Aggregate Flexibility of Thermostatically Controlled Loads

TLDR

It is widely accepted that thermostatically controlled loads (TCLs) can be used to provide regulation reserve to the grid. The study proposes modeling TCL aggregate flexibility as a stochastic battery with dissipation and aims to control aggregate power deviation to track an automatic generation control signal. The authors characterize the battery’s power limits and energy capacity using TCL parameters and random variables, and implement a priority‑stack control framework to select TCLs for regulation service provision. Simulation studies suggest the practical promise of our methods.

Abstract

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.