Aggregate Flexibility of Thermostatically Controlled Loads

• Published in: IEEE transactions on power systems Vol. 30; no. 1; pp. 189 - 198
• Main Authors: He Hao, Sanandaji, Borhan M., Poolla, Kameshwar, Vincent, Tyrone L.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aggregates; Batteries; Control; Control systems; Coordinated aggregation; demand response; Deviation; Electric batteries; Flexibility; Frequency control; frequency regulation; generalized battery model; load flexibility; Load modeling; Mathematical model; Mathematical models; Reserves; smart grid; Sociology; Statistics; thermostatically controlled loads
• ISSN: 0885-8950; 1558-0679
• DOI: 10.1109/TPWRS.2014.2328865

It is widely accepted that thermostatically controlled loads (TCLs) can be used to provide regulation reserve to the grid. We first argue that the aggregate flexibility offered by a collection of TCLs can be succinctly modeled as a stochastic battery with dissipation. We next characterize the power limits and energy capacity of this battery model in terms of TCL parameters and random exogenous variables such as ambient temperature and user-specified set-points. We then describe a direct load control architecture for regulation service provision. Here, we use a priority-stack-based control framework to select which TCLs to control at any time. The control objective is for the aggregate power deviation from baseline to track an automatic generation control signal supplied by the system operator. Simulation studies suggest the practical promise of our methods.