and heating power of a building based on load forecasts. A lower level controller is then used to track the scheduled baseline plus ancillary service reference signal. The schedule is periodically updated based on indoor measurements to ensure quality of service in spite of load forecasting error. The algorithm is tested in simulation. Results show that ancillary services in the frequency range of f is an element of [1/(1 hour), 1/(10 minutes)] can be extracted from commercial building HVAC systems while still maintaining a comfortable indoor climate.