Aggregate Flexibility of Thermostatically Controlled Loads

Abstract

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.

Leaky storage model for optimal multi‐service allocation of thermostatic loads

“…[3]. The dynamic equation of the generalised battery model is equivalent to the dynamic equation of the leaky storage model proposed in this work, but the associated power constraints are substantially different, as is the underlying control strategy.…”

“…periodically switches between two states: passive cooling/heating (no power consumed) and active heating/cooling (power consumption " #$ % ). This system is typically modelled by a first order temperature model ( [3], [4], [11], [13]), giving rise to the following ODE for the evolution of the appliance temperature with a variable cooling rate. Note that the temperature distribution of a population of identical but independent appliances may also be interpreted as a probability distribution for the temperature of a single appliance with unknown initial conditions [4,8].…”

Rolling horizon optimization for real-time operation of thermostatically controlled load aggregator

“…In this paper, the widely adopted R-C model is used for modelling the thermal transition of buildings with TCLs, which have been proved to be capable for capturing the main thermal dynamics of the buildings [3,4]. The R-C model includes two parameters: thermal resistance (R) and thermal capacitance (C).…”

“…When aggregating a large number of TCLs, it would be technically intractable to dispatch the TCLs individually. A feasible approach is to group the TCLs properly, and dispatch the TCLs on a group basis [4]. In this paper, we first assume that all the occupants are within a moderate activity environment and, consequently, set the value of M equal to 1.2.…”

“…Extensive effort has been devoted to date at studying the direct control techniques of thermostatically controlled loads (TCLs). For example, [3] outlined the fundamental requirements of direct load control (DLC) and presented a general optimization framework to do the feeder-scale load reduction, while [4] designed a priority based control scheme for TCLs to participate in grid frequency regulation. Reference [5] proposed a two-stage dispatch method for TCLs where, in a first stage, a day-ahead scheduling model is solved to determine the optimal TCL dispatch CrossCheck date: 26 July 2017 and, in a second stage, a real time control model allocates the desired setpoints to individual TCL.…”